Assessment Model for the Social Impact of Decommissioning Subsea Oil and Gas Systems

Abstract

The article aims to propose a social impact assessment model that can help operators in the oil and gas exploration and production sector to evaluate the social impacts in the onshore and offshore dimensions of the decommissioning of subsea oil and gas production systems. Based on the technical characteristics of the operation, the literature review and the workshops held with interested parties, the conceptual model was developed. The model includes 2 dimensions: (i) onshore, which encompasses impacts on logistics and infrastructure and onshore employability, and (ii) offshore, which involves external context, restrictions on artisanal fishing, restrictions on tourist activities and offshore employability. The impacts in both dimensions result from the operationalization of decommissioning. The contribution of this study is to propose a social impact assessment model that takes into account the onshore and offshore dimensions of the offshore-based decommissioning process of submarine systems and to propose future research. The proposed model can support decision-making by companies and governments in the process of decommissioning submarine systems and can also help other types of offshore installations.

1. Introduction

As a concept of concern and study, the social issue emerged in the 19th century in light of terrible working and housing conditions. Since then, the social issue is no longer a debate only about working conditions but involves other topics such as unemployment, education, health, transport, housing, basic sanitation, security, leisure, culture, and food security, as well as discussions about class inequality, gender, race/ethnicity, income, and/or socioeconomic status, among other topics that affect the general well-being of a given population.

In this way, the social issue does not have a single dimension as initially assumed; it acquires a multidimensional amplitude to the extent that the systemic effects produced by the economic issue are not only dimensionable within the scope of the production process. Through a systemic analysis, we can perceive the side effects of the emphasis on the economic issue outweighing the social issue, both from a positive and negative point of view, as well as throughout the entire production chain, from the extraction of raw materials through production, marketing, consumption, dismantling, until reaching the final destination. Decommissioning is an activity referring to the end of the life cycle of projects or activities in different sectors, such as a nuclear plant (Sudholt, 2013; Suh et al., 2018) [1,2], a mine complex (Amirshenava and Osanloo, 2018) [3], a solar energy generation plant (Guédez et al., 2015) [4], or decommissioning of oil and gas processes (Fowler et al. 2014; Kruse et al. 2015; Herion et al. 2015; Cripps and Aabel 2002; Ekins et al. 2006; Martins et al. 2020) [5,6,7,8,9,10].

The development of the first offshore oil and gas facilities dates back to 1897 (Bradley, 1987) [11]. There are approximately 7500 offshore oil and gas platforms and facilities, which include floating production, storage, and offloading (FPSO) vessels and sub-sea platforms and facilities (ICF, 2015) [12], located mainly in the North Sea, Gulf of Mexico, and areas offshore near California and Southeast Asia (Eduardo et al., 2008) [13]. Approximately 85% of these facilities need to be deactivated in the coming decades (Fowler, 2014) [5] in compliance with international and regional conventions, where the majority of them need to be removed completely to be dismantled and recycled (Li & Hu, 2021) [14].

For decommissioning projects with an emphasis on offshore sub-sea systems and equipment, the delimitation of the system boundary is to be considered at the end of the life cycle from a social point of view, i.e., the processes, activities, and flows of inputs and outputs involved since the withdrawal of waste from the seabed, until its final disposal, relates to activities carried out at sea (offshore) as well as on land (onshore).

Offshore activities refer to the movement of vessels involved, directly and indirectly, in the removal of waste to be decommissioned, and onshore activities refer to those involved in port operations and logistics related to the destination of pipelines and equipment.

Implementing decommissioning programs involves an extensive chain of activities, with high costs and complexity due to the involvement of various stakeholders, such as operators, supply chain suppliers, government organizations, NGOs and other users of the sea (Users of the sea are those who use the ocean for various purposes, such as maritime commerce, fishing, passenger transportation, tourism, leisure activities, and exploitation of mineral and energy resources, among others). These impact various affected dimensions, such as environmental, health and safety, social, economic, and technical, among others (Oil & Gas UK, 2015; Henrion, 2015; Ahiaga-Dagbui et al., 2017; Martins et al., 2020) [7,10,15,16]. For example, the action of decommissioning a submarine system can have the positive consequence of creating jobs in the territory. The road transport of extracted pipelines and equipment could negatively impact certain locations through an increase in traffic within municipalities directly involved, the pollution generated, damage to roads due to the use of heavy vehicles, and even the possibility of damaging houses with more fragile infrastructures.

Planning and managing decommissioning projects comprise a collective effort that involves several stakeholders. The big challenge is obtaining records of platforms that were built decades ago (Na et al., 2017) [17] and potentially conflicting objectives between thm, related to the breakdown of socioeconomic and environmental impacts generated from technological decommissioning alternatives (Martins et al., 2020) [10].

In April 2020, the National Petroleum Agency (ANP), the Brazilian regulatory body for oil and gas O&G, published the decommissioning regulation, ANP Resolution N^o. 817/2020. Besides updating and simplifying legal requirements, the technical regulation for decommissioning exploration and production facilities showed clearer standards and information necessary for decision-making.

Although the term “social” appears only three times in the text, it is in the sole paragraph of Article 5 that its importance in that document becomes clear. In this section, the ANP states that the operator “must have a social awareness and sustainability management system in place that adheres to the best practices of the oil industry, observing the contract and, where relevant, follow the guidelines to achieve the 17 Objectives of Sustainable Development (SDG) of the United Nations” (ANP, 2020) [18].

By citing the need to require the operator to have a social awareness management system, the ANP clarifies that projects cannot focus on impacts in a specific manner. A management system includes actions at all levels, strategic, tactical and operational, besides the participation of professionals from all areas of the operator who work directly and indirectly, interacting with different audiences. Therefore, besides the technical area, other areas, such as social responsibility, licensing, and legal and commercial risks, to name a few, must also be included.

It is important to highlight that Brazil was the first country to launch a certifiable standard on the subject by the Brazilian Association of Technical Standards (ABNT) in 2004, the ABNT 16001 [19]. The version revised in 2012 that is commonly used in the country follows the guidelines of the international social responsibility standard, ISO 26000:2010 (ABNT, 2010) [20]. It is worth highlighting that the alignment with the 17 SDGs also makes clear the regulatory agency’s concern with integrating the various decommissioning projects with public policies related to the country’s sustainable development.

The action of decommissioning is a process at the end of the economic and productive life of the asset, a decision on the best way to close the wells, clean, make the facilities safe, remove some or all of the facilities and reuse or discard them, as right to the closing of operations at the end of a field’s life.

According to Fowler et al. (2014) [5], decommissioning decisions involve a wide range of considerations, including potential environmental impacts, financial costs to the industry, socioeconomic impacts and health and safety issues. Various stakeholder groups may also have additional considerations that are specific to their interests. These considerations are important to ensure equality and avoid conflicts during decision-making. In this paper, modeling social impact categories and the proposition of a system of indicators will be the priority object of the intended description.

Thus, the analysis of the social context (jobs created and/or maintained, logistical and urban infrastructure, activities carried out at sea, among others) of each submarine system (pipelines and equipment) to be decommissioned is the basis for assessing social impacts generated by this process, mainly regarding the affected territories, since the people living in these territories are the most susceptible to suffering direct impacts from decommissioning actions.

Decommissioning is carried out safely when the options to be considered appropriate take into account social and environmental impacts and their geographic variations (Gourvenec, 2022) [21]. There are three themes related to the social values of offshore structures and social well-being related to material and immaterial resources; the interests of different stakeholder groups regarding the degree of support for decommissioning projects; and the resources and assets of these projects. (Elrick-Barr et. Al, 2022) [22].

The social impacts of decommissioning activities are assessed using social indicators. These indicators can be subjective or objective, quantitative or qualitative, and are linked to a specific set of values. They carry social significance due to their contextual dependence (UNEP-SETAC, 2009; Franks, 2011) [23,24].

Therefore, the proposition of impact categories comes after a system of indicators capable of evaluating the social impacts caused by any of the various decommissioning alternatives; it must have in its structure effective dialogical approaches that ensure the participation of society and territories correlated to the operations relating to the modeled system.

The assessment of social impacts is of great value for the management and prevention of technical and non-technical risks, especially in the extractive industry, as they point out the following benefits generated from the management of social impacts (Prenzel and Vanclay, 2014; BSR, 2011 and Esteves et al., 2012) [25,26,27]:

• Possibility of building a positive legacy through obtaining a competitive advantage;
• Opening dialogue with internal and external social actors;
• Prevention and reduction of social and environmental risks and conflicts between the community and the company;
• Prevention and reduction of project interruptions due to non-technical risks;
• Early identification of problems in a predictive way, generating an improvement in cost planning for their resolution.

The removal or retention of offshore structures does not have much support from society until there are more studies and empirical evidence available to justify decommissioning projects for marine artificial structures and must be decided on a case-by-case basis, taking into account the balance between costs and benefits at hand in a local level. (Knights et al., 2024) [28].

When assessing impacts, it is necessary to consider some aspects, such as the need for stakeholder involvement in the initial stages of identifying impacts associated with processes, understanding the impossibility of predicting all impacts because of the dynamic nature of territories and society, the need for experience by those responsible for assessing impacts, the search for meeting the expectations of interested parties, as well as their inclusion in the participatory and decision-making process (Esteves et al., 2012, Burdge and Vanclay, 2012, Silva, 2017) [27,29,30].

According to Fowler et al. (2014) [5], direct stakeholder participation is increasingly being used in socio-environmental decisions because it leads to a more holistic understanding of the problem requiring a decision; decisions are more likely to be optimized for multiple conflicting objectives and promote trust and acceptance of final decisions.

Stakeholders such as public authorities, the local community, workers, economic agents, and organized civil society also influence decommissioning activities based on interactions. In short, just as companies depend on the way society works, companies impact the functioning of society (Goedkoop et al., 2018) [31]. In this sense, the possibilities generated from the social impact assessment process are (Burdge and Vanclay (2012) [29]:

• Manage changes based on understanding the social context;
• Predict the potential social impacts of project implementation;
• Minimize social impacts through the planning, development and implementation of strategic mitigation plans;
• Develop mechanisms for monitoring unforeseen social impacts as a result of social change;
• Assess the social impacts arising from previous developments.

In this sense, social indicators are fundamental as they provide important information that allows evaluation of the status of achieving the intended objectives, provide fundamental data concerning the planning of future actions, and become more relevant in academia and the business world. They also promote greater transparency in the actions of economic agents (Huebíček et al., 2015) [32]. This occurs because stakeholders know the entire process, as organizations disclose their practices and the impacts of their actions related to sustainability (Calabrese et al., 2016; Bellantuono et al., 2016) [33,34].

When choosing a set of indicators that can represent the impacts generated, as well as their social significance in relation to the context of the decommissioning system to be analyzed, it becomes necessary to establish their level of materiality “from which the aspects become significant enough to be reported (GRI, 2015) [35].

Inserting sustainability considerations into the decommissioning process will increase existing decommissioning litigation and the development of new ones, and the panorama of international regulations for the decommissioning of offshore installations generally adopts the premise of complete removal at the end of the life cycle. However, considerations about the immediate impacts of issues relating to sustainability are important for the discussion (Balogun et al., 2023) [36]. This means that the economic, operational and/or environmental issues should not only subordinate the analysis and planning of the object of study—decommissioning offshore oil and gas exploration systems—as is usually encouraged. The study of the decommissioning of submarine oil exploration systems involves implementing a type of analysis not oriented exclusively to the determinants of economic and/or environmental issues but also social scenarios appropriate to activities in the territories influenced by decommissioning. Decommissioning the offshore oil and gas sector is crucial and highly complex, as variables such as costs, health and safety, and environmental consequences are at stake (Shams et al., 2023) [37].

Dubois-Iorgulescu et al. (2016) [38] presented two conceptual views of the system that normally coexist: a technical approach based on the definition of technical processes according to the stages of the life cycle and a socioeconomic approach that selects organizations as units of the system. Four groups set the criteria used here to delimit the system boundary: (1) social significance, these are qualitative criteria, which have a social meaning in terms of impact generated by the process, and which should only to be out from the system when they are not there is a change in the result; (2) empirical limitations, the cutoff criteria are justified based on the availability of data over time; (3) identical elements, are identical technical processes in the same region or organization that can be cut; and (4) significant and decision relevance, concerns the influence of the central company in a value chain.

The objective of this article is to support oil exploration and production operators in their assessments of social impacts related to logistics and infrastructure and employability in the onshore dimension, and in terms of the external context, restrictions on artisanal fishing activities, tourist activities, employability in the offshore dimension, involved in the decommissioning of submarine systems. To this end, life cycle thinking was used so that they can expect risks and impacts and intervene in a planned way in the solution or prediction of social situations that cause negative or positive impacts arising from the decommissioning of underwater systems for offshore oil exploration.

The remainder of this paper is organized as follows. Section 2 briefly reviews the analysis of the main social impact categories relating to decommissioning submarine systems. Section 3 introduces the methodological structure used in the construction of the social impact assessment model. Section 4 presents the proposed evaluation model. Section 5 presents the discussion about the model. Section 6 concludes the paper.

2. Literature Review

In this section, we present technological alternatives used in the decommissioning process of sub-sea facilities, and, based on the literature review, the categories of social impacts used to understand the impacts generated by the decommissioning process were identified.

2.1. Decommissioning of Offshore Oil and Gas Facilities

Before starting the procedure to understand the impact categories and indicators to be used to create the social impact assessment model for decommissioning submarine systems, it is necessary to understand the decommissioning procedure. The engineering process involved in decommissioning relates to the end of the facilities’ life cycles and the domain of reverse logistics (Fam et al., 2018) [39]. However, changes are necessary to adapt decision-making relating to technological alternatives and environmental, safety, regulatory and social aspects (Fowler, 2014; Schroeder and Love, 2004) [5,40].

The process of decommissioning offshore oil and gas installations has three stages: pre-decommissioning, execution of decommissioning, and post-decommissioning (Icf, 2015; Fam et al., 2018; Lyons, 2013; Parente et al., 2006; Li and Hu, 2021) [12,14,39,41,42].

The objective of pre-decommissioning is to build plans and make decisions that will support the implementation of projects, raise legal requirements, obtain government licenses, and prepare materials and documentation (Osmundsen and Tveterås, 2003) [43]. Generally, this stage takes around two to three years (Fam et al., 2018) [39]; stakeholders such as certification organizations, engineering companies and consultants join during this period to provide services that will support the decision-making system.

This stage has activities such as division of responsibility, collection of platform engineering information, cost, material inventory, risk and environmental impact assessment, evaluation of decision-making in relation to decommissioning alternatives, engineering simulation, resource mobilization, and acquisition of government licenses (Li & Hu, 2021) [14]. At this stage, academia contributes significantly through the construction of impact assessment models (Kaiser and Narra, 2018; Elliot et al., 2017) [44,45] and support for decision-making (Kaiser and Narra, 2018; Bressler and Bernstein, 2015; Bernstein, 2015, Martins, 2020) [44,46,47,48]. However, there are currently few assessment tools that transversally meet the multi-criteria necessary for decommissioning projects of offshore oil and gas installations (Li and Hu, 2021) [14].

The focus of the decommissioning execution stage is the implementation of the previously established plan. The activities to be carried out are directly related to the type of platform and submarine systems. Platforms are often removed entirely due to international or regional conventions. The most complex element is related to submarine systems due to decisions that involve costs, environmental impacts, and operational risks.

In the execution phase, the contribution of engineering design and academic research is focused on risk management, protection of the marine environment, and construction efficiency (Li and Hu, 2021) [14]. There are also specific contributions such as hydrocarbon leak prevention and control systems (Bakke et al., 2013) [49], the development of new equipment (Cavallo et al., 2004) [50], dynamic risk control that integrates climate, engineering and other factors (Babalye et al., 2018) [51], and multi-criteria decision analyses (Moraes et al., 2022) [52].

After the decommissioning execution stage, post-decommissioning aims to carry out activities related to the demobilization of teams, provision of completion reports, and monitoring the marine environment. These activities carry little value in the oil industry due to the need for third-party validation (Li and Hu, 2021) [14].

The management stage encompasses the three stages of decommissioning offshore oil and gas installations. It follows the logic of the five processes of a project’s life cycle: initiation, planning, control and monitoring, execution, and closure. This stage is of strategic importance in conducting decommissioning projects and involves activities related to waste management, reuse of materials, standards related to health and safety, equipment maintenance, provision of supplies, team transfer and public relations (Li and Hu, 2021) [14].

It is important to understand the process of each of the alternatives that objectively impact the identified audiences (stakeholders) to define the impact categories. Figure 1 presents the decommissioning options for sub-sea facilities (Li and Hu, 2021) [14].

The scope of the article is the decommissioning of sub-sea oil and gas facilities; however, there is literature associated with offshore platforms. For decommissioning sub-sea facilities, there are three options: leave in place, partially remove, or fully remove [14]. In the alternative related to remaining on site, the equipment stays at the seabed during decommissioning and only receives minimal interventions, such as a disconnection between different equipment that will have different destinations. Among decommissioning measures, leaving in situ has the lowest environmental impact (Shams et al., 2023) [37]. There is also the option of reusing some equipment in other fields; however, it is necessary to investigate the integrity conditions of the materials involved. For the reuse of structures to be decommissioned, potential negative impacts must be considered, including contaminants released into the marine environment, infringements on other marine users, and issues related to the ongoing maintenance and integrity of the reused infrastructure (Nicolette et al., 2023) [53].

Total or partial removal refers to the lifting of pipelines and equipment present on the sea bed to the deck of a service vessel. Some of this equipment has parts of its structure that can be partially removed, which would make up partial removal. In partial removal, the elements that remain on the sea-bed may be covered by sediments; in this case, the recommendation is to remain in situ, and for the elements exposed, there are three alternatives: entrenching and burying, covering with rock or cutting and lifting.

Due to rock deposition, the equipment that remains on the sea bed is covered by rock gravel in order to ensure that in the years following decommissioning, the natural degradation of these structures does not cause the detachment of parts that environmental loads could move and cause danger to navigation and/or marine fauna. The same applies to the entrenchment alternative, where instead of receiving a rock cover, the equipment is buried in the sea bed. In both alternatives, ships and specialized equipment carry out activities to minimize environmental impacts.

The cutting and lifting alternative involves dividing this equipment into smaller parts on the sea bed. After division using underwater cutting processes, the smaller, easier-to-handle parts are removed to be useful again, recycled, or scrapped.

A comparative study of four decommissioning options was carried out to determine the best decommissioning option for a specific offshore O&G platform, and the results indicated that the use of vessels in the decommissioning process is the largest contributor to environmental impacts and costs (Janjua and Khan, 2023) [54]. Based on publicly released accounting data from public and private oil and gas companies, it is estimated that the current value of liabilities related to oil and gas decommissioning in 2021 was between USD 311 and 362 billion, divided equally between onshore and offshore decommissioning (Kaiser, 2023) [55].

2.2. Social Impacts of Decommissioning Offshore Oil and Gas Sub-Sea Systems

We endorse an analysis of the social context more strategically, having as its basic line the concept that engagement with stakeholders has another meaning beyond identification and multilateral communication. To do so, it is necessary to know or research the categories of social impacts in that context. Reports and articles referring to the decommissioning process of offshore submarine systems with impact categories related to the social dimension were analyzed (

Table 1. Categories of social impacts from the literature review.

Reference	Categories of Social Impacts
Fowler et al. (2014) [5]	Access to recreational fishing/Effects on commercial fishing/Residual effects on navigation or other access/Impact on communities/Tax concessions/Employment opportunities/Economic stimulus/Cultural impacts/Public access/Public sentiment/Diving opportunities/bottom “cleaning” from the sea/Unobstructed view of the ocean
Kruse et al., (2015) [6]	Ecosystem values/Fishing with commercial value/Fishing with recreational value/Diving values
Henrion et al., (2015) [7]	Effects on commercial fishing/Residual effects on navigation or other access
Cripps And Aabel, (2002) [8]	Residual effects on navigation or other access/Changes in gear requirements/Gear damage
Ekins et al., (2006) [9]	Effects on Commercial Fishing/Jobs/Unobstructed Ocean View/Changes in Gear Requirements/Gear Damage
Martins et al., (2020) [10]	Effects on Commercial fishing/Employment/Communities
Li and Hu, (2021) [14]	Tax Concessions/Employment Opportunities/Economic Stimulus/Cultural Impacts/Public Access/Public Sentiment/Corporate Reputation/Legal and Regulatory/Access to Commercial Fishing/Recreational Fishing Opportunities/Diving Opportunities Clear Seabed/Unobstructed Ocean Views/Use of other shipping industry websites
Capobianco et al., (2021) [56]	Entrepreneurial investments/Job Creation/Social Well-Being/Business model innovation/Local economic impacts/Social Investments/Business ethic and corruption/Advocacy and lobbying
Melbourne-Thomas et al., (2021) [57]	Impact on fisheries/Ecosystem values/Impact on other marine sectors,
Moares et al., (2022) [52]	Effects on commercial fisheries/Employment/Communities
Vidal et al., (2022) [58]	Impact on communities/Users access to the ocean/Noise for population/Ship traffic at sea/Change in the sea route/Change in marine population/Impact on recreational diving/Tax Concessions/Employment Opportunity/Economic stimulus/Cultural impacts/Public access/Public sentiment/Impact on tourism/Maintaining commercial fishing/Recreational fishing possibilities/Diving opportunity/Clear seabed/Panoramic view of the ocean/Interest level of the bidders/
Khalidov et al., (2023) [59]	Impact on fisheries/Services/Communities
Pttep, (2015) [60]	Heritage/Indigenous Heritage/Heritage/non-indigenous heritage/Defense activities/Commercial fishing—community/Commercial fishing—State/Traditional and subsistence fishing/Recreational and tourism activities
Shell U.K., (2015) [61]	Effects on commercial fishing/Employment/Communities
Bg Group, (2016) [62]	Effects on commercial fishing/Employment/Communities
CNRI, (2013) [63]	Commercial impact on fishing/Socioeconomic impacts on Communities/Socioeconomic impacts on infrastructure
Ineos, (2018) [64]	Fishing and access to transport/Impacts on communities (onshore)/Local employment
Ithaca, (2018) [65]	Residual effect on fishing, navigation or other access (including cumulative)/Coastal Communities
Marathon Oil, (2017) [66]	The impact on other sea users, mainly the commercial fishing industry/Impact on surrounding onshore communities/Employment and regional development opportunities
Perenco, (2014) [60]	Fishing and transport access/Communities (onshore)
Repsol, (2018) [67]	Fishing/Aquaculture/Costs, jobs and provision of goods and services/Historical monuments/Transport
Spirit Energy, (2018) [68]	Effects on commercial activities/Communities or impact on amenities/Employment
Xodus, (2018) [69]	Fishing industry/Other groups
Dnv, (2018) [70]	Social impacts on land/Impacts on fishing/Impact on employment

).

To analyze the decommissioning phases of offshore submarine systems and their impact on land, information from the geographical and socio-cultural context, as well as site-specific data, must be used to identify true critical points and focus on the phases of the life cycle where greater control is possible (Jørgensen et al., 2011) [71].

Particular attention needs to be paid to data management, as issues of trust and transparency are currently greater barriers to data sharing than technological capabilities. Maintaining communication between stakeholders through workshops and working groups can build trust and develop working relationships that facilitate the development of data-sharing protocols and overcome identified barriers (Murray et al., 2018) [72]. Below, we describe some articles and reports that illustrate the dynamics of social impacts associated with decommissioning sub-sea oil and gas systems.

The article by Fowler et al. (2014) [5] recognized the existence of numerous offshore oil and gas facilities worldwide that are reaching the end of their life cycle and will need to be decommissioned in the coming decades. The complexity of this measure and the impossibility of achieving an ideal outcome in social, economic and environmental terms with all possible approaches are emphasized. A multi-criteria analysis method for evaluating and comparing decommissioning options is described, applying selection criteria in the environmental, social, economic, health, and safety fields. It also highlights the need to seek the views of experts and stakeholders to fill knowledge gaps on environmental impacts.

The report prepared by the Exploration and Production Public Company Limited (PTTEP) (Darwin, Australia) in 2015 describes the status and location of decommissioned infrastructure in the Jabiru and Challis fields, Australia. It does not present a decision-making methodology, only a description of the post-decommissioning scenario based on consideration of environmental, social and risk criteria. Government, industry and community representatives were consulted in the preparation of the report. Two social impact categories were not included in the presented model due to the greater convergence with economic factors; the excluded criteria were: “Oil exploration and production” and “Ports and commercial shipping”.

The article by Kruse et al. (2015) [6] pointed out that Southern California’s 27 oil and gas platforms reached the end of their useful life between 2010 and 2015. They mentioned that regardless of the type of decommissioning to be carried out (full or partial removal), the combination of environmental, social and economic factors associated with risks and opportunities makes the process complex due to the groups of stakeholders involved.

The work of Li and Hu (2021) [14] noted that many oil and gas facilities will reach the end of their life cycle, and the decommissioning of such facilities has become an urgent task due to high costs, major risks and issues related to the environment and public concern. A literature review is presented based on articles discussing multi-criteria decision models. As a result, two main problems of current decision-making models are highlighted: the lack of basic data and the incomplete application of the multi-criteria decision-making method.

Based on semi-structured interviews carried out with key informants and stakeholders from the Italian oil and gas sector, Capobianco et al. (2021) [56] carried out a Political, Economic, Social, Technological, Legal and Environmental (PESTLE) analysis to contribute to the creation of sustainable business models related to the decommissioning of offshore platforms, where social aspects related to jobs, economic impacts and aspects related to ethics and legislation were taken into consideration.

In the Australian context, for offshore decommissioning projects, complete removal of infrastructure is the regulatory standard; other options, such as partial or total removal, are considered. However, regardless of the option, environmental, social, economic and safety needs must be met to support risk and impact assessments, satisfy legislative requirements, and support offshore decommissioning decision-making (Melbourne-Thomas et al., 2021) [57].

Multi-criteria decision analysis (MCDA) and mathematical methods such as continuous-time Markov chains and regret functions can be utilized as new approaches to oil and gas decommissioning problems that seek to decommission and decommission offshore oil and gas facilities sustainably (Moraes et al., 2022) [52].

The literature review carried out by Vidal et al. (2022) [58] analyzed the decommissioning of oil and gas platforms and identified that the region where they are located and the type of platform are relevant factors for planning offshore oil and gas exploration, platform decommissioning and in other industries offshore. In this sense, the social aspects involved in offshore installation decommissioning projects must be analyzed on a case-by-case basis, respecting the socioeconomic characteristics of each region.

Multi-criteria decision analysis can be considered a very universal, reliable, and suitable model for choosing decommissioning options for oil and gas assets, must take into account qualitative and quantitative criteria, and can even be used in other types of offshore installations (Khalidov et al., 2023) [59].

The report by Shell U.K. (2017) [73] details the decommissioning process of the Brent field (North Sea), points out the social aspect as a criterion and three related sub-criteria, namely the impact on commercial fisheries, employment, and affected communities. This report considers the impacts on land and at sea. The impact assessment methodology takes into account the weighting of each criterion selected according to the decommissioning option recommended by the certification authority for the process.

Other reports unanimously note the impact on fisheries and communities (CNRI, 2013; Ineos, 2018; Ithaca, 2018; Repsol, 2017; Perenco & Tullow, Spirit Energy, 2018; Xodus, 2017) [60,61,62,64,65,67,68]. The impact on tourism activities was only reported by one company. The social assessment creates a cause–consequence effect in which the manager of the project or value chain process identifies critical issues and takes action to improve them.

This article focuses mainly on the review of models for the pre-decommissioning phase related to social assessment models based on decision models, theoretical frameworks, boundary conditions established in the relevant Brazilian laws and regulations, as well as the delimitation of the system boundary based on the life cycle approach.

The aim is to present the methodological guide developed to understand the variables related to the social impacts of sub-sea decommissioning projects, based on the categories of impacts and their respective indicators. By a social indicator, we mean “a generally quantitative measure endowed with substantial social meaning and used to replace, quantify, or operationalize an abstract social concept that is of theoretical (for academic research) or programmatic (for policy formulation) interest” (Giovanni and Nogueira, 2015) [74]. The model presented can be used in decision-making systems that exhibit some of the dimensions of sustainability.

3. Methodological Guideline for Modeling Social Impact Categories

The complexity inherent in modeling the social impact categories for decommissioning submarine systems requires listing some assumptions at the risk of them being ineffective and not informing the decision-making process.

• Onshore and offshore social impacts must be assessed;
• Socioeconomic aspects related to the development of the impacted territory were included;
• Need to evaluate regulatory documents specific to the decommissioning process;
• The internal public of oil and gas operators needs to be heard.

The impact assessment model developed seeks to interact based on the impact categories found in the literature, identifying stakeholders and the real perspective of interested parties based on preparing workshops explained below. The model combines theoretical and practical elements of the categories involved in decommissioning operations and the need to involve stakeholders through listening and collecting data/information (Shaw et al., 2018; Shell, 2017; CNRI, 2013) [61,63,75].

The methodological process for identifying impact categories goes through seven stages (Figure 2). The first one goes through a literature review in order to identify articles and company reports that consider the analysis of the assessment of social impacts in decommissioning projects for sub-sea oil and gas systems. A full description of this step is in Section 2 of this article.

The second step is the identification of stakeholders. We consider social actors to be any person, group or organization that can be positively or negatively affected by the actions of an organizational project and that, through this interaction, can influence the subsequent decision-making process. This stage aims to understand the perceptions of stakeholders. Such perceptions will contribute to the creation of impact categories for the decommissioning process, as well as provideopportunities for discussions and exchanges of opinions between stakeholders.

Social actors belonging to the government (regulatory agency, federal supervisory body, national defense, and auxiliary body of the legislative power), companies (dealers, operators, and suppliers) and organized civil society (NGOs, unions, and associations) were identified.

Since the decommissioning of a submarine system is a recent need in Brazil’s oil and gas sector, understanding stakeholders’ concerns regarding the possible impacts generated by such activity is essential for building the social impact category model. To carry out the workshops, an adaptation of the World Café method (Schieffer, 2004) [76] was used to collect information from participants.

Given the complexity of the decommissioning alternatives and the categories of impacts involved (environmental, economic, social, technical, and security), four workshops were held, with a total of 118 people attending representing 73 organizations, where one meeting was dedicated to the categories of social impact and occupational health and safety and was attended by 35 participants. It is important to highlight that in all workshops, the need to analyze social impact categories, which characterize the crossings of social impacts in all categories evaluated, was mentioned.

For the workshop regarding the social dimension, categories of potential impacts were identified. For the record, it is also interesting to present the potential impact categories relating to the social dimension raised in the other workshops (

Table 2. Social impact categories by workshop.

Stakeholder	Categories of Impact	Workshop
Academia	Project delays	Social
Health Agents	Increase in revenue
Suppliers	Contamination
Fishermen	Cost
Community people	Unemployment
Petrobras	Lack of knowledge
Public Power	Job Generation/Maintenance
Syndicate	Strike
Society	Loss of income
Workers	Loss of revenue
Fishing workers	Stricter regulations
Tourism workers	Training
Tourists
Fishermen		Technical
Community people	Judicial actions
Public Power
Fishing workers	Stricter regulations
Tourism workers	Loss of Revenue
Tourists
Academia	Project delays	Economic
Shareholders
Operator
Suppliers	Project delays	Environmental
Fishermen	Job creation/Maintenance
Petrobrás	Increased Revenue
Public Authority	Unemployment
Workers	Loss of Revenue
Fishing workers	Judicial actions
Tourism workers	Stricter regulations

). Steps 5, 6, and 7 of the model are presented in the case study.

Steps 5 and 6 are interactive and configure the initial set of potential impact categories. From the categories described in Step 4, it was identified that some do not have such objective dependency relationships in relation to social aspects or are categories that lack data, which makes their measurability impossible. Based on the exclusion and merger of some categories, the suggested analyses and redefinitions are the input data for Step 7, described below.

3.1. Categories of Impact

For this study, the end of the life cycle of submarine systems was defined—in this case, pipelines and submarine equipment used in oil and gas exploration in Brazil. The impacts generated in the offshore and onshore dimensions were considered. The analysis of the context containing data from each system to be decommissioned is of utmost importance for the assessment of the social impacts generated by this process, especially regarding the affected territory and some social actors, since this portion of society will be susceptible to the impacts directly from decommissioning actions.

The social criterion falls into six impact categories, four of which are offshore and two are onshore. They represent the most important social characteristics to be evaluated in the process of decommissioning submarine systems. Impact categories are the areas where the effects of social impacts are perceived, whether positive or negative. The proposed analysis integrates the following impact categories (

Table 3. Offshore and onshore categories of social impact.

External context	Offshore
Restriction on fishing activities
Restriction of tourism
Employability
Logistics and Infrastructure	Onshore
Employability

).

Four elements were chosen for the offshore impact categories: external context, restrictions on fishing activities, restrictions on tourist activities, and employability. Such choices were made based on the analysis of the results of the workshops, the analysis of activity flowcharts for technological alternatives used for the decommissioning of submarine systems, and technical reports from oil and gas operators operating in Brazilian territory. The definitions of each of the offshore impact categories are below (

Table 4. Offshore categories of impact.

Definition	Categories of Impact
It refers to the external environment in which the organization seeks to achieve its objectives. It may include: the cultural, social, political, legal, regulatory, financial, technological, economic, natural and competitive environment, whether international, national, regional or local; the key factors and trends that impact the organization’s objectives; relationships with external stakeholders and their perceptions and values. In this methodology, the degrees of influence/risk relating to society’s expectations were taken into account, especially municipalities directly impacted by decommissioning activities.	External context
One of the most important measures in the operation of offshore platforms is compliance with restrictions on fishing and navigation in areas surrounding oil platforms and other offshore units. This restriction aims to protect the facilities and, consequently, the environment, mainly by ensuring the safety of people and workers involved in the activities of oil companies at sea. In this methodology, the impacts on traditional fishing of vulnerable groups will be analyzed. This choice arises because this type of fishing is traditional along the Brazilian coast and is present in regions related to fields closest to the coast.	Restriction on fishing activities
Tourist products and itineraries are defined based on supply (in relation to demand) in order to characterize specific segments or types of tourism. For this model, nautical tourism will be analyzed as it is directly influenced by activities related to decommissioning.	Restriction of tourism
According to official IBGE data as a source of information, the Employment Generation Model (MGE) estimates the number of workers, formal and informal, needed to meet an increase in demand, at current prices, in any of the sectors of the Brazilian economy. For this model, we will use direct jobs generated and/or maintained in offshore operations.	Employability

).

The method does not include activities related to jobs generated and/or maintained in the recycling process. This section was defined due to the lack of data and/or studies on the topic. It is worth noting that the application of the method will be carried out five years before the start of decommissioning activities and must consider the final destination of the materials according to options available at the time of decision-making (ANP, 2020) [18]. In the onshore dimension, impacts on urban infrastructure (Logistics and Infrastructure) and jobs generated and/or maintained in port activities are analyzed (

Table 5. Description of Onshore Subcriteria.

Definition	Category of Social Impact
According to the IPEA (The Institute for Applied Economic Research/http://ivs.ipea.gov.br/index.php/pt/, accessed on 1 December 2023), the concept of Social Vulnerability introduces a new interpretative resource on social development processes and a way of capturing the absence or insufficiency of some social assets, creating the Social Vulnerability Index (IVS). This index is composed of three sub-indices: (i) Urban Infrastructure; (ii) Human Capital; and (iii) Income and Work. According to the IPEA, “they represent three large sets of assets, the possession or deprivation of which determines the conditions of the well-being of populations in contemporary societies”. To understand the impacts generated by the movement of pipelines and decommissioned materials, in this methodology, the average of the results of the sub-index related to the urban infrastructure of the municipalities that will be directly affected by the movement of cargo to its final destination point will be used.	Logistics and Infrastructure
For this model, we will use the direct jobs generated (combined office and administrative support services, vessel loading and unloading services, machining, turning and welding services and road freight transport in general) and/or maintained in onshore port operations.	Employability

).

Context analysis, containing socioeconomic data from the region affected by decommissioning operations, is important to assess the social impacts generated by the process, mainly on surrounding communities and their socioeconomic systems (tourism, culture, local commerce, and subsistence cultures).

Technical data, such as times and movements of vessels, restriction time generated by decommissioning and the amount of mass of pipelines and materials decommissioned, interface with the social dimension and are used to assess social impacts. From the understanding and definition of the identified impact categories, it was necessary to create two types of indicators. Social sensitivity indicators relate to the level of attention that must be given to the impact category through decommissioning actions, helping the organization to recognize, respond and adapt to social issues and problems. Social pressure indicators evaluate the external forces that affect the organization (

Table 6. Definition of Social Awareness and Social Pressure.

Definition
Measure of the susceptibility of a social factor to impact, signaling the level of attention that must be given to the impact category (social components) in concrete decommissioning situations.	Social Awareness
Effect (impact) of a decommissioning action on interested parties that may cause damage or disruption.	Social Pressure

).

Chandler (2018) [77] highlighted that some of the “indicators must allow the decision-making structure flexibility to adapt to changes in science, technology, stakeholder perceptions and other circumstances”. These decisions are important because if total removal is favored, it has a finite end point, whereas reuse will require complex legal and regulatory processes that require decisions around transfers of ownership and responsibility that must be provided for in any new regulatory framework.

3.2. Indicators of Social Awareness

As previously mentioned, the geographical distribution of the fields to be decommissioned and the different realities of Brazilian municipalities require that the analysis regarding impacts can analyze the susceptibility of a social factor to this impact, signaling the level of attention that must be given to the impact category (social components) in concrete decommissioning situations. For example, highly anthropic areas far from the coast have different awareness levels than projects in remote areas close to the coast, even if the indicators are the same. For each impact category, a factor called social awareness was established.

Social awareness is a parameter that represents the proportionality of decommissioning activities in relation to the determined sub-criteria. According to the characteristics inherent to each identified sub-criterion, an indicator of social sensitivity was defined. Below are the definitions of each of the sensitivity indicators (

Table 7. Definition of offshore and onshore indicators of social awareness.

Definition	Indicator of Social Awareness	Category of Social Impact	Dimension
Check the possibility of increasing capital due to the activities that will be carried out when hiring the vessels.	Changes in economic trends	External context	Offshore
Overlay of fishing maps and restricted areas due to decommissioning activities	Vessel movements interfering with traditional fishing activities	Restriction on fishing activities
Overlap of nautical tourism routes and restricted areas due to activities	Interference in tourism	Restriction of tourism
Number of employees (crew and divers) who will provide services.	Creation and/or maintenance of jobs	Employability
SVI index for each municipality from the IPEA Social Vulnerability Index website (http://ivs.ipea.gov.br/index.php/pt/, accessed on 1 December 2023)	Average of the “urban infrastructure” dimension of SVI of the municipalities directly affected	Logistics and infrastructure	Onshore
Number of professionals allocated according to each decommissioning alternative.	Creation and/or maintenance of jobs	Employability

):

For a better understanding of the calculation of social sensitivity indicators, as well as the method of verification and who is responsible for making the data available within the scope of oil and gas operators, refer to Appendices A and B.

3.3. Indicators of Social Pressure

Social pressure indicators are important to assess and manage the social risks involved in the decommissioning process of offshore sub-sea oil and gas facilities. These indicators help to understand how social conditions can affect the choices, behaviors, and results of an individual, group, or industrial activity.

Community engagement, impact on fishing and tourism activities, and safety are some of the key indicators to be considered to assess the impact of activities, providing a smooth transition and positive public acceptance of decommissioning activities. Below are the definitions of each of the sensitivity indicators (

Table 8. Offshore and onshore indicators of social pressure.

Dimension	Category of Social Impact	Indicator of Social Awareness	Indicator of Social Pressure	Definition
Offshore	External context	Changes in economic trend	Requirement of special licensing and/or authorization	Legal and/or infra-legal requirements that may affect the decision regarding alternatives and the operationalization of decommissioning
			Civil Society mobilization	Stakeholder actions that can affect the decision around alternatives
			Criticality of relationships	Stakeholder expectations regarding decommissioning activities
	Restriction on fishing activities	Vessel movements interfering with traditional fishing activities	Maritime traffic rate in the region around the base port	The rate identifies the flow of vessels in relation to alternatives and allows for assessing whether there will be an overload of fishing activities on nautical routes around the base port.
			Maritime traffic rate in the region around the area to be decommissioned	The rate identifies the flow of vessels in relation to alternatives and allows for assessing whether there will be an overload of fishing activities on nautical routes around the equipment to be decommissioned.
			Number of trips (port-materials)	Number of trips aiming to correlate with the number of jobs and interference in economic activities such as nautical tourism and traditional fishing
			Restriction time	The restriction time is exclusively related to the days in which artisanal fishing activities have to be interrupted due to decommissioning activities
			Restriction of traditional fishing after decommissioning	In some situations, parts of equipment that were not removed may affect traditional fishing.
			Fishing areas	Depending on the alternative, the impact that the activities may have on traditional fishing will vary.
			Number of traditional fishermen	The number of fishermen who may be impacted due to decommissioning activities may significantly affect the activity
	Restriction of tourism	Interference in tourism	Maritime traffic rate in the region around the base port	The rate identifies the flow of vessels in relation to alternatives and allows for assessing whether there will be an overload of fishing activities on nautical routes around the base port.
			Maritime traffic rate in the region around the area to be decommissioned	The rate identifies the flow of vessels in relation to alternatives and allows assessing whether there will be an overload of fishing activities on nautical routes around the equipment to be decommissioned.
			Restriction time	The restriction time is exclusively related to the days in which nautical tourism activities have to be interrupted due to decommissioning activities
	Employability	Creation and/or maintenance of jobs	Number of crew/divers	The number of crew varies depending on the type of vessel and the alternatives used
			Project time	Number of days that crew members will work on decommissioning activities
Onshore	Logistics and infrastructure	Average of the “urban infrastructure” dimension of SVI of the municipalities directly affected	Number of municipalities directly affected	Number of municipalities that are on the route between the port and the destination of the decommissioned material
			Total Gross Weight (TGW—materials)	Sum of the weights of the material removed and the truck that will transport it
			Number of trips (materials)	Number of trips that will need to be made
			Rock transportation	Option for the “rock deposition” alternative
			Distance between origin and destination	Kilometers of the route between the port and the destination of the removed material
	Employability	Creation and/or maintenance of jobs	Creation and/or maintenance of jobs	Number of professionals allocated onshore according to each alternative
			Project time	Number of professionals allocated on land according to Number of days that professionals will work in support activities on land in relation to alternatives

).

For a better understanding of the calculation of social sensitivity indicators, as well as the method of verification and the person responsible for making the data available within the scope of oil and gas operators, refer to Appendices C and D.

4. Social Impact Assessment Model for Decommissioning Sub-Sea Oil and Gas System

The social criterion in decision-making regarding the decommissioning process of submarine oil and gas systems includes the assessment of potential social impacts, negative and positive, arising from decommissioned submarine lines and equipment. Two dimensions were considered, onshore and offshore, six categories of impact (four offshore and two onshore), six indicators of social awareness (four offshore and two onshore) and twenty-two indicators of social pressure (fifteen offshore and seven onshore) (Figure 3 and Figure 4):

It is important to highlight some premises to be considered when evaluating the social criterion. The first is that the social issue must consider positive and/or negative impacts as objects of study so that desired and unwanted consequences have an equal assessment and can form the corpus of information to support decision-making. The other premises are as follows:

• For some indicators, social pressure will change due to the amount of materials to be decommissioned, regardless of whether they are equipment, rigid ducts, or flexible and umbilical ducts;
• The composition of equipment materials, rigid ducts, and flexible and umbilical ducts does not influence social impacts;
• The social pressure of the port considered was restricted to jobs generated in administrative and transport activities;
• The boundary of the system to be analyzed for the assessment of onshore social impacts is related to the transport activities of pipelines and equipment removed for appropriate disposal. For the technological alternative of decommissioning related to rock deposition, activities related to rock logistics and the jobs generated are taken into account;
• Operating costs, training and qualifications, and health and safety will not be covered, nor will the breakdowns arising from the technological development of the sector.

We sought to understand the technological alternatives used for decommissioning their impacts on the onshore and offshore dimensions and, based on the technical characteristics of the operation, impact categories were identified in the onshore and offshore dimensions and their respective sensitivity and social pressure indicators that will be analyzed to assess social impacts. The proposed social impact assessment model aims to recognize activities and sub-activities that objectively impact the target groups identified (stakeholders) in the onshore and offshore dimensions.

The description of activities and sub-activities of the process flowcharts of each of the decommissioning alternatives proposed in the PDI of some operators was used. The generation of offshore impacts takes into account the analysis of times and movements related to each decommissioning alternative, as this directly affects nautical tourism and artisanal fishing activities. To do this, it is necessary to collect information regarding the times and movements of the vessels, the total mass of materials to be decommissioned and the origin of the rental of the fleet to be used.

In the analysis of impacts in the onshore dimension, all decommissioning alternatives that will produce materials capable of being recycled, reused, or scrapped will be evaluated in terms of employment related to administrative activities at the port and the transport of equipment and materials used in the case of the alternative “Permanence due to Rock Deposition”, aspects related to logistics and infrastructure related to activities related to the movement of rocks to be used will also be evaluated.

Indicators of social awareness and social pressure associated with the onshore and offshore dimensions were presented. Based on the definition, information, calculation and verification method, as well as the person responsible for making the data available (Appendices A–D), the area responsible for applying the social impact assessment model must insert the data into a spreadsheet that will generate the importance score for each of the impact categories. Next, the process of applying the proposed methodology will be presented.

The methodological model for evaluating the social impacts of submarine system decommissioning projects is represented in Figure 5. The impact score for each category of impact is the result of multiplying the score for the indicators of social awareness and the score for social pressure. After this product, the values found in the product of social awareness by social pressure are averaged, thus generating scores for social impacts by category of impact.

For the proposed model application, three application phases are suggested: after defining the submarine system to be decommissioned, carry out a survey of the scores on the indicators of social awareness and social pressure, enter the data into the tool (Excel spreadsheet) and, finally, obtain the result of the impact categories by decommissioning alternative (Figure 6). Each of the three phases will be detailed below.

Phase 1

Collection of data regarding social awareness and social pressure scores

At this stage, technical and operational data are collected, including data such as the features, size, and total weight of the structure to be decommissioned, characteristics relating to the vessels, as well as the definition of the ports for supporting and unloading the materials, as well as the route to be carried out between the port and the final destination of the materials. In general terms, data on the characteristics of each category of impact of the model.

Data on the external context, times and movements of vessels, employability, logistics and infrastructure of the municipalities affected by transport are collected from areas responsible for the technical and safety criteria of the operators; for the others, they are extracted from external sources, such as IPEA.

Phase 2

Launching data into the tool

After collecting all the data on indicators of social awareness and social pressure obtained from the survey of the teams responsible for technical and security data, as well as searching for data from external sources, it becomes necessary to insert them into an Excel spreadsheet for the calculations to be carried out and the result to be collected.

The parameterization of the mathematical expression factors is carried out based on the analysis of data regarding social pressure and decommissioning alternatives. For each continuous variable indicator, the lowest and highest value among the alternatives is analyzed. After the comparison, Fpmax is assigned to be 10% higher than the value found for the indicator and Fpmin to be 10% lower than the minimum value found.

Phase 3

Results of categories of impact by decommissioning alternative

At this stage, the final result is represented in the synthesis of the social impact assessment model. The result is presented by the category of impact and decommissioning alternatives.

5. Discussion

A full analysis of the sustainability of sub-sea decommissioning activities requires studies based on multi-criteria decision models that can take into account environmental, technical, safety, waste and economic impacts, as presented in the work of Moares et al. (2022) [52].

As the social context is a complex issue, it is necessary to create a better and more effective basis for studies related to decommissioning by using a multidisciplinary team and involving stakeholders. It is necessary to create models that can present categories of social impact beyond the triad of employment, communities and impacts on fishing, and that describe impacts in the onshore and offshore dimensions.

The work of Fowler et al. (2014) [5] presented an extensive list of categories; however, the model presented does not explore them all. Kruse et al. (2015) [6] and Henrion et al. (2015) [7] did not present categories related to the onshore dimension. Cripps and Aabel (2002) [8] presented categories only for the offshore dimension, and Martins et al. (2020) [10] presented impact categories referring to employment, communities, and impact on fishing.

Reports submitted by oil and gas operators Shell U.K (2015) [61], BG Group (2016) [62], DNV (2018) [70], Ineos (2018) [64], Ithaca (2018) [65], Marathon Oil (2017) [66], Perenco (2014) [60], and Spirit Energy (2018) [68] presented impact categories focused on employment, communities and fisheries impact. In addition to the three categories mentioned, the operator CNRI (2013) [63] pointed out socioeconomic impacts on infrastructure. Repsol (2018) [67] presented impacts on the cost of the transport of historical monuments, and finally, Pttep (2015) [60] presented categories involving cultural heritage and tourist activities; however, only cites, without presenting a model to evaluate these aspects of greater subjectivity.

There are gaps in knowledge about the social and economic values of offshore structures related to variation in values according to the interested party consulted and for different types of offshore structures (platforms, subsea systems, and offshore wind) (Elrick-Barret et al., 2022) [22].

Therefore, the presented model describes impact categories in the onshore (logistics, infrastructure, and employability) and offshore dimensions (external context, restriction on fishing activities, restriction on tourism, and employability), as well as a system of sensitivity and social pressure indicators with their respective definitions and calculation memory, offering decision-makers an applicable model for assessing social impacts in real scenarios of decommissioning of submarine oil and gas systems.

Considering that studies on decommissioning of sub-sea oil and gas systems are increasing, the results of this work can contribute to progress in this field as it proposes a model for social impact assessment based on the life cycle approach. The model is based on the assessment in the pre-decommissioning phase.

The literature review has shown that the decommissioning of sub-sea oil and gas systems has potential social impacts on fisheries and local communities, whether in terms of job creation or preservation and activities related to tourism. Interventions in territories without the involvement of the various social actors that make them up do not do justice to today’s debate, as the meaning of territory no longer refers to a geographically or politico-administratively delimited space.

The concept of territory used today goes beyond geographical and similar spaces and often beyond the borders between countries. Territory stands for the interaction of actors that can explain social relations, productive or non-productive, that contribute to the definition of a particular identity (Siedenberg, 2006) [78].

This identity, in turn, is projected through the network connection of actors with common goals. Therefore, it is necessary to identify the social impact not only through the mathematical model to be developed but also through the involvement of the different stakeholders upstream, a priori, during monitoring and a posteriori, as a means of evaluation after the decommissioning has been completed.

6. Conclusions

The main objective of the study presented in this project is to contribute to the understanding of the potential social impacts caused by the decommissioning of sub-sea oil and gas systems through the creation of a social impact assessment model based on the life cycle approach, including the proposal of impact categories, and through the creation of a set of indicators.

During decommissioning processes, probably the most consistent way to conduct a social analysis is to promote forums with stakeholders from the affected areas. In other words, an oil and gas operator and/or the economic, legislative and regulatory bodies involved in the decommissioning process must identify and strongly invite in advance the different stakeholders (economic actors, public authorities and other organized civil society bodies) of the area/context where the decommissioning will take place, regardless of the decommissioning alternative chosen.

This article analyzed the literature in detail, with the aim of identifying the categories of social impacts present in the decommissioning of offshore oil and gas systems. Thus, a model for assessing social impacts was presented, which identified, based on literature and a workshop with experts, the main impacts in the onshore and offshore dimensions. These dimensions are interconnected as they are part of the decommissioning process of offshore oil and gas installations.

Some gaps were identified in the literature, such as studies directly related to the social impacts of decommissioning, impacts generated by collisions, the presence of norm and biofouling, pipelines that reach the coast and waste management. We suggest more research and partnerships between the oil and gas industry and universities, research centers, governments, and NGOs to fill these gaps.

We must not forget that although multi-criteria models have a marked quantitative orientation when it comes to social phenomena, the study takes on interpretative characteristics of a qualitative nature, i.e., the phenomenon can be better understood if it is subjected to its territorial context in which the study takes place and it must be analyzed from an integrated perspective. In this way, the need is emphasized that the research must try to grasp the phenomenon under study from the perspective of the social actors in order to take into account all the contributing points of view. The model sought to use indicators with a low level of subjectivity and traceability of information and data used and created from listening to interested parties; these are the characteristics that make such a model competitive and with differentiating characteristics in relation to the others presented.

This study contributes to the development of national and international legislation with regard to social impacts. Unlike the models discussed in the literature review section, the proposed model considers two dimensions, onshore and offshore, because they are part of the entire offshore decommissioning process. This achieves greater efficiency in assessing the social impacts of decommissioning. Aspects related to economic dynamics, interference in fishing and tourism, employability, logistics and infrastructure were addressed. These impacts must be analyzed from a positive and negative point of view according to each decommissioning option and territorial reality.

Although this article contributes to the knowledge of the social impacts of the decommissioning process of submarine systems, its development is limited, having been based on a literature review, and no case study application was made to validate the health assessment model proposed social impacts.