**4. Conclusions**

Seismic exploration based on reflections from a passive source uses the imaging of background noise, is cheap, and can be used as an effective supplement to methods of exploring deep active seismic sources. However, its computational cost and storage-related requirements constitute constraints on its further development.

Using a geometry based on the given geological structure can solve the above problem in practice. A set of geometric parameters that are suitable for the given area can reduce the cost of acquisition and the difficulty of data processing while improving their resolution. In this paper, we used experience in processing data on seismic exploration based on reflections from a 3D active source to design a reasonable and efficient geometry to obtain data for a 3D passive source. On the premise of ensuring a high signal-to-noise ratio, uniform folds, and reasonable azimuth, we used SPS files to guide the relevant correlations and obtain the virtual shot records; this improved the computational efficiency. At the same time, we obtained data on reflections of waves from the 3D passive source through forward modeling, and generated a clear seismic profile by calculating according to the above process.

In addition, we tested the feasibility of imaging based on direct migration using random reflection-induced noise. The method of generating virtual shot records is similar to the migration imaging algorithm based on correlation-based imaging conditions, that is, this method of migration can omit the correlations in the virtual shot records, thus reducing the requisite computational resources and storage space and improving efficiency. After intercepting multiple, random time windows of noise for multiple folds, the results also yielded images of high quality. The proposed method is thus efficient in terms of the seismic exploration of a passive source based on reflections.

The proposed method can accelerate the calculation of reflections from a passive source, and its many virtues can help promote the use of such technology on a large scale.

**Author Contributions:** Conceptualization, Y.L.; Software, Y.L.; Validation, Y.L.; Writing–original draft, Y.L.; Project administration, G.L.; Funding acquisition, G.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by the NSFC (Grant No. 42074131), and the National Key R&D Program of China (Grant Nos. 2021YFC2801404 and 2022YFC280016803).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
