# Fault Controls on Hydrocarbon Migration--An Example from the Southwestern Pearl River Mouth Basin
## 6 Conclusions  
In this study, the control of fault seals on basin-scale hydrocarbon migration and accumulations in the south western Pearl River Mouth Basin (PRMB) was illustrated. It has been shown that the primary hydrocarbon reservoirs within the southern Wenchang A subbasin are associated with fault-bounded structures, predominantly accumulating in the Oligocene Zhuhai Formation. The major faults of the study area, faults F1-F10, displayed their main activity during the deposition of the Late Oligocene E\({}_{3}\)z and Early Miocene N\({}_{1}\)z sequences, ceasing after the N\({}_{1}\)h sequence. However, the major hydrocarbon charging phase in the area was initiated around the middle Oligocene and has continued up to the present, coinciding with the faulting activity.  
The assessment of the lateral sealing capacity of the key sealing faults (F1, F2, F3, and F5) reveals the following patterns: F1-F3 exhibit high SGR values with relatively uniform distributions along their fault surfaces, whereas F5 demonstrates more variable SGR values  
Figure 12: Conceptual model of the hydrocarbon migration and accumulation controlled by fault sealing in the southern Wenchang A subbasin.  
across its surface. A correlation between SGR values and hydrocarbon distribution has been established, with most hydrocarbon-bearing layers displaying SGR values at or exceeding 20%. Notably, the lower limit of SGR that supports hydrocarbon columns in this study is at 15.8%, indicating that significant cementation might have occurred within the major sealing faults.  
An evaluation of the fault sealing characteristics of the bounding faults (F7-F10) in potential fault array traps yields the following insights: for fault lateral sealing, the upper segments of F7 and F8 act as lateral conduits, while the lower segments of F7, F9, and F10 function as lateral barriers. Regarding fault vertical sealing, F7 demonstrates robust vertical sealing capacity, while F9 and F10 exhibit moderate vertical sealing capabilities. Consequently, hydrocarbons anticipated to directly traverse the upper segments of F7 and F8, accumulating in the fault array traps positioned behind these faults. Conversely, the lower portions of F7 and F9 hinder further hydrocarbon migration, leading to accumulation in the hanging wall traps associated with these two faults.  
Conceptualization: [PERSON]; writing--original draft preparation: [PERSON]; writing--review and editing: [PERSON]; project administration: [PERSON]; Supervision: [PERSON], [PERSON] ([PERSON]) and [PERSON]; Software: [PERSON], L.X. and S.M.; Visualization: [PERSON], [PERSON] and Y.C. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research was funded by the China Scholarship Council (Projected number 202106450037).  
Not applicable.  
The data, figures, and tables used to support the findings of this study are included in the article.  
We thank the Zhanjiang Oil Company Ltd., CNOOC, for providing seismic data, well data, and a relevant research platform for this study.  
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.