ANALYSIS OF CONTROLLING FACTORS OF SHALE OIL RESERVOIRS IN JIYANG DEPRESSION

Unconventional oil account for an increasing proportion in the oil industry and still have a continuous growth trend. As an important type of unconventional resource, shale oil reservoir is an important resource replacement for conventional oil resources in Jiyang depression. Based on the necessary conditions of the formation of shale oil reservoirs, this article discusses the key controlling factors on shale oil enrichment in Jiyang depression. The results show that source rocks, faults and burial depth jointly affect the generation and accumulation of shale oil, and further control the scale and distribution of shale oil reservoirs. As the basis of oil generation, source rocks control the potential distribution range of shale oil reservoirs. Faults and burial depth affect the quality of argillaceous rock reservoir, and then affect the distribution of high-yield shale oil reservoirs. The mudstone stratum with burial depth less than 1000m has less cracks and poor reservoir quality. In the mudstone stratum with a buried depth more than 1000m, the density and maintenance of cracks around different types of faults are different, thus the reservoir quality around different parts of distinct faults is also different. The cracks around the flat slope fault in the low part of the structure are denser and more extensive than those in the high part of the structure. The crack development density at the low end of the structure of the reverse slope fault is denser than that at the high end of the structure. Affected by the intensity of fault activity, the middle part of fault plane distribution is the dominant position of crack development. Within the hydrocarbon supply range of source rocks with buried depth greater than 1000m, the crack intensive area around the fault is a favorable accumulation area of shale oil reservoir.