Controlling effect of Shaximiao Formation fault on gas accumulation in eastern slope area of Western Sichuan Depression

This paper is the result of oil and gas exploration engineering.

Objective The exploration potential of conventional structural advantage area of gas reservoir in Jurassic Shaximiao Formation in the eastern slope of western Sichuan depression is not great, and the geological understanding of the gas reservoir in the complex fault clamping area with low degree of exploration is obviously lagging behind.

Methods Based on the data in exploration and developent in recent years, using the theory of structural reservoir control, this paper studies the control of fault section morphology type and fluid potential difference on oil and gas accumulation, discusses the oil and gas distribution in the fault clamping area, and summarizes the difference of oil and gas enrichment in the north-south fault system.

Results The study shows that the river channel controlled by slope-flat fault has a high degree of oil and gas filling, which is conducive to high-efficiency reservoir formation, followed by low-angle shovel-like fault, and high-angle flat shovel-like fault has the worst reservoir formation.

Conclusions Fluid potential difference makes it difficult for hydrocarbon source cliff gas to fill long-distance sand bodies through high potential areas. Although it is difficult to form reservoirs due to the escape of oil and gas in the development of a narrow fracture network at both ends of the fracture clamping area, a relatively good oil and gas enrichment zone can be formed in the wider middle if the slope-flat fault and low-angle shovel-like fault are clamped and transported together.Therefore, it is believed that the structure in the south is superior to that in the northern and central clamping areas and has certain potential. The key factors of reservoir formation are still controlled by the fracture morphology and transportation capability.