Factors Controlling Hydrocarbon Reservoir Formation and Distribution and Prediction of Favourable Areas in the Jurassic Toutunhe Formation in the Fudong Slope,Junggar Basin,China

In recent years, many oil and gas reservoirs have been discovered in the Jurassic Toutunhe Formation in the Fudong slope, Junggar Basin. The total reserve in the formation is nearly 100 million tonnes, indicating huge exploration potential in the area. However, the main factors controlling the hydrocarbon accumulation remain unclear, and the mechanisms of hydrocarbon accumulation and enrichment are controversial. In this work, by studying the mechanism and main factors controlling hydrocarbon accumulation in the Toutunhe Formation in the Fudong area, a quantitative model of the reservoir rock and caprocks that control hydrocarbon distribution was constructed, the critical conditions for hydrocarbon accumulation were determined and favourable exploration areas were predicted. The results indicated that the oil in the Toutunhe Formation was derived from both Permian and Jurassic source rocks, the oil migrated from west to east after generation and both reservoir rock and caprock controlled the formation and distribution of oil reservoirs. The oil-bearing capacity improved with increases in the storage coefficient and caprock thickness. Accumulation did not occur when the reservoir rock and caprock index (RCI) was ≤ 0.5 but was favoured when the values were higher; this factor was the critical condition for hydrocarbon accumulation.