Lithologic hydrocarbon accumulation characteristics of Baikouquan Formation, Madong Slope, Junggar Basin: a case of YB 4 well block, Luliang Oil Field

In view of the unclear mechanism and distribution of lithologic reservoirs in the Baikouquan Formation on the Madong Slope of Junggger Basin in recent years, the sequence stratigraphy and sedimentary facies theory were used to analyze the characteristics and accumulation conditions of oil and gas reservoirs found in YB 4 well block. It is revealed that the lithologic reservoirs of the Baikouquan Formation in this area are mainly updip-tip-type, which are mainly controlled by four basic factors:“the development of a fan root channel or a alluvial channel sand body with an updip tip”, “debris flow plugged in upward direction”, “covered with high water level muddy caprock”, “a fault with a source of oil in the downdip direction”. Among them, the “debris flow plugging” and “high water level mud caprock” are the key controlling factors to hydrocarbon accumulation. The updip-tip-type oil and gas reservoirs are mainly distributed at the top of the T₁b₂ and the bottom of the T₁b₃, which are located in the upper part of the transgressive system tract of the Baikouquan Formation. In the future, it will be the main oil and gas exploration target in the Madong Slope area.