Structral Deformation And Hydrocarbon Accumulation In Langgu Sag

The Langgu sag is located in the northern part of the Jizhong depression.It is generally distributed in the NE-SW direction.The northwest side is controlled by the Daxing fault.It is a typical“half graben”with abundant oil and gas resources.The Langgu sag has a high degree of exploration,but the structural deformation analysis of the system is lacking.The structural control lithology and control of the reservoir formation mechanism are unclear,resulting in low oil and gas detection rate.Based on the theory of modern structural geology,the thesis applies seismic interpretation,balanced cross-section and structural analysis to study the structural deformation of Langgu sag.Combined with hydrocarbon accumulation rocks,reservoirs,caprocks and other accumulation factors,the influencing factors of hydrocarbon migration and accumulation are analyzed,and the hydrocarbon accumulation model in Langgu sag is discussed.Get the following understanding:1.There are two groups of faults in the Langgu sag:NE and NW,which are mainly in the northeast direction.Most fault formation development time is between Es3-Nm.According to the classification of fault activity,the Paleogene in the Langgu sag developed a three periods fault activity,and the fault activity often showed weak-strong-weak regular activities.2.The Langgu sag is a horizontally stretched structural family in which the base is involved.The main structural styles are:"y"and anti-"y",graben-horst,"?"and anti-"?",ladder,Cabbage,reverse traction anticline and reverse sliding Order.All of the above are controlled by the extensional stress field.Locally developed strike-slip structural styles and inversion structural styles.3.The structural evolution of the Langgu sag is divided into four stages:the initial period of the fault depression,the strong period of the fault depression,the adjustment period of the subsidence and the depression period,corresponding to:Ek period,Es₄-Es₃period,Es₂-Ed period and Nm period.4.The oil and gas in the Langgu sag is distributed around the depression.As a raw oil center,the gutters will transport the generated oil and gas to the surrounding uplift area for a long time,and the oil and gas will preferentially fill the traps with close distances,forming oil and gas around the depression.