Study On The Rule Of Oil And Gas Accumulation Of Bayantala Area In Hailaer Basin

On the basis of thorough analysis of the forming, distribution and evolution of structure in Bayantala area, the conditions of oil and gas accumulation are completely and systematically studied, the main controlling factors of oil and gas accumulation are summarized, the oil and gas accumulation model is established, and the rules of oil and gas accumulation are preliminarily discussed in the paper. Bayantala area is the transfer zone of Wuerxun depression and Beier depression. The structure pattern is shown as"sag in north, uplift in south, steep slope in west and gentle slope in east"as a whole. The numbers of faults are very large. The properties of faults are various. The faults are obviously divided into two systems in vertically, and the distributions of faults are zonal in plane. The types of local structural traps are various, and the forming of local structural traps is mainly impacted by faults. The main hydrocarbon source rocks are the Damoguaihe Formation, Nantun Formation, and Tongbomiao Formation in Bayantala area. They are the middle to good source rocks and mainly distribute in sag and local area of step-fault zone. The glutenite in fan delta plain and front of Tongbomiao Formation, and the sandstone in branch channel and bar of fan delta front of Nantun Formation are favorable reservoir, for they have larger acreage and better physical properties. The oil mainly migrate in short-distance way, and the distributions of reservoir are controlled by the scope of hydrocarbon source rock; the main oil and gas migration paths are the main faults and unconformity surfaces, and the directions of oil and gas migration and accumulation are controlled by structures; the reservoir physical properties are the major factor of oil and gas accumulation in Bayantala area. The oil reservoir types in Bayantala area are buried hill, fault-block and secondary reservoir. The mechanisms are migrated along unconformity surface and faults to form buried hill and fault-block reservoir in early stage, and along faults to form secondary reservoir in late period. The early stage fault-block and buried hill reservoirs are mainly distributed in the uplifted wall side of Bayantala Fault, and the secondary reservoirs are mainly distributed in the downthrow block side of Bayantala Fault. The early stage fault-block reservoirs have huge exploration potential, and are important exploration targets; the buried hill and secondary reservoirs also have definite exploration prospects, and are the replace targets of next step exploration.