乌尔逊-贝尔凹陷油气分布规律及其主控因素

DISTRIBUTION PATTERNS OF OIL AND GAS AND THEIR MAJOR CONTROLLING FACTORS IN WUERXUN AND BEIER SAGS

乌尔逊、贝尔凹陷是海拉尔盆地内目前发现的最有潜力的两大凹陷,区内构造复杂,断裂十分发育,油气藏的发育大都与断层密切相关。按成因将乌尔逊、贝尔凹陷的油气藏分为与断层有关的背斜油气藏、与断层有关的地层油气藏、与断层有关的岩性油气藏、与断层有关的断块油气藏4大类共13种油气藏。油气纵向和平面上的分布受优质源岩中心展布,有利岩相带及断层的走向、断距大小等的控制而呈现出明显的规律性:纵向上油气主要分布在主力烃源岩层下白垩统南屯组及其上、下的大磨拐河组、铜钵庙组及兴安岭群和布达特群;平面上油气主要分布在烃源灶周围的苏仁诺尔构造带、巴彦塔拉构造带、呼和诺仁构造带、霍多莫尔构造带和苏德尔特构造带内,油气较为富集在源岩附近、断距在200～300m之间、北东东走向的断裂附近的粉砂岩和砂砾岩储层中。

Wuerxun and Beier sags are the most potential sags discovered in the Hailaer Basin till now,where the structures are complex,faults are highly developed,and most of the pools are closly related with the faults.Four types and 13 kinds of oil and gas reservoirs are recognized in Wuerxun and Beier sags according to their genesis,including anticline reservoirs,stratigraphic reservoirs,lithologic reservoirs,and fault block reservoirs,all of which are associated with faults.The vertical and lateral distribution of the oil and gas are controlled by the locations of hydrocarbon kitchens,favorable facies belts,and strikes and displacements of faults.Vertically,the oil and gas are mainly distributed in the major source rocks of the Nantun Formation and the Damoguaihe Formation,Tongbomiao Formation,as well as Xinganling Group and Budate Group.While laterally,they are mainly distributed in the structural zones around the hydrocarbon kitchens,such as Surennuoer,Bayantala,Huhenuoren,Huoduomoer and Sudeerte.The oil and gas are relatively enriched in the siltstones and glutenites in the vicinity of source rocks,and near the NEE-trending faults with a displacement of 200-300m.