海拉尔盆地断裂构造特征及控藏机理

基于"同一应力场不同边界条件形成不同性质断层"的构造解析原理,认为海拉尔盆地断陷期受南南东—北北西向拉张应力场作用,形成北北东和北东东向断裂,北北西向断裂明显走滑变形。断-坳转化期拉张应力场方位调整为近东西向,形成近南北向断裂,北北东、北东东和北北西向断裂扭动变形。伊敏组沉积末期盆地回返,受近东西向挤压应力场控制盆地左旋压扭变形,北北东和北东东向断裂强烈反转。依据断裂变形特征叠加关系,海拉尔盆地形成4套断裂系统:早期伸展断裂、中期张扭断裂、早期伸展中期张扭断裂和早期伸展中期张扭晚期反转断裂。断陷构造层早期伸展中期张扭反向断裂形成断层遮挡圈闭,早期伸展断裂将凹中隆和斜坡切割破碎形成断层复杂化的背斜圈闭,早期伸展断裂与中期张扭断裂交叉组合,形成复杂的断块圈闭。断-坳构造层早期伸展中期张扭晚期反转断裂呈"梳状"组合,形成典型的断块圈闭。基于断裂活动时期与成藏期耦合关系以及典型油气藏解剖的结果认为,早期伸展和早期伸展中期张扭断裂在成藏关键时刻为遮挡断层,且封闭的烃柱高度一般均小于圈闭的幅度,早期伸展中期张扭晚期反转断裂为调整型断层。基于圈闭的样式、断层在成藏中的作用及输导体系分析,海拉尔盆地断裂控藏模式分为二型4类,二型为原生油藏和次生油藏。原生油藏包括3类:一是灶缘油气侧向运移反向断层遮挡成藏模式,控藏断裂为早期伸展中期张扭断裂系统;二是灶内油气初次运移断层遮挡"箱内"成藏模式;三是灶内凹中隆油气侧向运移"弥散式"成藏模式。这两种模式控藏断裂均为早期伸展断裂。次生油藏为油气沿断裂垂向运移"伞式"成藏模式,控藏断裂为早期伸展中期张扭晚期反转断裂系统。

Fault Structural Characteristics and Control Mechanism of Reservoir Formation of Hailar Basin

Based on the structural analysis principle, different boundary conditions forming different nature faults in the same stress field, indicate that the Hailar Basin is controlled by the SSE-NNW direction extensional stress field, forms NNE and NEE trending faults, and NNE trending faults express strike-slip deformation evident. Extensional stress field orientation adjusted to nearly EW direction, nearly SN trending faults formed, and NNE, NEE and SN trending faults twisted deformation in the stage of rift-depression transformation in Hailar Basin. The basin returned during the end of Yimin formation, emerged levorotation pressure torsion deformation controlled by nearly EW compressive stress field, and NNE and NEE trending faults inversed strong. Basis for fault deformation characteristics superposition relationship, there are 4 sets of fault systems in Hailar Basin: early extension faults, interim tensile shearing faults, early extension and interim tensile shearing faults and early extension, interim tensile shearing and late reversal faults. The early extension and interim tensile shearing reverse faults form fault sheltered traps, the uplifts within depression and slopes are cut and crushed into fault complication anticline traps, and the early extension faults and interim tensile shearing faults cross combination and form complex fault block traps in rift structure layer. The early extension, interim tensile shearing and late reversal faults, appearing \"comb-like\" composition, form typical fault block traps in the rift-depression structure layer. Based on the fault activity and accumulation period coupling relation and anatomy results of typical oil and gas reservoirs, concludes that the early extension faults and early extension and interim tensile shearing faults play sheltered faults at a critical accumulation time with the sealing hydrocarbon column height generally less than the traps amplitude, as well as early extension and interim tensile shearing and late reversal faults are adjustment faults. On the base of the analysis on trap style, the faults role of reservoir-forming and transporting system, fault controlling reservoir modes are divided into 2 types and 4 kinds in Hailar Basin. 2 types include primary and secondary reservoir and primary reservoir including three kinds: The first is oil and gas lateral migration in hydrocarbon kitchen margin and reverse fault sheltered reservoir-forming model, and reservoir-controlling fault is early extension and interim tensile shearing fault system; second model is oil and gas primary migration in the inside hydrocarbon kitchen and fault sheltered \"in the box\" reservoir-forming model; third is oil and gas lateral migration of uplifts within depression in the inside hydrocarbon kitchen, \"diffuse type\" reservoir-forming model. Both of models reservoir-controlling fault is the early extension fault. Secondary reservoir is the \"umbrella-shaped\" reservoir-forming model of oil and gas vertical migration along fault, the early extension and interim tensile shearing and late reversal fault system as reservoir-controlling fault.