万金塔构造特征及其对深层气藏的控制作用

The Structural Features of Wanjinta and Its Control Effect on Deep Gas Reservoir

万金塔地区位于德惠断陷西缘断垒带,其构造特征及变形机理与油气成藏密切相关综合区域地质、钻井及三维地震解释资料,对万金塔地区构造样式、断裂系统特征、断裂活动期次及应力场进行分析;选取贯穿研究区的两条地质剖面,利用平衡剖面技术进行复原,重塑构造演化史;基于断裂控藏作用,采用权重加权平均算法建立相应数学评价模型,提出"三参数评价法"定量评价深大断裂活动程度。研究表明:万金塔地区历经多旋回构造运动改造调整,构造叠加复杂,形成深部断陷期基底断裂及浅部反转期叠加断裂两套断裂系统。其中,沟通深部和浅部的深大断裂性质呈分段变化特点,在逆冲走滑地区断裂活动程度相对较高,控制了平面上CO_2气藏的富集,反之,在远离活动程度高的深大断裂、二期褶皱构造叠加断裂影响小、靠近沙河子组烃源岩灶的地区可能存在有机烃类气藏的富集。

The Wanjinta area is located in the step fault system at the western edge of the Dehui fault Depression.The structural features and deformation mechanism of the area are closely related with hydrocarbon accumulation.The structure,fault system features,periods of fault activity,and the stress fields of the WanJinta area were analyzed by employing information from regional geology,drilling,and three-dimensional seismic resolution data.Two geological sections that cross the study area were selected for analysis,and3D move-balanced sectional-structure recovery technology was used to recover and remodel the tectonic evolution history.Based on the fracture reservoir-control function,the average-weighted algorithm was used to establish the corresponding mathematical evaluation model.The“three-parameter evaluation method”was proposed to evaluate quantitatively the activity level of the deep fracture.Research shows that the WanJinta area has been subject to transformation adjustment following polycyclic tectonic movement.The area has a complex superimposed structure and forms two fracture systems,with deep rift-basement faults and a shallow reverse-fault system.The deep fault indicates deep formation change characteristics along segments of the deep part,and the shallow part shows the characteristics of section change.The level of fault activity in the reverse-fault slip region is relatively high,controlling the enrichment of the CO2gas reservoir in the plane.However,there could be reservoirs enriched in organic hydrocarbon gas in areas that are located far away from the deep faults subject to high-level activity,with little impact from a second fold structure superimposed fracture adjacent to the Shahezi Formation hydrocarbon source rocks.