鄂尔多斯盆地杭锦旗东部断裂特征及对天然气成藏的影响

Fault Characterization and Its Influences on Gas Accumulation in the Eastern Haggin Banner of Ordos Basin

针对鄂尔多斯盆地杭锦旗东部地区断裂对成藏控制因素认识不清的问题,利用地震及钻井资料,开展断裂性质、分布、活动性及封闭性研究。运用改进的断裂泥岩比率法和断面正压力法研究断裂的侧向和垂向封闭性。研究结果表明:断裂按走向可划分为NE、NW、NEE向断裂,按性质划分,主要为高角度逆断裂;断裂在不同层位封闭性存在差异,掌岗图西断裂在盒2+3段、盒1段侧向封闭性好,山1段侧向封闭性中等,山2段和太原组差,且在各层段垂向封闭性普遍中等;结合封闭性分析,通过气藏解剖,明确二级断裂控制了构造圈闭的发育,三、四级断裂控制着天然气的垂向运移与聚集,该研究为下一步优选有利目标区和勘探井位部署奠定基础。

Based on the seismic and field drilling data,the fault properties,distribution and sealing properties were studied to clarify the influences of fault on gas accumulation in the eastern Haggin Banner of Ordos Basin.The modified fault mudstone ratio and fault-section normal pressure methods were used to determine the lateral and vertical fault sealing properties.Research indicates that the faults can be classified into NE,NW and NEE according to the fault strike.The faults are dominated by high-angle reverse fault according to the fault properties.There are differences in the fault sealing properties in different horizons.The Zhanggangxi fault shows a better lateral sealing performance in He 2+3 and He 1 members,a medium sealing performance in Shan 1 Member and a poor sealing performance in Shan 2 Member and Taiyuan Formation.The Zhanggangxi fault shows a medium vertical sealing performance in each members.According to the sealing property and gas reservoir analyses,the secondary-order fault controls the development of structural traps,and the third-order and fourth-order faults control the vertical migration and accumulation of natural gas.This research could lay a foundation for the further favorable zone optimization and exploration well deployment.