复杂地质条件下超深层碳酸盐岩断控缝洞体成像及预测技术

Imaging and prediction technology of fault-karst reservoirs in ultra-deep carbonate rocks under complex geological conditions

复杂地质条件下的超深层碳酸盐岩断控油气藏是近年来油气勘探的热点之一,其所发育的超深层断控缝洞型储集体受走滑断裂控制。沙漠起伏地表造成地震波能量吸收衰减严重,储层的上覆地层的火成岩严重影响目的层成像,同时超深层储集体地震波有效信号弱、反射特征复杂,影响了预测精度。以塔里木盆地顺北油气田为例,对该地区储集体高精度成像及储层预测难点进行剖析,建立了针对性技术策略:采用以弱信号恢复为代表的地震资料预处理技术提升叠前道集品质,为速度建模及成像提供基础数据;将火成岩高斯束层析速度建模与宽频RTM成像技术相结合,有效提升火成岩及高陡构造的建模成像精度;建立了面向超深层断裂及储集体的多属性综合预测技术流程,通过模拟断控缝洞体的地震波场响应,分析不同类型储集体的地震响应特征,对断裂带边界及内幕的叠后多属性进行降维处理,实现对超深层碳酸盐岩断控缝洞体的有效预测,为塔里木盆地超深层碳酸盐岩油气勘探开发提供了技术支撑。

Oil and gas reservoirs in fault-karst,ultra-deep carbonate rocks under complex geological conditions have become a popular exploration target in recent years.The fault-karst reservoirs are controlled by strike-slip faults.The undulating surface of the desert causes significant energy absorption and attenuation of seismic waves,the effective signal of seismic waves in ultra-deep reservoirs is weak and the reflection characteristics are complex,which affects the prediction accuracy.Simultaneously,the igneous rocks in the strata overlying the reservoirs affect the imaging of the target layer.The difficulties of high-precision reservoir imaging and prediction are analyzed using the Shunbei oil and gas field in the Tarim Basin as an example.The seismic data pre-processing technology represented by weak signal recovery is adopted as a targeted technical countermeasure to improve the quality of pre-stack gathers,thus providing basic data for velocity modeling and imaging.The modeling and imaging accuracy of igneous rocks and high and steep structures can be effectively improved using the combination of igneous rock Gaussian beam tomography velocity modeling and broadband reverse-time migration(RTM)imaging technology.A multi-attribute comprehensive prediction process which analyzes the seismic response characteristics of different types of reservoirs is established for ultra-deep fractures and reservoirs,through seismic wave field response simulation.This uses post-stack multi-attribute dimensionality reduction to process the fault zone and its boundaries and predict ultra-deep carbonate fault-karst reservoirs.This method provides improved technical support for the exploration of ultra-deep carbonate rocks in the Tarim Basin and the development of fault-karst reservoirs in the area.