岩溶洞穴型储层发育期次识别技术及应用

The identification technology for developmental periods of karst cave reservoirs and its application

岩溶洞穴型储层连通性识别难,影响高效开发,其根本的问题在于对岩溶洞穴型储层发育期次的识别及其分布规律认识不清。采用岩溶洞穴型储层分层解释的方法对不同发育期次岩溶洞穴型储层分布进行预测,首先,在洞穴层主要受潜流面控制这一认识的基础上,恢复古地貌,按古地貌由高到低顺序选取代表井,确定岩溶排泄基准面,划分单井洞穴层;其次,选取等时沉积界面,拉平地震数据体,将单井洞穴层标定在地震剖面上;最后,精细解释出洞穴层,提取振幅均方根属性,预测每一层储层的平面分布。在分析单层洞穴分布规律的基础上,分析岩溶洞穴型储层的连通性,在塔里木盆地LGX地区奥陶系识别出22个缝洞单元,为油藏高效开发提供技术支持。

The connectivity of karst cave reservoirs is difficult to identify and affects their effective development. The root causes are attributed to the unclear identification of the development periods and distribution rules of the karst cave reservoirs. The method of layered interpretation of karst cave reservoirs was used to predict the distribution of the karst cave reservoirs in different periods. First, on the basis of the knowledge that the cave layers are mainly controlled by underflow surfaces, the paleogeomorphology was restored, and then representative wells were selected from high to low paleogeomorphologic structures, the karst discharge datum was determined, and the cave layers were divided into single wells; second, according to the isochronal sedimentary interfaces, seismic data volumes were flattened, and the cave layers for single wells were calibrated on seismic sections; and finally, the cave layers were finely interpreted, the RMS amplitude was extracted, and the lateral distribution of every reservoir layer was predicted. Based on the distribution law of single-layer caves, the connectivity of karst cave reservoirs was analyzed, and 22 Ordovician fracture-cave reservoir units were identified in the LGX area in the Tarim Basin. This may provide technical support for the effective development of the reservoirs.