OVT域方位各向异性技术在中非花岗岩裂缝预测中的应用研究

Application of azimuthally anisotropy by OVT gather for granite fracture prediction in Central Africa

裂缝预测是花岗岩潜山油藏勘探开发攻关的难题之一。为此,从花岗岩裂缝地质特征出发,优选敏感偏移距及方位角OVT道集,利用纵波方位各向异性技术预测花岗岩裂缝发育强度及走向;同时结合FMI测井、试油等数据得到具有实际地质意义的裂缝发育强度及走向结果。以中非花岗岩潜山裂缝储层为例,预测出的花岗岩裂缝发育特征与研究区构造地质特征吻合,单井预测走向与FMI测井一致,裂缝强度与试油产液量一致,验证了方位各向异性井震联合花岗岩裂缝预测方法的可靠性,并且使得裂缝预测精度得到很大提高。

Fracture prediction is one of the challenges in the exploration and development of granite fractured reservoirs.Based on geological characteristics of granite fracture,this paper optimally selects sensitive offsets and azimuth OVT gathers,and then predicts fracture strength and strike using P wave azimuthal anisotropy technology.Meanwhile,the FMI logging and testing data are used synthetically to obtain the fracture strength and strike with actual geological significance.Results from field tests on granite fractured reservoirs in Central Africa showed that the prediction of fracture development characteristics for granite basement are in agreement with the structural geology characteristics in the study area.The prediction of fracture strike in single wells is in agreement with FMI logging results,and the prediction of fracture strength is in agreement with fluid production of oil testing.The fracture prediction accuracy is improved to 80%from 50%by poststack seismic data.The test results show that the proposed method of azimuthal anisotropy is effective for granite fracture prediction by well seismic joint.