FMI资料在库车坳陷深层致密砂岩储层中的应用

APPLICATION OF FMI DATA IN DEEP TIGHT SANDSTONE OF KUQA DEPRESSION

库车坳陷白垩系致密砂岩储层埋深大、地震资料品质差,常规储层预测方法难以分辨该区沉积扇体内部结构及平面展布特征。通过岩心数据刻度FMI电成像资料分析了不同岩相及沉积构造的FMI成像响应特征,结合常规测井精细校正出研究区典型产气层的岩相,建立了辫状三角洲前缘、扇三角洲前缘4种典型微相砂体模型。认为研究区砂体展布受控于4个大型沉积扇体,扇体内部以板状交错层理中砂岩、板状交错层理细砂岩、斜层理细砂岩、槽状交错层理细砂岩的储集物性最好,且分布于主水道及水道分叉区。对区域地层沉积认识的深化,为致密砂岩储层预测奠定了基础。

Cretaceous tight sandstone reservoirs in Kuqa Depression are characterized by deep burial and poor seismic data quality, it is difficult for conventional reservoir predicting methods to identify the inner structures and planar distribution features in the sedimentary fan bodies. Through FMI （ formation microresistivity imaging ） data calibrated by the core data, the FMI response characteristics of different lithofacieses and sedimentary structures are analyzed, the lithofacieses of the typical gas-bearing reservoirs in the area are finely corrected by integrating the conventional well loggings, and moreover four typical microfacies sandbody models are established for braided delta front and fan delta front. The study shows that the sandbody spread and distribution are controlled by four largesized sedimentary fans, the best physical accumulating properties in the above fans are presented in the medium sandstone with platy cross bedding, fine sandstone with sheet-like cross bedding, fine sandstone with diagonal bedding and fine sandstone with trough cross-stratification, and furthermore distributed in the main water channels and water braiding area. The further understandings of regional formation sedimentation have laid a basis for the prediction of the tight sandstone reservoirs.