准噶尔盆地西北缘二叠系火山岩储层裂缝发育特征及分布预测——以金龙2井区佳木河组为例

准噶尔盆地西北缘金龙2井区二叠系佳木河组裂缝是该区火山岩储层油气主要的渗流通道。综合岩心、岩石薄片及成像测井等资料,识别出该区主要发育的裂缝类型为半充填或未充填高角度缝,其次为半充填低角度斜交缝与网状缝。成像测井解释裂缝方位近东西向,与岩心古地磁解释现今地应力最大主应力方向近似平行,有效性开启较好。火山岩储层裂缝发育主要受构造与岩性两种因素影响。距离断层越近,由于构造曲率增大,裂缝越发育,裂缝多沿断裂呈条带状分布。不同的火山岩类型,裂缝发育程度也不同。通过成像测井资料分析,认为研究区中-酸性火山熔岩及火山碎屑熔岩裂缝较发育,并进一步定量计算出单井裂缝密度、裂缝倾角、裂缝孔隙度等,确定单井裂缝发育特征。结合叠前地震预测方法,即叠前方位各向异性法(AVAZ),优选衰减起始频率属性,预测了佳木河组火山岩储层裂缝分布特征。

Fracture Characterization and Prediction of Permian Volcanic Reservoir in Northwestern Margin of Junggar Basin：A Case from Jiamuhe Formation of Jinlong 2 Oil Field

The fractures of Jiamuhe Formation of Permian volcanic reservoir are the main flowing channels for the reservoir in Jinlong 2 oil field .Through core observation ,thin slice identification ,and image logging data , the fracture types are identified : Unfilled or half‐filled high‐angle fractures are mainly develop in the reservoir ,followed by half‐filled low‐angle oblique and netted fractures .The main orientations of fractures interpreted by image logging data are nearly EW , and parallel with the current maximum principal stress direction .The fracture development in the volcanic reservoir is mainly affected by two factors :the tectonic position and rock type .The closer it is to the fault ;the bigger the structure curvature is ,and the greater the fractures are developed .They distributed zonally along the fault .The types of volcanic rocks impact the degree of fracture development .Through the image logging data analysis ,the fractures mainly developed in the intermediate‐acid volcanic lava and pyroclastic lava . The fracture density ,fracture dip ,and fracture porosity of single well can be quantitatively calculated . Combining with the method of amplitude versus azimuth (AVAZ ) in pre‐stack fracture detection technology , the fracture distribution in volcanic reservoir of Jiamuhe Formation can be predicted effectively and accurately .This study provides a reliable basis for a deployment of development well in a volcanic reservoir .