塔北隆起西部缝洞型碳酸盐岩储层表征与评价

Characterization and evaluation of fracture-cavity type carbonate reservoir in the western part of Northern Tarim uplift

缝洞型碳酸盐岩储层存在强烈的空间非均质性,储层表征与评价难度极大。塔北隆起西部W区块奥陶系中统顶部发育稳定的台地相碳酸盐岩缝洞型储层。应用古地理坐标转换构造建模技术、测井储层分析方法,并结合缝洞型储层地震属性进行储层相研究,以储层相分析成果为基础建立双孔隙度模型,对缝洞型储层进行定量表征,最后结合AVO流体预测,进行综合评价。研究表明:该区碳酸盐岩储层类型主要为裂缝型、裂缝孔洞型,裂缝既是储集空间又是孔洞形成的诱导因素;本征值裂缝属性和地震波形分类属性对裂缝与孔洞响应较为敏感;储层含油饱和度提高之后,AVO现象更趋明显,叠前AVO反演的流体预测技术能对缝洞型碳酸盐岩储层流体进行合理预测、评价。

Fracture-cavity type carbonatite reservoir has strong dimensional anisotropism, and hence reservoir characterization and eval-uation are very difficult. The plateau facies carbonatite fracture-cavity reservoir is stably developed in Middle Ordovician strata in west-ern W block of northern Tarim uplift. Utilizing paleo-geographic coordinate transform, logging reservoir analysis and sensibility attribu-tor analysis of the fracture-cavity type carbonatite reservoir, the authors studied the reservoir facies. Based on reservoir facies research and utilizing stochastic method, the authors built the dual porosity model for fracture-cavity reservoir, and characterized the carbonatite reservoir. Finally, in combination with AVO inversion and reservoir characterization, the carbonatite reservoir was evaluated. It is proved that the reservoir pattern in the study area is mainly of the fracture and cavity type, with fractures acting both as hydrocarbon ac-cumulation space and as the factor for the formation of cavity. AFE （ Automatic Fault Extraction） and wave classification attribution were sensitive to the fracture and cavity type reservoir. With increasing oil saturation, AVO of the reservoir became more obvious. The fluid prediction method based on pre-stack AVO inversion could reasonably forecast oil province of carbonnate reservoir.