陆相页岩油甜点地球物理表征研究进展

针对中国东部陆相页岩油甜点地球物理预测技术适应性不足等问题,从基础研究入手,构建陆相页岩油层岩石物理模型,分析地球物理响应特征;开展地质-测井-地球物理融合分析,认为富有机质纹层状岩相+裂缝为富集主控因素;在岩相、TOC、物性、含油性、脆性、压力、地应力等地震预测方法研究的基础上,攻关纹层状岩相、裂缝及地应力地球物理预测技术。基于岩石物理模型与各向异性叠前反演,形成层理缝密度预测方法,将层理缝密度地震属性作为沉积约束参数,实现纹层状岩相有效预测;基于正交各向异性介质AVAZ属性,提高裂缝表征精度;基于岩石三模量实现地应力大小预测,基于层间速度变化率预测地应力方向。通过研究,厘清了陆相页岩油甜点要素,明确了甜点要素指标体系以及岩石物理、地球物理响应特征,完善与建立了相应的甜点地球物理表征方法,在济阳坳陷预测了页岩油有利目标区。

Progresses in geophysical characterization of continental shale oil sweet spots

There are still many challenges on geophysical characterization of continental shale oil sweet spot in Eastern China in terms of technique applicability.Petrophysical models for continental shale oil layers are established to analyze geophysical responses based on the study on the fundamentals of continental shale oil.It's believed that the controlling factors for shale oil accumulation are organic-rick laminated lithofacies and fractures,following the integrated investigation of geology,well logging and geophysics.Besides,based on the existing methods for seismic prediction including lithofacies,TOC,rock physical property,oil bearing properties,brittleness,pore pressure and in-situ stress,new geophysical prediction methods are built for laminated lithofacies,fracture and in-situ stress.Based on petrophysical models and anisotropy pre-stack inversion,new methods are developed to predict the density of bedding-parallel fractures in shale,which is in turn regarded as a constraint for sedimentary analysis,so as to effectively predict the distribution of the laminated lithofacies.Orthorhombic anisotropy AVAZ algorithm is given to improve the seismic characterization of fractures;while the prediction of in-situ stress is achieved based onYoung's modulus,bulk modulus,and modulus of rigidity,and the direction of in-situ stress can be computed from interval velocity variation.The study clarifies the main controlling factors for continental shale oil sweet spots,establishes an index system for sweet spots,reveals the characteristics of petrophysical and geophysical responses of sweet spots,and optimizes the geophysical characterization method for sweet spots.These methods are successfully used to identify the favorable target areas for continental shale oil exploration in Jiyang Depression.