Liu Xiwu, Liu Yuwei, Liu Zhiyuan, et al. Progresses in geophysical characterization of continental shale oil sweet spots[J]. 2019, 40(3): 504-511.DOI: 10.11743/ogg20190306.
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.