Combined petrophysics and 3D seismic attributes to predict shale reservoirs favourable areas

Abstract

AbstractTo achieve the economic and effective development of shale gas, it is not only necessary to determine favourable geological areas but also to pay more attention to favourable engineering areas. Geologically favourable areas are measured on their total organic carbon (TOC) content, thickness of high-quality shale and fractures, and favourable engineering areas are assessed on brittleness and fractures, but in most cases fractures occur in both geological and engineering favourable areas. The Zhao104 well is located in the Sichuan Basin in China, in the Longmaxi (LMX) Formation, and has an abundant shale gas content based on drilling and well log interpretation. It is necessary to clarify the distribution of shale gas favourable areas in this area, which plays a vital role in determining horizontal wells. In this paper, petrophysics and three-dimensional seismic attributes are used to predict the favourable shale reservoir area. Based on the petro-physical model, the most sensitive elastic parameters of the TOC content and brittleness are determined, a relationship model of the sensitive elastic parameters with TOC content and brittleness is created from logs and pre-stack inversion is used to characterize the shale brittleness, TOC content and thickness of high-quality shale. Different scale seismic fracture attributes are used to predict the strength and direction of fractures. The field data show that combined petrogeophysics and 3D seismic attributes can effectively predict a favourable shale reservoir area, reducing the need for exploration and development risks.