Reservoir Characterization of Shale Gas Reservoir Using Seismic: The Case Study of Da’anzhai Member in Eastern Sichuan Basin

Yuting He¹, Zhongping Li², Ping Deng², Xiaona Yu², and Xinwei He^1
1Jason, Beijing office, Chaoyang District, Beijing, China
²Jianghan Oil Field, Sinopec, Wuhan, Bubei Province, China

Shale gas resources have emerged as a viable energy source in the last decade and more. The reservoir characterization job of shale gas reservoir is an international problem. It is different with the traditional approach. As different shale gas reservoirs have different properties, different method should be determined based on its individual geological attributes. In summary, the aims of geophysical is to find the areas with the characteristics organic richness and high brittleness, this information can be used to determine the optimal well bore trajectory. This paper demonstrates the workflow of reservoir characterization of Da’anzhai shale gas reservoir using seismic in eastern Sichuan Basin.

The Da’anzhai member is composed of a suite of lacustrine deposits in eastern Sichuan Basin. There are three sub-members (Da 1, Da 2 and Da 3) in it. Da 2 sub-member is the target layer, it is also the main shale-gas reservoir in this region, which is composed of black shale and a few thin limestone intervals. Core analysis shows the TOC content of Da 2 shale is about 0.5%~2%, and 40% samples is 1%~2% , indicating favorable geologic conditions for shale gas. It is imperative to study them before any exploitation plan is put in place. Figure1 shows the whole workflow of sweet spots predict of shale gas. The workflow is summarized as based on well logging interpretation and rock physical analysis, integrated use of seismic inversion, facies fluid probabilities technology and other technologies to delineate distribution, thickness, fractures, geomechanical characteristics of shale reservoir, and then look for shale gas "sweet spot", design horizontal wells bore trajectory. We discuss key steps of this workflow below.

AAPG Datapages/Search and Discovery Article #90180©AAPG/SEPM/China University of Petroleum/PetroChina-RIPED Joint Research Conference, Beijing, China, September 23-28, 2013