Seismic Characterization for Tight Gas Sand With 3D3C Data

Zhou, Yijun; Peng, Chaoquan; Wang, Daxing; Xu, Shang; Xia, Mili; Zhang, Xinhua; Daoyong, Du; Yan, Ronghui; Zhang, Yuhua

In this paper, we showed our recent and improved results using land-based multicompoent (MC) surveys in the largest gas filed in China, Sulige gas filed. The main gas reservoir, known as He8 formation, is located between 3200 and 3600 m in depth and is interbedded with sand and shale. Because the reservoir is thin (3-10 m) and strongly anisotropic, the average porosity ranges 5-10% and permeability is 0.06-2 mD, it is a typical tight gas sand reservoir with low porosity low permeability, which is very difficult to characterize using P-waves alone.Compared to the conventional one-component P wave exploration, MC method is more effective in lithology prediction and fluid identification for the integration of both PP and PS data.

Based on detailed rock physics analysis, we select the most sensitive elastic properties for reservoir characterization in Sulige gas filed. Through PP and PS event matching and alignment, the PP and PS data in PP domain applies to joint interpretation and inversion is obtained. Much more seismic attributes could be extracted from MC seismic data than from PP, sensitive MC attributes are selected through detailed analysis of wells and seismic attributes. Joint prestack inversion of MC data based on Knot-Zoeppritz equation is applied for more accurate elastic properties. Most prospecting area is selected with crossplots of multiple sensitive elastic properties and analysis of MC attributes.

The joint simultaneous inversion of PP&PS effectively improves the precision of fluid identification. And the integration of MC attributes analysis and joint simultaneous inversion of MC data significantly enhance reservoir characterization and has greatly improved the success ratio of exploration well in the study area, the integrated MC techniques has been applied in the 3D3C area of tight gas sand and has been supported by more than 80 wells with a success ratio of 86.6%.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013