Quantification of Gas Accumulation Efficiency of Tight Sandstone Gas Fields: Case Studies of Sichuan and Ordos Basin, China

Wang, Feiyu ¹; Zhang, Hui ¹; Wang, Hao ¹; He, Zhiyong ²
(1)Institute of Geoscience, China University of Petroleum, Beijing, China. (2) ZetaWare, Inc, Sugar Land, TX.

The source rocks in close physical proximity to reservoir rock are peculiar to the many tight sandstone gas fields, which result in secondary and tertiary migration loss are relatively small, therefore most of expelled gas from source rocks were accumulated in proximity to source rocks. Sulige tight sandstone gas field of Ordos basin, Guangan, Hechuan and Tongnan tight sandstone gas fields of Central Sichuan basin, are selected as quantitative, calibrated case studies that describe the relationships between source kitchen, fetch area, burial and uplift history, volume of expelled gas, gas resource size, to quantify gas accumulation efficiency from source kitchen to trap. Refined geological architecture have been established with 3D seismic and well strata data, and coal measure source rock have been drilled through and geochemical scanning analysis data are upgraded with ΔlogR algorithms to describe the heterogeneous source rocks(coal, carbonaceous shale, shale with different TOC intervals). Charge volume history of the play and prospect are calculated from expelled gas volumes of the fetch areas using Trinity 3D, and calibrated with measured data. Gas accumulation efficiency and possible scenario of gas generation and accumulation history,can be postulated through comparison volume of expelled gas and gas resource size, as well as measured carbon isotope data with calculated results, gas accumulation efficiency in the three gas fields in central Sichan and Sulige gas field in Ordos range from 12% to 35%, which much higher than previous opinion.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.