Journal Article

Methods for Shale Gas Play Assessment： A Comparison between Silurian Longmaxi Shale and Mississippian Barnett Shale

Songqi Pan Caineng Zou Zhi Yang Dazhong Dong Yuman Wang Shufang Wang Songtao Wu Jinliang Huang Qun Liu Dule Wang Ziyuan Wang

2015

Overview

Based on field work, organic geochemical analyses and experimental testing, a six-property assessment method for shale gas is proposed. These six properties include organic matter properies, lithofacies, petrophysical properties, gas content, brittleness and local stress field. Due to the features of continuous distribution over a large area and low resource abundance in shale plays, a sweet spot should have these following properties： （a） TOC〉2%; （b） brittle minerals content （〉40%） and clay minerals （〈30%）; （c） Ro （〉1.1%）; （d） porosity （〉2%） and permeability （〉0.000 1 mD）, and （e） effective thickness （30-50 m）. Applying these criteria in the Sichuan Basin, the Silurian Longmaxi shale consists of four prospecting sweet spots, including blocks of Changning, Weiyuan, Zhaotong and Fushnn-Yongchuan. Although these four blocks have some similarities, different features were usually observed. After comprehensive analyses using the six-property assessment method, the Fushun-Yongan Block ranks the most favorable sweet spot, followed by the Weiyuan Block. For the other two blocks, the Changning Block is better than the Zbaotong Block. By comparing with the Mississippian Barnett shale, characteristics that are crucial for a high-yielding in the Sichuan Basin include a high content of organic matter （TOC〉2.5%）, a moderate thermal maturity （Ro=0.4%-2%）, a high content of brittle minerals （quartz： 30%-45%）, a high gas content （〉2.5 m^3·t^-1）, and types I and II1 kerogen.

• Publisher: China University of Geosciences,Springer Nature B.V,School of Earth and Space Sciences, Peking University, Beijing 100871, China%Research Institute of Petroleum Exploration&Development, PetroChina, Beijing 100083, China%Southwest Petroleum University, Chengdu 610500, China
• Subject: Assessments / Basins / Biogeosciences / Brittleness / Clay minerals / Criteria / Earth and Environmental Science / Earth science / Earth Sciences / Geochemistry / Geology / Geotechnical Engineering & Applied Earth Sciences / Kerogen / Minerals / Oil shale / Organic matter / Permeability / Porosity / Shale / Shale gas / Shales / Silurian / Spots / Sweets / 地球化学分析 / 志留系 / 播放 / 气体含量 / 矿物质含量 / 评价 / 评估方法 / 页岩气