- 责任者：Wang Peng (State Key Laboratory of Petroleum Resources and Prospecting ; China University of Petroleum ; Beijing 102249 ; China) ; Ji Youliang
- 刊名：Natural Gas Industry
- 出版年：2013
- 卷期：33(12)
- 关键词：页岩气 ; shale gas ; 储层评价 ; reservoir evaluation ; 四川盆地 ; Sichuan Basin
- 页码：p.48-53
- 图表：6 illus., 1 table, 28 refs.
- 分类号：1003
- issnNo：ISSN1000-0976
- isbnNo：CN51-1179/TE
The brittleness of shale formation has an important impact on shale gas extraction. Brittle shale is favorable for the formation of natural fractures and the creation of complex fracture networks with good conductivity through fracturing, thus enhancing shale gas productivity. In order to understand shale brittleness, and to overcome the disadvantages of brittleness evaluation with a single technique, we proposed a comprehensive evaluation method that integrates X-ray diffraction, calculated elastic parameters and laboratory rock mechanics tests, i.e. comprehensively evaluating shale brittleness based on the analysis of mineral components, Pois- son＇s ratio, Young＇s modulus and S-P ratio as well as rock stress and strain characteristics. This comprehensive evaluation method was applied to brittleness evaluation of the black shale in the Lower Silurian Longmaxi Fm in Block W, Sichuan Basin. The following results were obtained. The brittleness of the second member of Longmaxi Fm is better than that of the first member. The shale in the interval of 1535 - 1541 m has a high content of quartz, a low Poissonrs ratio, a low S/P ratio, and a high Young＇s modulus. The shale sampled at a burial depth of 1541 m has a relatively steep negative slope in its stress-strain curve, and its brittleness index is greater than 50 M, being favorable for fracturing stimulation. Practices show that this method is highly effective and the evaluation results are in good consistence with the real fracturing test results, thus shale brittleness can be used as one of the major bases for fracturing optimization.