A calculation method for brittleness index of shale gas reservoirs based on the imaging spectroscopy mineral maps: A case study of the Lower Silurian Longmaxi shale gas reservoir in the southern Sichuan Basin

被引：0
|
作者：
Yan L. [1 ,2 ]
He C. [2 ]
Hou K. [2 ]
机构：
[1] College of Energy, Chengdu University of Technology, Chengdu, 610059, Sichuan
[2] Sinopec Southwest Oilfield Service Corporation, Chengdu, 610000, Sichuan
来源：
Natural Gas Industry | 2019年 / 39卷 / 02期
关键词：
Brittleness index; Calculation model; Early Silurian; Evaluation and fracturing performance; Imaging mineral spectrum; Reservoir; Shale gas; Southern Sichuan Basin;
D O I：
10.3787/j.issn.1000-0976.2019.02.007
中图分类号：
学科分类号：
摘要：
The brittleness index of shale gas reservoirs is one of the key parameters for the fracturing scheme design. At present, however, the current method to calculate the brittleness index is expensive, time and labor consuming, and overly dependent on coring data. In view of this, the Lower Silurian Longmaxi shale gas reservoir in the southern Sichuan Basin was taken as the research object in this paper. Firstly, the imaging log data of this area was analyzed and corrected, the images were enhanced in the form of histogram and the imaging log image was calibrated as the imaging spectroscopy mineral map. Then, based on the theory of normal distribution, combined with experimental analysis data, the mineral content of shale gas reservoirs was estimated by analyzing the mineral map. Finally, based on fracture characteristics, the calculation model for brittleness index was established. In this way, a new method for calculating mineral content and brittleness index was developed and has been verified in many shale gas wells in this area. And the following research results were obtained. First, this new method has the advantages of low cost, strong applicability, high calculation accuracy and practical value. Second, compared with the brittleness index calculation methods that are currently used, the data obtained by the new method are universal and its brittleness index calculation results are continuous. Third, this new method can accurately reflect the effects of bedding, thin layer and local lithology change on the brittleness index, playing an important role in evaluating the brittleness and fracturing performance of shale gas reservoirs. Fourth, field application reveals that the calculation results of this new method are in a better accordance with the actual drilling results. Industrial productivity of sh ale gas is achieved in many wells of this area during the testi ng. In conclusion, this new method provides a technical support for fracturing opt imization and evaluation of marine shale gas reservoirs. © 2019, Natural Gas Industry Journal Agency. All right reserved.
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页码：54 / 60
页数：6
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