倪小明, 张崇崇, 王延斌, 王向浩. 单相水流阶段煤层气井裂隙水运移的临界裂隙尺寸数学模型[J]. 工程力学, 2015, 32(4): 250-256. DOI: 10.6052/j.issn.1000-4750.2013.10.0936
引用本文: 倪小明, 张崇崇, 王延斌, 王向浩. 单相水流阶段煤层气井裂隙水运移的临界裂隙尺寸数学模型[J]. 工程力学, 2015, 32(4): 250-256. DOI: 10.6052/j.issn.1000-4750.2013.10.0936
NI Xiao-ming, ZHANG Chong-chong, WANG Yan-bin, WANG Xiang-hao. MATHEMATICAL MODELS ABOUT THE CRITICAL SIZE OF COAL RESERVOIR FRACTURE MAKE OF WATER MIGRATION FOR SINGLE-PHASE COALBED METHANE WELLS[J]. Engineering Mechanics, 2015, 32(4): 250-256. DOI: 10.6052/j.issn.1000-4750.2013.10.0936
Citation: NI Xiao-ming, ZHANG Chong-chong, WANG Yan-bin, WANG Xiang-hao. MATHEMATICAL MODELS ABOUT THE CRITICAL SIZE OF COAL RESERVOIR FRACTURE MAKE OF WATER MIGRATION FOR SINGLE-PHASE COALBED METHANE WELLS[J]. Engineering Mechanics, 2015, 32(4): 250-256. DOI: 10.6052/j.issn.1000-4750.2013.10.0936

单相水流阶段煤层气井裂隙水运移的临界裂隙尺寸数学模型

MATHEMATICAL MODELS ABOUT THE CRITICAL SIZE OF COAL RESERVOIR FRACTURE MAKE OF WATER MIGRATION FOR SINGLE-PHASE COALBED METHANE WELLS

  • 摘要: 查明煤层气井排采的单相水流阶段裂隙水运移的裂隙临界尺寸大小,能为煤层气井的压力传播研究提供理论依据。根据煤储层孔裂隙结构特征,构建了煤储层地质概念模型;基于弹塑性力学理论,构建了单相水流阶段煤储层裂隙中水运移的力学平衡方程;结合有效应力原理和损伤理论分析了裂隙周围的应力分配与损伤演化,建立了一种适用于不同储层条件的单相流阶段水运移的煤储层裂隙临界尺寸的数学模型。晋城寺河矿煤储层条件下的计算结果表明:原始状态下煤储层水运移的临界尺寸为0.1μm,所得结果与其他学者实验室测试结果基本相符。同时还得出:随着排采过程中水的产出,水运移的煤储层裂隙的临界尺寸有增大的趋势,但变化幅度较小,仍在0.1μm左右。所建模型能较准确预测不同条件下煤储层单相水流阶段水运移的煤储层裂隙临界尺寸及排采过程中临界尺寸的变化规律。

     

    Abstract: Identifying the critical size of coal reservoir fracture for single-phase water migration drained by coal bed methane (CBM) well provides the study of pressure transmission in CBM wells with theoretical basis. A geological conceptual model for coal reservoirs was established according to the characteristics of the fracture structure of coal reservoirs. Based on the elastic-plastic mechanical theory, the dynamic equilibrium equation of the water migration in coal reservoir fracture in its single-phase water flow stage was constructed. By combining effective stress principle and damage theory, the stress distribution and damage evolution around the fracture were analyzed, and the mathematical model of the critical size of coal reservoir fracture for water migration in its single-phase water flow stage was built. The calculation for the critical size of the coal reservoir fracture in Sihe mine in Jincheng showed that the critical size of water migration in coal reservoir was 0.1 μm in its original state. The result is basically in an agreement with the results of laboratory tests carried out by other scholars. Meanwhile, with the generation of water in a drainage process, the critical size of coal reservoir fracture for water migration increases slightly, which is still around 0.1 μm. The model established accurately predicts the critical size of coal reservoir fracture in varied conditions in its single-phase water flow stage, and the changing regulation of the critical size in drainage process.

     

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