牛丛丛, 刘曰武, 蔡强, 李海生. 煤层气井气水两相分布不稳定试井模型[J]. 力学与实践, 2013, 35(5): 35-41. DOI: 10.6052/1000-0879-13-161
引用本文: 牛丛丛, 刘曰武, 蔡强, 李海生. 煤层气井气水两相分布不稳定试井模型[J]. 力学与实践, 2013, 35(5): 35-41. DOI: 10.6052/1000-0879-13-161
NIU Congcong, LIU Yuewu, CAI Qiang, LI Haisheng. TRANSIENT WELL TEST MODEL FOR THE WELL WITH GAS AND WATER DISTRIBUTED IN COALBED[J]. MECHANICS IN ENGINEERING, 2013, 35(5): 35-41. DOI: 10.6052/1000-0879-13-161
Citation: NIU Congcong, LIU Yuewu, CAI Qiang, LI Haisheng. TRANSIENT WELL TEST MODEL FOR THE WELL WITH GAS AND WATER DISTRIBUTED IN COALBED[J]. MECHANICS IN ENGINEERING, 2013, 35(5): 35-41. DOI: 10.6052/1000-0879-13-161

煤层气井气水两相分布不稳定试井模型

TRANSIENT WELL TEST MODEL FOR THE WELL WITH GAS AND WATER DISTRIBUTED IN COALBED

  • 摘要: 煤层气是一种高效清洁的非常规天然气资源,其开采过程是一个排水降压采气的过程. 由于煤层气主要是以吸附态的形式存在于煤层中,当煤层压力降低到临界解吸压力以下时煤层气从煤层中解吸出来并与水一起采出,因此煤层中流体是气水两相分布的. 本文根据煤层气藏排采过程中的解吸特征,通过考虑气水两相分布的渗透率关系,提出了一种与解吸区域大小相关的煤层气井不稳定试井模型. 该模型较好地描述了煤层气排采过程中煤层内气水的流动状态,采用分区模式对气水两相进行描述. 通过有限体积方法求解了所建立的试井模型,计算得到了煤层气井气水两相分布不稳定试井理论曲线,分析了煤层气解吸系数、解吸复合半径、气水饱和度分布等对试井理论曲线的影响.

     

    Abstract: Coalbed methane (CBM) is a kind of efficient and clean unconventional gas resources, and its producing process is mainly drawing down the formation pressure by draining water. CBM is primarily adsorbed in the coal rather than the most conventional gases stored in the pore space. CBM is desorbed from the coal when the coal bed pressure is lower than the critical desorption pressure, and is produced out with water. So, the fluids in coalbed are gas and water in different distributions. This paper introduced a set of transient well test model on the basis of desorption characteristic of CBM, the permeability relationships depended on gas and water distributions and the size of desorption area. The flow state of gas and water was described very well by using the separated areas in the CBM producing process. The model was solved by using finite volume method(FVM), and its type curves were obtained. The effects of the desorption coefficient, the desorption composite radius, the saturation distribution of gas and water, etc on type curves are analyzed. The research results of this study are of great guiding significance to develop CBM economically.

     

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