煤层气产能预测新模型
A New Method of Productivity Prediction for Coal-Bed Methane Based on Equivalent Seepage Resistance Theory
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- 引用格式:
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王琰琛,陈胜,孙兰兰.煤层气产能预测新模型[J].天然气与石油,2018,36(4):0.doi:
Wang Yanchen, Chen Sheng, Sun Lanlan.A New Method of Productivity Prediction for Coal-Bed Methane Based on Equivalent Seepage Resistance Theory [J].Natural Gas and Oil,2018,36(4):0.doi:
- DOI:
- 作者:
- 王琰琛1 陈 胜2 孙兰兰3
Wang Yanchen1, Chen Sheng2, Sun Lanlan3
- 作者单位:
- 1.中国石化胜利石油工程公司井下作业公司,2.中国石油西部钻探工程有限公司钻井工程技术研究院,3.中国石化胜利油田分公司胜利采油厂
1. Downhole Service Company of Shengli Service Corporation , Dongying, Shandong, 257091,China； 2. Xibu Drilling Engineering Company, CNPC, Karamay, Xinjiang, 834000, China ; 3. Sinopec Shengli Oilfield Branch
- 关键词:
- 煤层气;吸附;扩散;等效连续介质理论;等效渗透率;稳态;IPR曲线
Coal-bed methane; Adsorption; Diffusion; Equivalent continuum theory; Equivalent permeability; Steady state; IPR curve
- 摘要:
- 煤层气藏通常采用压裂直井开发,由于其吸附、解吸和扩散特征,运用常规二项式产能方程分析煤层气藏稳态产能会产生较大误差。根据煤层气藏天然裂缝发育的地质特征,运用平行板理论、等值渗流阻力原理,首次建立了针对煤层气藏,考虑其吸附、解吸、扩散特征的连续等效介质模型。该模型将裂缝性双重孔隙介质的煤层气藏转化为运用等效渗透率表征的常规均质气藏,但对各相关参数赋予特殊值时,可简化得到各类常规气藏模型。通过计算分析煤层气藏压裂直井的IPR曲线,可以看出当考虑解吸扩散时,其IPR曲线异于常规气藏。兰格缪尔压力越小,曲线下凹越严重,绝对无阻流量越大;兰格缪尔体积越小,扩散系数越小,曲线下凹越严重,绝对无阻流量越小。通过实际对比分析,该模型误差小于10 ,具有较好的适应性。
Vertical well with hydraulic fractures is applied to develop coal-bed methane reservoir. Besides, due to the existence of adsorption, desorption and diffusion, it can induce large errors to analyze well performance of coal-bed methane with conventional binomial production equation. Therefore, in terms of natural fractured coal-bed methane reservoir, this paper initially establishes the equivalent continuous medium model with consideration of adsorption, desorption and diffusion using parallel-plate theory, equivalent seepage resistance principle.This new model can convert fractured dual-porosity coal-bed methane reservoir into homogeneous gas reservoirs characterized with certain equivalent permeability.It also can be simplified to various conventional gas reservoirs with special values of the relevant parameters.Taking the desorption and diffusion of coal-bed methane into consideration, IPR curves are different from that of conventional gas reservoirs,the smaller the Langmuir pressure, the deeper the curve concaves and the larger the absolute open-flow potential,while the smaller the Langmuir volume or the smaller the diffusion coefficient, the deeper the curve concaves and the smaller the absolute open-flow potential.Through the actual comparative analysis, the error of this model is less than 10% and this model has certain practical value.
