收稿日期: 2013-05-14
修回日期: 2013-10-07
网络出版日期: 2014-05-10
基金资助
国家重点基础研究发展规划项目“页岩气气藏工程方法基础研究”(编号:2013CB228005)资助.
Study on Numerical Well Test Method of Gas Reservoirs with Large-scale Fractures
Received date: 2013-05-14
Revised date: 2013-10-07
Online published: 2014-05-10
裂缝性气藏因储层中存在不同尺度的天然裂缝，总体表现为较强的非均质性。传统描述裂缝性气藏的双重介质及其扩展模型对于气藏等效过于理想，不能很好地解释裂缝特征参数对其试井曲线的影响。为此，根据蒙特卡罗法随机裂缝产生方法和非结构Voronoi网格数值生成方法产生气藏含有大尺度裂缝的离散裂缝网格模型，进一步采用控制体有限差分法建立对应的数学模型并利用全隐式法求解。最后在实例证明离散裂缝网络模型试井曲线正确性基础上，讨论并分析了大尺度裂缝特征参数(数量、角度、长度)对试井曲线的影响。研究结果表明：裂缝特征参数主要影响压力导数后期的曲线；裂缝数量越多，后期压力导数曲线下降幅度越大；裂缝长度越长，则压力导数曲线下降出现的时间越早，且下降幅度越大；裂缝角度对试井曲线特征总体影响不大，但当裂缝角度与井径向网格方向基本一致时，压力导数曲线下降出现时间最早，且下降幅度最大。
魏明强,段永刚，李彦波，方全堂，姚陆峰 . 存在大尺度天然裂缝的气藏数值试井分析方法[J]. 天然气地球科学, 2014 , 25(5) : 778 -782 . DOI: 10.11764/j.issn.1672-1926.2014.05.778
fractured gas reservoir has very strong heterogeneity when natural fractures with different scale exist.The traditional Dual Porosity Model and its extended models can′t explain precisely about the effect of the fracture factors on the well-test curve,because these models are too idealistic for the gas reservoir.Thus,the paper presents a discrete fracture network model for gas reservoirs which contain large-scale fractures based on Monte Carlo random fractures method and Voronoi Non-Structural grid method,then founds math model of reservoir by Controlling Volume Finite difference method,and uses the fully implicit method for solving problems.Finally,after proving the well test curve of discrete fracture network model by the real well test curve of fractured reservoir,the well-test curve effected by large-scale fracture parameters (including numbers,angles,length) are discussed.The research results suggest that:the late pressure derivative curve is affected by the fracture characteristic parameters;the more number of fractures is,the greater decline of late pressure derivative curve;the longer of the length of fracture is,the earlier of late pressure derivative curve will appear,also the greater decline of late pressure derivative curve;the angle of fracture has little effect on the late pressure derivative curve,but when the fractures′ angle is basically the same with the well radial grid direction,the pressure derivative curve decreased the earliest and had the biggest drop.
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