• 论文
主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
煤层气井单相水流拟稳态排采模型与应用效果分析
  • Title

    Single-phase water flow quasi-steady-state drainage model and its application effect analysis in coal-bed methane wells

  • 作者

    朱庆忠王宁张学英姚华杨延辉邹学学王晶孙晓波

  • Author

    ZHU Qingzhong1,2 ,WANG Ning1,2 ,ZHANG Xueying1,2 ,YAO Hua3 ,YANG Yanhui1,2 , ZOU Xuexue1,2 ,WANG Jing1,2 ,SUN Xiaobo3

  • 单位

    中国石油天然气股份有限公司 煤层气开采先导试验基地中国石油华北油田分公司 勘探开发研究院中国石油天然气股份有限公司 北京油气调控中心

  • Organization
    1. The CBM Exploration and Development pilot Test Base of CNPC,PetroChina Company Limited,Renqiu  062552,China; 2. Exploration and Development Research Institute,PetroChina Huabei Oilfield Company,Renqiu   062552,China; 3. Beijing Oil and Gas Center,PetroChina Company Limited, Beijing  100007,China
  • 摘要

    为实现煤层气井的定量化排采管控,有效提高单井产气量,以沁水盆地南部马必东试验区高阶煤为研究对象,依据裂缝储层饱和水单相渗流机理,分析了压裂返排后各级裂隙对排水效果的影响,结合压裂与排采数据,探讨了压裂改造范围内的压力传播特征,将排水区域划分为单相流弹性排水区与两相流弹性排水区,通过建立垂直裂缝线性流拟稳态模型,确定了与试验区地质条件相符的排采控制原则。研究表明:在饱和水单相流阶段,压裂裂缝是水相主要渗流通道,为水相强流动区,100 μm级(渗透率1×10-15~1.2×10-15m2)外生及微型裂隙对煤层应力、压力传播及气体解吸最为敏感,为水相弱流动区,排采过程中应同时考虑低压力梯度造成的非线性渗流效应与应力敏感作用;排采模型显示:在垂直裂缝拟稳态渗流阶段,储层压力分布呈抛物线型,近井区域产水量高于边界区域,表现为更易发生解吸,单相水流期的渗流阻力主要由煤岩渗透率、排采时间、煤岩压缩系数、裂缝尺寸、压裂改造半径、驱替压力梯度、孔隙压力等多种因素影响,为保证解吸气的连续、高效产出,马必东试验区按照“快-慢-缓”的排采原则,存在合理的排采界限(0.05~0.10 MPa/d);针对高阶碎裂煤,在定流压降幅条件下,产水曲线形态可划分为稳定型、上升型与下降型,同时反映了不同煤储层的供水特性,高产能井解吸前通常出现气驱水尖峰。

  • Abstract
    In order to realize the quantitative control of coal-bed methane wells,effectively improve the gas production per well,the high-rank coal in the Mabidong experimental area in the southern Qinshui Basin was taken as the re- search object. According to the single-phase seepage mechanism of saturated water in fracture reservoir,the influence of cracks on the drainage effect after fracture backflow is analyzed. Combined with fracturing and drainage data,the characteristics of pressure propagation within the range of fracturing transformation are discussed. The drainage area is divided into single-phase flow elastic drainage area and two-phase flow elastic drainage area. By establishing a vertical flow linear flow quasi-steady-state model,the drainage control principle consistent with the geological conditions of the test area is determined. The research shows that in the stage of saturated water single-phase flow,the fracture crack is the main seepage channel of the water phase,which is the strong flow region of the water phase,exogenous and micro- cracks of 100 μm (permeability 1×10-15 -1. 2×10-15 m2 ) are most sensitive to coal seam stress,pressure propagation and gas desorption,which is a weak flow zone of water phase. The nonlinear seepage effect caused by low pressure gra- dient and stress sensitive effect should be considered simultaneously in the drainage process. The drainage model shows that in the pseudo-steady-state seepage stage of vertical cracks,the reservoir pressure distribution is parabolic,and the water production in the near-well area is higher than that in the boundary area,which is more likely to desorb. The seepage resistance in the single-phase water flow period is mainly affected by various factors such as coal rock permea- bility,drainage time, coal rock compressibility coefficient, crack size, fracturing transformation radius, displacement pressure gradient,and pore pressure. In order to ensure the continuous and high-efficiency output of desorption gas,the Mabidong test area has a reasonable drainage limit (0. 05 -0. 10 MPa / d) according to the principle of " fast-slow- slow" drainage. For high rank fractured coal,the form of water production curve can be divided into stable,rising and falling types without the pressure drop of external water supply,and reflects the water supply characteristics of different coal reservoirs. Gas flooding spikes usually appear before desorption.
  • 关键词

    压裂返排饱和水单相流边界负滑移线性流拟稳态排采控制

  • KeyWords

    fracturing back;saturated water single phase flow;negative boundary slip;linear flow;quasi-steady state; drainage control

  • 基金项目(Foundation)
    国家科技重大专项资助项目(2017ZX05064);中国石油天然气股份有限公司重大科技专项资助项目(2017E-14)
  • DOI
  • Citation
    ZHU Qingzhong,WANG Ning,ZHANG Xueying,et al. Single-phase water flow quasi-steady-state drainage model and its application effect analysis in coal-bed methane wells[J]. Journal of China Coal Society,2020,45(3):1116-1124.

主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会

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