沁水盆地南部煤层气直井合层排采产气效果数值模拟  

Numerical simulation of gas production for multilayer drainage coalbed methane vertical wells in southern Qinshui Basin

作　　者：刘世奇[1] 方辉煌 桑树勋[1] 胡秋嘉 段卫英 贾慧敏 毛崇昊 LIU Shiqi;FANG Huihuang;SANG Shuxun;HU Qiujia;DUAN Weiying;JIA Huimin;MAO Chonghao(Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization,Carbon Neutrality Institute,China University of Mining and Technology,Xuzhou 221008,China;School of Earth and Environment,Anhui University of Science and Technology,Huainan 232001,China;Shanxi CBM Branch of PetroChina Co.Ltd.,Changzhi 046000,China;Huabei Oilfield Company of PetroChina Co.Ltd.,Renqiu 062552,China)

机构地区：[1]中国矿业大学碳中和研究院江苏省煤基温室气体减排与资源化利用重点实验室,江苏徐州221008 [2]安徽理工大学地球与环境学院,安徽淮南232001 [3]中国石油天然气股份有限公司山西煤层气勘探开发分公司,山西长治046000 [4]中国石油天然气股份有限公司华北油田分公司,河北任丘062552

出　　处：《煤田地质与勘探》2022年第6期20-31,共12页Coal Geology & Exploration

基　　金：国家自然科学基金项目(41972168,42030810)。

摘　　要：随着煤层气勘探开发的深入,多煤层合层排采受到广泛关注。合层排采管控工艺是确保煤层气合采井高产稳产的关键,而多煤层组合条件下复杂的地质条件增加了合层排采管控的难度。数值模拟技术是研究煤层气井合层排采管控工艺的有效手段,科学、可靠的模拟结果可为合采井排采管控提供依据。考虑温度效应、煤基质收缩效应、有效应力作用对煤层流体运移规律以及渗透率等煤层物性参数的影响,建立煤层气直井合层排采生产动态过程多物理场耦合数学模型,并进行有限元法的多物理场耦合求解。通过对沁水盆地南部郑庄区块煤层气合采井组的模拟,探讨不同排采速率下煤层气直井合层排采产气效果及渗透率等煤层物性参数动态演化特征,提出煤层气直井合层排采工程建议。模拟结果显示,郑庄区块3号、15号煤层整体含气量较高,煤层气合采井组具有较大增产潜力,提高排采速率对提高煤层气采收率的效果不显著;排采过程中,煤基质收缩效应对渗透率的影响强于有效应力作用,是提高煤层气井排采速率的保障,在确保排采速率不超过煤层渗流能力上限的基础上,适当提高排采速率可实现煤层气井增产。基于模拟结果,建议排采速率的调整以控制动液面或液柱压力为主;以3号、15号煤层气合采井增产为目标,产水阶段和憋压阶段,郑庄区块煤层气直井合层排采速率以液柱压力降幅0.12~0.20 MPa/d或动液面降幅12~20 m/d为宜,既可实现煤层气增产,又可避免储层伤害。With the development of CBM(coalbed methane)exploitation,multilayer drainage of the CBM well has re-ceived wide attention.The production control technology is the key to ensure high and stable gas production of CBM well multilayer drainage.However,the complex geological conditions of multiple coal seams increase the difficulty of production control of multilayer drainage.Numerical simulation technology is an effective method to study the produc-tion control technology of CBM well multilayer drainage.The scientific and reliable simulation results can provide a basis for production control.In this study,considering the influence of temperature effect,shrinkage effect of coal mat-rix,and effective stress on the fluid migration law in the coal seam,permeability and other coal seam physical paramet-ers,the multi-physical field coupling mathematical model for the dynamic process of CBM vertical well multilayer drainage was established.The coupled solution of the multiple physical fields was obtained by using the finite element method.Then,the gas production effect of CBM vertical well multilayer drainage at different drainage rates and the dy-namic evolution characteristics of permeability and other coal seam physical parameters were discussed by simulating a multilayer drainage CBM well group in Zhengzhuang block,Qinshui Basin,and corresponding engineering proposals were also put forward.The simulation results show that the gas contents of No.3 and No.15 coal seams in Zhengzhuang block are relatively high,and the CBM well group has a great potential to increase production,causing an insignificant effect of increasing the drainage rate on improving CBM recovery.In the production process,the effect of coal matrix shrinkage on permeability is stronger than that of effective stress,which is the guarantee to improve the drainage rate of CBM wells.On this basis,an appropriate increase in the drainage rate can increase the production of CBM wells when the drainage rate does not exceed the upper limit of the seepage capacity

关 键 词：合层排采效果 煤层气直井 排采速率 动液面 合采井 日产气量 渗透率 沁水盆地郑庄区块 

分 类 号：P618.13[天文地球—矿床学]