临汾区块煤层气井提产阶段排采控制研究  

Study on gas drainage control of CBM well in stage of increasing production in Linfen Area

作　　者：巢海燕[1,2] 聂志宏 王伟 张慧 CHAO Haiyan;NIE Zhihong;WANG Wei;ZHANG Hui(College of Geoscience and Surveying Engineering, China University of Mining and Technology(Beijing),Beijing 100083,China;Petrochina Coalbed Methane Company Limited, Beijing 100028,China)

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [2]中石油煤层气有限责任公司,北京100028

出　　处：《煤炭科学技术》2019年第4期218-224,共7页Coal Science and Technology

基　　金：国家科技重大专项资助项目(2016ZX05042002);中国石油天然气股份有限公司重大科技专项资助项目(2017E-1405)

摘　　要：为查找出影响临汾区块煤层气高产稳产井和峰后下降井稳产效果差异的原因,分别对高产稳产井和峰后下降井提产阶段的井底压力下降速度、日产气增速等排采控制指标进行了对比分析,首次揭示出了产气速度对煤储层压降扩展的影响机理及在排采控制中的重要性,制定出了临汾区块煤层气井提产阶段的排采参数控制指标与方法。研究表明:峰后下降井稳产效果差的原因在于提产阶段未对井底压力降速和日产气增速进行缓慢控制;产气速度过快,易引起大颗粒煤粉运移造成堵塞,且近井地带煤层中的气相相对渗透率快速增加,水相相对渗透率急剧下降,水的流动阻力增大,影响水的有效排出,造成压降扩展变慢;临汾区块煤层气井提产阶段的压降速度合理值应控制不超过0.01MPa/d,日产气增速应控制不超过15 m^3/d为宜,可采用阶梯式稳产、提产交替进行的方式进行提产。In order to find out the reasons that affect the CBM production difference between the stable and high-yield production wells and the post-peak production-descending wells in the Linfen Area, the speed of pressure drop in well bore and the growth rate of daily gas production in the production stage of both types of wells were contrasted and analyzed. The influence mechanism of fast gas production on pressure drop expansion of coal reservoir and its importance in drainage control was revealed and the control indexes and method for CBM well drainage parameters in the increasing production stage in Linfen were are formulated. The study results show that the reason for the poor stable production effect of the post-peak production-descending wells lies in the fact that the down hole pressure deceleration and the daily gas production increase rate are not slowly controlled during the production stage. If gas production rate is too fast, the migration of large pulverized coal particle and clogging will be induced by gas-water bubble flow. At the same time, gas saturation and its relative permeability in near borehole zones increase, and water relative permeability decreases as the flowing resistance is growing, which influence the effective discharge of water and cause pressure drop transmission becoming slower and hindered. The reasonable value of pressure drop speed in the increasing production stage of CBM wells in Linfen Area should not exceed 0.01 MPa/d, and the growth rate of daily gas production should be less than 15 m 3/d. It is advisable to use stepwise stable production and alternate production.

关 键 词：煤层气 提产阶段 渗透率 产气速度 排采 

分 类 号：TE132.2[石油与天然气工程—油气勘探]