煤层气水平井开发的理论技术初探——兼论煤层气和页岩气开发条件对比  

Preliminarily exploring the theories and technologies for coalbed methane production using horizontal wells:Comparison of conditions for coalbed methane and shale gas exploitation

作　　者：王红岩 段瑶瑶[3] 刘洪林 赵群[2,3] 陈尚斌 卢海兵[3] 施振生[2,3] 孙钦平[3] 陈振宏 周尚文[1,2] 杨明伟[1,2] 王聪 WANG Hongyan;DUAN Yaoyao;LIU Honglin;ZHAO Qun;CHEN Shangbin;LU Haibing;SHI Zhensheng;SUN Qinping;CHEN Zhenhong;ZHOU Shangwen;YANG Mingwei;WANG Cong(PetroChina National Institute of Excellence Engineers,Beijing 102200,China;National Energy Shale Gas Research and Development Center,Beijing 100083,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221008,China)

机构地区：[1]中国石油国家卓越工程师学院,北京102200 [2]国家能源页岩气研发(实验)中心,北京100083 [3]中国石油勘探开发研究院,北京100083 [4]中国矿业大学资源与地球科学学院,江苏徐州221008

出　　处：《煤田地质与勘探》2024年第4期47-59,共13页Coal Geology & Exploration

基　　金：中石油集团公司前瞻性基础性科技项目(2021DJ19,2022DJ80)。

摘　　要：经过30 a的不懈探索,我国煤层气开发井型逐渐由直井向水平井开发过渡,水平井开发煤层气的基础理论是制约当前煤层气开发的主要问题。和页岩相比,煤层页理和脆性矿物不发育,非均质性更强,不利于体积缝网的形成。但煤层顶底板封盖强,机械强度高,具备较好的水力压裂条件。部分煤层裂隙被方解石等填充,酸化有利于储层渗透率改善和复杂裂缝形成。因此,建立一套适合煤层气储层特征的水平井开发工艺尤为重要。针对煤层地质特征,从水平井长度优化、簇间距优化、压裂液选择、支撑剂选择、返排率、最终可采储量(EUR)特征6个方面,系统分析煤层气水平井开发技术经济政策,认为煤层气水平段长度一般不超过1000 m,簇间距15~30 m储层改造效果较好;深部煤层气压裂液中加入滑溜水破胶剂及少量低温辅助破胶剂可提高破胶效率;相比中浅部煤层气储层,深部煤层压裂支撑剂应提高大粒径(0.425/0.850 mm)比例;深部煤层(如大吉区块8号煤)达到最高产气时的压裂液返排率与威远-长宁页岩气相近;煤层气EUR偏低,但用液强度、加砂强度大,应提高煤层气开发效率及经济效益等。煤层气开发效果受地质特征和开发工程技术协同控制,从地质工程一体化角度,提出下步煤层气水平井开发的对策,指出应进一步优化煤层气水平井开发工艺;完善水平井钻完井与配套技术,降低单井钻完井成本;依据煤粉迁移规律,实现煤层气水平井控粉有序返排,提高排采效果;依据游离与吸附气赋存比例,优化生产控制技术提升单井EUR。Through 30 years of unremitting explorations,coalbed methane(CBM)wells in China have gradually transitioned from vertical to horizontal wells.However,the lack of basic theories on CBM production using horizontal wells is the main challenge to current CBM development.Compared to shales,coal seams exhibit heterogeneity and a minor presence of foliations and brittle minerals,hindering the formation of volumetric fracture networks.Nevertheless,the roofs and floors of coal seams have high sealing capacities and mechanical strength,creating excellent conditions for hydraulic fracturing.Some fractures in coals are filled with calcite,rendering acidification conducive to the improvement of reservoir permeability and the formation of complex fractures.Hence,it is particularly important to develop a technology for CBM production using horizontal wells that is tailored for CBM reservoir characteristics.Targeting the geological characteristics of coal seams,this study systematically analyzed the technical and economic policies for CBM production using horizontal wells from six aspects:the optimization of the horizontal well section length and cluster spacing,the selection of fracturing fluids and proppants,flowback rate,and estimated ultimate recovery(EUR).Key findings are as follows:(1)Encouraging reservoir stimulation performance can be achieved under a horizontal well section length of 1000 m or below and a cluster spacing ranging between 15 m and 30 m;(2)Adding slippery water gel breakers and a small quantity of low-temperature auxiliary gel breakers into fracturing fluids can improve the gel-breaking efficiency of deep CBM reservoirs;(3)Compared to middle and shallow CBM reservoirs,the ratio of proppants with large grain sizes(0.425/0.850 mm)should be increased for deep CBM reservoir fracturing;(4)Under the highest gas yield,the fracturing fluids’flowback rate for deep CBM reservoirs(e.g.,the No.8 coal seam in the Daji block)resembles that for shale gas reservoirs in the Weiyuan-Changning area;(5)Given the low EUR but

关 键 词：深部煤层气 页岩气 开发条件 储层对比 水平井 

分 类 号：TE37[石油与天然气工程—油气田开发工程]