沁水盆地煤层气田试采动态特征与开发技术对策

沁水盆地煤层气资源丰富，中国石油天然气集团公司于1994年起在该盆地内开展了大规模的勘探、试采和正式开发准备工作。从气田动态分析入手，系统研究了该煤层气田的开采特征。结果认为：压裂增产、多分支井是开发该煤层气田的有效手段；3#煤产气量高低与其地质因素关系密切；在煤层气排采过程中应保持动液面稳定下降。结合煤层气开采动态特征，提出了沁水盆地煤层气田合理的开发技术对策：①采用地面垂直井和多分支水平井相结合的方式开发该地区的煤层气资源，在此基础上优化合理的井网部署方式和增产方式；②3#、15#煤层的地质条件差异较大，建议优先考虑开采3＃煤层，15＃煤层在3＃煤层产量下降时可视储层发育情况择时投产；③在排水采气初期，应建立合理的排采工作制度，避免储层渗透率的急剧下降。

Characteristics of pre-production performance and technical countermeasures in the coalbed methane gas field of Qinshui Basin

There are abundant coalbed methane gas resources in the Qinshui Basin, and the China National Petroleum Corporation (CNPC) has performed large scale exploration, production test and pre production operation since 1994. Starting with the dynamic analysis of the geological features in the Qinshui methane gas field including structure, coalbed thickness and burial depth, coal rock characters and petrophysical property, gas content, evaluation on coalbed methane gas reservoirs, etc., this paper focuses on the production performance in the production test of this field, the characteristics of which are summarized as follows: ①the CBM gas production stimulated by fracturing and multi branched horizontal wells are the effective means of developing this coalbed methane gas field; ②the production data of the coal layer 3# demonstrates that gas production rate is closely related to geological features, especially to the three main factors of structure location, gas content, and the value of KH; ③the producing fluid level should be maintained at a steady decreasing state in the process of gas recovery by water displacement. Based on the above analysis, technical countermeasures are suggested as follows: ①vertical wells combined with multi branched horizontal wells, in addition to the optimized well patterns and different stimulation means, should be effective for coalbed methane gas recovery in this field; ②according to different geological conditions between the coal layer 3# and 15#, the coal layer 3# should be extracted prior to the coal layer 15#, and until the production rate of the former starts to decline the latter will not be put into production timely under the best situation of reservoirs; ③at the early stage of gas recovery by water displacement, a reasonable working system and routine operation should be worked out with working parameters under control to watch out the sharp drop of reservoir permeability.