煤层气低产井区增产改造地质靶区优选方法与应用

Optimizing method and application of geological target area for increasing production in coalbed methane low production well area

盘活煤层气低产低效井是解决我国煤层气单井产量偏低问题的关键任务之一,在分析地质因素对煤层气井开发效果影响的基础上,提出基于“储层参数再认识-产气地质潜力评价-储集层结构特征分区-增产改造地质靶区”的煤层气低产井区增产改造靶区优选方法(增产改造靶区“四步”优选法)。利用煤层气开发老区的压裂和排采资料,结合钻井、测井、实验室测试等数据,建立煤层气地质参数再认识的计算模型,分析影响煤层气开发效果的煤储层关键参数;应用多层次模糊综合评价法,提出低产井产气潜力评价指标体系;基于构造和煤体结构垂向组合特征,建立储层煤体结构特征分区方法;最后制定一套煤层气低产井区增产改造地质靶区的优选方法。采用“四步”优选法,在沁水盆地南部柿庄南煤层气区块选出42口低产井,增产改造后单井平均产气量由310 m^(3)/d增至960 m^(3)/d,增长3倍多,且保持产气上升或稳产趋势,相比在靶区外实施的试验井的单井产气增量和总体成功率有较大提升。该方法为煤层气低产井的治理选区指明方向且提供地质支撑。

Activating a large number of low-production coalbed methane(CBM)wells is one of the key tasks to solve the problem of low CBM production in my country.Based on the control characteristics of various geological parameters on the development effect of CBM,a new understanding of reservoir parameters:production gas geological potential evaluation-reservoir structure feature partition-increasing production improvement geological target area selection method for increasing production improvement geological target area of low production well area of coalbed methane(“four-step”optimization method of stimulation improvement target area).By analyzing the key parameters of coal reservoirs that affect the development of coalbed methane,making full use of fracturing and drainage data,and combining drilling,logging,and laboratory testing data,a model for recognizing key geological parameters has been established.The multi-level fuzzy comprehensive evaluation method puts forward a low-yield well gas production potential evaluation index system.Based on the vertical combination characteristics of structure and coal structure,the reservoir structure feature zoning method is established.finally a set of low-yield coal-bed methane wells is formulated to increase production method for rebuilding the geological target area.Using the"fourstep"optimization method,42 low-yielding wells were selected in the south Shizhuang CBM block in the southern Qinshui Basin.After stimulation,the average gas production of a single well increased from 310 m^(3)/d to 960 m^(3)/d,and the current gas production maintains a trend of rising or stable gas production.Compared with the experimental wells implemented outside the target area,the single-well gas production increment and overall success rate have been greatly improved.This method points out the direction and provides strong geological support for the treatment and selection of coalbed methane low-production wells.