贵州对江南井田煤层气地质特征及高效开发技术

Geological characteristics and high efficiency development technology of coalbed methane in Duijiangnan coal mine, Guizhou Province

贵州对江南井田煤层气开发进展缓慢,通过前期勘探阶段实践,该区块存在的主要问题是钻井效率低、固井漏失严重、压裂改造周期长,单井产量低,客观评价井田煤层气地质特征及开发技术对后续煤层气的开发至关重要。通过对井田煤层厚度、煤体结构、储层压力、含气量、渗透性等方面进行了系统研究,结合井田以往钻井、压裂及排采实践,提出了井田煤层气开发以定向井为主,在M18煤层构造简单、煤体结构好、含气量高、煤层稳定且厚度大于3m的区域,宜采用水平井的开发方式,在M25和M29煤,M78和M79煤构造简单、含气量高、煤层稳定且层间距小于5m的区域,宜采用层间水平井的开发技术,漏失井段宜采用空气潜孔锤快速钻进技术,非漏失井段宜采用螺杆复合钻进技术,固井宜采用变密度水泥浆+无水氯化钙的固井方式,直井和定向井压裂宜采用复合桥塞层组多级压裂,水平井宜采用油管拖动水力喷砂射孔压裂技术,排采宜采用合层排采+分层控压技术,形成一套适宜于对江南井田地形地质条件下的煤层气开发技术,为今后研究区大规模煤层气商业开发提供参考。

The development progress of coalbed methane in Duijiangnan mine field is slow.The main problems are low drilling efficiency,serious cementing leakage,long fracturing transformation period and low single well production in the block.Objectively evaluating the geological characteristics and development technology of coalbed methane is very important for coalbed methane in the future.The coalbed thickness,coal body structure,reservoir pressure,gas content and permeability are systematically studied,combining with the past drilling,fracturing and drainage practices.It is proposed that directional wells are the main method of coalbed methane development in the coalfield.The coal seam M18 which has simple structure,good coal structure,high gas content,stable coal seam and thicker than 3 m is developed by horizontal wells.The seams M25 and M29,M78 and M79 which have simple structure,high gas content,stable coal seam and less than 5 m interval are developed by interlayer horizontal wells.The technology of air downhole hammer is adopted in the missing section.The technology of screw compound drilling is adopted in non-leakage well section.The variable density cement slurry and anhydrous calcium chloride are used in cementing.Multistage fracturing of composite bridge plug formation is used in vertical and directional wells.Tubing-driven hydraulic sand blasting perforation fracturing technology is used in horizontal wells.The technology of combined layer drainage and stratified pressure control should be adopted in the block.A set of coalbed methane development technology suitable for Duijiangnan minefield is formed,which provides a reference for coalbed methane development.