滇东黔西煤层气开发技术及先导性试验

Development technology and pilot test of coalbed methane in eastern Yunnan and western Guizhou regions

“十三五”期间,针对滇东黔西地区构造复杂、地应力变化大、煤层多且薄、煤体结构复杂、煤系地层弱含水等特点,以及由此导致的甜点区较难确定、叠置含气系统不易划分、地层易塌易漏、改造效果差、排采时效低等技术难题,开展了系统攻关研究,取得了如下进展。构建了适用于多煤层的煤层气开发甜点选区选段技术,指导了滇东黔西地区煤层气有利区优选;形成了动静态集成分析的合采产层组优选与适应性开发技术;研发了高封堵易返排强防塌无固相钻井液和强胶结低伤害固井液体系,建立了适用于易塌易漏地层钻完井及储层保护技术;基于分形盒维数的岩石力学研究方法,形成了4项直井压裂改造技术;建立了弱含水多煤层合采流动模型,提出了三段三控合排全过程管控优化模式。基于上述技术,在滇东黔西地区优选有利区5个、甜点区5个,提出井位44口,提交煤层气探明地质储量超过100亿m^(3)。先导区多煤层合采平均日产气量达1000 m^(3),单井最高日产气量达6000 m^(3),实现工业化气流目标取得突破,为滇东黔西地区煤层气开发奠定了坚实基础。

In eastern Yunnan and western Guizhou area,there are problems of complex tectonic setting,great change of crustal stress,multiple thin coal seams,complex coal structure,and weakly water-bearing coal,resulting in dessert area is difficult to determine,multi-superimposed gas system is not easy to divide,the stratum is prone to collapse and leakage,the effect of stimulation is bad,the efficiency of drainage is low.Based on the above problems,this paper has carried out research during the period of the 13th Five-Year Plan and formed a series of achievements.The technology for selecting sweet spots and sections for CBM development suitable for multiple coal seams has been established,which guides the selection of favorable CBM areas in eastern Yunnan and western Guizhou regions.The optimization and adaptive development technology of commingled production layer group for dynamic and static integrated analysis has been formed.The high plugging,easy flowback,strong anti-slump solid-free drilling fluid and strong bonding low damage cementing fluid system have been developed,and the technology for drilling,completion and reservoir protection in collapse-prone and leakage-prone formations has been developed.Based on the rock mechanics research method of fractal box dimension,four vertical well fracturing techniques have been formed.A flow model of commingled production of weak water-bearing and multi-coal seams have been established,and a whole-process management and control optimization model of three-stage,three-control and combined-discharge has been proposed.Based on the above technologies,5 favorable areas and 5 sweet spots are selected in the eastern Yunnan and western Guizhou regions,44 well locations are proposed,and more than 10 billion cubic meters of proven geological reserves of CBM are submitted.In the pilot area,the average daily gas production of multi-seam joint production reaches 1000 m^(3),and the highest daily gas production of single well reaches 6000 m^(3),making a breakthrough in achieving the industrial gas flow,which laid a solid foundation for CBM development in the eastern Yunnan and Western Guizhou regions of China.