川南筠连岩溶发育区块煤层气钻井施工工艺

川南筠连地区煤层气资源丰富，但该区块岩溶发育，地质条件复杂，在煤层气钻井施工过程中容易出现井漏、井斜、井塌、排渣困难等问题，造成钻井效率低下。针对此种情况，采用了空气潜孔锤和普通钻井液循环相结合的钻井工艺：一开采用空气潜孔锤钻进，至一开完钻后，下入表层套管固井，继续采用空气钻井至最大井深，然后换用常规钻井液钻井至完钻。钻探效果显示，该种工艺的钻进周期比常规的钻井方法缩短了4-10d，钻井效率较高，取得了良好的经济效益。

CBM Well Drilling Operation Technology in Junlian Karst Developed Block, Southern Sichuan

CBM resources are abundant in the Junlian area, southern Sichuan. But since the well developed karst in this block, and complicated geological condition, issues of drilling mud loss, well deflection, well collapsing and difficult cutting removal are often happened during CBM well drilling process, and caused low drilling efficiency. In allusion to the situation, drilling technology of air down-the-hole hammer combined with common drilling fluid circulation is used： using air down-the-hole hammer in primary spudding, when it is finished, lowering down superficial casing to consolidate the well; continue to use air drilling to the maximum depth, then using traditional fluid drilling through to well completion. The drilling effect has demonstrated that the method can shorten drilling duration 4-10 days less than traditional drilling, thus high efficiency and good economic benefit.