欠平衡钻井技术在保护煤层气储层中的应用

APPLICATION OF UNDER-BALANCE DRILLING TECHNOLOGY TO CBM RESERVOIR PROTECTION

煤层气储层不仅具有低渗、低压特点,还具有对各类伤害的敏感性,从而决定了在煤层气钻完井、开采过程中要坚持采取系统的保护煤层措施。通过直井的油管向另一水平井环空注气实现欠平衡的钻井工艺在FP1-1井中得到成功应用,实现了及时、平稳注气,保护了煤层并维持井壁稳定,优化了单井筒水平井井身结构。为推广欠平衡钻井技术开发煤层气指出了方向。

CBM reservoir is not only characterized by low permeability and low pressure but also by harmful sensitivity,which decides that systematical protective measures for coalbed reservoir should be taken in the process of drilling and completing of CBM(coalbed methane) and its exploitation.The technology injecting gas into the annular of another horizontal well through tubing of straight well to realize under-balance drilling is applied in the well FP 1-1 successfully,which can not only realize stable gas injection in time to protect coal seams but also maintain steady borehole face.A further study on well structure of a single horizontal well gives a new orientation to popularize under-balance drilling for CBM exploitation.