气体钻井临界携水量计算  

Calculation of critical water-carrying capacity of gas in air drilling

作　　者：代锋[1] 李黔[1] 梁海波[1] 胡学明 徐晓蓉[3] 张光华[1] 

机构地区：[1]西南石油大学 [2]川庆钻探工程公司塔里木工程公司 [3]中国石化胜利油田分公司鲁明石油开发有限责任公司

出　　处：《天然气工业》2010年第2期94-96,共3页Natural Gas Industry

基　　金：中国石油天然气集团公司重大应用基础研究项目(编号:07A20402)

摘　　要：地层出水是制约气体钻井顺利实施的一个瓶颈,准确计算一定注气量下的临界携水量对于气体钻井现场安全施工、避免井下复杂至关重要。基于最小动能标准建立了计算气体钻井临界携水量的数学模型,该模型综合考虑了地层出水后环空多相流动状态,利用该模型可确定气体钻井注气量和临界携水量的对应关系。计算结果表明:增加注气量和降低液气表面张力是提高气体钻井临界携水量的有效途径;当增加注气量不能满足携水要求时,必须转换钻井方式,通过降低液气表面张力来提高临界携水量;气体钻井临界携水量计算需兼顾携带岩屑和携水两个要求,当所需的最小携水动能等于最小携带岩屑动能时,液气表面张力达到极值,进一步降低液气表面张力失去意义。实例验证表明,该研究成果能够用于指导气体钻井现场实践,为地层出水后气体钻井转换钻井方式提供了理论依据。Formation water production is one of the bottlenecks restricting the smooth operation in gas/air drilling.Therefore,to accurately calculate the critical water-carrying capacity under a certain gas-injection rate is essential for safe operation and prevention of complicated downhole accidents.Based on Guo's minimum kinetic energy theory,a mathematical model was set up for calculating the critical water-carrying capacity of gas in air/gas drilling.Taking into account the flow state of multi-phase fluids in the annular space after formation water influx,this model can determine the corresponding relation between air/gas injection rate and critical water-carrying capacity of air/gas.The calculation results demonstrate that a.to increase air/gas injection rate and to lower down liquid-gas interfacial tension are effective means to improve the critical water-carrying capacity of air/gas,b.when the increased air/gas injection can not meet the requirement of the liquid removal,the modes of drilling have to be transferred and the critical water-carrying volume will be enhanced by reducing the liquid-gas interfacial tension,c.the calculation of critical water-carrying capacity takes into consideration both water influx and debris carrying capacity,but when the required minimum kinetic energy of both are equivalent to each other,and the liquid-gas interfacial tension reaches the extreme value,there is no need to lower down the liquid-gas interfacial tension.Many cases of study prove that this model provides a theoretical basis for the guidance of gas drilling on fields and the switch of the drilling methods when the formation water influx occurs in air/gas drilling.

关 键 词：气体钻井 地层出水 临界携水量 注气量 最小动能 

分 类 号：TE21[石油与天然气工程—油气井工程]