深水钻井井筒中天然气水合物生成风险评价方法  

Risk evaluation methods of gas hydrate formation in the wellbore of deepwater drilling

作　　者：许玉强 管志川 许传斌 张洪宁 张会增 

机构地区：[1]中国石油大学石油工程学院,山东青岛266580

出　　处：《石油学报》2015年第5期633-640,共8页Acta Petrolei Sinica

基　　金：国家重点基础研究发展计划(973)项目(2010CB226706);长江学者和创新团队发展计划(IRT1086)资助

摘　　要：综合考虑天然气水合物相平衡条件、井筒温度-压力场和地温梯度,建立了深水浅部地层天然气水合物生成区域预测方法和深水钻井中井筒内天然气水合物生成区域预测方法。分析结果表明深水浅部地层钻井比深部地层钻井生成天然气水合物的风险更大。在此基础上引入过冷度密度对不同井深处的天然气水合物生成风险进行定量评价,同时基于施工参数的无因次化建立了重点区域天然气水合物生成风险定量评价方法。实例计算表明:深水钻井中海底井口附近和隔水管下部水合物生成风险等级最高;钻井液导热系数、入口温度、排量和NaCl浓度对井筒中天然气水合物生成风险影响最大,可以根据各施工参数的敏感因子并结合现场实际情况定量优化钻井设计和施工,从而降低或避免风险。Based on phase equilibrium conditions of gas hydrate,borehole temperature-pressure field and geothermal gradient,the prediction methods were established for gas hydrate formation areas in shallow strata and the shaft of deepwater drilling respectively.Through analysis,it was indicated that the risk of gas hydrate formation in shallow strata was greater than that in the shaft of deepwater drilling.On this basis,undercooling density was introduced to quantitatively evaluate the risk of gas hydrate formation at different well depths.Meanwhile,the quantitative evaluation method on the risk of gas hydrate formation in major areas was established according to dimensionless construction parameters.It was revealed from example calculation that the risk level of gas hydrate formation reached the maximum in the area adjacent to subsea wellhead and at the lower part of riser in deepwater drilling;the thermal conductivity of drilling fluid,inlet temperature,displacement and NaCl concentration would have the most impacts on the risk of gas hydrate formation in the shaft.Drilling design and construction could be optimized quantitatively according to the sensitive factor of each construction parameter in combination with onsite situations,so as to reduce or avoid risks.

关 键 词：深水钻井 天然气水合物 过冷度密度 风险评价方法 定量评价 

分 类 号：TE28[石油与天然气工程—油气井工程]