超高温地热井泡沫钻井井筒压力剖面计算方法  

A method of wellbore pressure profile calculation for foam drilling in ultra-high temperature geothermal wells at Olkari,Kenya

作　　者：王文勇[1,2] 龙俊西[1] 刘博伟[1] 李皋[1] 孟英峰[1] 

机构地区：[1]"油气藏地质及开发工程"国家重点实验室·西南石油大学 [2]中国石油长城钻探工程有限公司国际钻井公司

出　　处：《天然气工业》2012年第7期59-62,106,共4页Natural Gas Industry

基　　金：国家自然科学基金重点项目"气体钻井技术基础研究"(编号:51134004)的研究成果

摘　　要：肯尼亚OLKARI地区地热井地层温度高达350℃,主要采用泡沫钻井,然而其低压和超高温的特点可能造成泡沫流体相态变化,目前尚没有针对相变条件下泡沫钻井井筒压力剖面的计算方法。为此,利用流体高压物性分析仪,绘制出泡沫钻井液"p-T"相图,并指出了钻井液相态变化的规律。进而应用现有的欠平衡钻井流体流动模型,建立了一套适应相变的钻井工况参数计算模型。最后,利用OLKARI地区某地热井的温度、压力资料,计算了该口井的流体流动参数,得到了该井井筒中的泡沫相态分布规律。通过井筒内流体压力的计算,可以更准确地了解工作液的工作状态,为预防井下复杂事故的发生提供了理论依据。Foam drilling is often used in Olkari,Kenya,where the formation temperature of geothermal wells is 350 ℃.However,the low pressure and ultra-high temperature may lead to phase change in foam fluids.And there is no method available now to calculate the wellbore pressure profile when phase change occurs in the hole.In this paper,the p-T phase diagram of foam drilling fluids is drawn out by use of the fluid PVT analyzer,and the drilling fluid phase change law is presented herein.And then based on the existing fluid flow model of underbalanced drilling,a set of drilling parameter calculation model is set up for drilling conditions with phase change.In combination with an Olkari geothermal well's temperature and pressure data,the fluid flow parameters in this well are calculated,and the phase distribution regularities in that wellbore are also obtained.Through the calculation of the wellbore fluid pressures,the working conditions of the working fluid can be accurately known,thereby to provide a theoretical support for the prevention of downhole accidents.

关 键 词：泡沫钻井 钻井液 超高温 实验研究 井筒压力 计算方法 肯尼亚 OLKARI地区 地热井 

分 类 号：P634[天文地球—地质矿产勘探] P314[天文地球—地质学]