酸性气体在钻井液两相流动中的溶解度特性  

Solubility of acid gas in the two-phase flow of drilling fluid

作　　者：孔祥伟[1] 林元华[1] 邱伊婕[1] 董龙[2] 

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]东北石油大学

出　　处：《天然气工业》2014年第6期97-101,共5页Natural Gas Industry

基　　金：国家科技重大专项"微流量地面自动控制技术研究"(编号:2011ZX05022-005-005HZ);国家自然科学基金"H2S/CO2溶解度测试;预测及其与套管完整性的相关研究"(编号:51274170);黑龙江省青年科学基金项目"驱油用木质素磺基甜菜碱型表面活性剂的合成及性能研究"(编号:QC2012C128)

摘　　要：考虑CO2/碳氢气体在油基钻井液中的相变、溶解度等因素,根据质量及动量守恒方程建立了控压钻井中CO2/碳氢气体在两相流动中的溶解度方程,利用CO2/碳氢气体状态方程及差分的方法对其求解。结果表明:当温度及井底溢流量一定时,随套压增大、油基比增大,CO2/碳氢气体在油/水基钻井液中的溶解度均逐渐增大,碳氢气体增大趋势较明显;CO2气体在水基钻井液中的溶解度曲线呈倒S型,到达一定环空深度后,CO2气体在油基钻井液中的溶解度与井深呈线性关系;碳氢气体与油基钻井液物理性质相近度较大,致使碳氢气体在钻井液中的溶解能力增加,从而溶解度增加;由于井口段气体体积急剧膨胀,大量气体析出,使得井口段环空压力剧减,因此溶解度的变化较明显。结论认为,在控压钻井的多相流计算中,应充分考虑酸性气体在钻井液中的溶解度影响。这样做不仅可提高多相流计算精度,而且还可为井底压力控制提供一定的指导。With phase change, solubility, and other characteristics of CO2/Cx My gas in the oil-based drilling fluid taken into consideration, the solubility equation of CO2/CxHy gas in two phase fluid in managed pressure drilling was established according to mass and momentum conservation equations and was solved by CO2/Cx Hy gas state equation and difference method. The results showed that the solubility of CO2/CxHy gas in the oil-/water based drilling fluid gradually increases with the increases of casing pressure and the ratio of oil to water at certain temperature and downhole overflow, and CxHy gas increases more remarkably; the solubility curve of CO2 in the water-based drilling fluid presents a lain letter S, and a linear relationship exists between the solubility of CO2 in the oil- based drilling fluid and well depth when the annulus depth reaches some point; the higher similarity of physical properties of Cx Hy gas and oil-based drilling fluid results in a stronger solubility of CxHy gas in drilling fluid; gas volume at wellhead is rapidly expanded, and a lot of gas comes out, making annulus pressure sharply decreased, thus the solubility is obviously changed. Therefore, in the calculation of multiphase flow in managed pressure drilling, full consideration should be given to the solubility changes of acid gas in drilling fluid, not only improving the accuracy of multiphase flow calculation, hut providing a hasis {or down,hole pressure control.

关 键 词：酸性气体 钻进 钻井液 气液两相 溶解度 套压 空隙率 环空 控压钻井 

分 类 号：TE254[石油与天然气工程—油气井工程]