【作者】 王在明；

【导师】 邱正松；

【作者基本信息】 中国石油大学 ， 油气井工程， 2008， 博士

【摘要】 本文结合石油科技中青年创新基金项目“超临界二氧化碳连续管钻井液携岩特性研究”和中国石油大学博士创新基金项目“超临界二氧化碳钻井液特性研究”的有关研究内容,深入研究了二氧化碳流体在井眼条件下的密度、粘度、温度和压力等特性的变化规律,设计和建立了超临界二氧化碳钻井液循环模拟实验装置,通过模拟实验研究揭示了超临界二氧化碳钻井液携岩规律以及二氧化碳水合物溶解特性,为超临界二氧化碳钻井液的现场应用奠定了基础。二氧化碳流体是可压缩性非常好的非理想气体,常用的理想气体状态方程不适应于井眼内密度、粘度、温度和压力等参数的准确计算。基于Pen-Robinson方程和Chung方程,推导出了适合超临界二氧化碳钻井液在井眼条件下的密度和粘度计算公式,计算结果与实际误差都在5%以内,具有较好的实用性。应用传热学基本原理,建立了地层/钻具/二氧化碳流体之间的温度传递数学模型,给出了钻具和环空内二氧化碳流体的温度解析式,并绘制了井眼温度剖面。运用有限元基本方法和流体力学理论,推导出了在井眼条件下二氧化碳钻井流体的静液柱压力和摩擦压耗的数学模型,从而绘制出井眼压力剖面,为实现控制压力钻井提供了理论依据。利用相似性原理,研制出超临界二氧化碳钻井液循环模拟实验装置。该装置可模拟二氧化碳流体在2000米井深内的运行状态,能够做到温度可调,压力可控,并能在高温高压(90℃,15MPa)下具有可视化。该装置可用于完成超临界二氧化碳钻井液的携岩特性、循环压耗特性、水合物生成和溶解特性等方面的实验研究,实验结果重复性好。利用新研制的超临界二氧化碳钻井液循环模拟实验装置,试验研究了二氧化碳流体在不同状态和不同井斜情况下的携岩特性,发现在超临界状态下,0°～36°是携岩较容易的井斜范围,井斜超过36°后携岩开始变得困难,54°～72°为携岩最困难的井斜范围,72°～90°携岩变得相对容易;确定了不同状态下二氧化碳流体有效携岩的最低返速和最小流量;揭示出携岩能力随压力增加而增大、随着温度的增加而减少的变化基本规律。模拟实验装置中固液分离器是采用侧面旋流进气的锥形容器,它能够使二氧化碳、水充分旋流搅拌,在温度低于10℃,压力高于5MPa条件下,形成二氧化碳水合物。研究了二氧化碳水合物在地面环境中的稳定性,发现当环境温度高于30℃时,二氧化碳水合物分解速度是2℃、10℃、20℃条件下的1倍;实验探讨了二氧化碳水合物在热力学抑制剂乙醇以及无机盐氯化钙和氯化钠溶液中溶解特性;也实验分析了二氧化碳水合物在动力学抑制剂十六烷基磺酸钠溶液中的溶解特性,有助于超临界二氧化碳钻井液现场应用时产生水合物堵塞提供解决方案。更多还原

【Abstract】 The paper launch on research work according to petroleum science and technology innovating fund for middle-young people“Bring cuttings feature research of supercritical carbon dioxide coiled tubing drilling fluid”and China University of Petroleum doctor innovating fund“Feature research of supercritical carbon dioxide drilling fluid”. The regular patterns of density, viscosity, temperature and pressure in the borehole are researched thoroughly; The supercritical carbon dioxide drilling fluid circulating simulating experiment equipment is developed; By the simulating experiment equipment, bring cuttings law and carbon dioxide hydrate dissolution law are found. All these are base of the application of supercritical carbon dioxide drilling fluidCarbon dioxide fluid is a non-ideal gas with good compressibility, common use ideal gas equation isn’t fit for caculation of density, viscosity, temperature, and pressure in borehole .By modifing P-R equation and Chung equation, equations of caculating density and viscosity in borehole are developed with error no more than 5%,the two equation have good applicability. Using diathermanous concept temperature transfer math model of layer/drill pipe/carbon dioxide fluid is setted up. By resolving the math model, temperature at any well depth of in drill pipe and annular can be calculated and get temperature profile. With these basic data, divide borehole into many small unit, the hydrostatic column pressure and friction pressure consume can be calculated in these small unit, then pressure and pressure consume can be calculated at any well depth and get pressure profile.The supercritical carbon dioxide drilling fluid circulating simulating experiment equipment was designed and setted up. As similarity principle, the experiment equipment was proved fully comparable with practice borehole. The experiment equipment can simulate operation behavior of supercritical carbon dioxide drilling fluid in depth of 2000 meters. Tempreture can be adjust and pressure can be controled easily in the experiment equipment. The visulization can be achieved in the high tempreture and high pressure condition(90℃,15MPa) The experiment equipment can accomplish bring cuttings, pressure consume and carbon dioxide hydrate preparation.By circulation simulating experiment equipment, the feature of bring cuttings was researched in different state and different inclined angle. Experiment found that carring cuttings is easy when the angle is between 0°~36°in supercritical state, carring cuttings become difficult when the angle get to 36°and carring cuttings is most difficult when the angle is between 54°~72°.it is different with our mind’s eye that carring cuttings isn’t most difficult in horizontal well. The least uphole velocity and minimal rate of flow for carring cuttings are found in different condition. The law of carring cuttings capability is increasing with pressure increasing and decreasing with temperature increasing.Solid separator in the experiment equipment is a side face revolver; this can mix carbon dioxide and water, when the temperature is no more than 10℃and pressure more than 5MPa carbon dioxide hydrate can be preparation. Stability of carbon dioxide hydrate in air gas was researched , the research demonstrate that carbon dioxide hydrate decompose speed is double than 2℃, 10℃, 20℃when surroundings temperature is more then 30℃. Carbon dioxide hydrate dissolving feature was researched in thermodynamics inhibitor like grain alcohol and inorganic salt calcium chloride and sodium chloride solution.. Carbon dioxide hydrate dissolving feature was research in dynamics inhibitor like SAS. The research of dissolving feature gives a settling way of dissolving carbon dioxide hydrate when jam occurs.更多还原