深水钻井气侵期间井筒多相流流动规律研究

发布时间：2019-03-25 21:28

【摘要】：随着国家对能源需求的增加及陆上和海洋浅水区油气资源发现难度的增大,深水海域油气勘探与开发必将成为我国油气资源勘探开发的重要领域。受水深和复杂的海洋环境的影响,深水钻井面临的主要风险是井控风险。海上油田一旦出现井喷失控事故,将会给平台工作人员及海洋环境带来不可弥补的损害。为保证深水钻井安全,必须对深水钻井气侵期间井筒多相流流动规律进行研究。本文以传热学和热力学理论为基础,推导了深水钻井过程循环温度场预测模型,计算了深水井筒循环温度场随井深和时间的变化关系：基于气体在水基钻井液和油基钻井液中的溶解度计算模型,计算了不同温度、压力下气体在钻井液中的溶解度变化；基于质量守恒、动量守恒原理建立了考虑气体在钻井液中溶解度的连续性方程、动量方程,结合辅助方程、初始条件、边界条件,建立了井筒多相流控制方程组；采用有限差分的数学方法,追踪多相流前沿,对控制方程组进行求解；模拟并对比了深水钻井气侵期间油基钻井液和水基础钻井液气体溶解度、气相体积分数、混相速度、泥浆池增量、返出排量、井底压力等参数的变化规律；模拟了深水油基钻井液气侵期间不同钻井液排量、气侵速度、钻井液油水比下井底压力、泥浆池增量、返出排量等参数的变化规律,评价了泥浆池增量监测法、返出排量监测法在油基钻井液溢流监测中的效果,并进行了井底压力敏感性研究；对气体未到达隔水管前的井下多点压力随时间的变化规律进行模拟,评价了基于随钻井下多点压力实时测量的溢流监测方法的效果；根据理论模型,编制了深水钻井气侵模拟软件。模拟计算结果表明：深水油基钻井液气侵期过程既具备“隐蔽性”又具备“突发性”,在气体未从油基钻井液中析出之前,井底压力、泥浆池增量、钻井液返出排量变化不明显,而当气体开始从钻井液中析出后,以上参数快速变化,而水基钻井液气侵之初便会有明显变化；较小的排量和较低的油水比均有利于及早发现溢流,而当溢流发生后,可适当增大排量以尽快排出溢流的同时加强对井底压力的控制；传统的泥浆池增量监测法、返出排量监测法用于油基钻井液监测时具有明显的滞后性,在使用时应尽量降低溢流判定的标准；采用基于随钻井下多点压力实时测量的溢流监测方法能做到及时地发现溢流,但该方法依赖于精确的井筒压力预测以及实时、高精度的压力测量。本文所建立的井筒多相流模型可用于预测深水油基钻井液、水基钻井液气侵期间的井筒多相流流动规律,为井筒压力控制和溢流监测方法及标准的选择提供理论依据。
[Abstract]:With the increasing demand for energy and the difficulty of discovering oil and gas resources in land and offshore shallow water areas, oil and gas exploration and development in deepwater waters will certainly become an important field of exploration and development of oil and gas resources in China. Under the influence of water depth and complicated marine environment, the main risk of deepwater drilling is well control risk. Once a blowout out-of-control accident occurs in offshore oil field, it will bring irreparable damage to platform staff and marine environment. In order to ensure the safety of deep-water drilling, it is necessary to study the law of multiphase flow in the wellbore during the gas invasion of deep-water drilling. Based on the theory of heat transfer and thermodynamics, the prediction model of circulation temperature field in deep water drilling process is derived in this paper. Based on the calculation model of gas solubility in water-based drilling fluid and oil-based drilling fluid, the change of gas solubility in drilling fluid at different temperatures and pressures was calculated. Based on the principle of conservation of mass and momentum, the equations of continuity and momentum considering the solubility of gas in drilling fluid are established. Combined with auxiliary equation, initial condition and boundary condition, the control equations of multiphase flow in wellbore are established. The mathematical method of finite difference is used to track the front of multiphase flow and solve the governing equations. The gas solubility of oil-based drilling fluid and water-based drilling fluid, gas phase volume fraction, miscibility velocity, slurry pool increment, backflow rate and bottom hole pressure were simulated and compared during gas invasion in deepwater drilling. The variation rule of drilling fluid discharge, gas invasion velocity, drilling fluid oil / water ratio bottom hole pressure, slurry pool increment and return discharge during deep-water oil-based drilling fluid gas invasion was simulated, and the monitoring method of slurry pool increment was evaluated. The effect of back-out displacement monitoring method in oil-based drilling fluid overflow monitoring is studied, and the pressure sensitivity of bottom hole is studied. The variation of downhole multi-point pressure with time is simulated before gas reaches the riser, and the effect of overflow monitoring method based on real-time measurement of multi-point pressure while drilling is evaluated. According to the theoretical model, the simulation software of deep water drilling gas invasion is developed. The simulation results show that the penetration period of deep-water oil-based drilling fluid has both "concealment" and "sudden occurrence", and the bottom hole pressure and slurry pool increment before the gas precipitates from the oil-based drilling fluid. When the gas begins to release from the drilling fluid, the above parameters will change rapidly, while the water-based drilling fluid will change obviously at the beginning of the gas invasion, while the water-based drilling fluid will change obviously at the beginning of the gas invasion of the water-based drilling fluid. Smaller discharge and lower oil-water ratio are beneficial to early detection of overflow, and when overflow occurs, the discharge can be properly increased to discharge overflow as soon as possible, while strengthening the control of bottom hole pressure; The traditional mud pool increment monitoring method and the return discharge monitoring method have obvious lag when used in oil-based drilling fluid monitoring, and the criterion of overflow determination should be reduced as far as possible when used. The overflow monitoring method based on real-time measurement of multi-point pressure while drilling can detect overflow in time, but the method depends on accurate wellbore pressure prediction and real-time, high-precision pressure measurement. The wellbore multiphase flow model established in this paper can be used to predict the wellbore multiphase flow law during gas invasion of deep-water oil-based drilling fluid and water-based drilling fluid, which provides a theoretical basis for wellbore pressure control and selection of overflow monitoring methods and standards.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TE24

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