摘要
在深层油气藏钻进中,由于井筒与地层连通且安全密度窗口较窄,极易发生物质交换,导致溢流、漏失以及溢漏同存频发,进而引起井筒内的复杂多相流动。为了实现精确控压、确保井控安全,需要掌握各种工况条件下井筒多相流动规律。针对井筒内的复杂多相流动,基于漂移模型建立井筒气液两相流瞬态流动模型,并利用高计算精度的AUSMV格式进行求解。借助MATLAB软件,编程模拟气侵下井筒内的气液两相流动规律,分析气侵量、滑脱速度等参数对井底压力、井口套压、气体速度以及气体体积分数的影响。结果表明:气侵量越大,井底压力、井口套压越大,气体体积分数达到100%的速度越快,气体逆流现象越明显;滑脱速度越大,井底压力和井口套压达到稳定状态的时间越短,气体的运动速度越大,气体体积分数几乎不受滑脱速度的影响;流动参数对井口套压、井底压力和气体体积分数影响较小。该研究可以对精确计算关井后的相关压井参数起到一定的理论指导意义。
As the wellbore and formation is connected and the safe window is narrow, the exchange of mass between the well- bore and formation happens easily, and leads to leakage, overflow, existence of leakage and overflow at the same time when drilling the deep reservoirs, and then causes the complex multiphase flow in the wellbore. In order to achieve controlling the wellbore pressure accurately and ensure well control safety, the law of complex muhiphase flow should be studied for differ- ent working conditions. For the complex multiphase flow in the wellbore, a model for gas-liquid two-phase transient flow is established based on the drift flux model. The AUSMV scheme method is used for the numerical solution of the model. A MATLAB program is conducted to simulate the law Of gas-liquid two-phase flow and investigate the effects of gas influx vol- ume, slip velocity and flow parameter on bottom hole pressure, surface casing pressure, gas fraction and gas velocity. Accord- ing to the results, a larger volume of gas influx will t＇esuh in a higher bottom hole pressure and surface casing pressure. For larger influx volumes ,the gas fraction in the well will increase to 1.0 much faster and the counter-current gas-liquid flow will appear more apparent. The larger gas slip velocity, the less time that bottom hole pressure and surface casing pressure take to reach the stable state, the larger gas velocity will be. The slip velocity nearly has no influence on the gas fraction. The flow parameter nearly has little influence on bottom hole pressure, surface casing pressure and gas fraction. This study can provide a theoretical basis for accurately predicting the related parameters during the well-kill process after gas influx and closing the well.
出处
《世界科技研究与发展》
CSCD
2016年第6期1170-1176,共7页
World Sci-Tech R&D
基金
国家自然科学基金(51474186
51574202)
"十一五"重大专项(2008ZX050450307HZ)
"十二五"重大专项(2011ZX05045-03-01WX)资助
关键词
气液两相瞬态流动
漂移模型
气侵
AUSMV算法
数值模拟
gas-liquid two-phase transient flow
drift flux model
gas influx
AUSMV scheme
numerical simulation
