井底恒压法控压钻井气侵控制研究

发布时间：2018-01-16 20:41

本文关键词：井底恒压法控压钻井气侵控制研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：钻遇气侵时,井底恒压法控压钻井能及时检测到气侵,并可通过增加井口回压或者增大排量等方式快速有效地控制微-中量的气侵,相比于常规井控增加了气侵控制方式的选择,关井不再是气侵后的唯一控制措施。尽管井底恒压法控压钻井通过井口装置能快速有效的控制一定量的气侵,但是由于增加了控制设备,相应地也增加了安全风险,导致井控决策难度增大。国内虽然已经开始应用控压钻井技术并实现了设备国产化,但是在控压钻井井控方面的理论研究仍然较少,相关研究力度也不够,因此有必要对井底恒压式控压钻井气侵规律与控制进行深入研究。本文以井底恒压法控压钻井工艺理论为基础,结合渗流力学、单相流、气液两相流基本理论,建立了气侵后的环空多相流动模型,系统分析了不同参数对溢流后井底压力的影响规律和不同溢流阶段和采取溢流控制措施时的井底压力变化规律;最后,结合实际算例,系统分析了井底恒压法控压钻井从其气侵发生到气体完全排出整个控制过程中的井底压力等参数的变化规律和动态井控的井筒安全风险。模拟结果表明:气侵检测阶段通过精确的流量监测不仅能及时检测到气侵,还能在一段时间内比较准确地检测到气侵速率、气侵量等信息;采用快速增加井口回压控制气侵时,井底压力和套管鞋处压力也随之快速增大,而井口钻井液流量则不断减小,当井底-地层压力平衡时出口钻井液流量接近于循环排量;采用增大排量控制气侵时,当钻井液密度较低时,即便动切力和粘度都很大时,采用提高排量的控制效果依然有限;采用常规关井时,由于停泵会引起井底压力突然降低,采用MPD装置辅助关井可以避免停泵造成井底压力进一步下降;循环排气阶段井口回压仍会上升,且当气体移动到井口附近位置时井口回压增速较快;通过提高循环排量可以降低井口回压;循环阶段初期,井口气体流量和钻井液流量增长缓慢,气体移动到井口附近时,井口钻井液流量和气体流量先后出现峰值;提高循环排量时井口气体流量和钻井液流量会相应的增大,因此在提高循环排量时要考虑是否超过气液分离器处理能力。本文较为全面的研究了井底恒压法控压钻井气侵控制问题,对于丰富控压钻井井控理论有一定的实际意义。
[Abstract]:When drilling for gas invasion, the bottom hole constant pressure control drilling can detect the gas invasion in time, and can quickly and effectively control the micro-medium gas invasion by increasing the back pressure of the well head or increasing the displacement. Compared with conventional well control, shut-in is no longer the only control measure after gas invasion, even though bottom-hole constant pressure controlled drilling can control a certain amount of gas invasion quickly and effectively through wellhead device. However, because of the increase of control equipment and the corresponding increase of safety risk, it is more difficult to make well control decision. Although the technology of controlled pressure drilling has been applied in our country and the equipment has been made locally. However, the theoretical research on well control of controlled pressure drilling is still few, and the relevant research is not enough. Therefore, it is necessary to study the gas invasion law and control of bottom hole constant pressure controlled pressure drilling. This paper is based on the bottom hole constant pressure controlled pressure drilling technology theory, combined with seepage mechanics, single-phase flow, gas-liquid two-phase flow basic theory. The multiphase flow model of annulus after gas invasion is established. The influence of different parameters on bottom hole pressure after overflow and the variation law of bottom hole pressure in different overflow stages and overflow control measures are systematically analyzed. Finally, a practical example is given. The variation law of bottom hole pressure and the wellbore safety risk in dynamic well control are systematically analyzed from the occurrence of gas invasion to the complete discharge of gas during the process of bottom hole constant pressure controlled drilling. The simulation results show that:. The gas invasion can not only be detected in time through accurate flow monitoring in the gas invasion detection stage. The gas invasion rate and gas flux can be detected accurately in a period of time. The bottom hole pressure and casing shoe pressure also increase rapidly, while the wellhead drilling fluid flow rate decreases continuously when adopting rapid increase of wellhead back pressure to control gas invasion. When the bottom hole and formation pressure are balanced, the flow rate of the outlet drilling fluid is close to the circulating displacement. When increasing displacement is used to control gas invasion, when the density of drilling fluid is low, even when the dynamic shear force and viscosity are very large, the control effect of increasing displacement is still limited. When the conventional shutoff is adopted, the downhole pressure will be reduced suddenly because the pump shutoff will cause the downhole pressure to be reduced suddenly. The MPD device can be used to assist the shutoff well to avoid the further drop of the downhole pressure caused by the pump shutdown. At the stage of circulating exhaust, the wellhead backpressure will still rise, and when the gas moves to the position near the wellhead, the increase of wellhead backpressure will be faster. The well head pressure can be reduced by increasing the circulation discharge. At the beginning of the circulation stage, the gas flow rate and the drilling fluid flow rate increase slowly. When the gas moves to the well head, the drilling fluid flow rate and the gas flow rate of the well head appear the peak value one after another. When the circulation discharge is increased, the wellhead gas flow and drilling fluid flow will increase accordingly. Therefore, it is necessary to consider whether to exceed the treatment capacity of gas-liquid separator when increasing circulation displacement. This paper comprehensively studies the gas invasion control problem of bottom-hole constant pressure controlled drilling. It has certain practical significance for enriching well control theory of controlled pressure drilling.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE242

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