超深井高温高压井筒复杂流动压力演变规律研究

A Study on Evolution Law of Complex Flow Pressure in Ultra-deep Wells with High Temperature and High Pressure

邓虎 唐贵 张林

DENG Hu TANG Gui ZHANG Lin

川庆钻探工程有限公司钻采工程技术研究院, 四川 广汉 618300

Drilling & Production Technology Research Institute, CCDC, Guanghan, Sichuan 618300, China

超深井钻井过程中，因其高温、高压、高应力及复杂的地层环境，极易发生气侵。若发现不及时，井底压力将持续降低，气侵随之加剧，如此恶性循环，增大井控风险。超深井井筒压力控制的关键技术在于研究复杂多相流流动规律，但目前的研究还不够深入。因此，针对超深井井筒流体高温、高压流变特性展开研究，基于漂移流模型建立了一套超深井全井筒复杂流动数学模型，进行了求解，并以ST8井为例，针对单溢流和溢漏同存进行了模型验证和压力演变规律因素分析。研究结果表明，该模型计算出的立压和套压数据与现场作业测得的数据基本吻合，计算精度较高，可用于描述复杂流动压力演变规律。在相同工况条件下，溢漏同存的压力下降比单溢流下降幅度更大，后果更为严重。此外，密度和排量对井底压力都有影响，其中，密度主要影响静液柱压力，排量主要影响流动摩阻。

Due to the high temperature, high pressure, high stress and complex formation environment during the drilling of ultra-deep wells, gas invasion is prone to occur. If not discovered in time, the bottom hole pressure will continue to decrease, and gas invasion will intensify, leading to a vicious circle that increases the risk of well control. The key technology of wellbore pressure control lies in the study of complex multiphase flow laws in ultra-deep wells, but the current research is not deep enough. This study focuses on the high-temperature and high-pressure rheological characteristics of the fluids in the ultra-deep wellbore, and establishes a complex mathematical model of the full wellbore flow based on the drift flux model. The model is solved, verified and analyzed using the example of Well ST8 for pure overflow and simultaneous overflow and leakage. Research results show that the calculated standpipe pressure and casing pressure from this model are basically consistent with the field operation data, and the calculation accuracy is high, which can be used to describe the evolution law of complex flow pressure. Under the same working conditions, the pressure drop of the coexisting overflow is higher than that of the overflow condition, and the consequences are more serious. Both density and flow rate have an effect on the bottom hole pressure, in which the density mainly affects the hydrostatic column pressure, and the displacement mainly affects the flow friction.

10.11885/j.issn.1674-5086.2022.09.17.01