川渝地区深井注水泥环空流体掺混规律研究

A Study on Cement Slurry Circulation Fluid Mixing for Deep Well Casing Cementing in the Sichuan-Chongqing Area

杨涪杰 孙劲飞 胥珂维 罗涵临 李早元

YANGFujie SUNJinfei XUKewei LUOHanlin LIZaoyuan

油气藏地质及开发工程全国重点实验室·西南石油大学, 四川 成都 610500 西南石油大学理学院, 四川 成都 610500 西南石油大学人工智能研究院, 四川 成都 610500 中国石油西南油气田公司工程技术研究院, 四川 成都 610000

National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China College of Sciences, Southwest Petroleum University, Chengdu, Sichuan 610500, China Artificial Intelligence Research Institute, Southwest Petroleum University, Chengdu, Sichuan 610500, China Engineering Technology Research Institute, PetroChina Southwest Oil and Gas Field Company, Chengdu, Sichuan 610000, China

深井固井注水泥过程中，由于长封固段，窄间隙，高偏心等复杂井眼条件的影响，环空流体易发生掺混，混浆可能导致掺混段摩阻增大，造成固井漏失。针对川东高磨区块油层套管固井作业中高偏心环空的循环当量密度(ECD)预测不准确的问题，开展了固井注水泥流体掺混模拟及混浆流变性实验研究，研究基于计算流体力学(CFD)软件实时计算混浆段各流体占比变化，通过流变实验拟合流变性方程计算井筒ECD，结果证明了偏心度是影响混浆比例变化的主要影响因素，低偏心度时，钻井液、隔离液和水泥浆比例主要为5：1：4，而高偏心度时，比例主要为7：1：2；考虑混浆的ECD较常规ECD在上部混浆段高出0.2$\sim$0.8 g/cm$^3$，在下部纯水泥段要高出0.2$\sim$0.5 g/cm$^3$。本研究揭示了深井复杂井况对流体间掺混比例及混浆对井筒当量密度的影响，对保障川渝地区深井固井注水泥安全作业和提高固井质量具有重要意义。

During the process of cement injection in deep wells, due to the influence of complex wellbore conditions such as long sealing sections, narrow gaps, and high eccentricity, the annulus fluid is prone to mixing, and the mixing may increase the friction of the mixed section, causing cementing leakage. In order to solve the problem of inaccurate ECD prediction of high eccentricity annulus in the casing cementing operation of the oil layer in the Gaomo in eastern Sichuan, a cementing fluid mixing simulation and an experimental study on the rheology of the slurry were carried out. The study calculated the slurry in real time based on CFD. According to the changes in the fluid proportion of each section, the wellbore ECD was calculated by fitting the rheological equation through rheological experiments. The results proved that the eccentricity is the main factor affecting the change of the mixing ratio. When the eccentricity is low, the proportion of drilling fluid, spacer fluid and cement slurry is 5：1：4, and when the eccentricity is high, the ratio is mainly 7：1：2; the ECD of the mixed grout is 0.2$\sim$0.8 g/cm$^3$ higher than the conventional ECD in the upper grouting section, and is 0.2$\sim$0.5 g/cm$^3$ higher in the lower pure cement section. This study reveals the impact of complex well conditions in deep wells on the mixing ratio between fluids and the equivalent density of the wellbore. It is of great significance to ensure the safe cementing operation of deep wells in Sichuan and Chongqing and improve the quality of cementing.

10.11885/j.issn.1674-5086.2024.03.01.03