含CaCl2水基聚合物钻井液沿井周地层渗透规律研究

利用微生物诱导碳酸钙沉积（MICP）技术来提高油气井固井二界面胶结质量近年来受到了越来越多的重视。当前，针对3 000 m以浅油气井已实现了含成矿微生物的固井水泥浆技术。为了使固井水泥浆滤液中的成矿微生物在二界面处高效发挥MICP作用以提高二界面胶结质量，还需在钻井过程中利用钻井液携带CaCl₂的渗透向井周地层中预先注入一定量的钙源。因此，有必要研究含CaCl₂钻井液在井周地层的渗透规律，从而合理控制CaCl₂的注入量和钻井成本。基于此，以当前常用的环保水基聚合物钻井液为基本载体，综合考虑钻井液渗透时在井壁处泥饼动态形成机理、井周地层物性参数变化规律以及含CaCl₂水基聚合物钻井液流变性等因素，利用理论计算与模拟实验相结合的方法，建立了含CaCl₂水基聚合物钻井液滤液沿井周地层渗透量及渗透距离的定量预测模型。该预测模型的计算结果与模拟实验测试结果吻合程度较高，证实该预测模型具有较好的可靠性，有助于为钻井生产企业合理优化钻井液和固井水泥浆施工工艺提供理论支持。 

Study on permeability law of water-based polymer drilling fluid containing CaCl2 in wellbore formation

The use of microbially induced carbonate precipitation (MICP) technology to improve the cementation quality of oil and gas well cementing has attracted more and more attention in recent years. At present, cementing slurry technology containing ore-forming microorganisms has been realized for shallow oil and gas wells of 3, 000 meters. In order to make the ore-forming microorganisms in the cement slurry filtrate effectively play the role of MICP at the two interfaces to improve the quality of the two-interface cementation, it is necessary to use the drilling fluid to carry the CaCl₂ in the drilling process to pre-inject a certain amount of CaCl₂ into the wellbore formation. Therefore, it is necessary to study the penetration law of CaCl₂-containing drilling fluid in the wellbore formation, so as to reasonably control the CaCl₂ injection volume and drilling cost. Based on this, this paper takes the commonly used environmentally friendly water-based polymer drilling fluid as the basic carrier, comprehensively considers the dynamic formation mechanism of mud cake at the well wall, the variation law of physical properties of the surrounding formation and the water-based polymer drilling with CaCl₂. The factors such as liquid rheology and the combination of theoretical calculation and simulation experiment were used to establish a quantitative prediction model for the permeation and permeation distance of the drilling fluid containing CaCl₂ water-based polymer in the wellbore formation. The calculation results of the prediction model are consistent with the simulation test results, and have good reliability, which helps to provide the oretical support for drilling production enterprises to rationally optimize drilling fluid and cement slurry construction technology.