基于实时温度场的井筒稳定性优化模型研究

Research on Optimization Model of Wellbore Stability Based on Real-time Temperature Field

为了优化超深井钻井循环过程中井筒的稳定性,需要建立适宜不同层位的地层温度与孔隙压力耦合的超深井瞬态井筒传热模型。为此,通过寻找地层温度随深度和径向的变化规律,利用线性叠加原理将孔隙压力引起的应力诱导分量和地层温度变化引起的热诱导分量,组合到原位诱导孔隙弹性模型中。同时考虑了钻具旋转产生热源及不同工况下钻具与井壁接触产生热源,建立了充分考虑渗流、孔隙压力变化与地层温度变化影响的钻井液当量循环密度(ECD)计算模型,并加以实例验证。研究结果表明,该热孔弹性模型能为设计井眼清洁循环时间考虑温度的影响提供重要参考,不同进尺下地层渗流的影响比钻井液对井壁渗流的影响导致的坍塌风险更大。该稳定性模型能为优选实际循环操作参数以及钻井液比重设计提供理论依据。

In order to optimize wellbore stability analysis in the circulating process of ultradeep drilling,a transient wellbore heat transfer model of ultradeep well suitable for the coupling of formation temperature and pore pressure in different horizons needs to be built.Therefore,in the paper,by means of looking for the variation law of formation temperature with depth and radial direction,the linear superposition principle was used to combine the stress-induced component caused by pore pressure and the thermal-induced component caused by formation temperature change into the elastic model of in-situ induced pores.Meanwhile,the heat source generated by rotation of drilling tool and the heat source generated by contact of drilling tool and sidewall under different working conditions were taken into account,and an ECD calculation model fully considering the influence of seepage,pore pressure variation and formation temperature variation was built and verified by an example.The research results show that the hot-hole elastic model can provide an important reference for the design of wellbore cleaning circulating time considering the influence of temperature;the formation seepage under different footages has greater risk of causing collapse than the seepage of drilling fluid into sidewall;and the stability model can provide a theoretical basis for the optimization of actual circulating operation parameters and the design of specific weight of drilling fluid.