顺北一区小井眼超深井井筒温度场特征研究与应用

顺北一区小井眼超深井井筒温度高,部分井超过国内现有测量仪器抗温能力,易引起测量仪器探管烧毁和无信号等问题.为此,建立了井筒瞬态温度场数学模型,分析了不同参数下的井筒温度场剖面特征,提出了"临界温度井深"概念.基于此概念,为了降低井底循环温度,使临界温度井深下移并到达井底,对钻井液的流变性、热属性、排量、入口温度及钻柱热...

Study and Application of Wellbore Temperature Field Characteristics in the Ultra-Deep Slim-Hole Wells in the Shunbei No.1 Area

The ultra-deep slim-hole wells in the Shunbei No.1 Area have high wellbore temperatures. In some wells, the temperatures even exceed the temperature resistance of the existing domestic measuring instruments, which often leads to probe burnout and no signal input to the instruments. To solve this problem, a mathematical model was established for transient wellbore temperature fields, which analyzed the field profiles at different parameters, and introduced the concept of “well depth at critical temperature” (WDCT). On this basis, in order to reduce the bottomhole circulating temperature and move the WDCT down to the bottom, the sensitivity of seven parameters were analyzed, including rheology, thermal property, displacement, and inlet temperature of drilling fluid, and the thermal property of the drill string. Then the physical parameters that could significantly influence the wellbore temperature field were obtained. It is found by analysis that WDCT could be divided into true, transitional, and equivalent categories according to the variation curves of wellbore temperature. The wellbore temperature field was sensitive to the thermal conductivity of the drill string, the specific heat capacity of drilling fluid, and the thermal conductivity of drilling fluid in a descending order, which corresponded to the equivalent WDCT. The results showed that changing the thermal properties of drilling fluid or reducing the thermal conductivity of the drill string could effectively lower the bottomhole circulating temperature in the Shunbei No.1 Area.