油基钻井液高温高压流变参数预测模型

在高温高压深井中,钻井液流变性受温度和压力的影响较大。研究油基钻井液的高温高压流变特性,建立宾汉流体的流变参数预测模型,对于现场及时调整钻井液性能、精确计算环空压降、实现高温高压井当量循环密度的精确预测及合理控制井底压力具有重要意义。对具有典型配方的油基钻井液在高温高压下的流变特性进行了研究,通过对实验数据进行多元非线性回归分析,建立了预测高温高压条件下油基钻井液表观黏度、塑性黏度和动切力的数学模型。由模型得到的预测值与实测值具有较好的吻合性,相关系数均在0.98以上。该模型可用于深部井段流变参数的预测和现场水力参数的精确计算。

Prediction model for rheological parameters of oil-based drilling fluids at high temperature and high pressure

For the deep wells with high temperature and high pressure, the drilling fluids are often affected by temperature and pressure. The careful investigation on the rheological properties of oil-based drilling fluids at high temperature and high pressure is very important for precisely calculating the pressure drop in annular and predicting the equivalent circulation density as well as controlling the bottomhole pressure. The rheological properties of oil-based drilling fluids with typically compositions at high temperature and high pressure indicated that the effect of pressure on the apparent viscosity, plastic viscosity and dynamic shear force at ambient temperature was considerable. However, this effect could be gradually reduced with the increase of temperature. Temperature is the major factor influencing the rheological properties of oil-based drilling fluids. The mathematical model for predicting the apparent viscosity, plastic viscosity and dynamic shear force of oil-based drilling fluids at high temperature and high pressure was established using the regressive analysis method. The calculated data with the model are in good agreement with the measured data, the correlation coefficients are more than 0.98. The model can be used to accurately predict the rheological parameters and calculate the hydraulic parameters in the deep sections of oil wells during drilling operation.