高温高压下高密度全油基钻井液流变模式

Rheological Model Study on High Density All Oil-base Drilling Fluid Under High Temperature and High Pressure

在高温高压深井中,受温度和压力的影响,油基钻井液处理剂会发生降解、交联、甚至固化等,导致钻井液的流变性发生巨变,严重影响了钻井液的携岩性,甚至会导致钻井无法进行,为准确掌握油基钻井液在井底高温高压下的流变状态,建立了全油基钻井液的高温高压流变模式。使用Fann50SL型高温流变仪分析温度和压力对两种油基钻井液体系流变性能的影响,并采用回归分析方法对实验数据进行处理。实验及回归分析表明,钻井现场作业中普遍采用的宾汉模式不能完全准确表示全油基钻井液的高温高压流变特性,应根据具体地层条件和钻井液组成采用实验手段选出最优流变参数模型。

In high temperature and high pressure deep well,temperature and pressure would cause treating agents for oil-based drilling fluid degradation,cross-linked,even curing.In this case the rheological properties of drilling fluid can change dramatically,which affects significantly the carrying cuttings ability,and even leads to drilling termination.So it is necessary to establish the rheological model of the high density all oil-base drilling fluid under high temperature and high pressure to accurately grasp the rheological state of oil-base drilling fluid under high temperature and high pressure.Temperature and pressure influence on the rheological properties of two drilling fluid systems is tested by Fann50SL high temperature rheometer,and the data are analyzed by using the regression analysis.The results show that the Bingham model commonly used in drilling field operations cannot predict accurately the rheological properties of all oil-base drilling fluids in the case of high temperature and high pressure,and that the optimal rheological parameter model should be selected experimentally according to the specific formation conditions and drilling fluid composition.