一种水基钻井液在高温高压下的流变特性研究

Rheological Characteristics of a Water-based Drilling Fluid Under High Temperature and Pressure

高温高压环境对钻井液流变性会产生较大影响,进而影响水力参数计算和设计,并引起井眼清洁和井壁稳定等问题。本文针对现场采用的一种水基钻井液,使用OPITE高温高压流变仪研究了其在高温高压下的流变特性,并利用回归方法对实验数据进行分析和处理。结果表明,温度是影响实验所用水基钻井液样品表观黏度的主要因素,而压力对钻井液表观黏度的影响较小。该钻井液表观黏度随温度变化的规律为先减小后小幅增大,当表观黏度进入增大阶段表明该钻井液达到失效条件,该钻井液的临界失效温度约为140℃。在此基础上采用不同流变模式对实验数据进行了拟合,结果显示在100℃以下时,幂律模式和赫巴模式均能较准确地描述该钻井液的流变性,当温度达到100℃以上时,赫巴模式更适合描述其在高温下的流变性。

The high temperature and high pressure environment will have a great impact on the rheology of drilling fluid,thus affecting the calculation and design of hydraulic parameters,and causing problems such as wellbore cleaning and wellbore stability.In this paper,the rheological properties of a water-based drilling fluid used in the field under high temperature and high pressure are studied by using the OPITE high temperature and high pressure rheometer,and the experimental data are analyzed and processed by using regression method.The results show that temperature is the main factor affecting the apparent viscosity of water-based drilling fluid samples used in the experiment,while pressure has little effect on the ap-parent viscosity of drilling fluid.The change rule of the apparent viscosity of the drilling fluid with temperature is that it decreases first and then in-creases slightly.When the apparent viscosity enters the increasing stage,it indicates that the drilling fluid reaches the failure condition,and the criti-cal failure temperature of the drilling fluid is about 140℃.On this basis,different rheological models are used to fit the experimental data.The results show that when the temperature is below 100℃,the power law model and the Heba model can more accurately describe the rheological properties of the drilling fluid.When the temperature is above 100℃,the Heba model is more suitable for describing the rheological properties of the drilling fluid at high temperatures.