基于马氏漏斗黏度的油基钻井液表观黏度预测方法

Determination of the Apparent Viscosity of Oil-Based Drilling Fluid by Using Marsh Funnel Viscosity

为了研究油基钻井液漏斗黏度与表观黏度之间存在的联系,从马氏漏斗黏度计的结构出发,在水基钻井液研究成果的基础上,分析了油基钻井液在马氏漏斗黏度计中的流动规律,研究了利用油基钻井液马氏漏斗黏度预测表观黏度的可行性,推导了流体漏斗黏度计算公式,建立了油基钻井液马氏漏斗黏度与表观黏度函数之间的数学模型,并对该模型分别进行了室内试验和现场试验的验证。试验结果显示,室内和现场计算的表观黏度与实测表观黏度的最大相对误差分别为6.8%和8.2%,均在合理范围内;现场试验中,油水比从70∶30增大到91∶9,预测结果没有受到影响。研究结果表明,基于马氏漏斗黏度的表观黏度预测模型能够较准确地估测油基钻井液的表观黏度,钻井现场可以利用油基钻井液的马氏漏斗黏度估算其表观黏度,这为现场预测油基钻井液的表观黏度提供了方便。

To study the relationship between the funnel viscosity and the apparent viscosity of oil-based drilling fluid, the flow patterns of oil-based drilling fluids in the marsh funnel viscometer were analyzed. Based on the structure of the marsh funnel viscometer, research was conducted to determine the possibility of apparent viscosity determination for oil-based drilling fluid by using the marsh funnel viscometer. In ad dition, the equations for funnel viscosity of fluids were highlighted and mathematic models for marsh fun nel and apparent viscosity of oil-based drilling fluids were established. Lab and field tests were performed to verify the accuracy of the newly developed models. Research results showed that the maximum relative errors between the calculated apparent viscosity and the measured apparent viscosity of indoor and field tests were 6.8% and 8. 2%, respectively. Both of these errors were in a reasonable range. During field tests, the oil-water ratio was increased from 70/30 to 91/9 with no observable impact on final results. Lab and field test results showed the apparent viscosity of oil-based drilling fluids could be determined accurate- ly by using the newly developed prediction model. In fact, funnel viscosity could be used on the drilling site to facilitate the determination of the apparent viscosity of the oil-based drilling fluid on site.