Optimization of rheological parameter for micro-bubble drilling fluids by multiple regression experimental design

Abstract

In order to optimize plastic viscosity of 18 mPa·s circulating micro-bubble drilling fluid formula, orthogonal and uniform experimental design methods were applied, and the plastic viscosities of 36 and 24 groups of agent were tested, respectively. It is found that these two experimental design methods show drawbacks, that is, the amount of agent is difficult to determine, and the results are not fully optimized. Therefore, multiple regression experimental method was used to design experimental formula. By randomly selecting arbitrary agent with the amount within the recommended range, 17 groups of drilling fluid formula were designed, and the plastic viscosity of each experiment formula was measured. Set plastic viscosity as the objective function, through multiple regressions, then quadratic regression model is obtained, whose correlation coefficient meets the requirement. Set target values of plastic viscosity to be 18, 20 and 22 mPa·s, respectively, with the trial method, 5 drilling fluid formulas are obtained with accuracy of 0.000 3, 0.000 1 and 0.000 3. Arbitrarily select target value of each of the two groups under the formula for experimental verification of drilling fluid, then the measurement errors between theoretical and tested plastic viscosity are less than 5%, confirming that regression model can be applied to optimizing the circulating of plastic-foam drilling fluid viscosity. In accordance with the precision of different formulations of drilling fluid for other constraints, the methods result in the optimization of the circulating micro-bubble drilling fluid parameters.

Keywords

orthogonal experimental design / uniform experimental design / circulating micro-bubbles / plastic viscosity / multiple regression experimental design

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