Drilling Fluid Rheological Model Optimization And Hydraulic Parameters Optimization Design Research

In the drilling process, knowing exactly rheological properties of the drilling fluid system and predicting downhole circulating pressure loss, as well as drilling hydraulic parameters optimization design, have very important significance. The accurate calculation of the drilling fluid rheological parameters and the rational choice of rheological model is the premise of the drilling fluid hydraulic parameters optimization design, an accurate estimate of drilling fluid rheological parameters is the basis of a reasonable choice of the rheological model of drilling fluid. So drilling fluid rheological parameters of the model calculation problem is the core problem of the drilling fluid design required to solve.Commonly drilling fluid rheological model into linear and nonlinear two types. Linear rheological model using traditional linear regression method can estimate the rheological parameter values, but nonlinear rheological model, such as power-law. He-Pakistan. Carson drilling fluid rheological model, usually use a nonlinear least squares method solution. This paper bases on gauss-Newton method, combining with the characteristics of common nonlinear drilling fluid rheology equation, proposes effective method to seek initial value, finds an optimal initial value which is applied to parameter estimation of nonlinear drilling fluid rheological model. Gauss-Newton method is strongly dependent on the initial value in practical applications and iterations may not converge, this method can overcome the shortcomings, giving full play to the advantage of Gauss-Newton method such as computing workload of small at each step, fast convergence. A large number of the measured drilling fluid examples show that the rheological parameter estimate has fitting residual approximate unbiasedness and variance of the smallest good statistical characteristics, and smaller fitting variance than the traditional linear regression method and excellent the fitting residual statistical properties. Calculating the rheological parameter values can optimize drilling fluid rheology model by least squares method.The drilling fluid rheological model selection, combining the rheological parameter values can calculate in underground drilling fluid circulation system the pressure loss of each part, and in the rated pump pressure determine the optimal flow, the optimal combination of nozzle, draw up a comprehensive program to achieve the optimal design of the hydraulic parameters. Under the principle of wellbore stability, wellbore clean, the program effective and rational take advantage of hydraulic energy to improve the ability of drilling fluid rock breaking and carrying crumbs efficiency and reduce drilling costs.Finally using numerical calculation method, using the high-level computer language c#develops "drilling fluids engineering design and analysis system" computer programs, this system optimize rheological model using method introduced by this paper in combination with drilling data or the actual experimental data. Calling the library of algorithms of computer background and the dynamic calculation realize optimization design of drilling fluid hydraulic parameters. a lot of example calculation shows that the calculation results of "drilling fluid design and analysis system" have high precision, which is consistent with the actual situation height, the development of "Drilling fluid design and analysis system" solve the difficulties in artificial calculation,reduce unnecessary experiment, save a lot of human, financial and material resources and provide efficient and accurate calculation results for the actual application and indoor research.