Online Measurement And Intelligent Optimization Of Drilling Fluid Rheological Properties

Drilling fluid is an essential component of drilling engineering and is often referred to as the "blood" of the drilling process.Its performance plays a crucial role in ensuring drilling efficiency and safety.Drilling fluid rheological properties are critical to its performance.Optimizing these properties can improve the cleaning efficiency of cuttings at the bottom of the well,maintain the stability of the hole walls,enhance drilling safety,increase the rate of penetration,and ultimately reduce the overall drilling costs.In complex geological environments,formations can change rapidly,and drilling fluid may have complex components,high solid content,and high gel strength.Accurately,reliably,and frequently measuring the rheological properties of drilling fluid is necessary to optimize its performance,ensure its compatibility with the formation,promote drilling safety,and increase the rate of penetration.Furthermore,the optimal value of drilling fluid rheological properties in complex geological environments is unclear,and it is primarily dependent on the engineers’ experience.This dissertation aims to measure and optimize drilling fluid rheological properties in complex geological environments.It covers the design and optimization of pipe viscometers,including modeling of measurement error and range,physical construction,reliability optimization,and realtime performance optimization.Additionally,the dissertation includes optimal modeling of drilling fluid rheological properties while considering drilling safety constraints.(1)The pipe viscometer measurement error and range analysis method based on the shear rate of the six-speed rotational viscometerAccording to the characteristics of drilling fluid in the complex geological environment,the pipe viscometer is the most reliable and principle-based technology for online measuring of the rheological properties of drilling fluids.Currently,there is a lack of analysis regarding the impact of different design parameters on the measurement accuracy and range of pipe viscometers.It should be noted that the wall shear rate in pipe viscometers differs from that in six-speed rotational viscometers.To address the issues mentioned above regarding pipe viscometers,a method for analyzing measurement error and range in the pipe viscometer that is based on the shear rate of the six-speed rotational viscometer is proposed.An error model that incorporates the generalized flow behavior index of drilling fluid is established.The effect of the mainly design parameters(the inner diameter of the circular pipe and length of the differential pressure measurement section)on measurement error under different conditions(only considering sensor measurement error,measurement error due to external factors,and the generalized flow behavior index of drilling fluid).The generalized Reynolds number is introduced to judge the flow state of non-Newtonian fluids,and the impact of the inner diameter of the circular pipe and generalized flow behavior index on the measuring range are analyzed.The proposed method for analyzing measurement error and range provides a theoretical foundation for the subsequent construction of the pipe viscometer.(2)The construction scheme for the pipe viscometer that comprehensively considers error,range,volume,and cost,and a flow rate flow design scheme based on the shear rate of the six-speed rotational viscometerTo address the problems of large volume and high cost in pipe viscometers,a construction scheme that comprehensively considers error,range,volume,and cost is proposed.To solve the problem of unreasonable flow rate setting for the pipe viscometer,a flow rate design scheme based on the shear rate of the six-speed rotational viscometer is proposed.The number of differential pressure measurement sections,the inner diameter of the circular pipe,the length of the circular pipe differential pressure measurement section,the maximum and minimum flow rates,and the number of differential pressure and flow test groups are designed.To reduce cost and volume,the pipe viscometer uses one section of circular pipe to measure the differential pressure.The inner diameter of the circular pipe is designed to be 12 mm and the length of the circular pipe pressure measuring section is designed to be 1m.The pipe viscometer with this parameter has a small volume,small error,and is resistant to disturbance.To reduce the influence of drilling fluid generalized flow behavior index on the measurement range and wall shear rate of the pipe viscometer,an appropriate maximum flow rate is set.This not only increases the measurement range but also makes the maximum wall shear rate of the pipe viscometer roughly equivalent to the maximum shear rate measured by the six-speed rotational viscometer.The pipe viscometer is constructed according to the designed parameters.Suitable sensors and equipment were selected according to the designed parameters to construct the pipe viscometer.The appropriate test frequency(0.5～8Hz)and number of groups are set,so that the wall shear rate range measured by the tube viscometer is similar to that measured by the six-speed rotary viscometer,which effectively reduces the error.The initial construction of the pipe viscometer establishes a hardware foundation for conducting experiments aimed at improving reliability and realtime performance.(3)Reliability optimization of the pipe viscometer considering wall static pressure holesTo address the issue of blockage of static pressure holes on the wall in complex geological environments due to drilling fluids with high solid content and gel strength,a proposal has been made to enhance the reliability of the pipe viscometer by considering the static pressure holes.An experimental method is employed to analyze the impact of wall static pressure holes with various orifice diameters on errors in differential pressure and drilling fluid rheological properties.Results indicate that when the diameter of the wall static pressure hole is between 1 and 5 mm,the apparent viscosity error of the pipe viscometer is less than 1 m Pa·s.Therefore,the pipe viscometer can utilize a 5 mm wall static pressure hole,which has a smaller error and larger diameter,to enhance its reliability.(4)Real-time performance optimization of the pipe viscometer based on the optimization of pulsation damper and backpressure valve setting parametersIn complex geological environments where the formation changes rapidly,highfrequency measurement is required to obtain and optimize the drilling fluid rheological properties in time.Current non-variable pipe viscometers usually take more than 10 minutes to measure the drilling fluid rheological properties,which cannot meet the needs of high-frequency measurement.This dissertation proposes a method to improve the realtime performance of the pipe viscometer by optimizing the setting parameters of the pulsation damper and the back pressure valve.Experimental means were used,and drilling fluids of different fluid types and viscosities were selected to test and analyze the effect of shortening the measurement time on the error,under different combinations of pulsation damper inflation pressure and backpressure starting pressure.Results show that when the inflation pressure of the pulsation damper is 0 MPa gauge pressure and the takeoff pressure of the back pressure valve is 0.02 MPa,the time required to measure drilling fluid rheological properties can be set to 65 seconds.This improves the real-time performance of the pipe viscometer.(5)Drilling fluid rheological properties and rate of penetration model based on stacked generalization ensemble algorithm and intelligent optimization of drilling fluid rheological properties considering drilling safety constraintsTo address the issue of unclear optimal values for drilling fluid rheological properties in complex geological environments,a drilling fluid rheological properties and rate of penetration model based on stacked generalization ensemble algorithm and intelligent optimization of drilling fluid rheological properties considering drilling safety constraints method are proposed.A rate of penetration model based on the stacked generalization ensemble algorithm is established,taking drilling fluid rheological properties,other drilling fluid parameters,drilling parameters,and formation parameters as input.The model uses XGBoost as a secondary learner and combines five first learners-Support Vector Machine,Random Forest,Extreme Random Tree,Gradient Boosting Machine,and Light GBM-to improve the accuracy and generalization of the rate of penetration model.Based on this rate of penetration model,a particle swarm optimization algorithm is used to optimize drilling fluid rheological properties with the goal of achieving the best drilling rate,while considering constraints on pump pressure and circulating equivalent density to ensure drilling safety during the drilling process.The optimal drilling fluid rheological properties are obtained,which increases the rate of penetration.In this dissertation,an online measuring instrument for drilling fluid rheological properties with good accuracy,reliability,real-time performance,small volume,and low cost is developed,and the intelligent optimization of drilling fluid rheological properties considering drilling safety constraints is studied.This dissertation provides a new technology and solution for the online measurement and optimization of drilling fluid rheological properties during drilling.