Research On Virtual Downhole Weight On Bit-based Autodrillier System

With the rapid advancement of drilling rig automation and horizontal well technology intelligence,the in-depth development of oil and gas exploration and development puts forward new requirements on drilling technology.The existing autodriller system(autodriller system based on the surface weight on bit(SWOB))is difficult to accurately control the downhole weight on bit(DWOB),so it uses an excessive margin(the difference between the accurate value and the applied value)to control the SWOB.Realize automatic drill feed.Inappropriate margins may cause the drill string system to become unstable,and there is a risk of drill string "locking up".Under such conditions of intense contact fatigue accumulation,drilling tool failure and damage are likely to occur,resulting in drilling accidents such as stuck drills.Therefore,it is very necessary to develop a new type of autodriller system(autodriller system based on DWOB)to eliminate or shorten this margin,optimize the performance of the drill bit,and provide new solutions for high-efficiency drilling in horizontal wells.Theoretical ideas and technical support.Based on the real horizontal well model,based on drill string mechanics theory,drill string and borehole wall interaction mechanism,drilling automation principles,and similar principles,this paper takes the drilling process of horizontal wells as the research object,and focuses on the real-time DWOB acquisition mechanism and ground target drilling.The related research on the control strategy of pressure is carried out,combined with the SIEMENS S7-200 Smart PLC control system and the Smart-700IE-V30 touch screen monitoring system,the control and monitoring program of the autodriller system based on DWOB is written,and a set of Autodriller system for horizontal wells based on DWOB.The device obtains simulated weight-on-bit data through the detection of hook load sensors and downhole sensors.According to the PLC control system and the human-machine interactive touch screen,the motor continuously adjusts the motor to drive the winch drum to rotate,and then corrects the hook load in real time to achieve real-time monitoring and control of DWOB.Prediction,so as to obtain the ideal DWOB,achieve the goal of autodriller based on DWOB,and ensure the efficient drilling of the drilling rig.According to the actual measurement under different well depth conditions,multiple sets of hook load and DWOB values are obtained.From the regression equation obtained,it is concluded that the two trends are in good agreement.According to the regression equation,Matlab curve optimization fitting tools are used to determine the DWOB A prediction is made.After optimization,the minimum error between the measured DWOB and the theoretical DWOB is 0.21%,the maximum error is 22.90%,and the absolute error of the calculated overall data is 11.88%.Analysis of a large number of experimental data shows that the system responds quickly and accurately,and the actual measured value and the theoretical value match well regardless of the trend or the numerical value.It shows that this new system not only has the advantages of the conventional automatic drilling system,it can reduce or even eliminate the pressure difference between the SWOB and the AWOB of the well,and it can be integrated with the conventional automatic drilling system to transfer the research method to the real drilling operation and realize the bottom hole Accurate control of the DWOB will directly improve the performance of the drill bit and thus the efficiency of drilling,which has high practical application value.