Study On Distribution Of Magnetic Field Around Casings In Upper Vertical Sections Of Cluster Wells

In recent years,cluster wells and infill drilling technology has been widely used,the distance between the well and the well getting smaller and smaller,the magnetic interference between the sleeve phenomenon obviously,inclinometer data resulting in distortion,when cross-collision accidents have occurred borehole,how inclinometer data to be amended to avoid the cluster portion of the wellbore up hole impact has become a key issue.Existing technologies include anti-collision scanning,post collision probability analysis,which relies heavily on the accuracy inclinometer data,and magnetic inclinometer measurements can easily be affected by an external magnetic field source,especially the impact o the well casing.Based on positive drilling casing surrounding the magnetic field is determined with respect to adjacent wells location method is called passive anti-collision method,with respect to such anti-collision method,less an appropriate magnetic field model,the relevant experimental data is relatively lacking.Research this subject,one is adjacent well casing will affect the measurement accuracy of the magnetic inclinometer,it also provides support for neighborhood-based distribution of the magnetic field of the well casing borehole anti-collision warning technology.For these reasons,this paper by finite element software for the distribution of the magnetic field around a single casing were studied,and no single casing remanence magnetic field strength in three-dimensional space with the azimuth,horizontal distance,the variation of the longitudinal distance casing magnetic field distribution in a single three-dimensional space to form a comprehensive understanding;combined with field and laboratory data obtained sleeve remanence common conclusions and estimates in the range of about 1 bushing surface remanence times to 60 times the size of earth’s magnetic field,there is residual magnetism when analyzing a single casing surrounding the scope and extent of the superposition of the magnetic field,the residual magnetization found mainly in the end of the tube,the scope of the earth’s magnetic field is about 11.2 times the radius of the sleeve.Presented at cluster wells anti-collision warning and magnetic positioning technology in two important sensitivities distance and azimuth,by regression analysis,with a variety of examples establish the function model of the magnetic field strength with distance,the change in orientation,according to a given longitudinal when the magnetic field variation in the distance,estimated relative to the well casing adjacent lateral distance and azimuth.Vertical well section to cluster multiple vertical portion of the well casing finite element simulation was found to produce a more significant interference between the sleeve and the bias magnetic field significantly increased the scope of Disturbance;by simulating the actual site construction process to be drilling location in the vertical direction of the magnetic field strength,changes in laws and east-west direction north-south direction,at all stages of the construction cluster wells to provide effective guidance magnetic parameters;comparing cluster wells drilled in the distribution of the magnetic field around the casing and single distribution of the magnetic field around the casing,the casing found that when a smaller radius,the surface residual magnetism small range magnetic interference and disturbance adjacent well casing are very limited.A plurality of magnetic field around the casing of the full-size experimental tests carried out,and the distribution of the magnetic field around the casing of a comprehensive analysis,before two chapters around the casing of the magnetic field perpendicular to the finite element analysis provides a basis.