Wellbore Anti-Collision Method Research Based On The Magnetic Measurement While Drilling

The collision problem of cluster wells and infill wells is one of the most prominent problems encountered in drilling well,although there are all kinds of anti-collision technology,such as conventional anti-collision technology and active anti-collision technology,due to the limitation of the technology itself and the current stage of science and technology is not up to the requirements,causing the accident happened when drilling cluster wells and infill wells.It seriously delayed the drilling time and caused huge economic losses.Currently,there is no technical method to achieve perfect reliability and economy.Therefore,we need a new economic and accurate anti-collision method to provide technical support for such problems.This article,based on the infinite cannula calculating model in the geomagnetic field,explains the theoretical calculation method of residual magnetic intensity of infinite cannula and magnetizing field intensity.It develops from simplifying the former model,and obtains the calculation method of surrounding magnetic field intensity of single casing.The comparison between these empirical results and the theoretical calculating ones,the average relative error of which is from 20% to 40%,actually proves the rationality of the calculation method of surrounding magnetic field intensity of single casing.The empirical results of the three groups show that the position error of this method ranges from 0.5m to 0.9m.This article proposes a designing method of Crash-proof borehole track based on the adjoining wells location prediction method which is actually upon the magnetic measurement.The new method is to design the track from the magnetic anomaly end of the drilling well to the bottom and the track from the bottom to the end to drill.The position of adjacent wells magnetic measurement method based on prediction and collision prevention,is a kind of simple and easy well trajectory anti-collision method,when drilling in conventional measurement in casing string to add a set of gyro azimuth measurement device used to correct the azimuth,will not have any impact on adjacent production wells.For the approximately parallel wells with a roughness of less than 10 degrees,This method can prevent the occurrence of borehole anti-collision in the well drilling and adjacent wells to a certain extent.It can provide a reference for solving the problem of anti-collision and obstacle avoidance after magnetic anomaly.