Study and application of calculating the magnetic interference track by means of casing coordinate section method

During the construction of dense cluster wells, the magnetic interference of casing is complicated, the anti-collision construction is difficult and the location relationships between wells can be hardly determined. To solve these problems, it was proposed to adopt the casing coordinate section method to locate the well trajectory in the vertical section of cluster well with the magnetic interference of casing. The mathematical model of the magnetic field on the cross section of casing was established by simplifying the magnetization model of the space near the casing. In addition, the distribution laws of the magnetic field on the cross section of casing were figured out by performing simulation experiments on the magnetic interference of casing. Based on this, the casing coordinate section method was put forward. Then, it was used to invert the spatial location of measurement points in the casing and plot the trajectory of the hole section with magnetic interference in the well being drilled, so that the relative spatial relation between the measurement points and the neighboring casing can be discriminated accurately in the hole section with magnetic interference. The field construction test in 10 cluster wells of Huabei Oilfield verifies the accuracy and validity of casing coordinate section method. Thus, the anti-collision relation of cluster well is located accurately and the anti-collision problem in the construction of dense cluster well is solved.