A magnet ranging calculation method for steerable drilling in build-up sections of twin parallel horizontal wells

In drilling technology, adequate control over the distance between adjacent sections of twin parallel horizontal wells has a significant impact on the final recovery rate from unconventional oil and gas resources, such as heavy oil and natural gas hydrates. For this distance to meet design requirements and to reduce the duration of the drilling period, it is necessary to use a rotating magnet ranging system that helps drill an injection well starting from the build-up section. Usually, the build-up sections of the twin parallel horizontal wells are not parallel. Therefore, the spatial relationship between the build-up sections of the two wells can be divided into two types, namely, converging coplanar and non-coplanar. In this paper, we propose a method based on an algorithm for finding extreme values to calculate the radial distance between the build-up sections of the twin parallel horizontal wells. In addition, we propose and discuss a method for calculation of the direction between the magnetic sub and the probe tube in the build-up sections using coordinate transformations combined with the rotating magnet ranging calculation for the horizontal sections of twin parallel horizontal wells. The simulation results indicate that the magnet ranging algorithm for the build-up sections of twin parallel horizontal wells has a precision of a few percent and can meet the actual needs of the drilling site.