Numerical simulation and sensitivity analysis of accurate ranging of adjacent wells while drilling

Abstract

Cluster well drilling technology is the key to large-scale development of unconventional oil and gas, but it is difficult to measure the distance of adjacent wells accurately by using off-the-shelf tilting tools and algorithms. Therefore, this paper proposes a novel algorithm for accurate ranging of adjacent wells while drilling. Firstly, a double-layer radial medium model, a magnetic field distribution law model and a relative position relationship model were established. Then, by solving the above model, the accumulation discipline of low-frequency current on the casing and the distribution law of the magnetic field around the casing are revealed. The calculation method of the relative position relationship is also obtained. The model is also compared with the experimental data of previous scholars to verify its effectiveness. Finally, the sensitivity analysis of the electric field strength in the radial direction, the current distribution on the casing and the magnetic field strength of the measuring point were carried out. The analysis results show that the electric field strength in the radial direction has obvious jump at the interface between the drilling fluid and the formation; the current on the casing and the distribution of the surrounding magnetic field are affected by the current intensity, the conductivity of the drilling fluid, the distance between the wells, the size of the wellbore, and the relative inclination angle of the well; in addition, in the short-distance measurement process, as the distance from electrode to probe is greater than 60 m, the relative well angle of construction well and production well should be controlled within 3° to avoid collision. The research shows that the algorithm can provide theoretical basis for the high-precision measurement of clusters and infill wells.