Simulation and Application of Windowing for High-Grade Steel Thick-Wall Casing in Ultradeep Wells: A Case Study of ST102 Well

Abstract

Windowing processes in ultradeep wells (> 7000 m) with high steel grade (TP155V) and thick-wall (15.83 mm) casing not only face complex underground environments with high temperature and pressure but also have the difficulty of long operation time and high cost. To improve the success rate and operational efficiency, CAE software was used to establish the casing windowing side-drilling simulation model and optimize the windowing milling cone. Field applications were used to further demonstrate the simulation results. The main conclusions are as follows. The simulation shows that the milling shoulder and the outer circle of the cone top are the main working faces in window opening and window repair. The conical milling cone has the largest windowing stress, highest windowing efficiency, and regular shape of the window. A casing with a depth of 7473 m, wall thickness of 15.83 mm, and steel grade TP155V was successfully windowing using six conical milling cone in the ST102 well, taking 51.76 h, and generating 94 kg iron chips in total; the average milling speed was 0.06 m/h; The casing windowing progress can be determined by observing the return state of the cuttings. ST102 well set three records in China for the deepest drilling depth, highest steel grade, and thickest wall thickness.