Anti-collision design and control of vertical section in ‘well plant’ mode

The ‘well plant’ mode has been widely used in oil exploitation, especially in the exploration and development of unconventional oil and gas resources. With this mode, batch drilling and completion can be achieved in an operation line, so that operation efficiency is improved and operation cost is reduced. When this mode is applied, however, the well spacing is generally small, and the vertical section can not be maintained adequately due to many factors, leading to high risks of collision between wells. In this paper, it is proposed that vertical section should be drilled with both inclination and horizontal displacement strictly controlled in order to ensure the safety of well drilling in the ‘well plant’ mode. The relationships between the designed minimum well spacing and the inclination and horizontal displacement at the straightening point or the maximum allowable dogleg severity were discussed, and the control requirement on the inclination was proposed under the constraint of maximum allowable dogleg severity and horizontal displacement. The cluster well on X-Pad was taken as an example to illustrate how to control the inclination and horizontal displacement of vertical section of cluster well and what straightening measures to be taken when any collision may occur.