Maximizing Cut and Pull Casings for Plug and Abandonment

Abstract Plug and abandonment activity is expected to increase and remain an active service as wells need to be permanently abandoned and/or enable slot recovery. Throughout the life of a well, degradation of the mud system in the annulus can lead to migration of mud solids, which settle at areas of high deviation or increased dogleg severity or at above the top of the cement. In this process strong engineering model is needed in addition to the logging runs to maximize the length of the cut casings, to establish higher accuracy to estimate the cutting depth. Increased reliability for Cut and Pull in a single cut/trip is needed so that it provides safety to avoid flowing fluids to mitigate barrier breakdown. Cut and pull the casing pipe conditions require fast and accurate response. This paper describes an analytical model through which drag calculations are modified to determine: the force at the deepest cut point within the given limits of the pipe conditions; the measured weight or overpull within the margin required to pull; the measured weight required pull at any depth. The total drag is the sum of the mechanical frictional forces acting on the casing during the pull operation and the fluid frictional forces due to the fluid contact with the inside and outside of the casing. In addition, any solids packed around the casing will exert a frictional force with the outside of the casing. Kinetic friction and shear force required to break the bonding are also included. The percentage of solids and sediments and length of the contaminants are estimated through logs.