Completion Damage

Abstract

Formation damage has received significant attention over many years as one of the primary reasons for well productivity impairment, to the detriment of completion damage. The objective of this paper is to redress this imbalance and to focus on the central role that completion damage has on well productivity. Formation damage is a reduction in inflow performance due to damage of the near wellbore, while completion damage is an increased pressure drop effecting the lower completion, e.g., plugging of sand screens. A completion damage classification system is presented for the first time that relates this damage type to lower completion design throughout well lifetime. In addition, a review of some of the fluid qualification tests has been performed. Fluid compatibility. Computational fluid dynamics (CFD) was used to determine the displacement efficiency from drilling to completion fluid in a candidate well, and hence the mixing ratio of drilling fluid to completion fluid to be used in compatibility tests. Furthermore, CFD simulations provided an indication of the likely shear rates occurring during displacement that were later used in the testing. Fluid stability. To determine the influence of sag on fluid displacement efficiency, CFD was used to model the worst-case situation where all the weighting agent came out of suspension. Using the displacement efficiency and shear rates obtained, a new dynamic completion damage test was devised to determine the potential for screen plugging. Finally, an overview will be presented of how Equinor's approach to completion damage has changed because of this study, with increased focus on achieving a better balance in the evaluation of formation and completion damage.