Productivity Decline due to Fines Migration Associated with High Water Cuts

Abstract

Summary The objective of this work is to describe the extent of productivity decline due to fines migration during periods of increasing water-cut. Two models are presented which allow for estimating the formation damage due to fines migration in both homogeneous and heterogeneous reservoirs. The model utilizes a description of the fluid distributions withing the pore structure to determine the fines detachment during progressive sweep of the reservoir by an aquifer. In heterogeneous reservoirs, an extension of the Dietz model is used to calculate pseudo relative permeability curves accounting for any arbitrary permeability distribution in a layer-cake reservoir. Both models are compared with field productivity decline data to evaluate their validity. Both models allow for explicit predictions of the wellbore productivity during periods of increasing water-cut. A novel diagnostic plot, the well impedance plotted against the well fractional flow, allows for the isolation of the formation damage characteristics of the reservoir. Tuning the formation damage and reservoir properties using field data exhibits good agreement and allows for extrapolation of the curves to higher water cuts. The models provide unique insight into the future formation damage of the well and allow for strategic planning of well remediation and stimulation. For heterogeneous reservoirs, the new diagnostic plots are proven to be linear, regardless of the permeability distribution in the reservoir, providing a quick and easy tool for formation damage evaluation. The new models and diagnostic plot provide a simple method to extrapolate existing formation damage and estimate formation damage from laboratory studies and/or well analogues.