Successful High Pressure Abrasive Jetting Selective Stimulation of Oil Producer Wells with High Water Cut

Abstract

Abstract Drilling carbonate oil wells may encounter fluid losses, hence specific mud systems have been designed with loss control materials to stop losses and to reduce the risk of drill pipe stuck. Unfavorably, mud systems with loss control materials create near wellbore damage that lead to uneconomic hydrocarbons production. To overcome this challenge and revive wells back to the optimal production, matrix stimulation is carried out using coiled tubing with predetermined pumping schedule, where acid is injected into oil zones and diverter is squeezed into the high water cut (WC) zones. Thus prior to stimulation, diagnostic logs are usually constructed via well logging to identify water producing intervals. However, in some cases the post-stimulation WC is equal to or higher than WC prior the stimulation, suggesting that the diverter placement was not effective in sealing the water zone. Innovative methods had to be brought in to confirm the isolation of high WC zones before pumping acid and to reduce the risk of stimulating water producing zones. The method discussed here also includes the use of high pressure abrasive jetting tool to bypass the near wellbore damage and increase acid stimulation efficiency. This case history describes an open hole vertical oil well in which the operator was able to reduce the risks of acidizing high WC interval through the innovative use of Fiber Optic Enabled CT string (FOECT) and Fiber Optic Enabled Bottom Hole Assembly (FOEBHA) with pressure and temperature sensors for real-time downhole measurements. Distributed Temperature Surveys (DTS) traces were recorded with fiber optic cable inside CT to modify and evaluate fluid placement. The combination of high pressure abrasive jetting tool for selective stimulation technique, together with FOECT, FOEBHA and DTS, allowed stimulation treatment with maximized efficiency and fluids placement control. The acid was confirmed to have been stimulated only in the upper oil zone. As a result, the well production increased significantly without any increase in water cut.