The energy global demand is predicted to increase by an estimated 2-4 percent annually over the next decade. However, production decline from mature field such as West Lutong is estimated about 5-6 percent annually. Therefore, acid stimulation provides a cost effective method of increasing production and accelerating reserves. Previously, acid stimulation in West Lutong had always been plagued with "consistent" increasing average water cut of 5-10% due to accidental stimulation of water zones and "inconsistent" skin removal ranging from 30% to 75%.As part of continuous stimulation improvement effort, historical stimulation recipe and post treatment had been analyzed. An innovative "nitrified acid stimulation with refined oil soluble resin diverter recipe" had been chosen for the pilot implementation. Pre calculated volume of nitrogen is mixed on the fly with acid at surface before pump into the formation. Due to low solubility, nitrogen commingled with acid assumes state of compressed gas bubbles energizes the injected fluids. When the well pressure is relieved the gas bubble expands, greatly aiding the injected fluids into formation returning to surface. As a result, it increases radial penetration for given acid volume due to additional volume of gas. Oil soluble resin diverter stages had been reduced from two to one since the success rate is independent of stages pumped and for operation simplicity.The pilot job at Well # A had successfully increased oil production about 537% (instantaneous gain of 1289 bopd) contributed by 87% skin removal while reducing the water cut by 5 % since July 2009. In addition, 0.3 mmstb of reserves is expected to be monetized. This paper shares a detailed case study of Well # A in term of candidate's selection, nitrified acid stimulation recipe, execution, lesson learnt, and future recommendations. It is evident that nitrified acid stimulation with oil soluble resin diverter is feasible and economic for high water cut acid stimulation.

An operator needed to perform wellbore intervention on four low-bottomhole-pressure offshore wells in Malaysia. High sand production was consistent in all the wells, precluding access to the producing zones in the lower completion. The wells had been shut in since 2011, and previous cleanouts using conventional coiled tubing (CT) and nitrogen had been unsuccessful. The job had to be performed from a work barge in a catenary style, meaning that the injector head, blowout preventers, and power pack were on the platform, but all were operated from a barge. The advanced wireless catenary unit made it possible to complete the operation with only the CT and three flexible lines connecting the barge and the vessel. Due to the nature of the concentric coiled tubing (CCT)—designed to flow returns back to surface—all returns had to be routed away from the platform and onto the barge. After an analysis and planning session, the operator and the service provider decided to use a CCT cleanout system with a switchable jet-pump designed to remove solids and liquids from ultralow pressure wellbores that are not treatable with standard circulating methods. The operational plan also called for building a specialized CT connector that would enable conventional operations, such as fishing and sleeve manipulation with CCT. This was the first time that vacuuming technology and catenary CCT were used together to perform a cleanout operation. The results were impressive as extensive amount of sand was removed from the wellbores to surpass target production by 185%. This paper will focus on a campaign in the South Furious field of Sabah, Malaysia in which both the logistic and operational challenges were successfully overcome with 112 days of incident free operations.