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.
High annulus pressure in old producing wells in offshore Malaysia has become a serious issue when it reaches a limit that breaches a well’s integrity pressure envelope. According to the outlined criteria in the Operator Well Risk Management 3.0 (WRM), the operator will perform lubrication work using heavy brine. This action will temporarily reduce the annulus pressure but soon the annulus pressure will start to build up to the original threshold limit hence rendering lubrication using brine a failure, requiring operator to raise Management of Change (MOC) to keep well flowing with numerous action items needed to be in place while looking for the proper solution. Currently the usage of epoxy resin technology for leak repairs has become a regular practice in the industry. The idea of squeezing resin to seal off the micro-annulus leaks in well casing cemented annuli has become widely accepted in leak repairs. This integrity barrier entails placing and squeezing special epoxy resin into the annuli, filling up the void inside the sealed annuli and squeezing adequate volume of resin gels into the cement micro annuli. Placement of the resin gels can be difficult to execute due to the micro size path; therefore, high pressure is needed to be applied and maintained during pumping. Since 2016, the operator has had experiences in treating annulus leaks using lubrication methods and also the current deployment of epoxy resin in filling up voids and micro annulus which has enabled the operator to standardize the method to ensure high success. Surveillance logging data was utilised to determine the source of pressure and to estimate the maximum squeeze pressure to be applied during the treatment. Six wells were pilot tested and treated with this special epoxy resin squeeze, with four wells showing a complete seal while the other two wells have shown gradual pressure build up. This paper outlines the laboratory verification works on the resin mixtures to adapt to the field application in sealing the leaking annuli and describes all the six pilot tested wells that were carried out in one of offshore fields in Malaysia. The various considerations during the design of the rectification treatments as well as the experiences and lesson learnt during the execution phase are also highlighted.
With the current uncertain situation regarding the stability of oil prices in the world, operators have been pushed to develop their available resources in a cost-effective way. Lately, there has been increased interest in the application of Coiled Tubing Drilling, especially for accessing bypassed hydrocarbon in mature or late-stage fields. This paper describes the feasibility study done to examine the possibility of using Coiled Tubing Drilling package/equipment to drill and complete a sidetrack well in a karstic carbonate reservoir with total losses issue by applying the principles of Pressurized Mud Cap Drilling (PMCD). This will be the first time that such method is being utilized for developing karstic carbonate reservoirs in Offshore Malaysia. The paper will go through the background of the project (generic field information, reservoir properties, well design and architecture), the critical design elements for the system (technical requirements, safety standards, operational and logistical factors) and the contingency scenarios considered. Based on the aforementioned items, a fit-for-purpose Coiled Tubing Drilling equipment arrangement together with suitable PMCD method and light annular mud (LAM) selection were proposed to cater for the specific challenges of the well. It was concluded that the application of PMCD using Coiled Tubing Drilling Package is feasible with some modification to the equipment, line up and operational procedures.
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