Petronas Carigali Sdn Bhd (PCSB) is one of major oil and gas companies in South East Asia. It has had years of experience operating coil tubing unit (CTU) on relatively large oil and gas field platforms. Vast of field experience and project lessons learned have been captured, refined and eventually embedded in the company's CTU standard operating procedures. These have lead to zero lost-time incidents (LTIs) cases in 5 years of CTU operations particularly offshore Terengganu in South China Sea. The CTU operations are often complex and involve heavy lifting, weighty machineries, minimal deck space and long working hours. Hence, to achieve such a record through out the 12 months in a year with 2 units running concurrently is definitely something to be noted. In February 2009, PCSB embarked on it first barge mounted CTU operation at offshore Terengganu. The option was choosen to access marginal field with small platform deck space and limited crane capacities. These include the process of lifting heavy equipment from workbarge with 60 degree angle to a 50 ft high platform during high swell, having to mobilize crews back and fourth from workbarge to platform and rigging up in dynamic condition. Furthermore, it was the first time the work barge crews experienced such operation and communication constraints due to remote and weather conditions further complicated the situation. Knowing that field experience is almost zero for mounted barge CTU operations in PCSB fields, resources and time has been put to ensure that the HSE track record is intact. Starting with Project Risk Assessment (PRA) which involved all contractors and field operator personnel, the team then analyzed of the whole campaign chain. This paper will review PCSB project success experiences and lesson learns on how to do CT operation from Barge within small platform during moonson season with high level of safety.

PETRONAS Carigali Sdn. Bhd. (PCSB) operates a handful of small platforms at offshore Peninsular Malaysia, in the Malay Basin area, located in the South China Sea. Most of these platforms were designed with limited crane capacity of maximum 5 MT load and small deck space area that only suffice to accommodate slickline operations. After many years of production, the fields have started experiencing sand production, high water cut and a large skin factor. Thus, well interventions and treatments such as matrix stimulation, water shut off or sand clean out are required to sustain and enhance the production rate.Coil tubing (CT) well intervention is the most effective method to achieve these objectives. However, with limited platform facilities, it is a tremendous challenge to have big CT equipments catered on board. The solution to this is to have a minimal number of equipments on the main deck whilst the crane lifting will need to be done from the barge. CT operation with barge assistance was evaluated and finally opted for to execute the jobs at PCSB's small fields. Throughout the operation, only the coil tubing injector head, jacking frame and CT control cabin were erected on the platform whilst the remaining equipments were stationed on the barge.As this was the first CT barge assisted operation in the Malay Basin of South China Sea, two platforms were selected for the pilot campaign. The jobs objectives include water shut-off, wax and sand clean out that has a potential enhancement of 1000 bbl of crude. This paper describes the operational success stories, campaign preparation, proposed work programs, barge selection, jobs execution and project lessons learned.

Malong is part of an integrated marginal field developed in 1999 called MASA. Hydrocarbon is evacuated to a nearby Floating Production, Storage and Offloading (FPSO) facility for export. Its produced water system is currently being used up to its maximum design limit and hindering additional oil production. Malong main reservoir J2 contributes about 97% of the total production. Currently, 7 wells are producing at 7.7 kbopd with average water cut of 70 percent. 88 percent of 18 kbwpd comes from 5 deviated wells while the rest is from 2 horizontal wells. J2 is a water injected reservoir with moderate to strong aquifer. This high permeability sand is distributed fairly well across the field and is subdivided into upper and lower lobes. A comprehensive diagnostic of water flow entry mechanisms begins with compilation of critical information such as geological and reservoir data, production and injection data, cased hole data and well history. Subsequently, several analytical techniques such as material balance analysis, water control diagnostic plot, bubble maps and nodal analysis are applied. The water production mechanisms are primarily dynamic contact movement due to production and possibly accompanied by flow behind casing. In all the wells, the lower lobe is mostly flushed leaving some oil from upper lobe only. Screening of suitable water shut-off methods gets complex considering tubing integrity issue, i.e. multiple tubing leaks, poor cement bond and possible deep invasion due to high permeability formation. Detail evaluation is performed to weigh the pros and cons of mechanical type (cement squeeze) and chemical type (polymer gel). Finally, polymer gel is selected on the basis of less operational risk, controlled depth of invasion and easier removal. Additionally, coil tubing with packer is selected as the deployment method to ensure accurate placement of gel and to evade chemical loss through leaks. Introduction This paper is intended to outline the processes and challenges that were encountered in understanding the produced water problem and in designing the appropriate water shut-off methods considering the physical limitations of facilities as well as tubing integrity. The work has actually started since end of 2004 with downhole data gathering for some of the wells. More efforts were put into understanding the problem and coming up with practical solutions as more water are produced and putting higher constraints on the facilities. Understanding the Problems Without doubt, the first step would be to understand the problems in hand. Water has been produced together with oil since the beginning and the facilities on FPSO are designed to handle the produced water without jeopardizing the oil production. This is anticipated since Malong J2 reservoir driving mechanism is moderate to strong aquifer drive with water injection for pressure maintenance. However, the actual water produced has exceeded the design capacity and thus prompted effective water control measures to be in place. The reservoir water flow mechanism needs to be well understood to enable effective implementation of water control measures. In addition, the economics of selected measures are imperative so as not to erode the profitability of the operation.

Angsi is one of the major fields for PETRONAS Carigali Sendirian Berhad. Located at offshore Terengganu in the Malay basin area, Angsi had become the top priority in terms of oil production. One of its oil producers, A-66L was idle since 2007 due to high water cut observed after few years of production. Due to its high inclination, their first attempt to perform water shut-off and additional perforation were decided to be conveyed by electric line tractor. The job, planned to isolate the I-33 zone using a mechanical bridge plug conveyed by eline tractor, turned into a major failure when the plug is suspected to get stuck in hole. The incident happened during pulling out the tool after activating it and the decision made at that point of time was to cut the eline cable at surface and to temporarily suspend. Fishing job using braided line was successfully done after that. A total of 4800 meters eline cable was successfully retrieved and left the well with the failed mechanical bridge plug which was set above the targeted zone to be isolated. The team had come out with a brilliant idea of shutting off the water out zone and successfully perforated the new zone of interest with a small clearance from the existing top of fish. The well is now producing about 400 bopd. This paper will discuss in detail the complexity of the overall operation, well challenges, water shut off bypassing existing fish and the selection criteria of perforation techniques to accommodate the small clearance. The decision making process and well intervention equipment selection will also be highlighted throughout the overall job operations.

Well integrity possesses major challenges for field operators all over the world. A packer leak is common amongst many other well integrity issues especially for old well. One well in South China Sea was diagnosed with ultrasonic and temperature logging and proved to have such problem forcing the field operator's to shut in the well due to safety concern as the leak create high tubing annulus pressure. Total production lost was 500 bbl of oil per day. Through tubing wellwork was chosen as preferred option because it is more economical relative to workover particularly for such well in a mature field where reserve was depleted. A multiple through tubing wellwork operations using calcium carbonate and cement design with different strategies and methods had been attempted but results are temporary cure at best. Determine to success, previous work program was thoroughly examined inclusive the slurry recipes. The intervention methods were reviewed and challenged, then later refined. Finally, enhanced and optimized cement slurry is engineered together with different approach of well work in which specifying the requirement for acoustic fluid level monitoring. The packer leak was successfully repaired. This paper will discuss the previous coiled tubing method or approach that was failed, the reasons behind the failure and current work program that prove as successful. The innovative slurry design and best practices will also be deliberated. Introduction An oil and gas producing field is located at 260km from Kerteh, Terengganu. It was first explored in the block in 1971, which then produced its first oil in 1978. The field is located at southeastern part of the Malay basin with average water depth of 70m. The field consists of both gas and oil reservoirs. Currently, the field has two mother platform and 1 satellite drilling platforms which locate all the surface facilities such as oil and gas processing, produced water system, water injection facilities and other utilities system. The produced oil and gas then being transported to the shore via a common crude oil pump platform for oil and to a common gas processing platform (CPP) for gas.