Dulang is the major oilfield in the Malay Basin. Owned by the Malaysia national oil company, Petronas, it is located in the South China Sea, about 130 km offshore the east coast of Peninsular Malaysia in water depths of about 76 m. This field, consisting of sandstone formations, was discovered in 1982 and developed fully in 1991 resulting in 48 wells being drilled and produced. Currently, the reservoirs in this field are nearly depleted, having many idle wells with high Gas Oil Ratio (GOR) and water cut (up to 95%). An attempt was made to revive the idle wells with potential recoverable reserves. A collaborative team was formed to devise a solution. The main focus was given to idle wells with high water cut. The objective was to increase oil production and reduce water cut.A number of options were reviewed, with one of the strategies being to increase oil production by shutting the water/gas production. However, due to various operational challenges that these well possess, (i.e. difficulty in mechanical isolation due to dual completion and availability of multiple water/oil zones) no direct approach could be employed. In order to keep the drive and market of idle wells afloat, a different strategy was proposed and marketed which focused on increasing the oil production with little or no water increase. The water cut in response to this strategy would be expected to be either maintained or decrease resulting in higher oil production. The introduction of matrix acidizing utilizing a high temperature viscoelastic surfactant-based diversion system has made it possible to achieve such results. A high temperature viscoelastic surfactant-based diverter was engineered to selectively plug the zone with high water saturation, allowing the treatment system to enter the zones with high oil saturation. Another advantage over the conventional particulate diverters is that it contains only a surfactant and does not have any solids or polymers. This paper discusses application and results of using high temperature viscoelastic surfactant-based technology in the Dulang fields. This paper will also cover candidate selection, pre-job laboratory testing, execution and evaluation challenges in order to properly execute the job. Candidate selection, which is the most crucial task in this project, determines the right and potential candidates for the treatment. Extensive laboratory experiments, such as crude oil and acid compatibly (emulsion and sludge tests), and core studies (SEM, XRD, core flow, etc.) have been carried out to develop the most effective acid recipe. Previous treatment results will also be discussed in this paper. The success of the treatment in Dulang has proven the potential success of the application of this high temperature viscoelastic surfactant-based diverter for selective stimulation of high water cut oil wells. results Five wells were successfully stimulated in the Dulang field using this new diversion technique resulting in oil gain ranges from 100 - 300 bopd per well (originally the wells were in idle conditions).In many cases, the wells were producing 90% water before shut-in and now producing around 80% after the stimulation treatment. A comparison of oil and water production, pre and post job is presented. The field results from the use of this system clearly demonstrate the effectiveness of the technology in selective oil zone stimulation in oil-water sections. Introduction The Dulang Unit Area (Map 1) covers the central part of highly heterogeneous Dulang Field which is located offshore Peninsular Malaysia. The Unit Area consists of a 19-stacked shaly sandstone reservoir that are divided into approximately 90 fault blocks containing multiple fluid contacts. The estimated Original-Oil-In-Place (OOIP) is around 700 million stock tank barrels (MMSTB). The crude gravity averages about 39 deg API. The associated gas production is about 45 million standard cubic feet per day and it contains more than 50% CO2. The E group of sands includes E10/11, E12/13, and E14 reservoirs and is one of three most significant groups in terms of reserves.
fax 01-972-952-9435. AbstractThis paper discusses the application of fibers for the Frac and Pack application for Brunei Shell Petroleum (BSP). Seven wells with a total of seventeen fracturing treatments in this study are on a multilayered unconsolidated formation, where sand control is a part of well management during the production life of the wells. Previous techniques of open hole external gravel packing and cased hole Internal Gravel Packing (IGP) for controlling formation sand were challenged by reduced flow efficiency of the wells.The recent development of Expandable Sand Screen (ESS) combined with fracturing treatment could not control produced sand, due to failure in perforation techniques. An improved idea of perforating only the lower side of deviated wells using minimum viscosity fluids and minimum amount of pad with limited proppant sand concentration resulted in low net pressure build up.These challenges were prevailed over by the application of a new fiber technology in which fiber is used (1) to transport higher sand concentration to the fracture, and (2) to control the sand flow back during production as well. Since this technology is physical rather than chemical, the proppant flowback is controlled without specific shut-in time, temperature, or pressure constraints. The use of fiber technique prevents sand falling down from perforations and ensures the ESS running smoothly. This technique enabled Brunei Shell Petroleum to cost effectively complete the highly deviated wells with stimulation and sand control. In presence of the fiber, higher proppant concentrations upto 9 ppa could be used successfully even with linear guar gel. This promotes the net pressure build up which is vital for fracturing treatment in high permeability reservoir. Eleven fracturing treatments on five different wells have been performed with excellent results.
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