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Results
High-Water-Cut Wells Stimulation Combined Viscoelastic Surfactant
Al-Mutawa, Majdi (Kuwait Oil Company) | Al-Matar, Bader Suilaman (Kuwait Oil Company) | Dashti, Azziz (Kuwait Oil Company) | Kelkouli, Redha (Schlumberger Well Services) | Liu, Hai (Schlumberger) | Razouqi, Maen Mahmoud (Schlumberger)
Abstract Dual completed wells producing from the mature carbonate formation in northern Kuwait are encroached by injected water from adjacent wells presenting a challenge for the operating company. Greater oil demand coupled with limited surface water handling facilities increased the importance of stimulating this type of challenging wells due to the drastic permeability contrast across the pay zones. Typically the treating fluid in a matrix treatment flows into high permeability sections and/ or high water saturation "thief zones" resulting in higher water cut due to the over stimulation of the water zones instead of the oil bearing zones. The objective of the present field case study was to place the stimulation fluid equally throughout all intervals of the oil bearing layers while temporary protect the zones suspected to be mainly contributing with water from the stimulation fluid, using two different types of viscoelastic surfactant (VES) polymer free diversion systems placed with coiled tubing (CT) providing effective plugging of the layers producing water and providing a uniform stimulation fluid coverage across the entire pay zone. Subsequent production rates showed substantial oil production increase and water production decrease, 360% and 40% respectively. Background In the Sabriyah field of northern Kuwait, the wells are usually completed with a dual completion string which provides the mean to access both Mauddud carbonate formation and underlaying Burgan sandstone formation (see Fig. 1). Mauddud formation is a thin low permeability carbonate layer with an average permeability of 20 md and porosity of 22%. The formation contains large amount of natural fractures and produces 23–25º API gravity oil. Due to the lack of nature water influx, the formation has been under water flooding since 1997 in order to sustain the reservoir pressure and field production. However, water breakthrough becomes an issue as soon as the water flooding was started. This is confirmed by the production logging results. Once the water is broken through those high permeability streaks or natural fractures, the oil production rate is dropped dramastically. The formation damage like organic deposits and scales has also contributed to the decline of oil production. The ideal solution would be shut off the water breakthough intervals and then stimulate the oil bearing intervals only. However, conventional isolation tools and stimulation techniques will not work in this case because the Mauddud formation is usually completed in the short string. It is quite challenging to isolate the water intervals and place the stimulation fluids precisely into the oil bearing intervals unless the entire completion is pulled out and each particular interval can be accessed seperately by using a straddle packer. This approach will not only involve the workover rig but also impact the production from the lower Burgan sandstone formation, as well as formation damage associated with the workover operation. Several wells were treated with this approach in the past, but the results showed not to be very cost effective considering the complexity of the operation as well as the production loss from the lower Burgan formation during the workover. Thus an engineering solution of stimulating oil bearing intervals but avoiding suspected water breakthough intervals with the current completion in place is highly required.
- Asia > Middle East > Kuwait > Jahra Governorate > Rawdatain Basin > Lower Burgan Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Upper Marrat Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Sargelu Formation (0.99)
- (2 more...)
Application of a Highly Efficient Multistage Stimulation Technique for Horizontal Wells
Al-Mutawa, Majdi (Kuwait Oil Company) | Al-Matar, Bader Suilaman (Kuwait Oil Company) | Abdulrahman, Yousef M.A.M. (Kuwait Oil Company) | Liu, Hai (Schlumberger) | Kelkouli, Redha (Schlumberger Well Services) | Razouqi, Maen Mahmoud (Schlumberger)
Abstract In the recent years horizontal well technology evolved in the Middle East field development strategies becomes favored over vertical and deviated wells offering the advantage of maximized reservoir contact, higher production rates and better access to reserves. However, most of these horizontal wells are completed openhole with little alternatives for stimulation, water shutoff or workover treatments. A very challenging task to stimulate long openhole sections effectively due to poor acid distribution especially in reservoirs with high permeability streaks that require effective diversion techniques. The efficiency of chemical diverting agents in terms of flow distribution and uniform coverage is limited when it comes to treat such complex wells with long openhole intervals (see Fig. 1). This paper illustrates a case history where an innovative technique was used on stimulating a naturally completed horizontal well that experienced a production drop to zero shortly after the completion in 2004 due to formation damage and incomplete cleanup. This technique combined mechanical and chemical diversion, using selective openhole completion allowing the wellbore mechanical segmentation into six small intervals based on petrophysical and reservoir evaluation, so that the selected sections can individually be stimulated evenly and inflow contribution from the entire openhole section can be maximized win one continuous operation. The treatment used the advanced emulsified acid technology to achieve deep penetration and better etched fracture conductivity. Viscoelastic surfactant self-diverting Acid (VES diverting acid) was used as the chemical diverter to assure good zonal coverage across each stimulation stage. Greatly increasing the effectiveness of the treatments the combination of technologies allowed successful stimulation of the well with 20:1 permeability contrast. The last stabilized measurement indicates sustained natural production of 10,000 bopd, which is five times the field average and three times greater than the best well in the field without requiring artificial lift. Background With more than 8% of world reserves Kuwait is blessed with an abundance of oil. However, oilfield operators recognize that there are many fields where the recovery of the resources are more challenging and required the use of advanced technologies. One of the flagrant examples is the challenging Mauddud formation in the Sabriyah field in Northern Kuwait, where in the last decade a couple of attempts at drilling horizontal oil producer were mostly unsuccessful and showed very disappointing production figures, with higher than expected production of unwanted fluid and completion costs. Since the oil could not be recovered economically, work to develop these reservoirs was suspended for not saying abandoned. In 2006, Kuwait Oil Company (KOC) contracted the service company to revisit this problem and determine if the technology had been invented which would allow this suspended reservoir to be developed and achieve the planned field production objectives. A task force with team members from both KOC and the service company worked closely together to recover the resources in these very challenging environments through the use of the latest openhole stimulation technologies available in the market today. An innovative technique used for stimulating these horizontal wells was introduced. It combines mechanical and chemical diversion using selective openhole completion along with the VES diverting acid technology.
- Asia > Middle East > Oman > Strait of Hormuz > Mauddud Limestone Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Upper Marrat Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Sabriyah Field > Marrat Formation > Sargelu Formation (0.99)
- (2 more...)