Abu Dhabi’s Zakum Development Company (ZADCO) is working at full stretch on the enormous expansion of drilling and production to achieve its goal to produce 750 KBPD of crude oil by 2015, raising output by 200,000 barrels per day.
In order to achieve the huge ramp up, ZADCO is shifting from traditional offshore platform production to a network of artificial islands, from which greater production is anticipated. Drilling reach will be extended from 10,000 feet to around 30,000 feet from the new islands.
According to ZADCO two pilot wells have already been successfully drilled.
In August, one of the first UZ750 project landmarks emerged from the waves in the southern part of the Upper Zakum field. The appearance of sand above the high water level marked a milestone in the history of the company in the transition from wellhead platform tower based facilities and jack-up rig drilling to island based facilities and land rig based drilling.
The artificial islands concept:
ZADCO has a strategic target to increase the production rate from Upper Zakum from 550 thousand to 750 thousand barrels of oil per day by 2015, sustainable for 25 years.
Initially the development plan to achieve these targets was based on an additional 25 Wellhead Platform Towers, together with hundreds of kilometers of new flow lines. Major facilities upgrades on existing satellites and the central processing platform were also planned. Inherent in these development plans was the need to more than double the jack-up drilling rig fleet in order to achieve the necessary production build-up rate.
The flexibility to manage long term reservoir performance, well integrity issues, corrosion and aging of existing structures and subsea flow lines has led ZADCO to seek out a better and more economical future development concept.
ZADCO embarked on an assessment of possible alternative concepts and the findings provided a compelling case for change from the conventional development plan to one that consolidates drilling centers and processing facilities on artificial islands, and utilizing new technologies in Extended Reach Drilling (ERD) and Maximum Reservoir Contact (MRC) to effectively develop the entire field.
ZADCO’s mandate to achieve sustainable production of 750 MSTBD based on full field development, including areas of lower reservoir quality, is a challenging task.
The concept of artificial island based drilling and production facilities was evaluated relative to expansion of the current, traditional steel piled structures. The island concept was found to offer significant advantages in overcoming bottlenecks in the existing processing facilities and intra-field pipeline network, as well as providing a foundation for land rig based drilling. To support this concept, ZADCO has established its own drilling division in collaboration with shareholder ExxonMobil.
Historically, ZADCO has drilled wells up to approximately 10,000 feet deep. However, with this new technology it is planned to reach up to 30,000 feet or more. To date ZADCO has successfully drilled two MRC pilot wells, each nearly 20,000 feet total drilled length, setting several new records for ZADCO. The data and experience gained from drilling these wells will be used to guide the design of future wells and their completions. Many of the island wells will be more complex and expensive than previous Upper Zakum wells but the higher production rates and reduced number of wells will justify the higher capital investment in each well.
Being a ZADCO shareholders, ExxonMobil is a key enabler for the application of this drilling technology and they will be supported by NDC and industry leading directional drilling and completion service providers to ensure success in the execution phase.
Advantages of using artificial islands:
Artificial islands provide a more flexible and robust development base for the redevelopment of the UZ field. This will significantly reduce life-cycle development costs and enable long term maximum recovery levels to be achieved. The ‘green fields’ development on islands accelerates oil development rate, is safer and more capital efficient. Gas lift application on the islands will be much easier than from WHPT and will help improve long term reservoir recovery. The current development plan has the potential to extend the production plateau for up to more than 15 years and significantly delay the need for full field EOR / WAG application and investment.
New horizons:
The redevelopment of the UZ field will present many technological and operating ‘firsts’ for ZADCO which will provide opportunities for additional development applications in the Gulf. The centralized drilling and production centers coupled with ERD and MRC technologies open opportunities in offshore shallow waters. Across the ADNOC group, ZADCO is the pioneer, being the first to intensively apply such complex drilling completions in terms of extended reach drilling (ERD) and with higher reservoir contact (MRC).
Contract Awards:Â
The contract to construct the four artificial islands (three satellites and one main central island) was awarded to the Abu Dhabi based National Marine Dredging Company in November 2009. After a series of trials both outside and inside the field area, construction of the South Island began in August 2010 with the first visible signs appearing above the waves last month. There are many more months of work ahead to place almost three million cubic meters of dredged material required to complete the first satellite island but the first tangible sign of the new era in the development of the Upper Zakum field is now clearly visible in the south area of the field.
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