Subsurface Development Challenges in the Ultra Deepwater Na Kika Development
Authors: Rajasingam D.T. , Freckelton T.P. 
Published: October 2008

The Na Kika Development is located in water depths ranging from 5,800 to 7,000 feet in the US Gulf of Mexico. The project, a joint effort by Shell and BP (approximately 50% each), is a sub-sea development of five small to medium sized, oil and gas fields tied back to a centrally located, permanentlymoored floating development and production host facility located in Mississippi Canyon Block 474. The sub-sea infrastructure consists of 10 wells connected via three 25-mile flowline loops, 23 flowline sleds, and 50 miles of umbilicals o the semi submersible-shaped host with topsides facilities for fluid processing, and pipelines for oil and gas export to shore. The Na Kika Host facility has a processing capacity of 110 mbopd oil and 425 mmscfd gas. First production was achieved in November 2003. The host and sub-sea infrastructure is designed for other tiebacks to enable further development in the area. A sixth field will be tied back in 2 004.

The Na Kika fields consist of multiple stacks of turbidite reservoirs deposited in an unconfined by-passed slope setting. These reservoirs are characterized by mud-rich depositional environments punctuated by sand rich channel/levee systems.

The diversity and complexity of Na Kika's subsurface offered a number of challenges requiring a novel approach to the development and application of well and sub-sea technology. The successful deployment of this technology together with excellent execution has enabled an economic development concept of what would otherwise be five subeconomical developments on a stand-alone basis.

The key subsurface development risks and challenges included reservoir quality, continuity and connectivity (areally and vertically), aquifer size and support, well and reservoir performance and management, reservoir compaction, and fluid compatibility (ashphaltenes).

Introduction

The ultra-deepwater Na Kika development concept represents a new movement in the exploitation of hydrocarbon reservoirs in deepwater environments - one that does not rely on a single large accumulation to justify development. Instead, Na Kika utilizes a cluster development concept, leveraging technology and innovative thinking to turn a collection of small to medium sized fields into an economic cluster development tied to a floating production and storage vessel with sub-sea production systems, illustrated in figures 1 and 2.

As the "big cats" in deepwater environments are found and developed, the cluster development concept and application of exploration and production technology will have to become the norm to enable companies to develop further into the deepwater.

The joint venture arrangements associated with the development are as unique as its technical nature. The design and construction of the surface and subsurface development infrastructure has been executed by Shell as the 'preproduction operator', with BP assuming the 'post production operator' role upon start-up of the first well. This unique endeavor, rooted in the historical ownership arrangements of the various fields, has leveraged the best of both companies to the benefit of the partnership as a whole.

Exploration and Appraisal History

The first exploration leases for what would become the Na Kika area were acquired in 1985 over the Kepler, Ariel, Fourier and Coulomb fields (see figure 3). East Anstey and Hershel leases were acquired in 1988.