Na Kika Intelligent Wells - Design and Construction
Authors: Stair C.D. , Dawson M.E.P. , Jacob S. 
Published: December 2007

Field development, subsea well completion design, and completion installation in Shell/BP's ultra deepwater Na Kika field development required the marriage of several new technologies and completion methods. While many of the new techniques had been implemented separately in recent completion programs in the Gulf of Mexico and abroad, this completion program brought many of them together for the first time.

Reservoir uncertainties such as compartmentalization, proximity and connectivity between gas- and oil-bearing reservoirs, and aquifer size made it necessary to design a development plan for maximum flexibility. Intelligent well technology was required to mitigate these uncertainties in two of the five Na Kika fields, enabling an economic development. The final development plan for Na Kika featured four intelligent wells that would develop reserves from a total of eleven discrete reservoirs. Required functionality of these wells included competent sand control with low completion skin, remote zonal control, and continuous pressure/temperature monitoring capability for each zone. This functionality enabled producing reservoirs to be commingled or isolated as well as reservoir diagnosis to be performed remotely from the host facility, allowing optimal assessment of reservoir drainage and depletion management.

This paper will discuss the economic drivers for the intelligent well completions at Na Kika, design challenges in fluid-loss control and zonal isolation during installation, and novel use of the interval control valves as well suspension barriers. Completion operations are discussed in detail to illustrate the benefits of the intelligent well functionality during installation.

Introduction

The Na Kika Development is located 144 miles southeast of New Orleans, Louisiana, in water depths ranging from 5,800 to 7,000 feet in the US Gulf of Mexico.1,2 The project is a subsea development of five small- to medium-sized independent fields tied back to a permanently moored floating development and production host facility, centrally located in Mississippi Canyon Block 474 in 6,340 feet of water. Na Kika is the first deepwater application of the concept of a dispersed subsea development tied back to a centrally located deepwater host that does not depend upon a single large accumulation of oil and gas.

The core Na Kika development is comprised of five moderately sized (20 to 100 MMBoe) fields, containing both oil and gas reservoirs (Fig. 1). Individual reservoirs in each of the fields contained recoverable reserves as small as 10% of the field totals. The play type can be characterized as amplitude supported, structural-stratigraphic traps in the middle to upper Miocene of the Eastern Gulf of Mexico. The moderate size of the average Na Kika field is a direct function of the geologic setting and nature of the channel/levee systems encountered. A wide variety of sub-facies is found in these systems, with an associated wide range in reservoir quality/type.

Two of the five fields at Na Kika featured multiple stacked pay sequences, requiring stacked completions to enable an economic development concept. Stacking multiple completions in a single wellbore carries risks such as differential depletion and crossflow, or early water breakthrough, requiring costly well intervention.

Intelligent well technology was employed in four of the ten Na Kika wells to manage the production uncertainties associated with commingling and to avoid well intervention.