Gulf of Mexico Ultra-Deepwater Development Study
Authors: Clarkston Bradley J. , Dhuldhoya Nimish P. , Mileo Michael A. , Moncrief John R. 
Published: October 2008

The deepwater Gulf of Mexico (GoM) is a strategic exploration focus area for Texaco. Many of Texaco's prospects are located in water depths between 3,500 and 7,500 feet and areas where the necessary infrastructure either does not exist or is marginally developed. The major challenge in developing oil and gas prospects in ultra-deepwater is achieving acceptable financial metrics in today's uncertain and unstable oil and gas environment.

Principal development concerns are water depth, reservoir uncertainty, recovery per well, drilling and completion costs, oil and gas transportation costs, and operational logistics. Utilizing conventional approaches to field development can result in marginal to non-commercial development economics. Consequently, the need to investigate and test innovative field development approaches is necessary in order to achieve requisite financial metrics.

This paper discusses such an innovative development approach targeted specifically for the GoM, but which is also applicable to other deepwater areas worldwide. The principal conclusion is that ultra deepwater development is both technically and commercially feasible. However, savings in the development cost can be realized by implementing emerging technologies that are aligned with project commercial drivers.

Introduction

The principal objective of this study was to identify specific development concepts in support of selected deepwater prospects in the Gulf of Mexico. The approach was to investigate emerging technologies, which if implemented could result in reduced overall field development costs. This led to the identification of a low cost development concept ("Innovative Case"), which was robust enough to withstand the uncertain economic environment of today's oil and gas industry with an acceptable level of risk. A secondary objective was to define a technology plan in support of this low cost development concept.

This paper discusses an innovative development philosophy targeted specifically for the GoM, but is also applicable to other deepwater areas worldwide. This innovative philosophy is based on a development concept, which consists of a floating drilling, wellhead, and partial processing facility that supports dry "Xmas" trees, or Dry Tree Unit (DTU). The partially processed fluids are transferred, via pipeline, to a FPSO for processing, storage, and shuttle tanker export to market. The concept is applicable for developments that require either single or multiple drill centers. The principal premise is that significant reduction in development cost is achievable by minimizing DTU topside payload, using standard facilities with emerging technologies, as well as providing offshore storage and offloading coupled with shuttle tanker transport.

Background

During the late 1970's, drilling technology was developed that allowed the exploration of oil and gas in water depths greater than 1,000 feet. The earliest developments in deep water were accomplished using subsea completion systems producingback to floating production units in the field. These floating productions systems were typically either converted tankers (FPSO) or semi-submersible drilling rigs (FPU). In most cases, these early deepwater developments were relatively simple subsea systems that incorporated little or no subsea manifolding and very simple direct hydraulic control systems. Much of the deepwater subsea system experience and technology was first developed and deployed in places like the Campos Basin of Brazil.