Deepwater Gulf of Mexico Development Challenges

Abstract

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 113011, "Deepwater Gulf of Mexico Development Challenges Overview," by Frank Close, Bob McCavitt, SPE, and Brian Smith, Chevron North America E&P Company, prepared for the 2008 SPE North Africa Technical Conference and Exhibition, Marrakech, Morocco, 12–14 March. The paper has not been peer reviewed. A high-level review of recent development challenges for the deepwater and ultradeepwater fields in the Gulf of Mexico (GOM) is presented. How these challenges were addressed and how Chevron plans to address even-more-demanding challenges in the future are summarized. Introduction Operating in all areas of the world presents many challenges. The GOM, although a long-established and prolific hydrocarbon basin, has, over the past 15 or so years, evolved into an arena where operations challenges have been encountered in ever-increasing water depths further from the coast. These challenges include seismic acquisition, drilling operations, completion operations, subsea operations, production operations, logistics support, and many more. Fields are being developed in the GOM that pose the greatest engineering challenges that the company has addressed. It is anticipated that developing resources in water depths of 10,000 ft will be fundamental to the continued long-term success of the GOM as one of the world's major producing basins. Challenges Many of the prospects in the ultradeep-water GOM have a unique combination of challenges. The combination of deep water (to 10,000 ft water depth), high pressure (>10,000 psi shut-in pressures), high temperatures (>350°F bottomhole temperature), problematic formations (e.g., salt or tar zones), deep reservoirs (more than 30,000 ft true vertical depth), tight-sandstone reservoirs (<10 md), and fluids with extreme flow-assurance issues separates many GOM deepwater and ultradeepwater wells from deepwater and ultradeepwater wells in other parts of the world. As Fig. 1 shows, much of the prospective GOM deepwater exploration area is in 4,000 to 10,000 ft of water. Most of this area is in a subsalt environment, with salt canopies ranging from 7,000 to 20,000 ft thick and target depths ranging from 25,000 to 35,000 ft true vertical depth. The vast salt zones inhibit deep-seismic resolution, presenting great challenges in exploration, appraisal, and development operations. Understanding the geology associated with the massive salt and, more importantly, the quality of imaging below the salt is paramount. A key technology being developed to address this challenge is wide-azimuth-towed-streamer technology. This technique allows better subsurface imaging for effective reservoir management and will dictate well placement and number of wells required to drain the reservoir optimally. The true vertical depths of some deepwater wells are in excess of 34,000 ft. Fig. 2 shows some of the drilling challenges.