Technology Focus: Deepwater Projects (June 2010)

Abstract

Technology Focus Deep water can be an unforgiving environment, one mistake can cost millions and in the worst case cost lives. So why are so many companies willing to take the risk and spend billions on new deepwater fields? Perhaps it is the billions of barrels of hydrocarbon that have been discovered and produced over the last 20 years and the prize of unlocking the latest Lower Tertiary trend in the Gulf of Mexico (GOM) with estimates up to 80 billion bbl. The ability to overcome the challenges and successfully develop and produce this latest trend will not be easy. So what are the big challenges for these newly discovered fields and how will they be overcome? If we focus on the challenges and what it will take from the completion side to unlock this new trend, there are three major components that need to be addressed: rock quality, high pressure, and depth. For the first time in deepwater GOM, the reservoir rock will not provide naturally commercial rates and will require stimulation. Some say it is like onshore fracturing, but those that understand the Lower Tertiary realize that this reservoir is not like most onshore reservoirs. There really are no good analogs. To determine the optimum completion efficiently, numerical models that can grid to a completion-component level, incorporate a fracture, and honor the reservoir-property changes with pressure is a must. Why? A big difference between land and offshore is that offshore cannot afford many partially successful look-back analogs. Each well has to be right the first time. High pressures (~25,000 psi) and depths, >30,000 ft, require great attention to detail for each piece of equipment. Pressures, both absolute and differential, must be understood through all phases: initial installation, unloading, production, shutdowns, artificial lift, recompletions, and abandonment. Solutions become a balance between minimizing yield strength of the high-yield nickel-alloy metals and maximizing inner and outer diameters. Depths in excess of 30,000 ft bring challenges that will have to be dealt with for the life of the well. Great depths bring high tubular-stress loads and thus limits to coil and other intervention tools. First-time success of high-pressure equipment requires involvement of experienced engineers from both the operator and the service company from design and manufacturing to qualification. It also requires management sponsorship from both companies to ensure that it is a high priority. Because everything must work and work the first time, front-end loading before first oil can take years of detailed engineering work and requires highly skilled engineers who can design and develop equipment for pressures and depths that stretches past current technology. Engineers must have the expertise to model, design, and execute a sandface completion that provides commercial rates and recoveries. Hence, as in past deepwater-field developments, there are challenges to overcome, but with the right people, it is possible. Deepwater Projects additional reading available at OnePetro: www.onepetro.org SPE 124535 • “Flow Assurance Design and Initial Operating Experience From Blind Faith in Deepwater Gulf of Mexico” by S. Subramanian, SPE, Chevron, et al. SPE 124857 • “A Unified, Multidisciplinary Approach to the Planning and Design of Deepwater Waterflooding Projects” by Fady R. Chaban, SPE, GATE LLC, et al. SPE 128190 • “Drilling Deep in Deep Water: What It Takes to Drill Past 30,000 ft” by Crispin Chatar, Schlumberger, et al.