Gulf of Mexico Oil Disaster Symposium

Deepwater Gulf of Mexico oil reserves and production

November 22, 2010, 10:40 am
Source: BOEMRE
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Shell Oil Company's Mars tension leg platform, located in the Gulf of Mexico. Credit: Shell Oil Company; NASA



For purposes of this article, deep water is defined as water depths greater than or equal to 1,000 ft (305 m), and ultra-deep water is defined as water depths greater than or equal to 5,000 ft (1,524 m). A few other definitions are useful at this point:

  • Proved Reserves are those quantities of hydrocarbons that can be estimated with reasonable certainty to be commercially recoverable from known reservoirs. These reserves have been drilled and evaluated and are generally in a producing or soon-to-be producing field.
  • Unproved Reserves can be estimated with some certainty (drilled and evaluated) to be potentially recoverable, but there is as yet no commitment to develop the field.
  • Known Resources refer to discovered resources (hydrocarbons whose location and quantity are known or estimated from specific geologic evidence) that have less geologic certainty and a lower probability of production than the Unproved Reserves category.
  • Industry-Announced Discoveries refer to oil and gas accumulations that were announced by a company or otherwise listed in industry publications. These discoveries may or may not have been evaluated by the Minerals Management Service (MMS) and the reliability of estimates can vary widely.
  • Field is defined as an area consisting of a single reservoir or multiple reservoirs grouped on, or related to, the same general geologic structural feature and/or stratigraphic trapping condition. There may be two or more reservoirs in a field that are separated vertically by intervening impervious strata or laterally by local geologic barriers or both.

Expanding Frontier

In the late 1990s, a new era for the Gulf of Mexico (GOM) had just begun with intense interest in the oil and gas potential of the deepwater areas. At that time, there were favorable economics, recent deepwater discoveries, and significant leasing spurred on by the Deep Water Royalty Relief Act (DWRRA; 43 U.S.C. §1337). Historically, deepwater production began in 1979 with Shell’s Cognac Field, but it took another 5 years before the next deepwater field (ExxonMobil’s Lena Field) came online. Both developments relied on extending the limits of platform technology used to develop the GOM shallow-water areas.

Since then, deepwater exploration and production technology has tremendously advanced. In February 1997, there were 17 producing deepwater projects, up from only 6 at the end of 1992. Since then, industry has been rapidly advancing into deep water, and many of the anticipated fields have begun production. At the end of 2008, there were 141 producing projects in the deepwater GOM, up from 130 at the end of 2007.

Over the last 15 or so years, leasing, drilling, and production moved steadily into deeper waters. There are approximately 7,310 active leases in the U.S. GOM, 58 percent of which are in deep water. (Note that lease statuses may change daily, so the current number of active leases is an approximation.) Contrast this to approximately 5,600 active GOM leasesin 1992, only 27 percent of which were in deep water. There was a maximum of 31 rigs drilling in deep water in 2008, compared with only 3 rigs in 1992. Likewise, deepwater oil production rose about 786 percent and deepwater gas production increased about 1,067 percent from 1992 to 2007. Production from seven deepwater fields began in 2008, including Thunder Horse, the largest daily producer in the GOM. [READ MORE]



Nomack, M. (2010). Deepwater Gulf of Mexico oil reserves and production. Retrieved from


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