Chevron starts U.S. gulf's first Lower Cretaceous flow

New Developments in Gulf of Mexico Shelf [74,232 bytes] Chevron USA Production Co., New Orleans, is slowly bringing on gas production from the U.S. Gulf of Mexico's first fields to produce from Lower Cretaceous rocks. Chevron plans to start production from its Mobile 991 No. 1 well this month. The trend's first producer is the Viosca Knoll 68 No. 2 well, which went on line Apr. 26 at the anticipated rate of about 15 MMcfd of gas. Chevron has also tested its Viosca Knoll 114 discovery

June 15, 1998

4 min read

G. Alan Petzet
Exploration Editor

New Developments in Gulf of Mexico Shelf [74,232 bytes]

Chevron USA Production Co., New Orleans, is slowly bringing on gas production from the U.S. Gulf of Mexico's first fields to produce from Lower Cretaceous rocks.

Chevron plans to start production from its Mobile 991 No. 1 well this month. The trend's first producer is the Viosca Knoll 68 No. 2 well, which went on line Apr. 26 at the anticipated rate of about 15 MMcfd of gas. Chevron has also tested its Viosca Knoll 114 discovery well, drilled in August 1997.

Five gas discoveries since 1994 in a trend that extends from Mobile Block 991 (September 1996) to Viosca Knoll Block 252 (March 1994) have "recoverable reserve potential of over 600 bcf (gross trend) of natural gas," Chevron said. It said that figure could grow to more than 1 tcf (OGJ, Apr. 27, 1998, Newsletter).

The discoveries came in a formation that is rarely the primary exploration objective even in onshore wells and from which production has been spotty. However, it was the main objective in the Viosca Knoll 252-1 well, Chevron's first discovery in this trend, said Steve Thurston, Chevron's eastern shelf profit center manager.

The company will test the VK 251 well, drilled in November 1997, and drill one or two more delineation wells this year. A gas well drilled on VK 208 in January 1995 is a delineation well in the same reservoir as VK 252-1. The 1999 program will probably consist of two to four exploratory wells and a greater number of delineation/development wells, Thurston said.

The activity provides a shot in the arm for the eastern gulf.

Carbonate trend

Chevron's discovery wells cut net pay thicknesses of 35-115 ft in the James. The company has dubbed the play the Viosca Knoll Carbonate Trend.

The wells are on the mature shelf in 120 ft of water about 25 miles south of Pascagoula, Miss. Depth of the pay is about 15,000 ft.

Thurston declined to divulge reservoir properties, gas composition, and the number of wells needed to develop each discovery. Chevron is still learning about the reservoirs, he noted. VK 68 No. 2, the trend's first well to start producing, was drilled in June 1997.

The first wells are being placed on production through facilities originally designed for Miocene production from about 3,000 ft. As flow rates exceed capacity of those small sized facilities, proximity to Chevron's 9 tcf Norphlet gas trend is likely to become important, Thurston said.

Chevron is operator and holds the dominant working interest in around 75 leases covering more than 350,000 gross acres in the carbonate trend. Five more leases were still to be awarded from the Mar. 18 federal lease sale.

Chevron holds 100% working interest in more than half the leases. In the rest it holds 50-80% interests, mainly in partnership with Samedan Oil Corp., Ardmore, Okla.

Chasing the James

Lower Cretaceous James has not been a high volume oil or gas producer in most settings. It is perhaps best known as an oil and associated gas reservoir in giant Fairway field (1960) in Anderson and Henderson counties, East Texas, where it is about 9,900 ft deep.

Fairway field is about 450 miles northwest of the nearest discovery in Chevron's offshore trend. The Fairway field reservoir is a combination structural-stratigraphic trap in the James lime member of the Pearsall formation (OGJ, Feb. 22, 1982, p. 177).

Hunt Petroleum Co., Dallas, operates a hydrocarbon miscible gas injection project that dates from March 1966 on the 22,618 acre unit.

OGJ estimated that Fairway field has produced around 200 million bbl of oil through Jan. 1, 1998. The field produced close to 2 million bbl in 1997 from about 100 producing wells. Oil is 48° gravity.

James lime in the field has 12.6% porosity and 11 md permeability. Hunt said the project is profitable and in OGJ's "half finished" category in terms of project age.

James also produces in Poplarville, Hub, and West Sandy Hook fields in the Mississippi Salt basin northwest of the Wiggins arch in Marion, Washington, and Pearl River counties, Miss. Loucks et al. described those reservoirs in the GCAGS Transactions 1996.

Lower Cretaceous reservoirs are among the main producers in Mexico's Campeche Sound and Golden Lane fields.

Among other U.S. fields in which James has produced oil or gas:

Arkansas: Nichols, Nevada County; Canfield, Columbia and Lafayette counties.

Louisiana: Angie, Washington Parish; Leatherman Creek, Claiborne Parish; Northeast Hodge and Clay, Jackson Parish.

Texas: Aventura Ranch and Norcabarro, Van Zandt County; Tyler South, Smith County; Huxley, Shelby County; Sand Trap and Tee Box, Henderson County; and Crabbs Prairie, Walker County.