John C. McCaslin
Exploration Editor
The Tuscaloosa formation of the Upper Cretaceous is found in many areas of the Gulf Coast region.
This prolific pay zone is best known perhaps along the Tuscaloosa trend of southeastern Louisiana, a deep gas-condensate bearing belt stretching more than 200 miles from Vernon and Beauregard parishes east-southeastward through Baton Rouge, north of New Orleans, thence into the Gulf of Mexico. Through the years since 1975, large gas reserves have been tapped in the 20-30 mile wide trend with estimates of reserves at 3-60 tcf. Proven gas reserves in the 13 fields along the trend as of late 1979 were set at 1.6 tcf.
NEW SUCCESS REPORTED
Exploration for the lower Tuscaloosa has been sporadic in the past few years, particularly since 1982 when operators learned to face economic obstacles that couldn't be overcome by sweat, improved casing programs, and downhole corrosion inhibitors.
High interest rates, reduced pipeline takes amid a natural gas surplus, and declining demand for deep, high priced gas - linked to the declining price of No. 2 fuel oil - led some operators to trim development programs because of the bad economic conditions of those days.
But there is a new discovery in West Feliciana Parish that may signal the rebirth of a play that dominated the scene in the late 70s and early 80s. Griffin & Griffin Oil Co. 1 Alice Spillman, opener of Spillman field, 47-1s-2w, flowed 1,650 Mcfd of gas and 255 b/d of 50 gravity condensate through choke with tubing pressure of 3,730 psi. Production is from the lower Cretaceous through perforations at 13,928-932 ft. The operators control a block of about 2,700 acres near the discovery well. The 2 Alice Spillman is in completion stage.
ON A DOWNDIP TREND
All pre-1975 Tuscaloosa Production in Louisiana is from the updip formation which was deposited north of the Edwards reef edge on the Cretaceous continental shelf.
The current action and after 1975 discoveries took place on the downdip Tuscaloosa which was deposited south of the Edwards reef edge on the continental slope. Chevron USA's 1975 discovery of a large natural gas reservoir capped more than a decade of expensive exploration for hydrocarbons in the deep Tuscaloosa formation. The 1 Alma Plantation, 87-6s-lie, Pointe Coupee Parish, opened False River field with production at 19,836-19,916 ft. In 1976, the field was extended into West Baton Rouge Parish at 1 Poplar Grove, 37-6s-11e, 2 miles east-southeast of the discovery well. Later, production was found in the field at 20,568-20,982 ft.
False River produces from an elongate rollover anticlinal structure located on the downthrown side of a large, buried embayment-type fault. According to The Tuscaloosa Trend, a publication by Petroleum Information of Denver, it is a part of a structural complex, which is interpreted to include Chevron's Judge Digby field to the northeast, estimated to be 20 miles long and about 2 miles wide.
It became very apparent that the deep Tuscaloosa could become a trend of regional extent and importance when Chevron opened another field at Rigolets, 110 miles southeast of Baton Rouge. This discovery well was completed in December 1975 flowing gas and condensate at 14,724-776 ft.
The first Tuscaloosa discovery in Livingston Parish was made by Amoco Production Co. in 1979, 18 miles east of Irene field. Lockhart Crossing became the 14th strike on the trend since its inception.
The latest strike in West Feliciana may get things rolling again.
Copyright 1990 Oil & Gas Journal. All Rights Reserved.
