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The AAPG/Datapages Combined Publications Database

GCAGS Transactions


Gulf Coast Association of Geological Societies Transactions Vol. 58 (2008), Pages 463-468

EXTENDED ABSTRACT: Production History, Depositional Environments and Future Hydrocarbon Potential for Main Pass Blocks 4, 10, and 49 in Louisiana State Waters

Chacko J. John, Bobby L. Jones, Brian J. Harder, and Reed J. Bourgeois

Louisiana Geological Survey – Louisiana State University, 3079 Energy, Coast and Environment Bldg., Baton Rouge, Louisiana 70803


The Main Pass area is located offshore to the east of St. Bernard and Plaquemines parishes, Louisiana, in the eastern portion of the Gulf Coast depositional basin (Fig. 1). Exploration for oil and gas in the Main Pass area since 1948 has resulted in the dis

covery of 23 fields (state waters). Production in this area has been from the upper Miocene (Bigenerina “A” & “B,” Discorbis “12,” and Textularia) and the upper portion of the middle Miocene (Cibicides carstensi, Textularia “W” and Bigenerina humblei) with most production coming from sands to depth of 12,000 ft (3658 m). Available data from the Louisiana Office of Conservation through the end of December 2006 show Main Pass 4, discovered in 1984, to have produced 942,598 BBLs (barrels) of liquids and 13,119,251 MCFG (thousand cubic ft of gas). Main Pass 10, discovered in 1999, has produced 190,316 BBLs of liquids and 14,426,933 MCFG, while Main Pass 49, discovered in 1985, produced 619,146 BBLs of liquids and 29,589,099 MCFG.

Wells drilled in this area encounter the typical Gulf Coast sequence of sedimentary facies that begins with a massive sand facies, followed by alternating sands and shales, below which is found the deepwater shale facies. Numerous east-west trending southdipping faults with anticlinal closures on the downthrown side control most of the hydrocarbon accumulation. Electric log signatures show that typical deltaic depositional environments are found in these fields, with distributary mouth bars, channel sands, crevasse splays, and subdeltas being common. These sand bodies are limited in areal extent and separated from each other. Sands originating in the same genetic environment have similar log signatures and thus have the potential of being misrepresented as the same sand, although they are different and separated bodies and should be individually tested for hydrocarbon production. The existence of numerous thin bypassed stratigraphically isolated sands and deeper Middle Miocene sands offer excellent opportunities for successful commercial exploitation for additional reserves of oil and gas, with technical advances combined with the current high cost of energy in the world market. Information on the three fields discussed in this paper are summarized below.


Location: Offshore from Plaquemines Parish, Louisiana, in Main Pass Block 4, Breton Sound Block 1 and Chandeleur Sound blocks 69 and 70.

MainPassAreaNMain Pass (State Water Area Only) Main Pass Block 4 Field Main Pass Block 10 Field Main Pass Block 49 Field 1 2 3 1 2 3

Figure 1. Index map of the Main Pass area showing the three study fields.

Discovery Well: Prairie Producing Company, State Lease 11300 No. 1, 10,017 ft (3053 m) TD (total depth), completed on July 26, 1984.

Wells Permitted: 21 (7 oil, 11 gas, 2 dry, and 1 expired).

Deepest Well Drilled: Yuma E & P Company, State Lease 16300 No. 1, 11,575 ft (3528 m) TD, completed on April 6, 2002.

Production Depth Interval: Bigenerina “B” (4840 ft [1475 m]) to Lower Bigenerina Humblei (11,417 ft [3480 m]).

History: Main Pass Block 4 Field was discovered on July 26, 1984, when Prairie Producing Company completed their State Lease 11300 No. 1 well from perforations 10,059-10,066 ft (3066-3068 m) in the 9000’ sand after drilling to a total depth of 10,917 ft (3328 m). Following this discovery, Prairie Producing Company completed three more wells in 1984, six in 1985, and 1 dry hole in 1986. Completions were made in ten different sands from the 4800’ sand to the 9700’ sand.

Tex-Oil Company completed two wells in 1986, one in 1988 and one dry hole in 1989. No additional development occurred until Yuma E & P Company, Inc. completed a well in 2000. They proceeded to drill a well each year from 2001 to 2004. LLOG Exploration Company completed one well in 2002. All of Prairie Producing Company’s wells were plugged and abandoned in 1989.

Production is found in sands from the Bigenerina “B” to the Bigenerina humblei zone on the upthrown block of a 400 ft (122 m) north-dipping fault that strikes east-west across the northern portion of blocks 3 and 4. Most of the wells are drilled directionally along the upthrown trace of this north-dipping fault.

The history of production for Main Pass Block 4 Field is shown in Figure 2.

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