Mexico’s analysis of the deepwater play on its side of the border includes wells from its northern border to offshore Campeche Bay. (Graphic courtesy of Pemex)

Although the play isn’t open to outside investors, Mexico is making steady progress in developing a deepwater Gulf of Mexico play that could account for 54.8% of the country’s remaining prospective reserves.

According to Petroleos Mexicanos (Pemex) figures, the deepwater zone holds up to 29.5 billion boe of the country’s total 53.8 billion boe in prospective reserves.

Some efforts continue in Pemex and the government to find a way to bring in outside capital and expertise in deepwater without violating the constitutional requirement that Pemex must own all hydrocarbons, but the company came closest with its development contracts in the Burgos Basin south of the Texas border, where it contracted outside companies to develop fields for a fixed cost that was not tied to production volumes. Contractors would only get paid from production, however. That approach hasn’t yet been tried offshore.

Mexico has done its homework with extensive 2-D and 3-D analysis, pre-stack depth migration, basin-wide seismic correlation, seal integrity and retention capacity, shallowwater hazards, pore pressure prediction and a studied, analytical approach to an exploration program that moves into deeper and deeper water, according to Adan Oviedo in a 2006 presentation in Houston.

Deepwater exploration started in 1999 with the Chuktah-201 in the Nox-Hux area field area in 1,683 ft (513 m) of water followed a year later by the Chuktah-1 in 1,260 ft (384 m) of water about halfway between the coast cities of Coatzacoalcos and Campeche. Nab-1, to the northeast in the same area in 2,234 ft (681 m) of water resulted in a 2003 discovery with 9º degree gravity heavy oil.

Noxal-1, drilled in 2,256 ft (689 m) of water in 2005 probably was the most controversial discovery in the chain. That well, in the Holok-Alvarado on the Mexican Ridges area off Veracruz, was a widely broadcast discovery that prompted then-President Vicente Fox to claim a 10 billion bbl find. That wasn’t quite right. It turned out the well had marginal, probably non-commercial, amounts of natural gas. The well also provided some valuable information.

About the same time, Pemex drilled the Caxui-1, a stratigraphic test in 2,195 ft (670 m) of water to the north in the Lankahuasa Profunde area offshore Tuxpan de Rodriguez Cano. That was a dry hole.

The company followed up with the Lakach-1 wildcat in 2006 a short distance west-northwest of the Noxal well in 3,242 ft (988 m) of water. That’s the best discovery to date. The well came in with an initial potential of 20 MMcf/d to 30 MMcf/d and probable reserves of 308 Bcf. It has 673 Bcf of possible reserves and 1.3 Tcf of potential reserves.

Mexico drilled the latest well in the series, the Lalail-1, last year in 2,641 ft (805 m) of water east of Noxal and Lakach. That well also was a non-associated gas producer, according to Carlos Morales Gil, E&P chief for Pemex.

According to a Dow Jones newswire report, the Diamond Offshore Ocean Voyager semisubmersible rig left the Lalail site to move a short distance to the east to drill the Chelem-1 well. That well should be completed early in 2008.

Still on the drawing boards but planned for drilling are the Leek-1 southwest of Lalail to complete the Area B program as the situation stood in 2006

Then the analysis moves north to the Lankahuasa Profunde area for the Eslipua-1, Talipau-1, Kalipu-1 and Patini-1 wells. The Kalipu and Patini wells will break through the 3,050-ft (1,000-m) mark for water depth offshore Mexico. Those wells were planned for 2007, but the schedule is running behind, at least partially because of a lack of available rigs to drill in deep water.

The next step, originally scheduled for this year, includes the Maximino-1 in 9,485 ft (2,891 m) of water and Pep-1 in 9,646 ft (2,940 m) of water, both near the northern border of the Mexican Gulf of Mexico and across the border from Shell’s Perdido project in southern Alaminos Canyon on the US side of the border.

Although Great White, Tobago and Silvertip fields, the three fields in the current Shell development are more than 5 miles (8 km) north of the border, future development probably will include Chevron’s Trident field, which is on the border on the same Perdido Foldbelt trend and possibly on a structure that extends into Mexico.

Shell plans first oil production from subsea wells to the Perdido spar platform near the end of this decade.