Pemex close to subsalt target in Perdido

Drilling ahead: the semi-submersible rig Bicentenario

Pemex is closing in on its first subsalt target in the Perdido fold belt, hoping to support its claims to retain such acreage under ongoing energy reform in Mexico.

Pemex’s pioneering deep-water drilling progamme at the Vasto-1 wildcat using the Bicentenario semi-submersible is close to breaching the 3000-metre mark, just 10 years after the company launched deep-water operations.

Deep-water activity is already making an important contribution to Pemex’s reserves replacement. Pemex has sustained a 35% success rate in exploration, despite wading out into deep-waters for the first time, with 30 wildcats.

The Perdido fold belt is offering the most exciting discoveries, with a series of finds that have already yielded more than a billion barrels.

Among them, the Exploratus light oil strike, which was initially pegged at 234 million barrels of proven and probable oil based on data from an Eocene Wilcox reservoir has now been uprated to close to 500 million after a deeper probe to Early Oligocene targets, according to deputy exploration manager Manuel Teran. In addition, Trion’s two pay zones, with crude at 25 and 29 degrees API, have yielded reserves of 482 million barrels that could be fully certified at the end of the year, while the Maximino discovery’s reserves are put at 439 million barrels of 42 to 44 degrees API crude.

At present, the Seadrill-owned drillship West Pegasus is drilling a delimitation well on Maximino, in a record depth of 3017 metres of water. The Supremus discovery was smaller, estimated at 98 million barrels.

At Vasto-1, which is being drilled in 2890 metres of water, the probe is homing in on a target that could move some Mexican Perdido prospects to more than the 1 billion barrels.

“We are under the salt now, which was a first for us here, although we have not yet reached the target zone,” Teran said.

Pemex has also drilled a pioneering well in the shallower waters of the Salina del Bravo basin.

Here, the Vespa wildcat was drilled to a total depth of 3418 metres in 700 metres of water, and encountered 24 degree crude though Pemex hit problems with sand inflows, preventing testing.

“We did not identify a resource that was commercially viable as a deep-water development, but we found the oil system and we think this area will be important in the future,” said Teran.

Pemex invested between $5 billion and $6 billion on its deep-water exploration programme between 2007 and 2013, including the 30 wells and 3D seismic acquisition, according to exploration manager Antonio Escalera.

Deep-water wells accounted for 57% of the reserves that were added by Pemex in 2013, compared with less than 15% in 2007 and about 20% of the company’s reserves are now in deep-water, Escalera said.

Pemex is now being courted by scores of international oil companies interested in bringing technology, know-how and financial resources for a much bigger push into Mexico’s deep-water plays.

The company was permitted to apply for offshore areas in zones that have actually been drilled.

Pemex is reluctant to state which deep-water areas have been requested, but Upstream has learned that they account for at least 90% of the areas explored so far. Pemex is set to look for pragmatic solutions, through partnerships.

“We want to develop the deep-water areas we have already explored and do so in consortia that bring together the best industry capacities,” Pemex chief executive Emilio Lozoya told a Mexican conference audience last week.

“We also want to accelerate the demarcation and development of reservoirs as much as possible and with the lowest costs possible.

“This will mean that it will be more economic to develop the first barrels using existing US infrastructure, although this will change as our own industry develops.”

Pemex is also waiting for the conclusion of the assignment process to assess its need for additional deep-water rigs.

“If we get the areas we have requested, then we will need more rigs, but we will have to wait and see,” said Escalera.

Pemex recently chartered another midwater rig from Diamond Offshore, for use in a rich trend of extra-heavy oil in the Bay of Campeche.

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