Pacific Rubiales Energy Corp., Toronto, has set casing to test the Yaraqui-1X exploratory well on a subsalt prospect on the Topoyaco block in the Putumayo basin foothills in Colombia.
Drilling and logging provide encouraging indications of the potential of the subthrust play, a new exploration horizon for the company, Pacific Rubiales said.
The well drilled through Tertiary and Cretaceous and penetrated 61 ft of Precretaceous basement before reaching a total depth of 10,651 ft measured depth. The well was drilled directionally with a southeast-northwest orientation in a subthrust monocline structure,referred to as structure D, that covers 4,500 acres.
Petrophysical evaluation of the logs indicates that the well encountered 142 ft of potential hydrocarbon-bearing sandstones distributed among the base of the Rumiyaco formation and in the Villeta and Caballos formations, all of which have proven to be commercial reservoirs elsewhere in the basin.
In the Rumiyaco formation, the Arena Neme sandstone unit was encountered at 9,714 ft MD, 8,801 ft true vertical depth with 20 ft of net oil sandstones with 10% porosity. In the Villeta formation, the pay units were found at 9,748 ft MD, 8,828 ft TVD, with a total of 120 ft of potential oil pay, 10 ft in the M2 sandstones encountered at 10,110 ft MD, 9,126 ft TVD, 40 ft in the U sandstones that start at 10,202 ft MD, 9,201 ft TVD, and 70 ft in the "T" sandstones, found at 10,354 ft MD, 9,327 ft TVD.
The U sands have average porosities of 10% while the "T" sands have porosities in the order of 11%. In the Caballos formation, found at 10,510 ft MD, 9,458 ft TVD, a total of 2 ft of potential hydrocarbon sandstones was found, with porosities of 11%.
Pacific Rubiales is operator of the block with 50% interest, and PetroMagdalena Energy Corp. has 50%.