Eastern Llanos gets possible multipay oil find

By OGJ editors
HOUSTON, July 14 -- Colombian subsidiaries of two Canadian companies have drilled a heavy oil discovery on the CPE-6 block in Colombia’s Llanos basin that appears to have light oil potential.

Petrophysical analysis of the Guairuro-1 stratigraphic test indicates 28 ft of net pay with 28% average porosity and identified oil-bearing sandstones down to 3,377 ft measured depth, 2,540 ft true vertical depth subsea. This results in a 45-ft gross oil column in Carbonera C7 and the basal sandstones of the Mirador formation.

Pacific Rubiales Energy Corp., Toronto, operator with 50% working interest, said cores also show evidence of possibly lighter oil in two intervals of the Carbonera C7 sands, which may indicate that oil accumulations at these upper levels could also extend to the northern part of the block. A Talisman Energy Inc. subsidiary holds the other 50%.

The stratigraphic well cannot be production-tested, and Pacific Rubiales is preparing to pressure-test 30 levels and collect two fluid samples from the upper C-7 intervals. The company will drill five more wells in the 2010 third quarter to honor the CPE-6 minimum work program.

The company intends to investigate the regional extent of the basal sandstone play found on the Rubiales and Quifa blocks 100 km east-northeast of CPE-6. Four wells drilled on CPE-6 in the early 1980s showed sandstones with 10.5-12° gravity oil in the northern part of the block that were interpreted to represent the same play found on Rubiales and Quifa.

Guairuro-1 exhibited oil-impregnated cores in every sandstone from Carbonera C-7 down to 3,377 ft MD in Mirador basal sandstones, indicating that oil had enough mobility to reach more than 100 ft vertically, possibly through faults, from the basal sandstones into the C-7 units, Pacific Rubiales said.

Revised petrophysical evaluation of the four 1980s wells, Guairuro-1 data, and seismic interpretation of the stratigraphic pinchout of the basal sandstones has allowed the company to remap the prospect on which the five wells are located and has established that the possible area for the stratigraphic trap can reach at least 25,200 acres from the pinchout to the average oil-water contact. This acreage corresponds with the existence of a regional belt of heavy oil that may extend farther northeast and reach the Rubiales-Quifa areas.

Pacific Rubiales will integrate 678 line-km of 2D seismic shot as part of the CPE-6 work commitment with existing data to remap the trap and identify locations for the next five wells. The company will move toward production once it elects to convert the technical evaluation agreement to an exploration and production contract.