Pacific Rubiales Energy has provided an operational update of its drilling campaign in the Rubiales Field and Quifa blocks, both located in the Llanos Basin, Colombia. The update describes the results of three appraisal wells in Rubiales; two wells in prospect D (Rub-251 and Rub-266) and one well in prospect B (Rub-310) and two exploratory wells in prospects B and C in the Quifa block.
The appraisal wells, Rub-251 and Rub-366, were drilled as part of the appraisal campaign on prospect D to confirm reservoir extension and production potential of this northern area of the Rubiales Field. The Rub-251 well found the top of the Carbonera basal sands, at 2,913 feet measured depth (MD), or 2,271 feet true vertical depth at sub-sea level (TVDSS), and the oil-water contact (OWC) at 2,963 feet MD, or 2,321 feet TVDSS, for a total gross oil column at the well of 50 feet. The Rub-266 well found the top of the Carbonera basal sands, at 2,890 feet MD, or 2,300 feet TVDSS and the OWC at 2,926 feet MD, or 2,336 feet TVDSS, for a total gross oil column at the well of 36 feet.
The company said that petrophysical evaluation of both wells indicates a net pay zone of 31 feet, and porosities of over 30%. These wells were drilled as appraisal wells on prospect D, at a distance of 6.81 km and 2.61 km, respectively, southeast of the discovery well Rub-147 (Rub-147 well was drilled on October 2008. These wells confirmed the extension of this discovery to the southeast, and its continuation into the Quifa block, which was first evidenced with the Quifa-9 well results. The company is now planning to test the wells and complete them as vertical hole producers.
The Rub-310 well, drilled on prospect B, to the eastern part of Rubiales field, found the top of the Carbonera basal sands at 2,552 feet MD, or 1,977 feet TVDSS, and the top of the basement at 2,644 feet MD. This well showed a total thickness of 92 feet and porosities of 29%; however, it was 100% water saturated. The company is now planning to convert it for use as an injector well.
As part of the exploration activity at Quifa block, two exploratory wells were drilled on prospects B and C, located in the least known area of the block at 15 to 18 km northeast from the Rubiales field and on the eastern part of the Quifa block. The Quifa-15 well, drilled on prospect B, found the top of the Carbonera basal sands at 2,671 feet MD, or 2,064 feet TVDSS and the top of basement at 2,868 feet MD. The Quifa-16 well, on prospect C, found the top of Carbonera basal sands at 2,564 feet MD, or 2,010 feet TVDSS, and the top of basement at 2,722 feet MD, or 2,168 feet TVDSS.
Although both wells showed good reservoir characteristics in the basal sand intervals (159-158 feet thick and 30% average porosity), none of them showed a presence of hydrocarbons in the column. Since both wells were located in the highest part of the structure of the Rubiales-Quifa area, mapped with a regional 6×4 km seismic grid, with no evident structural separation from the Rubiales reservoir, the absence of oil in this area could indicate the existence of a stratigraphic barrier to the west-southwest that separates this area of the Quifa block from the Rubiales field, regulating the hydrocarbon charge to this part of the block.
Before drilling more exploratory wells in this eastern area of the Quifa block, the company will analyze these results and use the information obtained from these wells to prepare a seismic inversion exercise (calibrated with the new wells), to identify the stratigraphic anomaly that did not allow the connection from the Rubiales field towards this zone, and consequently did not permit the migrating oil to reach the area targeted by the Quifa-15 and 16 and wells.
The Quifa-15 and Quifa-16 wells are located in the Quifa Block, in the Llanos Basin of Colombia. The Quifa Block is an Association Contract with Ecopetrol in which Meta Petroleum (a wholly-owned subsidiary of Pacific Rubiales) holds a 60% working interest and Ecopetrol holds a 40% working interest.