Falkland log results disappoint Desire

By OGJ editors
HOUSTON, Dec. 6 -- Desire Petroleum PLC plans to drill the 100% interest Dawn/Jacinta prospect in the North Falkland basin at the company expressed “extreme disappointment” at log results from the 14/15-2 Rachel North well that it had proclaimed as an oil discovery.

Desire will plug and abandon Rachel North as an oil show well. It summarized the latest log results as follows:

• Preliminary results from interpretation of initial log data indicated that the well had encountered a 349-m gross interval of sands and shales with hydrocarbons, of which 57 m was net pay in multiple zones. However, sampling of the main sand has shown that the hydrocarbons are residual and that the mobile fluid is water.

• Analysis of the formation water recovered by sampling indicates much lower salinity than anticipated, and when this value is incorporated into a revised log interpretation it is confirmed that the sands are water-bearing. The salinity impacts the resistivity of the formation water that is used to calculate the saturation of hydrocarbons in sands.

• Using industry standard procedures, the initial interpretation was based on a calculated value from a clear water sand only 55 m above the target sand of the same stratigraphic age and depositional setting. This calculated value was consistent with measurements from other wells in the basin. Unexpectedly, the actual resistivity value in the sample taken from the main sand turned out to be markedly different, and that sand is now interpreted to be water-bearing.

• Formation pressures and sampling confirm the presence of good reservoir quality in the upper sands. A deeper target is still interpreted to be oil-bearing, but the interval is thin and reservoir quality is poor.

The wells Desire drilled in the Rachel area have identified five fan systems of varying areal extent and reservoir properties. Good reservoir development has been recorded in a number of the fans. Some of the sands are of a similar age to the sands in Rockhopper Exploration’s Sea Lion discovery.

All fans will be remapped incorporating data from the wells to identify areas where better quality reservoir can be expected and stratigraphic traps developed. As these fans can only be mapped on 3D seismic, final mapping will await the new 3D survey, to start shortly.

The Dawn/Jacinta prospect in Tranche I is independent of Rachel. Targets are sands at a number of levels. The well will explore the prospectivity on the southern margin of the basin immediately updip from the main oil source rock (see map, OGJ, Nov. 1, 2010, p. 61).

After Dawn/Jacinta, Desire is likely to drill another well at a location to be decided. The forward drilling schedule is still to be finalized.