WesternZagros Resources Ltd. has completed its testing program in the deepest of the three stacked reservoirs drilled by the Kurdamir-2 exploration well in the Kurdistan region of Iraq. The testing confirmed an oil discovery in low permeability fractured limestones of the Cretaceous-age, Shiranish formation, adding to the previously announced major oil discovery in the Oligocene reservoir, the company announced.
The Shiranish reservoir exhibited non-commercial flow rates in this location.
The combined audited unrisked mean estimate for all three reservoirs on the Kurdamir prospect is 1,609 MMbbl of prospective oil resources as at May 31, 11% of which (181 MMbbls), is attributed to the Cretaceous, the release said. The company now expects this number for the Cretaceous to be revised downward, although it is not expected to materially change the estimate of prospective resources of the whole Kurdamir prospect.
As previously reported in March 2012, the first drill stem test on the Kurdamir-2 well resulted in a major oil discovery in the Oligocene interval. The well was then drilled to a total depth of 4,000 m (13,123 ft) in June. In addition to the oil-bearing intervals encountered in the Oligocene and Eocene reservoirs, the release stated hydrocarbon shows and wireline logs indicated the presence of a gross hydrocarbon-bearing interval of approximately 500 m (1,640 ft) of fractured limestones and marls in the Shiranish formation, which was the focus of the recent testing program.
The Shiranish testing program consisted of three cased hole tests over a 221 m (725 ft) gross interval and resulted in the flow of light, 39° to 40° API oil at sub-commercial rates. Further evaluation, including additional analyses of the test results, followed by the already planned extensive 3D seismic program, will be required to better understand if the Shiranish is likely to have commercial reservoir characteristics, according to the release.
The company said it is encouraged that the Shiranish testing program recovered oil from a depth that is significantly deeper than the limit of closure of the Kurdamir structure at the Cretaceous level as mapped from seismic data. This finding supports the observation that the Shiranish reservoir, in a similar fashion as the Oligocene reservoir, is also involved in a considerably larger trap and that Kurdamir and the neighbouring Tophkana structure share a common oil accumulation in the Shiranish reservoir.
The testing operations in the Shiranish interval were concluded on Oct. 9, following a number of delays due to downhole tool problems. Preparations are currently underway to conduct a cased hole testing program on the interpreted 275 m (902 ft) of gross oil pay in the Eocene before moving further uphole to conduct additional testing on the main zone of interest in this well, the 118 m (387 ft) of gross oil pay already discovered in the Oligocene, according to the release.
The operator, Talisman (Block K44) B.V., and WesternZagros are also planning a 3D seismic program over the Kurdamir and Topkhana structures and a further appraisal well (Kurdamir-3) to assess the ultimate size of the Kurdamir discovery. WesternZagros and Talisman each have a 40% working interest in the Kurdamir Block, with the Kurdistan regional government holding the remaining 20%.
