Oryx Petroleum Corp. Ltd. announced in a press release the discovery and testing of crude oil at Ain Al Safra. The Ain Al Safra discovery will be appraised in 2014 as part of the multiwell appraisal and development drilling program in the Hawler license area in Kurdistan, where Oryx Petroleum is the operator and has a 65% participating and working interest.

The Sakson Hilong 10 rig spudded the exploration well targeting the Ain Al Safra prospect, a broad fault-bounded anticline, in the Hawler license areas in early June, according to the release. The AAS-1 well targeted oil potential primarily in the lower Jurassic and Triassic and secondarily in the Cretaceous. Netherland Sewell & Associates Inc. estimated as of march 31, 2013, that the Ain Al Safra prospect contained 225 MMbbl of unrisked gross prospective resources (risked: 44 MMbbl).

The AAS-1 well reached a depth of 3,039 m (9,970 ft) in the uppermost Triassic in early September and was originally scheduled to be drilled to a total depth of 3,700 m (12,139 ft), according to the press release. Drilling was suspended and the well secured at the 3,039-m depth since heavy losses of drilling fluids caused the bottomhole assembly to become stuck. The well was logged down to the lowermost Jurassic, and there was evidence of oil shows in the Cretaceous, Jurassic, and lower Jurassic of varying quality.

As previously reported, the Cretaceous reservoir was deemed wet and not tested, according to the release. In the lower Jurassic reservoirs, free oil on the shakers and sizable losses of drilling fluids were observed during drilling, with significant quantities of oil flowing to surface. As such, three cased-hole drillstem tests were conducted in the lower Jurassic zones.

The results of the AAS-1 testing program are as follows:

  • The first and second drillstem tests tested the Butmah and Adayiah formations, respectively. While logging results of each formation indicated the presence of fractures, the results of both tests were inconclusive since the tests were unable to connect to a permeable fracture network and flow fluids to surface.
  • The third drillstem test tested the base of the Alan formation and the Mus formation together since the corporation believes fracture systems in the two formations are in communication. Two intervals were perforated in a section totaling 58 m (190 ft). The well was successfully flowed using 20/64-in. and 16/64-in. choke sizes. The two choke sizes yielded average flow rates of 850 b/d and 657 b/d, respectively, over eight-hour flow periods. During the entire test period oil was flowed through a separator using a variety of choke sizes for a total of 38 hours inclusive of the two eight-hour flow periods using the fixed choke sizes. Thirty-six hours of pressure buildup also were recorded for the test. Well performance during testing appears to have been highly impaired by the rise of heavy mud in the tubing during the flow periods as an analysis of pressure gauge records indicates the well was still cleaning up at the end of the well test. The heavy mud was used to control the well during drilling.

Field tests designed to measure the crude gravity produced conflicting results with some samples indicating heavier (18°API) gravity oil and some samples indicating lighter (29°API) oil, according to the press release. Fluid samples have been sent to a laboratory for further analysis. Some natural gas was encountered with the gas-oil ratio of approximately 4.5 cm/bbl (160 cf/bbl). Hydrogen sulfide also was encountered and measured at 20% in the gas phase.

The data gathered from the well and field tests should be considered preliminary until such as a pressure transient analysis or well test interpretation has been carried out. Test results are not necessarily indicative of long-term performance or of ultimate recovery, according to the release.

Oryx Petroleum is conducting further analysis of the AAS-1 well and intends to drill an appraisal well at Ain Al Safra in 2014, the company said. In addition to appraising the discovery in the Alan and Mus formations, appraisal drilling is expected to include the Traissic Kurra Chine formation, which was not possible with the AAS-1 well. Oryx Petroleum also intends to retest the Butmah and Adayiah formations, where logging information acquired during drilling indicates the presence of fractures.