Tethys Unveils Testing Results On AKD01 Oil Discovery In Kazakhstan

Published: 08-Feb-2010

Tethys Petroleum (Tethys) has revealed initial results of testing on the upper zone of the AKD01 oil discovery in Kazakhstan. The upper zone flowed oil at a restricted rate of over 5,400 barrels per day.

Combined with the recent testing on the lower zone, the AKD01 well has now flowed oil at a combined rate in excess of 6,800 barrels per day.

Well AKD01 encountered two oil-bearing zones, the lower zone being a Jurassic dolomite sequence at approximately 2,355 metres and an upper zone, Cretaceous sandstone, at approximately 2,174 metres.

The upper zone has interpreted net pay of nine metres with a porosity of 23%. 8 metres were perforated and a maximum flow rate equivalent to 5,436 barrels of oil per day (bopd) was achieved on a 12 mm (30/64") choke with a flowing tubing head pressure of 15.7 atmospheres (230 psig) and with the well still appearing to be cleaning up.

The oil is a 37 degree API light crude which appears to have low viscosity, low paraffin content and a low pour point. The gas-oil ratio is estimated at approximately 331 cubic feet of gas per barrel of oil. No water was observed with the oil and no oil-water contact is interpreted in the sand.

The maximum flow rate appears to have been mechanically restricted by the tubing or other downhole equipment and if these restrictions were to be removed then a higher production rate should be possible. Limited storage on site also restricted rate of oil production and the length of the flow period. No depletion was observed on test and surface pressure buildup data suggests good productivity, the company said.

Testing of the lower dolomite reservoir zone was carried out in December 2009 and January 2010 and flowed (after acidisation) at rates of up to 2,803 barrels of fluid per day on a 24 mm (60/64") choke with 1,373 bopd and with a flowing tubing head pressure of 14.2 atmospheres (209 psig).

The oil was a 45 degree API light crude oil and test data indicated that the reservoir has good permeability and is laterally extensive. The total thickness of the zone has been interpreted as being approximately 25 metres with a possible oil-water contact roughly half way through the sequence. It appears that this deeper water zone was the source of the water produced on test, this being channelled behind the casing following the acidisation. The lower zone was sealed off with a bridge plug prior to the testing of the upper zone.

Current mapping indicates that the AKD01 well is in a downdip location on the prospect (named Doris) with approximately 56 metres of elevation updip of the well, potentially bringing all of the lower reservoir into the oil zone. The prospect covers an area of roughly 60sqkm, with some possible downdip upside potential in the upper reservoir zone. The 180 metre vertical separation between these two reservoirs and the different oil gravities suggests that they may not have a common oil-water contact but should be able to be developed simultaneously with a dual completion. The combined flow rate of these two tests in this well was over 8,200 barrels of fluid per day.

The company's plans for the appraisal of the Doris prospect (which are still being firmed up) include appraisal drilling and further seismic surveys. Four further similar prospects have been mapped in the Akkulka and Kul-Bas block near to Doris and the results of the AKD01 well improve the exploration potential of these prospects.

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