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Karoon Gas Australia hits oil in Santos Basin

Oilfield Technology,

Karoon Gas Australia Ltd’s Kangaroo-2 appraisal well, located in exploration Block S-M-1165, confirmed a 250 m gross (135 m net) oil column in Paleocene and Maastrichtian aged reservoirs, announced 26 November 2014. Karoon is the operator and has a 65% interest in the jointly held Block S-M-1165, Santos Basin, Brazil. Pacific Rubiales Energy Corp holds the remaining 35% interest.

As at 06:00 hrs AEST on 6 January 2015, production testing over the Paleocene A, B and C oil bearing reservoirs was complete. Preparations are underway to commence a side-track programme to better define the resource size and recovery factors. The results from the test are as follows:

Oil flowrate

Production test DST-2A was conducted in the Paleocene A, B and C sandstone reservoirs over the intervals 1663 -1681 mRT, 1695 - 1729 mRT and 1735 - 1753 mRT with a 12 hr main flow period. The maximum oil flowrate attained was 3700 bpd (stabilised rate of 3450 bpd) through an 88/64 in. choke with a flowing tubing head pressure of 270 psia, a gas-oil-ratio of 540 ft3/bbl.

Production test DST-2 was conducted in the Paleocene C sandstone reservoir over the interval 1735 - 1753 mRT. The maximum oil flowrate attained was 2500 bpd through a 44/64 in. choke with a flowing tubing head pressure of 425 psia and a gas-oil-ratio of 450 ft3/bbl. The well was then flowed on a 40/64 in. choke at a stabilised rate of 1820 bpd with a flowing tubing head pressure of 420 psia, a gas-oil-ratio of 450 ft3/bbl. At the end of a main 24 hr flow period, the well was shut-in for a 48 hr pressure build-up period.

Oil specification

DST-2A produced a 33° API oil with zero CO2, H2S, water or sand produced. DST-2 produced a 31° API oil with zero CO2, H2S, water or sand produced.

Production well potential

Based on the oil rates obtained in DST-1A (Maastrichtian section) and DST-2A (Paleocene section), Managing Director, Mr Robert Hosking said “Karoon is very pleased with the production testing results from Kangaroo-2. Based on the flowrates achieved in both the Paleocene and Maastrichtian reservoirs, a vertical production well could produce 6000 to 8000 bpd from the combined reservoirs. In addition, horizontal production wells could be expected to produce at higher rates.”

Kangaroo-2 side-track programme

After the well testing string is removed and the Paleocene reservoirs are plugged back with cement and a cement retainer, the well will be side-tracked in both a down-dip and up-dip location in order to better define the resource size and recovery factors.

Side-track-1 will be drilled to a down-dip location to target the Paleocene and Maastrichtian reservoirs on the eastern side of an interpreted north-south trending fault, and to evaluate potential hydrocarbon accumulations in the Campanian. Wire-line logs and a pressure survey will be conducted.

Side-track-2 will be drilled into Paleocene and Maastrichtian reservoirs in an up-dip location to test reservoir and hydrocarbon potential towards the salt wall. The information obtained from Kangaroo-2 will be important for assessing the commerciality of the Kangaroo oilfield and will be valuable for a front end engineering and design (FEED) phase bringing the project a step closer to commerciality.

The Kangaroo-2 appraisal well is located in exploration Block S-M-1165, approximately 300 m up-dip and 4 km south of Kangaroo-1 and is the first well in the Santos Basin exploration and appraisal drilling campaign.

Forward programme

Following the completion of all operations on the Kangaroo-2 appraisal well, the rig will be moved to drill Kangaroo West-1 exploration well (the second firm well in the programme) and evaluate the prospect approximately 4.5 km distant on the western side of Kangaroo salt structure. Due to the large size and proximity to Kangaroo, a successful outcome at Kangaroo West-1 would materially add to any possible development of the Kangaroo oilfield.

The exploration and appraisal drilling campaign is expected to continue through first half 2015. The rig contract provides Karoon with two firm wells plus two option wells, and, in the event of a successful drilling outcome in the first 2 wells provides maximum flexibility for further appraisal of the Kangaroo oil discovery, additional drilling at Kangaroo West or possibly targeting other prospects.

The salt flank play was first proven by Kangaroo-1 with the intersection of a 76 m gross oil column and oil recovered to surface from wireline DSTs. Results of the Kangaroo-2 further confirm the viability of the play. Kangaroo West-1 is located on the western flank of the same salt structure as Kangaroo-1 and has the same trap type and reservoir and seal intervals that have been mapped into the prospect from surrounding wells.

The Olinda Star semi-submersible rig is drilling the entire campaign.

Adapted from press release by Cecilia Rehn

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