Quadrant Energy has set the timing and location of the Roc-2 well in WA-437-P, offshore Australia.

Quadrant is the operator of the exploration permit with 80% interest, and Carnarvon Petroleum is its partner.

Carnarvon said on Wednesday that the well has been designed to appraise and test the Roc-1 gas-condensate discovery announced in January 2016.

Carnarvon Managing Director and CEO, Adrian Cook, said: “In the success case, the Roc-2 appraisal well will confirm our gas and condensate volume estimates and provide us with important information on the flow rates of these hydrocarbons from the reservoir.

“We also have plans to explore a secondary deeper objective in the Roc-2 well, targeting a zone that contained encouraging hydrocarbon shows in the bottom hole section of the Roc-1 well, following success in the primary target and accommodating well conditions.

Roc-2 well timing

Diamond Offshore’s rig Ocean Monarch is expected on location at the Roc-2 site in the last week of June or the first week of July. The Ocean Monarch will have the capability and approvals to undertake well testing if the expected hydrocarbons are confirmed whilst drilling this well.

The Roc-2 appraisal well is required to delineate the extent of the Roc field, calibrate reservoir parameters, understand reservoir deliverability and characterise fluid properties.

Roc-2 will be drilled to a depth of 5,250m with capacity to extend to 5,700m if justified by hydrocarbon shows, reservoir quality and drilling conditions.

Full well-bore coring and flow-testing are planned for this well over the Caley sandstones, taking the total time to drill, core and test to around 98 days.

Roc-2 location and volumes

The Roc-2 well is located in around 100m water depth, approximately 160 km north-east of Port Hedland in the Bedout sub-basin of the greater Roebuck basin.

Roc-1 encountered a gross reservoir section of around 120 metres in the Caley, with the top 40 meters being hydrocarbon bearing. The Roc-2 well is designed to appraise this reservoir section in an updip location, around 5km to the east of the Roc-1 well.

According to Carnarvon, the Roc-2 well is designed to appraise the contingent volumes and to explore for the prospective volumes in order to aggregate a total contingent volume above the minimum economic field size (MEFS) threshold.

For contingent volumes, encountering similar quality sands across the same 40m gross column in the Roc-2 location is expected to prove up (in the mid case) a volume of around 270 Bscf and 13 million barrels of condensate recoverable (gross).

Encountering the additional 80 metre sands above the gas-water contact in Roc-2, as has been interpreted on 3D seismic, is expected to prove up (in the mid case) an additional volume of around 193 Bscf and 9 million barrels of condensate (gross). These quality sands were discovered in the Roc-1 well below the gas-water contact and accordingly were non-hydrocarbon bearing at that location.

A mid case contingent and prospective resource outcome is expected to comfortably satisfy the MEFS threshold, Carnarvon said.

Roc-2 well testing

The proposed well test in Roc-2 across the Caley reservoir will aim to prove up potential commerciality by demonstrating flow potential. The well test will primarily demonstrate that the Caley sandstone is capable of production at commercial rates.

Additional information that will be collected by the well test include average reservoir properties such as permeability across the tested zones, connected volumes and indications of reservoir architecture including boundaries and calculation of in-flow performance relationship.

The well test can also be used to collect downhole and surface samples of the producing fluid.

The final well test program will be decided once the Roc-2 well has drilled through the Caley reservoir, but it is envisaged to take a total of around 20 days to complete.

Roc-1

Carnarvon also reported that several sidewall core samples from the Roc-1 well were fast tracked through routine core analysis in order to determine porosity and permeability parameters.

The results have given more confidence in the range of gas and condensate in place with porosities being reported of 14.5% for Sand 2 and 12% for Sand 4, the company said.

More importantly, the permeabilities reported of 300 to 500mD in Sand 2 and 40mD in Sand 4 are significantly better than expected and give confidence for positive flow rates being achieved during well flow testing.

The Roc prospective and contingent resources are within the WA-437-P exploration permit in the North West Shelf of Australia.