Partners to evaluate North Sea gas-condensate discovery

After completing the drilling of a sidetrack well and performing a drill stem test (DST), Austria’s oil and gas company OMV will work with its partners to evaluate a gas-condensate discovery at an exploration well located in the North Sea, in a bid to maximise flow rates in a potential, future development.

Back in September 2022, OMV decided to drill a sidetrack well and perform a drill stem test after confirming a gas-condensate discovery at its Oswig exploration well 30/5-4S due to challenges with collecting a full suite of data from the existing wellbore. The high-pressure high-temperature (HPHT) well was drilled using the Noble Intrepid (former Maersk Intrepid) jack-up drilling rig, which was hired in December 2021.

The well 30/5-4S, located in the licence PL1100, was spud at the beginning of August 2022. The licence is operated by OMV with a 40 per cent interest while other partners include Wintershall Dea Norge (20 per cent), Source Energy (20 per cent), and Longboat Energy Norge (20 per cent).

In an update on Thursday, OMV’s partner, Longboat Energy, disclosed that the Oswig sidetrack well 30/5-4A was drilled to a depth of 4,726 metres TVDSS to conduct a drill stem test in the Upper Tarbert Formation. The firm outlined that the average production rate from the DST was approximately 2.1 mmscfd (60 kSm3d) of gas and 280 bpd (45 Sm3d) of condensate – around 650 boepd in aggregate – through a 10/64-inch choke over two flow test periods followed by 24- and 48-hour pressure build-ups.

Moreover, a mini-frac test was carried out as part of the test programme to gather important geomechanical data for optimising the evaluation and design of potential future production wells. According to Longboat, the preliminary estimate of recoverable resources is between 10 and 42 million boe based on in-place volumes of between 100 and 215 mmboe. The firm underscores that the condensate/gas ratio is 110-130 bbl/mmscf, based on the preliminary test data collected.

Longboat highlights that the DST “successfully proved the ability of Oswig to flow hydrocarbons from a poor quality reservoir” and supports a potential development via nearby infrastructure in the Northern North Sea. The water depth is 95 metres at the well location and the Oswig exploration well 30/5-4S and the sidetrack 30/5-4A will be permanently plugged and abandoned.

As “a substantial amount” of data and samples have been collected in the main exploration wellbore, the sidetrack and the DST, the partners in this licence intend to evaluate the potential of the discovery in more detail, including the location of any further appraisal drilling and possible well configurations – horizontal, multilateral and/or fracked wells – with the objective of “maximising flow rates in any future potential development.”

Helge Hammer, Chief Executive of Longboat, commented: “Longboat is pleased to have made a discovery at the Oswig well, albeit at the lower end of pre-drill expectations. The thick gas column is within the Tarbert Formation in a well-defined structure with excellent-quality gas and high condensate content. The Oswig fault block drilled has substantial volume potential and is located close to existing infrastructure.

“In addition, there is a possible large extension towards the south in the same fault block. Longboat looks forward to working with the partnership to define an appraisal programme and optimal well configuration for maximising flow rates from future potential development wells.”