Testing of an oil discovery offshore Angola by Cobalt Energy has confirmed the find’s reserves sufficiently for the US independent to pencil it in as a subsea tieback to its planned pre-salt Cameia field development.

The Cobalt-operated deepwater Mavinga-1 pre-salt well in Block 21 is located approximately 12.5 km northwest of the company’s 2012 Cameia discovery in the frontier Kwanza Basin. The probe reached total depth and hit approximately 30 m (100 ft) of net oil pay.

The company said that the discovery was confirmed by the successful production of oil from mini drillstem tests, direct pressure and permeability measurements, and log and core analyses. However, it did go on to add that efforts to establish a sustained flowrate from a full drill stem test were not successful.

Cobalt is in the early stages of determining what operational issues may have prevented the production from the oil reservoir during the drill stem test,” it stated.

The company is confident in the discovery’s upside potential, saying that it estimates a gross oil column of up to 200 m (650 ft) at the crest of the Mavinga structure, updip of the Mavinga-1 well. Additional drilling will be required to confirm the ultimate gross thickness of the mound and its reservoir quality, it said, but Cobalt is already expecting to tie Mavinga back to the planned ‘Cameia Mound Development Project’, also in Block 21.

No conceptual plan has yet been released for Cameia, but DI hears it is likely to follow the same route as many others off West Africa, using a leased FPSO unit. A bidding and tendering process for that is unlikely much before mid-2014, although Cobalt has also indicated it wants possible project sanction next year in order to have Cameia onstream during 2017.

However earlier this year a disappointing drillstem test of the lowest interval on Cameia saw that well fail to produce measurable hydrocarbons, although Cobalt stressed at the time the test results had “no bearing” on the commerciality of the Cameia Mound Development Project (see DI, 6 May 2013, page 6).

Following the temporary abandonment of the Mavinga-1 well, Cobalt mobilised the Ocean Confidence rig to start drilling on the nearby Bicuar-1A pre-salt exploratory well south of the Cameia and Mavinga discoveries and in the same block. The well is expected to take between 130-150 days to drill.

Cobalt’s partners in Block 21 are Sonangol P&P, Nazaki Oil and Gaz, and Alper Limitada.

Cobalt also announced at the same time as the Mavinga results that in neighbouring Block 20 its Lontra-1 wildcat had reached total depth, and confirmed another oil and gas discovery. Further evaluation, including a drill stem test, is required to assess its potential, it added. Cobalt expects to provide more information on Lontra before the end of the year.

Upon completion of testing operations on Lontra, Cobalt plans to mobilise the Petroserv SSV Catarina drilling rig to the Orca-1 pre-salt exploratory well (formerly the Baleia prospect), approximately 25 km northeast of Lontra. The well will test the pre-salt section updip of the Baleia-1A well, with new seismic indicating a larger structure with thicker reservoir potential.

Cobalt’s partners in Block 20 include Sonangol P&P and BP Exploration Angola (Kwanza Benguela) Ltd.
Joseph H. Bryant
, Cobalt’s Chairman and CEO, said: “While operations are still continuing at Lontra, it’s clear that each of Cobalt’s four wells to date has been successful in finding and delineating new hydrocarbon resources in the Angolan pre-salt. This is a remarkable and highly unusual start to the exploration of such an immense new basin.”

  • On a less bright note Cobalt also announced a net loss of US $160 million for the third quarter of 2013, compared to a net loss of $39 million in Q3 2012. The current quarter included $108 million for the impairment of expenditures, including $94 million associated with the Ardennes-1 exploratory well and related prospect leases in the US Gulf. Cobalt’s updated 2013 expenditure forecast is $850-$950 million.