Search and deploy

Paul Boughton

It’s been a busy few months in the exploration sector. Louise Smyth highlights some of the latest advances.

Although the ‘oil bust’ of 2014 is the gloomy story that’s dominating current media coverage, the effects of this drop in price on exploration will take some time to trickle through. Some commentators remain optimistic that oil companies will not start scrapping new projects because they fear they are unprofitable. And as the past few months have shown, despite this uncertain economic backdrop, exploration – not only in oil but also in gas – has been booming.

Petrobras, as one would expect, is a player with plenty of news in this sector. Perhaps its most interesting announcement in recent months was an unprecedented natural gas find at a block off Columbia’s Carribean coast, which it owns in partnership with Ecopetrol and Repsol. The discovery was the result of successful drilling of the Orca 1 exploratory well in the Tayrona block, located 25 miles off the coast of the northern Colombian province of La Guajira. The well was drilled to a water depth of 640m (400ft) and penetrated 4,240m (13,900ft) into the rock layer. The gas (its volume was not announced) was discovered at a depth of 3,600m (11,800ft), making it the first hydrocarbon find in deep waters off Colombia's Caribbean coast. Petrobras will keep drilling in order to evaluate the size of the discovery.

In late November 2014, Petrobras completed drilling the first appraisal well in the Libra Consortium, the 3-BRSA-1255 (3-RJS-731), known as NW1. Located in the Northwest portion of the Libra block, in the pre-salt layer of the Santos Basin, the well is approximately 4km southeast of the discovery well, the 2-ANP-2A-RJS. The well reached final depth at 5,734m and is located 185km off the coast of Rio de Janeiro, at a water depth of 1,963m. Drilling results confirmed an oil column of approximately 290m and a reservoir that shows good porosity and permeability. Samples collected from the well confirmed that the oil of 27° API is the same as the one found in the well 2-ANP-2A-RJS. A formation test is expected in the oil-bearing zone to verify its characteristics and the reservoir productivity.

Aussie rules

Meanwhile, in Australian news, a four well exploration and appraisal campaign is currently underway, targeting gas and gas liquids in the Patchawarra Formation and Tirrawarra Sandstone. Canunda-2, the first well in the programme, was cased and suspended in October 2014. Maupertuis-1, the second well in the programme, was spudded in November 2014 with oil fluorescence and moderate gas shows in the Tirrawarra Sandstone detected during drilling. The well was cased and suspended, with Beach Energy electing not to participate. Antechamber-1 is the next well in the programme and is expected to spud as this publication goes to press.

In other Aussie news, the Swan Lake-11 appraisal well (Beach 20.21%, Santos 66.6% and operator, Origin 13.19%) was drilled in the north-east sector of the field and confirmed gas pay in the Toolachee, Epsilon and Patchawarra Formations and Tirrawarra Sandstone. It was subsequently cased and suspended. As a result, the field limit was extended and the results of this well have de-risked planned future development drilling. Up to six development wells are planned for Swan Lake in year 2015.

Meanwhile PGS has announced the successful commencement of the Springboard MC3D programme in the Ceduna sub-Basin offshore South Australia. The Springboard MC3D is being acquired by the Ramform Sovereign, a seismic vessel that utilises PGS’s GeoStreamer technology.

The proven capabilities of GeoStreamer technology will enhance hydrocarbon exploration efforts by giving greater confidence in subsurface imaging, improved prospect definition and identification as well as better geological modelling with less reliance on sparse well data. The programme will see some 8,000 sq km of GeoStreamer data acquired in this frontier area. It is widely expected that drilling will commence in this deep water area in 2016/2017.

South Australia is also seeing more exploration news from the Arckaringa Basin. Singapore-listed Linc Energy has reported that hydrocarbon shows have been detected in the Stuart Range Formation at the Pata 1 exploration well, the first of three wells in this year’s exploration programme in the Arckaringa Basin in South Australia.

The Stuart Range Formation, which was the first of the three formations targeted in this well, was intersected at 3,408ft (1,039m) and has been interpreted to be 470ft (143m) thick. This is the first occasion that the Stuart Range Formation has been intersected at this depth in any exploration programme in the Arckaringa Basin. The oil shows in the Pata 1 well were logged in the cuttings from the Stuart Range Formation between 3,730ft (1,137m) to 3,877ft (1,182m).

Linc Energy reports that dull, pale brown, even fluorescence was found in a siliceous siltstone with minor fine grained sandstone and increased with depth from approximately 10% at the top of the unit to 90% at the base of unit, providing evidence of an oil bearing formation. It has announced that in light of these findings, a full suite of wireline logs and rotary side wall cores will be run at total depth to further define the prospectivity of the Stuart Range Formation at this location.

Abandonment issues

In less positive news, Rocksource was left disappointed with efforts in the Norwegian Sea. The company said it encountered thick, well-developed basin floor fan sand with a gas-accumulation at the top in the Kvitnos target in the PL 528 Ivory exploration well in the Norwegian Sea. In the deeper Lysing target, the well penetrated a poorer than expected water-bearing sand. The company says that it is not possible to determine if the gas discovery is economically recoverable.

The primary objective of the Ivory well was to prove the presence of hydrocarbons in the Kvitnos formation sandstones, with a secondary target in the Lysing formation. Much data acquisition has been performed including cores, wireline logs, fluid samples and VSP. The discovered hydrocarbon column in the Kvitnos formation is estimated at the well location to be 12m total vertical depth, thinner than pre-drill estimates. Preliminary Rocksource volume estimates indicate a resource base below the pre-drill low case estimate of 280Bcf of gas.

The partnership will now evaluate the results with respect to commerciality and remaining prospectivity of the license. The exploration well was drilled to a total depth of 4264m below sea level. The well, being drilled by the West Navigatordrill ship, will now be permanently plugged and abandoned.

Meanwhile, Arctic water exploration plans are also being shelved as a result of Russia’s sanctions. Exxon Mobil and OAO Rosneft (ROSN) terminated contracts for five service vessels operated by Norway’s Siem Offshore.

Siem received termination notices from an Exxon and Rosneft joint venture on contracts for work in 2015 in the Kara Sea for two of its anchor-handling tug supply vessels and a platform supply ship. Rem had contracts for two platform-supply vessels terminated.

US and EU sanctions against Russia over its involvement in Ukraine are jeopardising Rosneft’s plans to explore Russia’s Arctic waters with western companies such as Exxon after the two made a 1 billion-barrel discovery in the Kara Sea in September 2014. Exxon is looking for alternative assignments for the West Alpha rig that made the discovery and was supposed to return to the Kara Sea for more drilling in summer 2015.

Egypt expansion

BP Egypt has announced that it has been awarded two new exploration blocks as a result of the 2013 EGAS bid round. BP and its partners have committed to invest a total of US$240 million in the blocks over different phases.

Block 3, North El Mataria, is BP’s first entry into the Onshore Nile Delta. The block is located in the northeastern part of the Nile Delta cone, approximately 57km to the west of Port Said city. BP will operate the block with 50% equity and Dana Gas of Abu Dhabi will hold the remaining 50% working interest.

Block 8, Karawan Offshore, is located in the Mediterranean Sea, in the northeastern part of Egypt’s economic waters. The block lies at approximately 220km to the NE and 170km to the NW of Alexandria and Port Said cities respectively. BP will have 50% equity and the block will be operated by ENI which holds the remaining 50%.

The programme will include 3D seismic and three exploration wells in each of the onshore and offshore blocks in phases over six to eight years.

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