From Alaska to Ireland and Indonesia, many exploratory campaigns are producing positive results. Eugene McCarthy explains.
Three wells drilled by Repsol during a recently completed winter exploratory campaign in an oil-rich area of Alaska have found crude oil at different depths. The initial production tests carried out on two of the wells yielded encouraging results for future development, says the company.
Repsol operates the discovering consortium with a 70 per cent stake, in association with 70 & 48, a subsidiary of Armstrong Oil and Gas, (22.5 per cent) and GMT Exploration (7.5 per cent).
The Qugruk 1 (Q-1) and Qugruk 6 (Q-6) wells produced two hydrocarbon shows, with encouraging results during production tests. In the Qugruk 3 (Q-3) well, hydrocarbons were identified at multiple levels.
Exploration can only be carried out during four months of the year, when the terrain is frozen. Wells Q-1, Q-3 and Q-6 reached depths of 2493 metres, 3214 metres and 2637 metres respectively. Assessment and exploration work will continue during the 2013-2014 winter campaign.
These results are encouraging for the future development of the resources discovered, says Repsol. Recent tax reform passed in Alaska was a critical factor in ensuring the development of this project, where extreme climate conditions and geographical remoteness result in high operating costs.
The North Slope of Alaska is an especially promising area for Repsol, as it has shown itself to be oil-rich. In the USA, Repsol also explores for and produces hydrocarbons in the Gulf of Mexico and the Mississippian Lime. The company currently employs a staff of 380 in the country.
Repsol has significantly increased its exploration investment in recent years, acquiring acreage in 14 new countries since 2004. The result of this greater exploratory activity and success is much higher reserve addition rates than the industry average, along with a significant increase in production. Repsol posted a reserve replacement ratio of 204 per cent in 2012.
To this end, the company expects to dedicate around 80% of its €19.1 billion programmed investment over the coming five-year period to exploration and production.
In other news, Sound Oil, the Europe-focused upstream oil and gas company, has provided an operations update on the Nervesa appraisal well, onshore Italy.
The company has been advised by the owner of the contracted Drilltec TB2100S drilling rig that the rig has reached total depth at its current location in the Netherlands. The well will now be completed, after which the rig will mobilise to Italy where spud of the well is expected shortly.
Sound Oil has also published an update on its Badile project, located onshore in the Po Valley in Northern Italy.
Badile is an exploration prospect some 45 km south-west from the geologically analogous Malossa gas field and has been independently assessed low-best-high prospective resources of 47-175-938 billion standard cubic feet (bscf) respectively in Upper Triassic reservoirs.
Following the decision to retain Sound Oil's 100 per cent operated position (and therefore the significant upside of this prospect), the company has completed the technical work required for the drilling application and an environmental impact assessment (EIA).
As a result of this technical work the company has made the following enhancements to the detailed Badile drilling programme: reduction in target depth from 5300 metres to 4200 metres targeting only the Upper Triassic Dolomia Conchodon reservoir without significantly reducing the likelihood of encountering hydrocarbons; a shorter period required for drilling (down from an estimated 164 days to 143 days) resulting in significantly lower costs (from €20 million to €18 million); associated reduction in drilling complexity due to lower expected pressures and temperatures; and increased likelihood of gas-condensate occurrence in the target section.
James Parsons, Sound Oil's chief executive officer, commented: "This positive re-framing of the Badile drilling programme is an important step forward for the company which will lower the technical complexity of the well, shorten its drilling time, lower costs and increase well deliverability in the case of success. In addition, we expect that the revised programme objectives will accelerate the approval of the well by the various permitting authorities without compromising the economic proposition for shareholders.”
The drilling request and EIA will be submitted shortly in anticipation of spud in 2014.
Exploration company Premier has issued results from the testing of the Matang gas discovery on Block A Aceh (Premier equity 41.67 per cent) in Indonesia.
The Upper Bampo limestone formation has been tested over the interval 7785 feet true vertical depth (TVD) to 7853 feet TVD and has flowed gas at a rate of 25 million scfd through a 52/64 inch choke. Initial sampling indicates that the gas contains approximately 15% carbon dioxide. The gross resource estimate for the Matang structure remains in line with the pre-drill estimate of 100-400 billion cubic feet (Fig. 1).
"We are pleased that this successful well test has confirmed Matang as an important discovery coming as it does on the back of exploration successes in the UK and Norway,” noted ceo Simon Lockett.
Lockett was referring to the successful well test of the Luno II discovery on PL 359 in the southwestern flank of the Utsira High in the Norwegian North Sea (Premier equity 30 per cent).
The production test achieved an average flow rate of 2044 barrels of oil per day of good quality (36 degrees API) crude oil through a 48/64 inch choke, with a gas to oil ratio of 1012 scf/barrel.
Premier estimates gross resources across the Luno II structure to be in the range of 75-130 million barrels of oil equivalent (mboe) of which approximately 80 per cent are liquids. An additional 10-40mboe has been mapped immediately North of the discovery in a low risk Triassic prospect.
Further appraisal work is planned by the joint venture partnership prior to making development decisions.
In a third announcement, Premier says that oil production from the Huntington field in the UK Central North Sea commenced on 12 April. After an initial ramp up period, the field is expected to produce 25,000-30,000boe/d (gross).
“This marks the first of four UK North Sea projects from our development portfolio which will come on-stream over the next few years. We look forward to the field making a significant contribution to our worldwide production and cash flow growth,” commented Lockett.
Finally, Irish oil and gas exploration and appraisal company Providence Resources has confirmed that drilling activities have now commenced on the 44/23-1 Dunquin exploration prospect in Frontier Exploration Licence (FEL) 3/04, off the west coast of Ireland.
ExxonMobil Exploration and Production Ireland (27.5 per cent interest) operates FEL 3/04 on behalf of its partners, Eni Ireland (27.5 per cent interest), Repsol Exploracion Irlanda (25 per cent interest), Providence Resources (16.0 per cent interest) and Sosina Exploration (4.0 per cent interest). Drilling operations are expected to take several months to complete using the Eirik Raude semi-submersible drilling unit.
Commenting on this news, Tony O’Reilly, chief executive of Providence, said: “This is a landmark well given that it is the first to be drilled in the central part of the deep-water southern Porcupine Basin and is designed to test a new and potentially material Lower Cretaceous carbonate exploration play concept.”
Tullow success in East Africa
From Southern Ethiopia’s South Omo block, Tullow Oil reports that its Sabisa-1 well has been drilled to a total depth of 1810 metres. Hydrocarbon indications in sands beneath a thick claystone top seal have been recorded whilst drilling, but hole instability issues have required the drilling of a sidetrack to comprehensively log and sample these zones of interest. The sidetrack recently commenced and a result is expected very shortly. Tullow (with 50 per cent) is the operator of this well with Africa Oil (30 per cent) and Marathon Oil (20 per cent) having the other interests.
Meanwhile, at the Ngamia-1 well in Block 10BB in Kenya, the first of six drill stem tests has now been completed. The test was carried out in the Lower Lokhone formation. The well flowed 281 barrels of 30 degree API oil per day using a progressive cavity pump. The other tests will be carried out in the Auwerwer reservoirs (formerly Upper Lokhone) which produced very well in the recent tests at the Twiga South-1 well. The mobilisation of the drilling rig from Paipai in Block 10A to the Etuko (previously Kamba) location in Block 10BB in Kenya continues on schedule with drilling underway. Tullow operates the Ngamia-1 well and Africa Oil (50 per cent) has a non-operated interest.
Angus McCoss, exploration director of Tullow Oil, commented: “The Sabisa-1 well has proved to be technically challenging, as is often the case in frontier basins, and the well now requires a side-track to re-drill, log and sample the objective section. The results from the first flow test at Ngamia are also very encouraging and prove the first potentially commercial flow from the Lower Lokhone reservoir section.”