Shares in Tullow Oil fell up to 3% yesterday after the Irish-founded exploration company announced its founder and chief executive Aidan Heavey is to step down and that its 2016 revenues are likely to have fallen by almost 19%.

Shares in Tullow Oil nosedived by over 11% yesterday after the Irish-founded exploration firm was downgraded by two high profile brokers.

The next five years is a make or break period for Ireland’s burgeoning offshore exploration sector, an industry analyst said yesterday.

Northern Trust’s chief economist has cast serious doubt over the possibility of a significant oil price recovery this year as the ongoing price war continues.

Shares in Tullow Oil were up by more than 12% in London for much of yesterday’s trading session, hitting a two- month high in the process, as the Irish-founded explorer issued an upbeat trading update and said it is financially protected against the continually weakening oil price environment.

Tullow Oil has stated that its much-anticipated $5bn flagship Tweneboa Enyenra Ntomme (TEN) project, off the coast of Ghana, is now 75% complete and remains on schedule and on budget to deliver first oil by the middle of next year.

Tullow Oil has reiterated its full-year production guidance of 72,000-78,000 barrels of oil equivalent per day after confirming that its flagship project has returned to full output levels.

Production levels at Tullow Oil’s flagship project – the Jubilee field off the coast of Ghana – are expected to return to full pelt next month.

Tullow Oil’s first half revenues are likely to tumble by nearly 40%, year-on-year. However, the Irish-founded explorer is also anticipating a significant rise in production levels for 2015.

Tullow Oil has said it is discussing redundancies with employees as the energy explorer in Africa seeks to cut costs amid low oil prices.

Tullow Oil lost over £200m (€274m) of its market value yesterday, hit by concerns that a boundary dispute between Ivory Coast and Ghana could delay a project off the coast of west Africa.

Tullow Oil’s management is hopeful the company will return to profit this year, after posting its first net loss for 15 years in 2014.

Tullow Oil is to take a $2.3bn (€1.97bn) hit as a result of plummeting world oil prices.

Tullow Oil is to significantly redistribute its short-term capital spend levels away from exploration and more towards the development and production of its already proven assets.

Tullow Oil has continued its non-core asset disposal programme by agreeing the sale of four Dutch -based gas assets for almost €63m.

Tullow Oil is confident the Dutch-based International Arbitration Court will overturn a ruling by the Ugandan Tax Appeal Tribunal saying it owes a further $260m in unpaid tax regarding the 2012 farm-out of assets.

Tullow Oil is writing off $150m (€110m) of current year exploration costs linked with failed drilling work.

Tullow Oil hasn’t ruled out adding Ireland-based assets to its portfolio and has called for more clarity regarding the Government’s tax regime plans for the local exploration sector.

Shares in Irish exploration firm, Fastnet Oil & Gas jumped nearly 6% yesterday, on the back of it revealing that initial result readings from 3D seismic surveys of its Celtic Sea assets have identified 22 “structures”, or indications of oil.

Tullow Oil has said there is a good chance it may complete the planned farm-out of part of its stake in the highly-rated Ten oil project in Africa this year, although it reiterated that it is in “no rush” to do so.

Annual results for Tullow Oil due next month are set to show double-digit percentage growth in revenue, to $2.6 billion (€1.9bn) and a near 4% jump in gross profit.

Kenya, Uganda, and Ethiopia hold “enormous” potential for Tullow Oil in the coming years, the Irish-founded exploration firm’s chief executive Aidan Heavey has said.

Tullow Oil has reached agreement to sell its operations in Bangladesh to Far Eastern exploration firm, KrisEnergy for $42.35 million (€32.4m).

Tullow Oil should be rid of much of its non-core gas assets by the middle of this year, with the sale of its eight Asian gas licences in Pakistan and Bangladesh finally set to conclude before the end of June.

Tullow Oil has a record year of drilling activity planned for 2013 — saying yesterday it anticipates drilling 49 wells and achieving annual production rates of between 86,000 and 92,000 barrels of oil equivalent per day (boepd).

Tullow Oil is on track to return to full-scale production levels at its headline asset — the Ghana-based Jubilee oil field — ahead of schedule, later this year.

Tullow Oil has reported record half-year revenues of $1.15bn (€915.6m), a rise of nearly 8.5% on the same period last year.

Tullow Oil has entered talks aimed at selling off its non-core Asian assets, but no deal is expected to conclude before the end of the year.

Tullow Oil has said it is on course to deliver further significant growth in 2012, having seen excellent progress in the year to date.

Executive pay at Tullow Oil shot up by nearly £2.3m (€2.8m) last year on the back of the Irish-founded exploration company’s second consecutive year of record financial and operational growth.

A 35% increase in production levels helped Tullow Oil achieve a second consecutive year of record financial growth in 2011.

Tullow Oil has formally concluded its long-awaited $2.9 billion (€2.19bn) sale of certain Ugandan assets to its two developmental partners, China’s CNOOC and French company, Total.

TULLOW Oil has said that its 2011 performance — set to show a doubling of revenues — effectively makes it one of the exploration industry’s “super-independent” players, enabling it to seek out more high-profile development partnerships.

The Business and Finance Awards have taken place in Dublin last night.

TULLOW Oil has forecast record full-year results for 2011, chiefly on the back of strong cash flow from its Jubilee field off the coast of Ghana, which started producing late last year.

TULLOW Oil has doubled its interim dividend per share — to 4p — this year, on the back of a record set of first half earnings.

Oil and gas exploration and production firm Tullow Oil has announced record results for the six months ended June 30, 2011.

IRISH exploration company, Ormonde Mining has applied to the mining authorities in Spain for the re-activation of the La Zarza copper mine in the south of the country.

HIGHER sales volumes and a lift in commodity prices are likely to have boosted Tullow Oil’s revenues to a record level of over $1 billion in the first half of this year.