Lee Tillman, chief executive officer of Marathon Oil told investors last month that the company was sitting on the equivalent of 4.3 billion barrels in its US shale acreage.
That number was 5.5 times higher than the one Marathon reported to federal regulators.
Such discrepancies are rife in the US shale industry. Drillers use bigger forecasts to sell the hydraulic fracturing boom to investors and to persuade lawmakers to lift the 39-year-old ban on crude exports. Sixty-two of 73 US shale drillers reported one estimate in mandatory filings with the Securities and Exchange Commission while citing higher potential figures to the public, according to data compiled by Bloomberg. Pioneer Natural Resources' estimate was 13 times higher. Goodrich Petroleum's was 19 times. For Rice Energy it was almost 27-fold.
As shale gas exploitation proliferates, new research into the contents of the fluids involved in the process raises concerns about several ingredients.
Young people are much more in favour of renewables than fracking for shale, a poll suggests.
The survey revealed that 18-24-year-olds who were aware of fracking wanted the Government to develop other sources of energy in the UK, with 44% backing solar as one of the technologies they most favoured, 41% for wind and 38% for tidal power.
Chevron will sell a 30% stake in one if its ventures to produce oil and natural gas in North America to the Kuwait Foreign Petroleum Co for $1.5 billion.
The agreement will create a partnership for the appraisal and development of liquids-rich shale resources in an area of 330,000 acres in the Kaybob area of the Duvernay.
