BP has offered US$8 a share for Penn Virginia, which drills for oil in Texas and elsewhere in the US, and has a market capitalisation of about US$319.2mln, according to people familiar with the matter.
Penn is understood to have rejected the offer because it believes the terms offered undervalue the company, and is holding out for at least US$10 a share.
It is believed rivals to BP such as Exxon Mobil Corp and Chevron may also be interested in buying the company.
Penn’s share price has fallen to about US$4.50 a share from just below US$17 a share in June last year as oil prices have plummeted.
In 2010, Penn decided to shift its investment and production focus from natural gas towards higher margin oil.
It sold natural gas assets in south Texas in January 2014 and further assets in Mississippi in July last year to focus on the Eagle Ford Shale in south Texas.
The Eagle Ford Shale is one of the biggest onshore unconventional finds in the US, but billionaire Penn shareholder George Soros, who is thought to own about 8% of the group, has reportedly urged it to find a buyer or a partner that could exploit its reserves more efficiently.
Penn is understood to have appointed Bank of America Corp to help it in its search for potential buyers.
An oil analyst in London speaking on condition of anonymity pointed out that BP has been rationalising its business in the US following the Gulf of Mexico rig blowout in 2010, but the analyst said: “It’s a good time to buy cheap assets for majors trying to replace reserves and production.”
The analyst added: “Consolidation in the US has to happen and there are players with deep pockets who would take out some smaller US independent explorers and producers who may not be able to fund their production themselves.”
A spokesman for BP said: “We would not normally comment on market rumour and speculation.”
Penn increased production in the Eagle Ford Shale by 23% to 21,390 barrels of oil equivalent per day (boepd) in the first quarter of 2015 against 17,459 boepd in the three months to the end of December last year. In October last year, it owned about 104,300 net acres in the Eagle Ford Shale and said it planned to further increase its acreage position near its existing holdings. It said its lease position gave it more than 1,600 drilling locations or the equivalent of about 12 years of drilling sites.