LONDON -- Oil prices have remained range-bound this week, with Brent crude on the January contract gaining just 0.7% to $108.87 per barrel over the last five days. Meanwhile, WTI crude has slipped 1.07% to $85.25 per barrel during the same period.

Elsewhere, U.S. natural gas has made solid gains this week, and gas for December delivery was up by 5% at $3.68/mmbtu shortly before U.S. markets opened on Friday.

Of course, many investors prefer to invest in commodity ETFs rather than directly in futures, and the United States Oil Fund (NYSE: USO) closed almost unchanged on the week on Thursday, down 0.32% at $31.49.

Thanks to the rising price of gas, the United States Natural Gas Fund (NYSE: UNG) performed better and closed up 3.4% at $21.72 on Thursday.

The nature of oil and gas companies means that they can succeed or fail regardless of energy prices. Indeed, this week's risers have all outperformed the price of oil by a big margin in recent months.

Heritage Oil (LSE: HOIL.L) has risen 53% to 185 pence over the last six months, following the company's bold and transformational purchase of the 1.1-billion barrel OML 30 onshore license in Nigeria.

Heritage announced the completion of the Nigerian deal last Friday and is now focused on refurbishing the field's existing infrastructure to increase production from the current level of 35,000 barrels of oil per day.

Soco International (LSE: SIA.L) has gained 5% to 348 pence this week after touching a 14-month high in the wake of Indonesian state oil firm Pertamina bidding for Coastal Energy, which operates in the same region of Southeast Asia as Soco.

Soco's share price has been in the doldrums for years, but the company has been ramping up production in recent months and has long been suggested as a likely bid target, as Asian oil firms seek to grow their production capacity to meet local demand.

Providence Resources (LSE: PVR.L) has been one of this year's biggest winners, rising 176% to 571 pence since the start of 2012.

The Irish Sea is fast becoming a hot location for oil explorers and Providence is the biggest of the area's junior players. This week the company announced it had identified a new drilling target for its Drombeg license, which it estimates could have a recoverable resource potential of 872-million barrels. Providence has an exciting drilling calendar planned for 2013 and investors are expecting further oil discoveries from its promising assets.

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