Oil prices have continued to gather strength this week. Brent crude on the November contract was up by 3% on the week at $114.85 per barrel shortly before U.S. markets opened on Friday, down slightly from Thursday's peak of $116.01. U.S. WTI crude was up 3.9% on the week to $92.17, just below an overnight peak of $92.59 per barrel.

Natural gas for November delivery has also had a strong week and was up by 5% to $3.56/mmbtu on Friday morning after big gains on Tuesday and Thursday.

Many investors prefer to invest in commodity ETFs rather than directly in futures, and the United States Oil Fund (NYSE: USO) was up by 2.4% on the week at $34.19 when U.S. markets opened on Friday. The United States Natural Gas Fund (NYSE: UNG) fared better and was up by 5.6% on the week at $23.04, just after the opening bell.

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

Lansdowne Oil & Gas (LSE: LOGP.L) has gained 12% to 63.5 pence over the last five days, following the announcement of the expected recovery factor for the Barryroe field in the Irish Sea, the company's principle asset. Barryroe operator Providence Resources said that it planned to use a 31% recovery factor for development planning, cheering investors.

Newfield Exploration (NYSE: NFX) has risen 9.9% over the last five days to $33.46, after a large shale-oil discovery was made in an area close to Newfield's 135,000-acre Cana Woodford project in Oklahoma. The nearby discovery, which was made by Continental Resources, is said to be geologically similar to the Bakken region, according to a slide presentation by Continental.

Synergy Resources (NYSE: SYRG) has soared by 52% over the last month to $4.31 as investors poured into this Colorado-focused small-cap oil and gas explorer. The company's revenues are on course to rise from $10 million to $25 million this year as production scales up, and analysts expect revenues to rise to $45 million in 2013.

Small oil and gas shares are always volatile, and this week's winners could be next week's losers. To learn more about how to select oil and gas shares with the potential to deliver outstanding multi-bagging profits, I strongly recommend you download the latest special free report from the Motley Fool, "How to Unearth Great Oil and Gas Shares." It's completely free and includes details of how to select shares and structure your portfolio to maximize your potential profits and minimize your risks. Hurry, though, this new report will only be available for a limited time -- so download it today.

Are you looking to profit as a long-term investor? "10 Steps to Making a Million in the Market" is the latest Motley Fool guide to help Britain invest. Better. We urge you to read the report today -- while it's still free and available.

Further investment opportunities: