Fortune Oil [LON:FTO] was the sector's biggest riser for the second day in a row with another double-digit jump in its share price.

The group - which saw its share price soar yesterday after it conditionally agreed to inject its natural gas business into China Gas, for a total consideration of US$400m - was up by more than 10% in late afternoon trading.

Heritage Oil [LON:HOIL] has increased its stake in PetroFrontier Corp to nearly 20%.

Heritage says it acquired 1,900,000 PetroFrontier common shares - 2.39% of the outstanding shares - and now holds 15,860,467, representing 19.98% of the outstanding shares.

Heritage also sold 2,311,767 previously acquired warrants.

All shares held by Heritage in PetroFrontier have been acquired for investment purposes.

Max Petroleum [LON:MXP] reported revenue of US$49.2m during the six months to the end of September, up 102% compared to US$24.4m a year ago.

Total sales volumes of 664,000 barrels of crude oil ("bbls"), were up 58% from 421,000 bbls sold in the comparative period in 2011.

Average realised price of US$74.07 per bbl, up 28% from US$57.93 per bbl during the six months ended 30 September 2011, due to increased export volumes relative to domestic sales.

Cash generated from operations of US$31.1m, up 291% from US$7.9m in the comparative period.

Loss before tax for the period of US$0.5m, compared to a loss before tax of US$0.3mduring the six months ended 30 September 2011.

EBITDA for the current period of US$17.9 million, up 67% from US$10.7 million during the six months ended 30 September 2011.

During the half year the company entered into a US$7m equity for services agreement with Zhanros Drilling LLP to drill up to four post-salt exploration wells.

As announced on 27 November 2012, Max Petroleum entered into a US$90 million loan agreement with SB Sberbank JSC to refinance the Macquarie Bank credit facility, redeem all of the Company's convertible bonds for a combination of cash and ordinary shares, and provide up to US$30 million for drilling future development and exploration wells and associated expenses.

The restructuring is expected to close before 31 December 2012, subject to shareholder and bondholder approval, and will reduce the group's total debt from approximately US$140m to approximately US$90m.

PetroNeft Resources' [LON:PTR] Arbuzovskoye well 111 in Russia has been successfully completed and put into production.

There has been an initial oil flow rate of 150 barrels per day (bopd).

It is now drilling well 112 targeting the eastern side of field.

Dennis Francis, Chief Executive Officer of PetroNeft Resources, commented: "We are pleased with the initial flow rate on well 111 and the fact that there is no water production associated with the well. We continue to expand our understanding of the field and are now drilling well 112 on the eastern side of the field where we have seen the highest flow rates to date.

"The operational challenges and variation in results are as expected. We look forward to completing further wells in Arbuzovskoye over the coming months as we continue to focus on materially increasing our production profile and cash flows."

Korean conglomerate LG International Corporation is taking a 20% interest in GeoPark's [LON:GPK] Colombian subsidiary.

GeoPark Colombia holds GeoPark's Colombian assets which includes interests in 10 hydrocarbon blocks.

GeoPark and LGI have also agreed to extend, in March 2013, their strategic alliance to build a portfolio of upstream oil and gas assets throughout Latin America.

This partnership, formed in 2010 and which now includes joint projects in Chile and Colombia with interests in 16 exploration, development and production blocks, is currently targeting new project acquisitions in Brazil, Colombia, Peru, Argentina and Chile.

The sector's biggest fallers were Regal Petroleum [LON:RPT] and Xtract Energy [LON:XTR] - down by more than 18% and over 11% respectively.