By Jon "DRJ" Najarian, co-founder of OptionMonster.

McDermott International ( MDR) is seeing heavy options activity amid rumors that PetroChina ( PTR) is interested in buying the engineering and construction company.

Normal call activity for McDermott in the 30 days has been 5,100 contracts for a full session, but today some 22,400 contracts traded in the first 30 minutes alone, according to OptionMonster's real-time tracking systems. The feeding frenzy saw 8,500 calls change hands at the May 20 strike against open interest of just 1,506.

McDermott shares are up nearly 5% on the session to $16.68 in midday trading.

McDermott works in offshore oil and gas construction and power generation. The space has been hot lately, especially with interest in Calpin ( CPN) and Mirant ( MIR) in the power industry and Halliburton ( HAL) in oil and gas. Some of today's chatter has McDermott and PetroChina in late-stage acquisition talks.

The writer has long positions in McDermott.