Gas leaking from Gulf sea floor

Apache natural gas well has leak beneath floor of U.S. Gulf

AlertNet,

17 February, 2013

NEW YORK, Feb 16 (Reuters) - Natural gas from a well being drilled by Apache Corporation in the U.S. Gulf of Mexico has flowed underground, leading U.S. regulators to order the company to prepare to drill a relief well to control the flow if necessary, the U.S. Bureau of Safety and Environmental Enforcement said.

Apache shut in the well on Feb. 5 after it had a "kick" upon encountering a zone of "abnormally pressured" natural gas while drilling, the company said in a statement on its website.

A kick commonly refers to a temporary loss of control over the well due to higher than anticipated pressures being encountered while drilling, leading to fluids or gas flowing into the well.

Non-essential personnel have been evacuated from the Ensco Plc drilling rig Ensco 87 and no gas or oil has leaked into the Gulf of Mexico, Apache said.

The incident occurred in shallow waters in Main Pass block 295, approximately 50 miles (80.5 km) east of Venice, Louisiana.

Apache is moving another rig it has under contract owned by drilling firm Rowan Companies Plc to the site to drill a relief well if necessary to stop the gas from flowing underground.

A relief well is typically used to stop an uncontrolled flow of gas or fluids from a well when other methods fail.

Apache readies rig for relief well

US independent Apache said a relief rig is en route to the location of an offshore Louisiana well where natural gas has been said to be flowing underground for more than a week.

Upstream,

15 February, 2013

According to US media reports, non-essential staff were evacuated from the shallow-water well that was being drilled by the jack-up Ensco 87 at Main Pass 295 in the Gulf of Mexico.

Houston-based Apache spokesman Bill Mintz confirmed in an emailed response to Upstream that the well began flowing natural gas on 4 February.

“The well was shut in, and the blowout preventers are functioning properly,” he said.

However, testing had detected an underground migration of gas from the bottom of the well (about 8261 feet) to a shallower sand formation at about 1100 feet below surface.

Mintz said Apache was now working with Boots and Coots well control experts to kill the well.

He added that at the direction of the Bureau of Safety and Environmental Enforcement, the company was mobilising another jack-up rig, Rowan Cecil Provine, to the well location in case the drilling of a relief well was necessary.

No one was injured in the incident, Apache said.

It did not offer an explanation of the perceived cause of the underground gas movement.