Vol. 28, No.6 Week of February 05, 2023
Providing coverage of Alaska and northern Canada's oil and gas industry

AOGCC’s rescheduled Alpine gas release hearing set for March 23

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Kristen Nelson

Petroleum News

The Alaska Oil and Gas Conservation Commission has rescheduled a hearing, originally set for October, on the March 2022 release of natural gas from ConocoPhillips Alaska’s Alpine CD1 drillsite.

The hearing will be March 23 at 10 a.m. at the commission’s Anchorage offices. The audio call-in number is (907) 202-7104 conference ID 531 706 515#.

The commission said ConocoPhillips’ investigative report identified the natural gas as originating from Colville River unit well WD-03 during drilling operations and “identified findings and causal factors for the gas release.”

Hearing issues

The commission said it conducted an internal investigation into the gas release and called the hearing on several issues:

*Casing and cementing on WD-03 “as it relates to confining fluids to the wellbore, preventing the migration of fluids from one stratum to another and protecting significant hydrocarbon zones.”

*Gas disposition from drillsite CD1 “as it relates to waste of resources.”

*Conduct of operations for WD-03 as related to the company’s internal plan “for the well and communication of pressure limits to the field.”

*Well safety valve systems related to producing natural gas up the outer annulus of WD-03.

*Change of approved program related to application for sundry approvals following oral approval from the commission.

Gas release background

Natural gas, later determined to be from the C10-Halo interval in the WD-03 disposal well, then being drilled at CD1, was observed March 4, ConocoPhillips told the commission in its May 3 final report, as “intermittent, low pressure natural gas releases at CD1-05, which is approximately 450 feet away from WD-03.”

“By March 8, ConocoPhillips had secured the location, determined the most probable gas source, and established a controlled flow path for the gas up the outer annulus of the WD-03 well into the Alpine Central Facility,” ConocoPhillips said in a May 10 letter answering questions about the release from Congress.

The company told the commission April 1 that an estimated 7.2 million cubic feet of natural gas was not captured and said it believes most of that gas escaped to the atmosphere between March 4 and March 8. In its May 3 final report to AOGCC ConocoPhillips said an estimated 24 million cubic feet was recovered, based on metering data from the flow directed to the Alpine Central Facility from the WD-03 outer annulus from March 8 through March 29, when source control was achieved and WD-03 stopped producing gas after circulation of kill weight fluid.

The company identified two causal factors and said in its letter to Congress that neither related to well design: “a surface casing shoe in WD-03 that broke down when pressure limits were exceeded during freeze protection operations” and subsequent pressure increases in the outer annulus of the WD-03 well which were not recognized or addressed and “which could have led to more immediate investigation or remedial action.”

The company said the pressure limits were exceeded Feb. 27 during an annular leak-off test and freeze protection operations and “most likely broke down the casing shoe and provided an initial pathway for gas migration around the outside of the WD-03 surface casing.” A subsequent injection of 300 barrels of water to displace mud “likely expanded the pathway.”

Pressure increases in the WD-03 outer annulus from March 1 to March 3 were not recognized, and the company said the volume of gas released “would have been reduced” if elevated pressures in the WD-03 outer annulus had been addressed earlier.

In its final report to the commission, ConocoPhillips said: “Based on historical evaluation methods used to successfully drill 49 other CD1 wells, the C10/Halo at the WD-03 well path was determined not to be a ‘significant hydrocarbon zone’ or ‘abnormally geo-pressured area’ during pre-drill planning and/or during drilling operations,” so no cement isolation was deemed necessary.

The company did, however, note a potential missed indicator. “A well in proximity to WD-03’s well path potentially had indications of gas from shallower zones than the Qannik. Further review into the source of this gas may have informed WD-03 well planning.”


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