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Another CI oil field?
Hilcorp looks to new development from North Cook Inlet Tyonek platform
Alan Bailey Petroleum News
Hilcorp Alaska has prepared an initial development plan for a known oil pool below the North Cook Inlet gas field. Drilling of the first development well from the offshore Tyonek platform should happen in 2020, the company told Alaska’s Division of Oil and Gas in the 2019 plan of development for the North Cook Inlet unit. The Tyonek platform currently supports production from the gas field. Because the oil development well will penetrate the top of the structure of the Sterling and Beluga gas sands, the well will also enable an evaluation of remaining dry gas development in the unit, the company told the division.
In the early 1990s ARCO discovered oil in a major geologic anticline under the gas field. In 1998 Phillips Petroleum conducted some appraisal drilling in the oil accumulation, termed Tyonek Deep. Although the company applied for a right of way for an oil pipeline from the Tyonek platform to the west side of the Cook Inlet, in 1999 the company put the project on hold, saying that viability required higher oil prices. At that stage the company said that it had tested two wells in the oil pool and run completion tubing in a third well, with the wells being ready for production. But the development never proceeded.
New oil line In preparation for reviving the oil field development Hilcorp has now laid most of a new subsea oil pipeline from the Tyonek platform to the Inlet’s west side. The company has been installing the line in conjunction with a major Cook Inlet pipeline reconfiguration, conducted in 2018. The reconfiguration project involved converting one of the twin subsea Cook Inlet Gas Gathering System pipelines from the carriage of gas to the carriage of oil. To maintain adequate gas transportation capacity across the inlet, Hilcorp laid a new subsea gas pipeline from the Tyonek platform to the west side of the inlet - that new pipeline ties up with the existing gas pipeline from the platform to the inlet’s east side.
Hilcorp’s plan of development says that all but 400 feet of the oil line from the platform were laid in 2018, with weather and pulling constraints preventing completion of the pipe laying operation. Hilcorp told the division that it anticipates completing the laying of the line in May of this year.
The company is also in the process of replacing the crew quarters on the Tyonek platform, and plans to upgrade the cranes and the helideck, and to remove drilling and mud pits.
Meanwhile production from the North Cook Inlet gas field continues. Hilcorp’s plan of development indicates that in 2018 the field produced 6.2 billion cubic feet of gas. That compares with 7.1 billion cubic feet in 2017.
Hilcorp has also filed new plans of development for the Granite Point, Middle Ground Shoal, Trading Bay and North Trading Bay units.
The Granite Point unit According to the new plan for the Granite Point unit, during calendar year 2018 Hilcorp produced 611,000 barrels of oil and 447 million cubic feet of gas from the Granite Point platform; 307,000 barrels of oil and 277 million cubic feet of gas from the Anna platform; and 108,000 barrels of oil and 279 million cubic feet of gas from the Bruce platform. That amounted to a total of about 1 million barrels of oil and about 1 billion cubic feet of gas from the unit, a significant uptick from the production of 879,000 barrels of oil and 752 million cubic feet of gas in 2017.
During the period of the last plan of development for the unit, starting on July 1, 2018, the company installed a water injection pump in one well, and conducted a subsea sonar survey of all pipelines associated with the platforms. The sonar surveying also monitored the M/V Monarch, which sank at the platform in 2009. In addition, Hilcorp conducted acoustic monitoring of the natural vibrations of the three offshore platforms and completed inspection and repairs on some platform leg welds.
Hilcorp told the division that it continues to evaluate further development drilling in the unit, including the possibility of drilling multilateral, sidetrack wells from existing well bores. For the coming plan period, running from July 1, 2019, through June 30, 2020, the company anticipates drilling two sidetracks.
Middle Ground Shoal unit In 2018 Hilcorp produced 520,000 barrels of oil and 111 million cubic feet of gas from the Middle Ground shoal unit. That compares with 308,649 barrels of oil and 83 million cubic feet of gas in 2017. Production in 2017 was impacted by a field shutdown as a consequence of a leak in the subsea pipeline that delivers fuel gas to the offshore platforms.
Since July 2018 Hilcorp has conducted well workover operations in the field, converting an injection well to a producer; perforating five wells; and performing coiled tubing cleanouts on two wells. The company also inspected some locations on a gas pipeline, conducted sonar surveys on all subsea pipelines and reconfigured the subsea gas pipeline manifold on one platform.
The field currently has two active platforms, Platform A and Platform C, while two other platforms, the Baker and Dillon platforms, are currently dormant.
In anticipation of the potential future reactivation of the Baker and Dillon platforms, and to address issues relating to the inspection of the field’s subsea gas pipeline, Hilcorp plans to install two subsea power cables to these platforms from platforms A and C, possibly during the summer of 2020. Reactivation of the dormant platforms would entail major upgrades to the platform facilities, Hilcorp told the division.
Hilcorp continues to evaluate the economics of reactivating drilling rigs on the A and C platforms. Potential drilling operations would include updating the well completions, adding perforations, cleaning out wells and repairing damaged wells. There are also some potential new drilling prospects - the company is in the process of interpreting new and reprocessed seismic data, to better delineate the structure of the field, and hence identify possible drilling targets. Drilling possibilities include infill drilling and step-out exploration tests, the company told the division.
In terms of continuing maintenance, Hilcorp plans to complete diver inspections of some subsea components of Platform A, and of the subsea gas pipeline.
Trading Bay unit In the Trading Bay unit the McArthur River field produced 1.7 million barrels of oil and 9.7 million cubic of gas in 2018. That oil production was virtually the same as production in 2017, while gas production increased from 7.2 million cubic feet. Since July 1, 2018, Hilcorp has completed two new wells in the field and has started but not completed a third well. The company conducted workovers on four wells on the Grayling and Steelhead platforms. The company also converted one well to gas lift and reperforated another well.
Hilcorp plans to continue to evaluate new rig workover opportunities in the field while also identifying new subsurface possibilities.
The Trading Bay field, the other field in the unit, produced 595,000 barrels of oil and 1.3 billion cubic feet of natural gas in 2018. That compares with 675,000 barrels of oil and 1.1 billion cubic feet of gas in 2017. Since July 1, 2018, Hilcorp has been conducting workover operations on two wells and anticipates workover of a third well shortly.
The company is working on a study of the field, to identify rig workovers, sidetrack drilling, waterflood optimization and other activities that may bolster field production.
North Trading Bay unit Hilcorp continues to anticipate restarting production from the North Trading Bay unit, using a sidetrack well drilled from the Monopod platform that supports the adjacent Trading Bay unit. North Trading Bay used to produce from the Spark and Spurr platforms, but oil production ceased in 1991 and gas production in 2005. The two platforms have been maintained in lighthouse mode since then - Hilcorp has in the past indicated that restarting these platforms would not be viable.
The company told the division that, following some additional seismic evaluation, it now anticipates starting a sidetrack from the A-10RD well in May of this year. If this sidetrack proves successful, Hilcorp anticipates applying for a unit expansion, to include newly producing acreage.
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