Buccaneer Energy Ltd., Sydney, paused drilling at 5,600 ft at its Cosmopolitan-1 well in Alaska’s Cook Inlet after encountering hydrocarbon liquids shows in the Lower Tyonek formation about 400 ft higher than expected.
The company will run wireline logs and pressure tests and take sidewall cores before drilling ahead. It will set casing at 5,485 ft before drilling through the Lower Tyonek and into the proven oil-bearing Starichkof and Hemlock formations and reach target depth of 8,000 ft after drilling the prospective West Foreland formation.
The well has penetrated three primary gas zones totaling 175 ft in which logging while drilling equipment indicated good resistivity, permeability, and porosity. The results need to be confirmed with wireline logs and flow testing, if warranted. No flow tests are planned for the oil formations.
The current plan is to take cores in the oil formations to augment known reservoir data. The objective of this coring operation is to further optimize the future oil plan of development.
The gas zones were all accompanied with a sharp increase in gas relative to background gas measurements. Generally, gas levels over background gas amounts increased by a multiple of 5-10, measured resistivity from 10-30 ohms, and permeability and porosity characteristics would indicate production-capable sands based on previous basin experience, Buccaneer said.
There are four more potentially gas-bearing zones of interest, similar in total thickness to the primary zones, that the company classifies as secondary zones of interest. The well will ultimately be plugged back to the bottom of the Tyonek gas-productive zones and be temporarily abandoned as a future gas producer.
Buccaneer Energy acquired 25% interest and became operator of Cosmopolitan last year, and BlueCrest Energy II LP, Fort Worth, has 75% (OGJ Online, July 23, 2012).