|
Put River added to Prudhoe Bay oil pool AOGCC approves adding Kalubik interval to Prudhoe; four lobes overlie Prudhoe; development will be from existing facilities Kristen Nelson Petroleum News Editor-in-Chief
The Alaska Oil and Gas Conservation Commission has approved an application from Prudhoe Bay operator BP Exploration (Alaska) to add Put River to the Prudhoe Bay oil pool and authorize enhanced oil recovery from the interval.
The commission said in a Nov. 22 order that the Put River sandstone is part of the Kalubik formation within the Prudhoe Bay oil pool and “stratigraphically overlies the Prudhoe Oil Pool, as currently defined” by the commission, in the vicinity of Prudhoe Bay unit drill sites 1, 2, 5, 6, 15 and 18. The commission said inclusion of Put River in the Prudhoe Bay oil pool is based on juxtaposition of, and pressure communication between, Put River and the Sag River formation, which is part of the Prudhoe Bay oil pool.
There are four “vertically significant and laterally extensive sandstone bodies” within the Put River interval: the southern, central, western and northern lobes, which are “interbedded within shales” of the Kalubik formation.
“BP’s justification to include the (Put River) within the Prudhoe Bay Oil Pool is based upon the direct juxtaposition of, and pressure communication of the Northern Lobe with the Prudhoe Oil Pool,” the commission said, and noted that the southern, central and western lobes “overlie the Jurassic Kingak Shale and are not in hydraulic communication with the Prudhoe Oil Pool.” Range of hydrocarbons API gravity in the lobes is 26.9 degrees in the southern lobe, 3.12 degrees in the central and 57 degrees and 59 degrees respectively in the western and northern lobes.
The commission said there are no indications of a free gas column in the southern or central lobes, while the western and northern lobes “are comprised of gas and gas condensate.”
Estimated oil in place is 12.5 million to 19.2 million barrels in the southern lobe and 1.1 million to 2.7 million barrels in the central lobe. Estimated gas in place is 6.9 billion cubic feet to 10.5 bcf in the southern lobe, 0.5 bcf to 1.3 bcf in the central lobe, 69.6 bcf to 104.4 bcf in the western lobe and 108.4 bcf to 160.4 bcf in the northern lobe.
Some Put River production has occurred from Prudhoe Bay wells, with flows ranging from 73 barrels per day to 1,820 bpd.
The commission said the northern lobe is a portion of the Prudhoe Oil Pool gas cap and will be managed as an area within that pool.
Primary depletion from the southern and central lobes is estimated to recover 10 percent of the oil in place and waterflood is being evaluated for the southern lobe, with estimates of incremental recovery of 10-25 percent with waterflood.
Development will be from existing Prudhoe Bay pads, primarily drill sites 1, 2, 6, 15 and 18 will use Prudhoe Bay facilities.
The commission said the southern lobe is the main oil target development area.
| 