ANCHORAGE (AP) BP Exploration (Alaska) Inc. has completed new seismic surveys of most of the Prudhoe Bay oil reservoir, updating data from the 1980s and 1990s, along with checking areas around Deadhorse never before surveyed.
The new surveys provide detail of the oil-bearing rock far below the surface, according to Gordon Pospisil, BPs field-wide depletion and forecasting manager for greater Prudhoe Bay.
You get information from all the different angles ... that allows you to build a three-dimensional picture of these layers,'' Pospisil told Petroleum News.
With the earlier data, geologists could detect something say a fault as little as 80-feet thick. Using new technology and a higher density of signal receivers, now we can see something that's down in the 40- to 50-foot-thick zone,'' he said.
The new seismic data will help BP better understand what the remaining oil targets are throughout Prudhoe Bay.
The seismic survey has just been completed. By September, it will be used to generate new cross sections and maps. After that, he said, we'll be generating field-wide maps and starting to influence the wells that we're drilling.''
We'll have on the order of 200 wells that will benefit from this new, improved picture,'' Pospisil said. We'll drill better and different wells than we would have without the data.'' The wells will be drilled over the next five to eight years.
BP has been drilling 50 to 70 new wells a year in Prudhoe Bay, mostly sidetracking wells that have played out or where production has dwindled either because natural gas has migrated to the well bore or water has broken through from offset water injectors.
So we're actually sidetracking to new targets within the same region where we can identify higher oil saturation,'' Pospisil said.
Prudhoe has about 1,300 wells.
The seismic survey covered 180 square miles and included all of the facilities at Prudhoe Bay and the Deadhorse Airport, which has never been surveyed because of logistics problems involving airport operations. Seismic surveys were also shot through the town of Deadhorse itself, where many oil-service companies are based.
Pospisil estimated the unsurveyed area was probably 600 to 800 acres, several well spacings where we didn't have information.''
Since this is all within Prudhoe Bay and within the footprint of the existing facilities, any oil concentrations can be reached from existing pads. The improved imaging, he said, lends itself to what we now understand is a game of pursuing smaller and smaller targets ... the remaining interval areas that haven't been swept effectively.''
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