"We were able to bring sand mixed with the oil up the well on a regular and sustained basis, and to create a series of small fissure -- we call them "wormholes" -- in the reservoir to allow oil to flow. We used a device called a progressive cavity pump to create a suction to bring the oil-sand mixture up the well."
BP was able to create a significant flow of heavy oil, although Rinehart did not give figures. It was enough, however, to convince BP that the reservoir "appears to be fairly robust" in its potential.
The initial flow of sand and oil was 50 percent sand but that dropped to 20 percent sand by the end of the 30-day test, he said.
"We were also encouraged by the success of separating the oil from the sand, which was done with heating," Rinehart said. There are still technical challenges, however. One is whether the sand/oil mixture can be extracted from a horizontal well, BP's West said in a briefing for reporters in September, when the production test began.
BP has been working on the technical feasibility of heavy oil production for about three years, and ConocoPhillips has been working on it for more than a decade. The resource has been known for a long time but the technical and economic challenges are daunting.
"We know where the heavy oil is and where it isn't because we drill through it all the time to reach the deeper conventional oil reservoirs," West said in a briefing on the project during September. "We know how much oil is in place with some precision. The question is how much we can produce."
If BP proceeds with heavy oil development, it would require a large number of wells and would most likely be done with horizontal multi-lateral production wells involving a several underground production legs drilled off a single "mother" well to the surface, West said.
Whether horizontal and multi-lateral wells can be used isn't known, but it could be a way to reduce the surface impacts and costs. BP and ConocoPhillips use horizontal multi-lateral wells on the Slope to produce viscous oil, which is of higher quality than heavy oil, as well as conventional oil.
The jury is still out on heavy oil production, but BP and ConocoPhillips hope to make it part of the "bridge" strategy until natural gas production from the North Slope.
One of the big attractions of heavy oil wells, if they can be shown to produce commercially, is that they could last a very long time, much longer than oil produced from the conventional oil well.
Conventional oil production from the North Slope fields will continue to decline and at some point gas production will begin to help support the production infrastructure on the slope, BP's West said.
If it is feasible to produce, heavy oil could be a key part of a strategy to mitigate the decline of oil fluids, West said. That way, when gas does start flowing, there will still be a healthy production of oil and gas.
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