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Aggressive work aimed at making Badami productive Success at “the Badami laboratory,” with technology pushed to limit, would open up similar prospects across the North Slope Kristen Nelson PNA News Editor
When BP Exploration (Alaska) Inc. declared a time-out at Badami Feb. 1 it was to prevent infrastructure damage because of low production rates and very cold temperatures.
The company took the opportunity to reevaluate its approach to the field and to upgrade and remediate facilities, Gary Osborne, BP Exploration (Alaska)’s east North Slope subsurface manager, told PNA June 3.
“We wanted to basically assimilate all the data that we’d acquired during this rapid development which occurred over the previous six to eight months,” Osborne said. In addition, “On the surface or facilities side we also wanted to take the opportunity to restore any part of the facilities or infrastructure that needed to be upgraded or remediated.”
“So it was a tremendously busy time even though from the external point of view it would appear to be relatively quiet,” Osborne said of the period through May 1, when Badami production was started up again. Data being received now, he said, allows the company a check on the assumptions made during the winter shutdown.
Rethinking the complexities One of the challenges in developing Badami — a known risk going in, Osborne said — was the question of how connected the portions of the reservoir are.
The reservoir at Badami was laid down in seven depositional events, Osborne said. Within that seven-lobe system there are 61 different fans which are “tremendously heterogeneous in a vertical sense — thin sands, silts, sands, silt, thin sands, shales, silt.” If, he said, you could strip away surface geology and permafrost “you’d see a patchwork quilt of thin sands and shales. And what that means is, with any given vertical or near vertical penetration you may hit a number of different sands, but they don’t go very far.” Reworking for gas injection “We focused our initial development on what we called the amalgamated sands — where we thought sands were deposited on sand. Vertically more continuous and hence believed to be laterally more continuous.”
A related issue is gas injection. All non-fuel related gas is injected back into the reservoir at Badami, but, Osborne said, it hadn’t been possible, in the initial development, to sustain gas injection.
A possible reason for this, he said, was wellbore condition — perforated intervals might have become blocked. So, during shutdown, well bores were cleaned out.
“If I’ve got a laterally continuous sand,” Osborne said, “then I ought to be able to inject a lot of gas into it… If it’s laterally highly discontinuous, then I fill it up with gas. I’m done. I can’t inject any more.”
Since startup in May, he said, BP has been able to sustain injection in two wells picked for injection.
Quality of crude another risk “The other key risk identified was the quality of the crude that was resident in the reservoir,” Osborne said. There were known to be crude oil with American Petroleum Institute gravities ranging from 19 into the mid and high 20s, he said.
Under extreme conditions of temperature and pressure drop, a fraction of the crudes contain asphaltines that will precipitate out as temperatures and pressures are lowered.
These crudes also, he said, have a tendency “to evolve wax at relatively modest temperature conditions.”
The Badami development “program was designed to develop the portion of the reservoir which had the lighter more mobile crudes and avoid the necessary fractionation problems.”
“So,” Osborne said, “you’ve got two elements of a petroleum system here that prove to be most challenging. You want to hit the optimal reservoir in terms of thickness and lateral continuity and you want to find it were it contains the lightest most mobile crude.”
Developing the field, he said, represented a “very aggressive stance taken by BP and partner Fina.” BP has a 70 percent interest in the field, Petrofina Delaware a 30 percent interest.
New technology BP has also been working in new technology at Badami, drilling two tri-lateral wells at the field. These wells have, in addition to the main well bore, two additional well bores which are also producing. “It’s a master well bore with two subsidiary holes off of it,” he said, a good way to reach discontinuous accumulations.
“With new technology in a remote harsh environment, we’ve been disappointed in a number of these attempts. For instance, our tri-laterals are not our best producers. We’ve got to understand why that is. Is it how we positioned them? Is it how we completed them? Or drilled them?”
How’s it going? Osborne said that BP was pleased at being able to sustain gas injection since the field was started up again May 1 and is carefully monitoring production. So far there hasn’t been the precipitous drop that would force another warm shutdown. And the ninth well being drilled in the field “encountered the best Brookian section yet in terms of thickness and quality” and is being deepened as an exploration well to evaluate additional reservoir potential in the area. Osborne said that results were not being made public from that exploration well.
What’s at risk “The complexity is not yet resolved,” Osborne said. “It has, is, and will be a very complex system. The part of the story that’s not yet written is how we resolve this complexity to an economically viable project — that’s what this is all about.”
There is no doubt that there is a resource, he said. What’s needed is a way to produce it. “We’ve already seen that we can’t be below a threshold level in the harsh temperatures of the winter.”
“We’ve called it the Badami laboratory,” Osborne said, because we’re trying new technologies, we’re pushing technology to the limit here. We think if we can resolve some of these questions it represents a significant strategic breakthrough that can be applied across the slope. There are a number of other Brookian prospects that the partners would be very interested — and the state would be very interested — if they were to be commercially viable. And what we learn here will impact that question.”
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