Downhole plumbing, flow-friendly process optimize production: in every oil or gas field development, decisions that drive the design of production equipment from the bottom of the hole to the sales line, must accommodate a wide range of production volumes and possible changes in the makeup of the wellstream.

Publication: Oil and Gas Investor

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COPYRIGHT 2005 Hart Publications, Inc.

To make those decisions near the beginning of a field's life--usually before production begins--engineers need as much information as possible, which they need to analyze quickly. An early understanding of the expected performance of a reservoir is especially critical to making smaller reservoirs financially viable.

"We get a lot of information up front as we are drilling the wells that helps limit the number of surprises," said Jim Abercrombie, senior vice president and general manager, western business unit. "We soon know a lot about the characteristics of the wellstream, such as the presence of paraffin or asphaltenes that might affect the design of production facilities."

Much time is spent analyzing reams of information before the development scheme is sanctioned. But the ability to develop accurate models quickly is better than it was just a short time ago.

"That capability is much greater today than it was even 3 or 4 years ago when we were looking at Devils Tower," Abercrombie said. "And at that time, it was much greater than 3 or 4 years earlier."

Production capacity is just one of the design criteria that is a challenge to pin down at an early stage. Equipment must be able to handle the low initial throughput and the low volumes as the field nears the end of its life, as well as peak volumes.

For Devils Tower, reservoir models and other simulations based on a given well completion design were used to determine how the production facility would be loaded to optimize production. Those simulations were used to create three scenarios--minimum case, most likely case and maximum case.

"Then the design was made to accommodate the most likely case plus some upside," Abercrombie said. "At the end of the day, you settle on a facility size that you believe can handle the majority of the production cases that are likely to be faced."

For Devils Tower, that turned out to be a production system that can handle 60,000 b/d of oil and 110 MMcf/d of gas.

There is some upside margin, he said. "We believe we could increase throughput by 5% to 15% if necessary."

If reservoir conditions change significantly, such as a waterflood is needed,...

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