Multilaterals more to forefront of early production solutions

Multilateral technology, which cut its teeth in the North Sea market may be poised to move into the less mature theaters where the challenges, and rewards are higher. At the second annual High-Tech Wells conference in Galveston, Texas, Halliburton company Sperry Sun addressed the growing need for advanced multilateral technology in areas such as the US Gulf of Mexico and offshore West Africa.

Multilateral technology, which cut its teeth in the North Sea market may be poised to move into the less mature theaters where the challenges, and rewards are higher.

At the second annual High-Tech Wells conference in Galveston, Texas, Halliburton company Sperry Sun addressed the growing need for advanced multilateral technology in areas such as the US Gulf of Mexico and offshore West Africa.

Used for years now in the North Sea and many onshore regions to more efficiently drain mature reservoirs, these technologies are advancing at a pace that will make them economic and reliable enough to apply in primary recovery programs elsewhere. As the installation times come down and reliability goes up, it becomes more and more attractive to put these systems in deepwater wells.

According to Ray Smith, global operations manager for multilateral technology at Sperry Sun, the installation times on a complex, Level 5 multilateral from 22 days to only 4. This is accomplished by improvements in the installation practices as well as the hardware. Smith said in earlier applications the downhole components were assembled in the wellbore. With system improvements often this can be done on the surface, ahead of time. This not only cuts down on the required rig time, but improves reliability. Holes that were once milled through casing have been replaced with advanced liner-hanger systems that again save time while improving reliability.

With the increasing cost of drilling and completing deepwater wells, it is more important than ever that early recovery rates are as high as possible. Other advancements also brought forward at this three-day conference will work in concert with the multilateral technology. Specifically, the idea of a monobore completion would mean larger casing sizes deeper in the well. This, in turn, allows more room to maneuver for companies interested in installing multilaterals.

Advancements in downhole sensors and intelligent systems also enhance the capabilities of a multilateral well, especially the more complex multilaterals. If, for example, these multilateral systems are installed in two distinct pay zones through one vertical well bore it is possible to close off production from one level while the other is allowed to produce. Sensors would determine the level of water cut and advise operators when it is time to close off one level and begin producing from the other. With some systems it is also possible to produce from both levels at once in varying degrees.

With all these tools at hand, an operator has a much stronger collection of options when designing a completion program. Currently, the technology is treated almost as an after thought, brought in when production is declining. If these systems were included in the early stages of design, it would be possible, in many cases, to not only increase early returns from the field, but improve production overall, Smith said.

One of the goals for system providers like Sperry Sun is to educate their consumers about the reduced risk associated with such systems and the many advantages it offers. While operators are always going to be risk-adverse, there are so many opportunities to design more efficient wells that it is getting hard to ignore the multilateral advantages.

In addition to the benefits seen once the well is completed, there is much to be learned while these legs are being drilled. LWD and MWD technology can examine the reservoir as a horizontal section is being drilled through the pay zone. This data can be used to help prove up the reservoir model, which in turn will guide the direction of future horizontal legs. In this way the original seismic data becomes a starting point directing the development of an "earth model". This model not only improves the placement of the multilateral legs but is used throughout the life of the field to design the reservoir drainage program.

One company that is embracing this approach, according to Smith, is Norsk Hydro. That company is now designing multilaterals into its new developments. The Troll expansion for example, includes 19 multilateral candidates, Smith said. He estimates the application of multilateral technology on the Troll field has allowed production to double since its inception and use over the last three years. This is helpful not only to the service company involved, but also to the market overall. Such developments give the emerging technology a valuable track record and show the other operators the benefits of including these systems in new developments.

While there are many successes in the North Sea, there are challenges unique to the Gulf of Mexico market that must be addressed before the most complex applications of this technology can be introduced. Smith lists sand control as the number one challenge coming into this market. For the Gulf of Mexico, and West Africa, operators are looking for these systems to include sand screens and support Frac-Pacs. As the technological hurdles are overcome, the application of this technology in new areas becomes a matter of risk vs. reward. Risk will continue to decline with improvements in reliability, while the reward becomes increasingly important in the deeper, larger offshore plays.

02/19/03

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