Scientists have studied hydrates, and drillstrings have penetrated them, but the first deliberate US attempt to reach hydrates is in the works.

An Arctic onshore platform that uses an offshore design aims to do more than simply extend the Far North drilling season or leave a significantly smaller environmental footprint. It will be the launch pad for a well just south of the Kuparuk River field 60 miles (96 km) west of Deadhorse, Alaska, and the first US attempt to tap a potentially immense future energy source.

Methane hydrates, a frozen combination of water and natural gas, are found most commonly in Arctic permafrost and deep water offshore. "They essentially are ice crystals containing natural gas that are trapped below the surface," said Carl Michael Smith, assistant secretary for fossil energy at the US Department of Energy (DOE).

No one has attempted to produce methane from hydrates in Alaska so far. But the gas contained in them exceeds the amount found in conventional reservoirs many times over. Industry estimates place the amount of gas in hydrates worldwide as high as 700,000 Tcf, compared to 7,000 Tcf of conventional worldwide gas resources. In Alaska alone, an estimated 168,000 Tcf of methane lie in hydrates offshore, with another 590 Tcf onshore. Producers will need to learn both how to retrieve this frozen energy and transport it to markets economically and commercially, however.

Earlier wells on Alaska's North Slope have encountered hydrates, but producers and operators have considered them more of a nuisance than a prospect. The Arctic platform is the first US drilling directed specifically at hydrates. The US Department of Energy (DOE) is providing US $6 million of the project's anticipated $10.5 million cost, with the remainder coming from Anadarko Petroleum Corp. and two Noble Corp. subsidiaries, Maurer Technology Inc. and Noble Engineering and Development. Another $2 million is budgeted for deployment and testing, with DOE planning to contribute half.

The project also could be the forerunner of a new onshore drilling approach that would leave a significantly smaller environmental footprint than current techniques. Producers have made significant progress already in reducing environmental impacts associated with exploration and production operations, according to Smith. Today's typical onshore well leaves a footprint 25% smaller than its predecessor 25 years ago, he told reporters during a briefing in Washington, D.C. "The Arctic platform could be the industry's next major step toward the day when exploration and drilling would leave virtually no lasting trace on the surface," he said.

Anadarko developed the platform's concept, which employs a 100-ft by 100-ft (31-m by 31-m) elevated pad that stands a dozen feet above the tundra on steel pilings. The approach could allow the Houston independent producer to develop holdings economically that are 160 miles (257 km) from existing infrastructure at Prudhoe Bay, said Anne P. Vincent, Anadarko's communications manager for Alaskan and international operations. "One way is to be able to stay on the tundra outside the frozen period. That would shorten the exploration cycle," she explained.

The modular platform uses lightweight, easily assembled components similar to - but obviously much larger than - Lego toy building parts, which make it easy to move and install. Anadarko and Noble expected to drill the well through 1,200 ft (366 m) of permafrost containing sands with hydrate potential at 3,000 ft (915 m). A test is planned for early next fall.

"This is not a conventional oil and gas operation. Our goal is to get the fluids out before the gas hydrates disassociate. We had to think out of the box," said Thomas E. Williams, Maurer Technology's vice president for marketing and business development. The project uses a Dynatec 15 slimhole rig, a type normally used for mining that has been modified for Arctic use. Other specially made equipment has been assembled at a mobile laboratory on the platform. "This is the first time a remote lab has been put on-site to analyze what comes out," said Williams.

Noble's DrillSmart system will allow project participants to view continuous live data and images from the platform. The system consists of two applications: one calculates and presents target weight-on-bit (WOB) to allow the driller to optimize the rate of penetration with the calculated target. The other segment allows the operator to handle and display electronic drilling recorder sensor data and spot trouble more easily with user-friendly data manipulation and improved viewing capabilities.

Other applications complete the system. Event recognition for well control is an early kick detection program that helps recognize formation influx, loss circulation, swabbing surging and inadequate hole-fill for early kick detection. The daily operations report automatically updates well history data, time vs. depth graphs, flat spots and well and equipment problems. It also generates a report that summarizes the well upon a project's completion. The Lessons Learned database captures knowledge from drilling operations and makes it available via Noble's Web site.

Experts from DOE's Lawrence Berkeley National Laboratory, the US Geological Survey (USGS) and Schlumberger Ltd. are analyzing core samples of the recovered hydrates at the laboratory. Paulsson Geophysical Services of Brea, Calif., plans to use a sophisticated technique, vertical seismic profiling, to image the hydrate target zone. The University of Alaska at Anchorage and the USGS also assisted in preparing the project.

Anadarko designed the Arctic Platform specifically to extend drilling beyond winter, when ice provides the support necessary for conventional rigs to operate without damaging the tundra. The new platform's self-contained, elevated modular system could allow operators to work almost year-round, subject to regulatory approval. Over-ground movement of heavy equipment still would be restricted during the spring thaw and critical wildlife protection periods in some areas, but most other operations could be carried out during most of the year with some minor modifications. Like production platforms used offshore, the Arctic Platform could be used both as a temporary drilling facility and a long-term production installation.

It also offers several environmental benefits. Its specially designed equipment and materials are light enough to be moved to the site either by helicopter or by a special low-impact vehicle called a "Rolligon" or other specially equipped tracked vehicles, minimizing chances of damaging the tundra. If a commercial field is discovered, the unit can become a production platform, potentially eliminating the need for a permanent gravel pad or even permanent access roads.

The platform's pilings support a deck made of interlocking aluminum modules, each of which has channels around the edges to capture any produced water or fluid that might drain off the deck. A smooth, three-ply top covers the modules. The rig and associated equipment are then placed on top of the modular deck. "Virtually everything is contained from drilling fluids to human activity," said Smith.
If oil or gas is found in commercial quantities, a modified platform may be left in place to house and protect the wellhead. The well site can be restored to its natural state by removing the platform and pilings, refilling the holes and covering them with native tundra material when drilling or production is completed.

Project participants recognize that this is a long-term effort that could require about 10 years before they can produce gas from hydrates. The newly designed platform could be put to use sooner in the Rocky Mountains, coastal Louisiana and other domestic onshore areas where traditional pads are more environmentally intrusive. "It's going to be a changing, evolutionary process," said Vincent. "We view the Arctic platform as one potential solution to working in the Arctic. It is not the only solution, but we think it could help unlock more oil and gas resources."

"If we can learn how to extract the natural gas trapped in hydrates economically, we could dramatically strengthen the nation's future energy security," DOE's Smith said. "And if we can tap this enormous resources in a way that minimizes the impact on fragile ecosystems, we can take a major step toward both our energy and environmental goals."

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