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BP applies to drill gas hydrate strat test Mount Elbert well in Milne Point unit on North Slope will help determine whether gas hydrates could become viable gas resource Alan Bailey Petroleum News
BP Exploration (Alaska) has taken a further step towards drilling the North Slope gas hydrate stratigraphic test well that it has been planning in recent months. In a plan of operations submitted to Alaska’s Division of Oil and Gas on Jan. 20 the company says that the well will be on state land one half mile east of the Milne Point unit E-pad and that the well will drill into the Mount Elbert prospect in the northern part of the Eileen gas hydrate trend. Eileen is one of two known, large gas hydrate trends in the central North Slope.
BP is the unit operator for the Milne Point unit and will be operator for the test well. Drilling should start in mid to late March and will require an ice pad and a short ice road from the existing road infrastructure, according to the plan. The company expects the bottom hole true vertical depth to be less than 4,000 feet below sea level.
Akita/Doyon’s new Arctic Fox No. 1 rig will drill the well. The drill site location is at section 30, township 13 north, range 11 east, of the Umiat meridian. Approximately 30 people will be involved in the project. Team project A team from industry, government and university has been investigating the known gas hydrate deposits in the central North Slope. BP Exploration (Alaska), ASRC Energy Services, Ryder Scott Co., the U.S. Geological Survey, the U.S. Department of Energy, the University of Alaska Fairbanks and the University of Arizona have all collaborated in this project, which completed an initial phase of seismic calibration, reservoir modeling and economic evaluation in 2004. The stratigraphic test well that BP has been planning is the latest step in this project and is designed to obtain detailed field data about the gas hydrate deposits, Scott Digert, subsurface team leader for BP, told Petroleum News in November.
By drilling into a prospect identified from seismic data, the well will test the effectiveness of some seismic techniques established in the previous phase of the project, Digert said. Verifying the accuracy of the seismic techniques should enable more accurate pinpointing of gas hydrate prospects in the future.
However, sampling and logging from the well should also provide invaluable information, such as the amount of free gas associated with the hydrates. The data should also provide insights into the saturation of the hydrates in the rock formation and the water saturation in the hydrate-bearing zone, Digert said.
Gas hydrates concentrate natural gas by combining methane with water to form a solid crystalline substance under certain temperature and pressure conditions. The hydrates have enormous gas carrying capacity, because when they break down or disassociate they can yield 164 to 180 times their volume of free gas. There is a gas hydrate stability zone under wide areas of the North Slope and researchers have assessed the possibility of as much as 519 trillion cubic feet of natural gas in the form of gas hydrates in the region.
The Northwest Eileen State No. 2 well drilled above the Prudhoe Bay field in 1972 discovered the Eileen trend and oil wells drilled in the central North Slope have encountered gas hydrates in the two known trends. The USGS has estimated that the trends contain as much as 100 trillion cubic feet of natural gas. Many challenges remain Development of gas hydrates under North Slope permafrost faces some daunting challenges: there are known ways of extracting gas from the hydrates but no one has yet proved an economically viable way of achieving the extraction.
The team investigating the central North Slope deposits did some reservoir modeling of possible extraction techniques in the first phase of its project. The results of that modeling looked encouraging and the data from the test well that BP plans to drill should shed more light on the economic feasibility of gas hydrate production. A future step could be a field test of gas extraction, but that type of test still looks some way off and would involve additional drilling.
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