LSU Research

DRILLING IN THE DEEP
Engineer seeking cost-effective drilling methods for natural gas

The U.S. Department of Energy predicts that total natural gas consumption will increase by about one percent annually for the foreseeable future, despite increasing economic growth, continuing rise in electricity demand, and below average hydroelectric power levels in the Pacific Northwest.

The number of new natural gas wells is expected to remain high through 2005, increasing from 20,000 wells in 2003 to more than 23,000; however, natural gas production in existing wells is decreasing and the new wells are expected to only moderately increase levels of U.S production, keeping natural gas prices high.

Lower natural gas prices and a cost-effective method of producing it are the goals of Department of Petroleum Engineering Assistant Professor John Rogers Smith. Smith is working on better ways to drill in deep water areas of the Gulf of Mexico where high drilling costs can prevent natural gas resources from being developed for use.

The industry standard for ultra-deep water pertains to depths greater than 5,000 feet. According to Smith, substantial efforts have been made to reduce the costs of production systems used at this depth, but drilling machinery and methods have received less attention.

Substantial natural gas resources lie in wait in the deep water off of Louisiana’s coast, and Smith’s goal is to find a cost-effective drilling mechanism for companies to access them. He stresses that time is of the essence. Oil production in the Gulf of Mexico will slow and eventually stop because of depletion of resources, and companies will leave the area.

“We need to get the stars to align and develop the technology before current infrastructure disappears. It’s hard to restart after they leave,” says Smith. “Natural gas resources are generally less valuable than oil. Therefore they are much more likely to be tapped for use if it is done in conjunction with developing the oil, sharing some of the same equipment, personnel, support facilities, and pipelines.”

Smith’s project pertains primarily to floating rigs that are used to drill wells in ultra-deep water. Basically, the rig itself is a ship, or semi-submersible barge, that drills the well into the seafloor through a large pipe called a riser, connecting it to the seafloor.

Smith’s research is focused on what is called the dual density drilling method. As its name states, dual density drilling systems use two different density substances like mud and nitrogen. Mud, which is denser than gas and water, keeps pressure on the natural gas in the subsurface formations to prevent it from flowing into the well until after drilling is completed and the well is ready to produce. The nitrogen, which is less dense, is mixed with the mud as it enters the riser and returns to the surface. The decrease in the riser’s fluid density would create pressures in the well and riser during drilling that would be more like the natural pressures that exist below the sea floor.

Smith says use of this dual density method would improve the industry’s ability to prevent blowouts, while reducing the cost of drilling in deep water. This lower cost to develop deepwater natural gas resources would ultimately reduce the prices people pay for utilities, and allow increased production of a cleaner burning, environment-friendly hydrocarbon, natural gas.

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LSU Department of Petroleum Engineering
U.S. Department of Energy