GETTING IT OUT

Technically, recovering the methane trapped in Brown shale is very different from a conventional gas well, which taps gas either from large underground pockets, or from formations such as sandstone, with a permeability (ability to let liquids or gases flow through it) at least 1,000 times higher. Shale gas will flow at reasonable rates only from fractures, where it accumulates after oozing out from the Brown shale layers. Even so, the flow of gas is comparatively slow once the fracture has been tapped and emptied of its initial content, dropping to perhaps 50 Mcf/day; on the other hand, since this longterm flow is due to the steady release of the gas from the shale, the rate holds up for many decades (whereas in a conventional gas well the rate and pressure decreases in a few years as the pockets are being emptied).

Artificial fractures can be produced in the formation in a number of ways by explosive fracturing, or by hydraulic fracturing in which the fluid is injected into the formation at a rate and pressure that will shatter it, and several others. A stimulation method that has been proposed for shale is "directional drilling." Most natural fractures in Devonian shale run vertically; wells curving away from the vertical should therefore intercept several such natural fractures, and their yield can be augmented by hydraulic and explosive fracturing (see figure below).

[More: Gas Potential from the Devonian Shales of the Appalachian Basin, Office of Technology Assessment, Nov. 1977; 77pp., $2.50 from Government Printing Office, Washington, DC 20402; stock no. 052 003 00500 0]

But as usual, the major hurdle is economic. For the reasons just given, the delivery rate of single shale gas wells is low; numerous wells over a large area, together with an extensive pipeline system, are therefore needed.

The OTA study quoted above estimates the cost betwen $2 and $3 per Mcf. The rest is the familiar story: "The major barrier to increasing production using available technology is the present controlled level of the interstate wellhead price of gas. . . A significant and substantial policy option is to permit free market prices for gas from Brown shale sequences." The case for gas deregulation has often been made, but here is a particularly succinct and persuasive formulation:

"The decontrol of producers prices for new natural gas would provide further incentive for new exploration and would help our nation' s oil and gas operators attract needed capital. Deregulation of gas would encourage sales in the interstate market and help lessen the prospect of shortages in the nonproducing states which rely on interstate supplies. While encouraging production, this proposal will protect the consumer against sudden, sharp increases in the average prices of natural gas."

That statement comes from an open letter sent to the governors of Texas, Louisiana and Oklahoma on Oct. 19, 1976; it is preceded by the pledge "First, I will work with the Congress, as the Ford administration has been unable to do, to deregulate new natural gas."

Its author: Jimmy Carter.