By OGJ editors
HOUSTON, Jan. 11 -- A new technology—developed in a project sponsored by the US Department of Energy—is being used to tap into large volumes of natural gas trapped in the tight rocks of New Mexico's San Juan basin.
The project, the cost of which is to be shared between DOE and Midland, Tex.-based GeoSpectrum Inc., uses 3D seismic data to locate fractures that provide access to "millions of cubic feet of untapped gas" from four wells, one of which is producing as much as 2 MMcfd of gas.
The area of study is in the Canyon Largo unit of New Mexico's Rio Arriba County.
"The key innovation in this project is the integration of technologies that map previously unseen fracture lineaments and perturbations in seismic data and then target fracture 'sweet spots' where multiple fractures intersect," said geophysicist Francis Toro, who manages the project for DOE's National Energy Technology Laboratory.
DOE awarded the contract in 1999 to spearhead development of technologies and methods to locate known resources of gas contained within naturally fractured, tight reservoirs.
"Locating those fractures is important because they provide pathways for gas flow in rocks that have very low permeability. By drilling in those locations, greater supplies of natural gas can be accessed and recovered," the partners reported.
About 460 tcf of gas—nearly three times the amount of existing gas reserves in the US—is estimated to exist nationwide in low-permeability reservoirs, the partners said.
To find natural fractures, GeoSpectrum, along with lease owner Burlington Resources Inc. and Huntington Energy LLC, applied a technology that combines seismic analysis, petrophysical analysis, and analysis of existing wells to identify potential fracture sweet spots, where gas is concentrated and able to flow to a wellbore.
"The successful demonstration shows that the technology can locate natural fractures in gas-bearing formations while reducing the risks associated with drilling in tight reservoirs," the partners said.
In December 2003, Huntington drilled, logged, and cased the Canyon Largo Unit No. 452 well to a depth of 7,590 ft. Two Lower Dakota sandstones were perforated—the Burro Canyon (7,518-24 ft) and the Encinal (7,420-55 ft)—and both intervals had gas shows.
The decision was then made to produce from the shallower Encinal unit because of potential water problems below the Burro Canyon reservoir. The Encinal, isolated and fracture-stimulated on Jan. 14, 2004, produced gas at an initial rate of 4 MMcfd.
As of March 2004, the well was producing 1.4 MMcfd of gas at a pressure of 175 psi. Three additional wells have been permitted.