Lee F. Krystinik1,
John C. Lorenz3
(1) Union Pacific Resources, Fort Worth, TX
(2) Union Pacific Resources
(3) Sandia National Labs, Alberquerque, NM
Abstract: Hunting fractures three miles down: integrated reservoir geology, drilling and production for the UPR/DOE Rock Island 4-H well, Frontier Formation, southwest Wyoming
The UPR Rock Island 4-H well(RI-4H) culminates a 5 year cooperative research partnership between DOE-FETC, Union Pacific Resources and GRI to explore ways to economically produce gas from the fractured, over-pressured, tight sandstone of the Frontier Formation in southwestern Wyoming.
Results include: (1)Cost for drilling deeper than 15,000' reduced to 50% below the previous industry average;(2)Over 400 fractures intersected in a 1750' horizontal leg (14,950' TVD);(3)The deepest horizontal tight-gas sandstone cores in the world;(4)One of the highest gas flow capacities ever encountered in the tight-gas province of the Frontier Formation(14 mmcfd);(5)Initiation of ongoing drilling to exploit this resource.
Core, log and production test information from an offsetting well, combined with regional 3-D seismic data were critical to site selection. The reservoir is massive to hummocky cross-stratified, very-fine grained, nearshore-marine sandstone, with 10-12% porosity, 25 microdarcy permeability, and intense fracturing. Fractures in a vertical offset well and in the horizontal RI4-H indicate shear displacement with a dominant strike orientation ranging from 80 to 110 degrees. The fractures are open to partially filled with calcite, quartz, kaolinite and bitumen. Fracture spacing is variable and is most intense near several small faults penetrated by the well. Open fractures which strike east-west, nearly perpendicular to the well bore, occur along the entire length of the well, as observed in core and microresistivity images. Dissoultion of feldspar and lithic grains along microfractures significantly enhances permeability.
This project underscores the value of government and industry research partnerships aimed at solving problems which have eluded industry.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana