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in creator/contributor: "Lorenz, J.C."

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Sedimentology of the Mesaverde Formation at Rifle Gap, Colorado and implications for gas-bearing intervals in the subsurface

The exposures of the Mesaverde Formation at Rifle Gap, Colorado, are of a regressive series of marine to fluvial deposits about 1650 m (5000 ft) thick. Grading up out of the marine Mancos Shale, the blanket shoreline sandstones of the Corcoran, Cozzette, and Rollins Sandstones record substages of the regression as delta lobes were activated and abandoned in northwestern Colorado during Late Cretaceous time. The overlying coals, sandstones, and carbonaceous mudstones were deposited on the paluda… more

Date: March 1, 1982

Creator: Lorenz, J.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Multiwell experiment

The Multiwell Experiment is a research-oriented field laboratory. Its overall objectives are to characterize lenticular, low-permeability gas reservoirs and to develop technology for their production. This field laboratory has been established at a site in the east-central Piceance basin, Colorado. Here the Mesaverde formation lies at a depth of 4000 to 8250 ft. This interval contains different, distinct reservoir types depending upon their depositional environments. These different zones serve… more

Date: January 1, 1985

Creator: Sattler, A. R.; Warpinski, N. R.; Lorenz, J. C.; Hart, C. M. & Branagan, P. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Multiwell experiment: Overview

This field laboratory has been established about 7 mi southwest of Rifle, Colorado. Here the Mesaverde formation lies at a depth of 4000 to 8250 ft. This interval contains different, distinct reservoir types depending upon their depositional environments. These different zones serve as the focus of the various testing and stimulation programs. One key to the Multiwell Experiment is three closely spaced wells. Their 110 to 215 ft separation at depth is less than the nominal dimensions of the len… more

Date: January 1, 1987

Creator: Lorenz, J. C.; Sattler, A. R.; Warpinski, N. R.; Thorne, B. J. & Branagan, P. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Characterization of natural fractures in Mesaverde core from the multiwell experiment

Natural fractures dominate the permeability of tight sandstone reservoirs in the Mesaverde Formation of the Piceance Creek Basin, north-western Colorado. Roughly 1900 natural fractures, detected in 4200 ft of Mesaverde core from the US Department of Energy's Multiwell Experiment (MWX), have been differentiated into 10 different fracture types on the basis of fracture morphology, inclination, the presence of slickensides, the presence of dickite mineralization and/or host lithology. Approximatel… more

Date: September 1, 1988

Creator: Finley, S.J. & Lorenz, J.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Fractures and stresses in Bone Spring sandstones

This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents th… more

Date: September 1, 1990

Creator: Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R. & Northrop, D.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurement and analysis of fractures in vertical, slant, and horizontal core, with examples from the Mesaverde formation

Optimum analysis of natural fracture characteristics and distributions in reservoirs requires conscientious supervision of coring operations, on-site core processing, careful layout and marketing of the core, and detailed measurement of fracture characteristics. Natural fractures provide information on the in situ permeability system, and coring-induced fractures provide data on the in situ stresses. Fracture data derived from vertical core should include fracture height, type and location of f… more

Date: January 1, 1991

Creator: Lorenz, J.C. (Sandia National Labs., Albuquerque, NM (United States)) & Hill, R.E. (CER Corp., Las Vegas, NV (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Subsurface fracture spacing

This study was undertaken in order to document and analyze the unique set of data on subsurface fracture characteristics, especially spacing, provided by the US Department of Energy's Slant Hole Completion Test well (SHCT-1) in the Piceance Basin, Colorado. Two hundred thirty-six (236) ft (71.9 m) of slant core and 115 ft (35.1 m) of horizontal core show irregular, but remarkably close, spacings for 72 natural fractures cored in sandstone reservoirs of the Mesaverde Group. Over 4200 ft (1280 m)… more

Date: January 1, 1991

Creator: Lorenz, J.C. (Sandia National Labs., Albuquerque, NM (USA)) & Hill, R.E. (CER Corp., Las Vegas, NV (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Natural fracture systems studies

The objectives of this program are (1) to develop a basinal-analysis methodology for natural fracture exploration and exploitation, and (2) to determine the important characteristics of natural fracture systems for use in completion, stimulation, and production operations. Natural-fracture basinal analysis begins with studies of fractures in outcrop, core and logs in order to determine the type of fracturing and the relationship of the fractures to the lithologic environment. Of particular inte… more

Date: September 1, 1992

Creator: Lorenz, J. C. & Warpinski, N. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development of stimulation diagnostic technology. Annual report, January 1991--December 1992

To apply Sandia`s expertise and technology towards the development of stimulation diagnostic technology in the areas of in situ stress, natural fracturing, stimulation processes and instrumentation systems. The approach to stimulation diagnostics is to integrate in situ stress measurements (including microfracs, anelastic strain recovery, circumferential velocity analysis, and coring-induced fractures) with natural fracture characterization, stimulation analyses (including Fracpro, other models… more

Date: February 1, 1993

Creator: Warpinski, N. R.; Lorenz, J. C.; Sleefe, G. E. & Engler, B. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Core based stress measurements: A guide to their application. Topical report, July 1991--June 1993

This report is a summary and a guide to core-based stress measurements. It covers anelastic strain recovery, circumferential velocity anistropy, differential strain curve analysis, differential wave velocity analysis, petrographic examination of microcracks, overcoring of archieved core, measurements of the Kaiser effect, strength anisotropy tests, and analysis of coring-induced fractures. The report begins with a discussion of the stored energy within rocks, its release during coring, and the … more

Date: June 1, 1993

Creator: Warpinski, N. R.; Teufel, L. W.; Lorenz, J. C. & Holcomb, D. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Rationale for finding and exploiting fractured reservoirs, based on the MWX/SHCT-Piceance basin experience

The deliverability of a reservoir depends primarily on its permeability, which, in many reservoirs, is controlled by a combination of natural fractures and the in situ stresses. Therefore it is important to be able to predict which parts of a basin are most likely to contain naturally fractured strata, what the characteristics of those fractures might be, and what the most likely in situ stresses are at a given location. This paper presents a set of geologic criteria that can be superimposed on… more

Date: August 1, 1993

Creator: Lorenz, J. C.; Warpinski, N. R. & Teufel, L. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Geotechnology for low permeability gas reservoirs; [Progress report], April 1, 1992--September 30, 1993

The objectives of this program are (1) to use and refine a basinal analysis methodology for natural fracture exploration and exploitation, and (2) to determine the important characteritics of natural fracture systems for their use in completion, stimulation and production operations. Continuing work on this project has demonstrated that natural fracture systems and their flow characteristics can be defined by a thorough study of well and outcrop data within a basin. Outcrop data provides key in… more

Date: November 1, 1993

Creator: Lorenz, J. C.; Warpinski, N. R. & Teufel, L. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Geomechanics of horizontally-drilled, stress-sensitive, naturally-fractured reservoirs

Horizontal drilling is a viable approach for accessing hydrocarbons in many types of naturally-fractured reservoirs. Cost-effective improvements in the technology to drill, complete, and produce horizontal wells in difficult geologic environments require a better understanding of the mechanical and fluid-flow behavior of these reservoirs with changes ineffective stress during their development and production history. In particular, improved understanding is needed for predicting borehole stabil… more

Date: September 1, 1994

Creator: Holcomb, D. J.; Brown, S. R.; Lorenz, J. C.; Olsson, W. A.; Teufel, L. W. & Warpinski, N. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Recognition and use of induced fractures and other features in core produced by the coring process

There are several distinctive types of coring-induced fractures that can be recognized in core on the basis of morphology, assisted by certain characteristics such as edge effects and surface ornamentation. The shape and orientation of many of these induced fractures offer information on the in-situ stress conditions and the coring process. Petal, petal-centerline, scribe-knife, disc, and torque-related fractures may all be caused by coring in vertical wells. Saddle fractures, (related to petal… more

Date: July 1, 1995

Creator: Lorenz, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stresses and fractures in the Frontier Formation, Green River Basin, predicted from basin-margin tectonic element interactions

Natural fractures and in situ stresses commonly dictate subsurface reservoir permeability and permeability anisotropy, as well as the effectiveness of stimulation techniques in low-permeability, natural gas reservoirs. This paper offers an initial prediction for the orientations of the fracture and stress systems in the tight gas reservoirs of the Frontier Formation, in the Green River basin of southwestern Wyoming. It builds on a previous report that addressed fractures and stresses in the wes… more

Date: January 1, 1996

Creator: Lorenz, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Geomechanical numerical simulations of complex geologic structures

Ability to predict mechanical response of rock in three dimensions over the spatial and time scales of geologic interest would give the oil and gas industry the ability to reduce risk on prospects, improve pre-project initial reserve estimates, and lower operating costs. A program has recently been initiated, under the auspices of the Advanced Computational Technology Initiative (ACTI), to achieve such a computational technology breakthrough by adapting the unique advanced quasistatic finite el… more

Date: May 1, 1996

Creator: Arguello, J.G.; Stone, C.M. & Lorenz, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Characterization and fluid flow simulation of naturally fractured Frontier sandstone, Green River Basin, Wyoming

Significant gas reserves are present in low-permeability sandstones of the Frontier Formation in the greater Green River Basin, Wyoming. Successful exploitation of these reservoirs requires an understanding of the characteristics and fluid-flow response of the regional natural fracture system that controls reservoir productivity. Fracture characteristics were obtained from outcrop studies of Frontier sandstones at locations in the basin. The fracture data were combined with matrix permeability … more

Date: August 1996

Creator: Harstad, H.; Teufel, L. W.; Lorenz, J. C. & Brown, S. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Permeability reduction by pyrobitumen, mineralization, and stress along large natural fractures in sandstones at 18,300 ft. depth: Destruction of a reservoir

Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (car… more

Date: November 1, 1996

Creator: Lorenz, J.C.; Billingsley, R.L. & Evans, L.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The interplay of fractures and sedimentary architecture: Natural gas from reservoirs in the Molina sandstones, Piceance Basin, Colorado

The Molina Member of the Wasatch Formation produces natural gas from several fields along the Colorado River in the Piceance Basin, northwestern Colorado. The Molina Member is a distinctive sandstone that was deposited in a unique fluvial environment of shallow-water floods. This is recorded by the dominance of plane-parallel bedding in many of the sandstones. The Molina sandstones crop out on the western edge of the basin, and have been projected into the subsurface and across the basin to cor… more

Date: March 1, 1997

Creator: Lorenz, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Conjugate fracture pairs in the Molina Member of the Wasatch Formation, Piceance basin, Colorado: Implications for fracture origins and hydrocarbon production/exploration

The sandstones of the Molina Member of the Wasatch Formation in the Piceance basin of northwestern Colorado contain a suite of fractures that have a conjugate-pair geometry. The fractures are vertical and intersect at an acute angle of between 20 and 40 degrees. Although direct evidence of shear is rare, the fracture surfaces commonly display small steps. The fracture geometries suggest that the maximum compressive stress during fracturing was in the plane of the acute angle of the conjugate fr… more

Date: May 1, 1997

Creator: Lorenz, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department