03765nmc a2200205 4500 20260521183907.0 260224s xxu CD I249 1 0013788 Schenk, Christopher J. 22613 International Gas Union, IGU 13105 World Gas Conference (22nd. : 2003 jun 1-5 : Tokyo) 22029 Geologic definition and resource assessment of continuous (unconventional) gas accumulations in the United States 12/09/06 ; 22/07/2003 6 p. Disponible en CD en formato PDF Transcripción del abstract original del autor: The U.S. Geological Survey (USGS) is currently re-assessing the potential for undeveloped continuous (unconventional) gas resources of the U.S. For the USGS assessment continuous accumulations include basin-centered gas, shale gas, tight gas, coal-bed gas, shallow biogenic gas, and, in the future, gas hydrates. Continuous gas resources are becoming increasingly important for the U.S. energy mix as the discovery rate for new conventional gas accumulations decreases in the major producing areas of the country. Defining the geologic limits and characteristics of each suspected continuous gas accumulation is not trivial, and involves a multidisciplinary approach to the problem. Multiple lines of geologic and engineering evidence are required to adequately define a continuous gas accumulation. Each characteristic by itself is equivocal, but taken together several lines of evidence may strengthen the interpretation that a gas accumulation is continuous. The following are the major lines of evidence used by the USGS in defining a continuous gas accumulation; 1) Regional extent, 2) No welldefined gas-water contact, 3) Abnormal formation pressures: 4) Reservoirs have low matrix permeabilities, 5) Reservoirs in proximity to hydrocarbon source rocks, 6) Few truly dry holes: 7) Little water production: 8) Occurrence of geologic "sweet spots": 9) No obvious seal or trap: 10) Existing "fields" commonly merge into a single regional accumulation: 11) Large in-place gas resource number, but very low recovery factor: 12) Natural reservoir fracturing common: and 13) Estimated Ultimate Recovery (EUR) of wells in continuous accumulations compared to conventional accumulations. In 1995 the USGS released the first assessment of continuous gas accumulations in the United States, with several basins updated with new assessments through 2002. The definition of additional continuous gas accumulations, as well as the re-assessment of continuous resources, is on going at the USGS. Several basins with significant continuous gas resources remain to be assessed, including the Wind River and Big Horn basins in the Rocky Mountain region and northern Alaska. The focus of the effort is to screen all U.S. basins for continuous gas accumulations, and to develop a geologic basis for the interpretation of geologic sweet spots within these accumulations, and assess the potential for gas resources. The assessment indicates that, at the mean, approximately 303 TCF of natural gas is a potential recoverable resource in the United States from continuous gas accumulations. Of this mean total, about 63 TCF (or 21 percent) is estimated to be coal-bed gas. For the United States this represents a significant resource base for the future. The mean of 303 TCFG does not encompass all continuous accumulations, as continuous accumulations in some basins remain to be defined and assessed. For comparison, the USGS estimated that about 260 TCFG remain to be discovered in conventional gas fields in the U.S. International Gas Union, IGU 13105 CONGTP ddc 149984 149984 0 0 0 0 217803 BAAB BAAB CD I249 1 0013788 2026-03-04 200025990 0 CD I249 1 0013788 200025990 2026-03-04 16:39:10 2026-03-04 ARCHIVO