Content Conventional and Continuous Resources Concepts and Examples Threshold geological parameters for source-rock resource potential Heterogeneity of source-rock systems USGS oil and gas assessments Continuous resource assessment methodology U.S. Department of the Interior U.S. Geological Survey
Conventional vs. Continuous Accumulations Conventional Unconventional (Continuous) Resources Assessment methodology differs for conventional and continuous resources. Modified from McCabe, 1998
Impact of Technology Innovation Market Price Resource Quality Reservoir & Hydrocarbon Properties An assessment identifies that part of the resource that is recoverable within the foreseeable future Molecule size Modified from McCabe, 1998 Compiled from many sources, includine Nelson (2009), Chalmers et al. (2012), Clarkson et al. (2012), Loucks et al. (2012), & Ruppert et al. (2012)
From Super-Giant Fields to Shale Resources Conventional Continuous Resources: Areas Involved Bakken isopach from Lin et al. (2012)
Threshold Geological Parameters for Source-Rock Resources Geological Foundation for Continuous Resources Revolution Organic rich (>2% TOC) rock typically shale Kerogen type oil prone (HI > 250 mg/g) Type II or IIS appears to be best Type appears to be viable Thickness >15 meters Thermal maturity 0.6 1.3% vitrinite reflectance for oil 1.1 3.5% vitrinite reflectance for gas Overpressure important perhaps essential Presence of brittle lithologies to sustain fractures Enclosing strata that constrain fractures Relatively simple tectonic history to retain petroleum system CC, conventional core; RS, rotary sidewall core Map from Harper (2008); modified from Piotrowski & Harper (1979)
Mapping Parameters in a Maturely Explored Basin Fayetteville-Caney Shale: Net Thickness of Gamma-Ray >150 API Mapping Parameters in a Immaturely (Frontier) Explored Basin Brookian Shale: Net HGR Mapping Appears to Work Fayetteville-Caney Wells (November 2009)
Mapping Parameters in a Immaturely (Frontier) Explored Basin Shublik Formation: Systems Tract Mapping As Alternative Mapping Parameters in a Immaturely (Frontier) Explored Basin Shublik Formation: Systems Tract Mapping As Alternative Robison & Dawson, 2001 Modified from Hulm, 1999
Mapping Parameters in a Immaturely (Frontier) Explored Basin Shublik Formation: TST Isopach + Vitrinite Reflectance Heterogeneity is Fractile! Shublik Example Chalmers et al. (2012) Hulm, 1999
Heterogeneity is Fractile! Woodford Example Heterogeneity is Fractile! Bakken Example Is oil retained in source rocks or migrated into low perm. Interbeds? Kuhn et al. (2012) Kuhn et al. (2012) Caldwell (2012)
USGS Oil and Gas Assessments 1 Assessment results are: Probabilistic estimates of technically recoverable resources Reported by province (basin), with greater granularity in linked reports Available in map and table format at: http://energy.usgs.gov/ USGS Oil and Gas Assessments 2 Assessment categories: Conventional Continuous (unconventional) Methodology differs by category USGS assesses: All domestic onshore & statewater areas (by law) International onshore & offshore areas as comprehensively as possible BOEM responsible for U.S. Federal waters (OCS) Conventional Methodology Estimation of sizes & numbers of undiscovered accumulations Continuous Methodology Performance-based Area, EUR, Drainage area, Success ratio
Conventional Accumulations Fundamental Characteristics Conventional Accumulations Occupy limited, discrete volumes of rock defined by traps, seals, and down-dip dip water contacts. Depend on buoyancy of oil or gas in water for their existence. Conventional Accumulations Assessment Methodology USGS Methodology Estimates of SIZES and NUMBERS of undiscovered accumulations Relies heavily on discovery history trends, including exploration maturity Geologic analysis focuses on new reservoirs and new concepts Map View Discrete Little or no expansion in area after initial development Boyd, 2002 Production History Rapid identification of most known petroleum volume Modest additions with additional effort Example of discovery history trend: Arkoma Shelf AU gas fields
Continuous Accumulations - Fundamental Characteristics Continuous Accumulations Consist of large volumes of rock pervasively charged with oil or gas. Do NOT depend on buoyancy of oil or gas in water for their existence. Map View Extensive accumulations Expansion in area during development Production History Known petroleum volume grows with Boyd, 2002 effort (wells, knowledge,technology) Significant additions through time with additional effort CBM Continuous Accumulations Main Assessment Steps 1. Geologic definition of assessment unit 2. Estimation of drainage area 3. Number of potential cells in AU UNCERTAINTY ASSOCIATED WITH EACH PARAMETER ACCOMMODATED WITH PROBABILISTIC INPUTS 4. EUR distribution based on historical production Pollastro et al., 2008 5. Estimate success ratio based on historical data
Note vertical scale Haynesville initial production much higher than others (more on this later) Plots colored by completion year Note Learning Curve Monthly production declines from peak by 50 70% within 12 months Decline trajectory difficult to forecast with limited time series Inflection of decline trajectory appears variable among shale formations Monthly production declines from peak by 75-85% within 36 months Above observations are those of DH, not necessarily authors Above observations are those of DH, not necessarily authors Baihly et al. (2011) Baihly et al. (2011)
Generation of Probabilistic EUR Distributions Time series of production data hyperbolic curves fit to decline EUR Distributions for Assessed Continuous Resources Each curve is one assessment unit; Diamonds are means of distributions Example Woodford Shale-Gas Production in Arkoma Basin Troy Cook, USGS USGS Oil & Gas Assessment Team (2012)
Methodology Review & Refinement USGS assessment methologies reviewed by AAPG Committee on Resource Evaluation (CORE) Refinement of existing methodology Research on development of new methodologies Collaboration with other assessment groups Other U.S. and State agencies Agencies of other nations (Germany, Denmark, Britain, Australia, etc.) U.S. and International petroleum companies Thanks for your Attention! Geostatistical model of cell EUR, Woodford Shale Gas (Olea et al. (2012); Gas-in-place and key input parameter distributions, Lower Carboniferous of Germany (BGR, 2012)