QO Photomicrograph of an uncemented sandstone from the Jurassic Morrison Fm. Blue is epoxy that fills primary pores (between grains) and some secondary pores that have developed from partial dissolution of some detrital feldspar grains. Photomicrograph from a tight sandstone in the Bossier Fm. It is tight due to abundant quartz overgrowths (QO), and porosity exists between adjacent quartz overgrowths
Goal of USGS Assessments
Continuous Methodology Geologic characterization of assessment units Drainage areas of wells (cell sizes) Number of potential cells (tested and untested) Engineering data – well production and performance EUR (estimated ultimate recovery) distribution Woodford Shale – Horizontal Well Density
USGS Continuous Oil and Gas Resource Estimates ssmentsData/NationalOilGasAsses sment/AssessmentUpdates.aspx
USGS Shale Gas and Tight Gas Resource Estimates
Source rocks of the Alaska North Slope: estimates (95-percent to 5-percent probability) range from zero to 2 billion barrels of oil and from zero to nearly 80 trillion cubic feet of gas.
Example: Bakken Formation (2008) Mean total = 3.65 BBO (F95=3.0 BBO; F5=4.3 BBO) Changes result from improved geologic understanding, technological developments, other factors USGS 1995 Bakken Assessment: Mean total = 151 MMBO 973 MMBO 909 MMBO 868 MMBO 410 MMBO 485 MMBO Resource Assessments Change Over Time
Bakken Oil Production
U.S. Unconventional Gas Production Billions of Cubic Feet Year Coalbed Methane Shale Gas Source: Energy Information Administration
Hydraulic Fracturing Water use Chemicals used Fate of injected fluid Flowback quality
Collection of produced water Characterization, Impacts, and Use of Produced Waters USGS produced waters database and extent of U.S. shale gas plays Bakken Formation – extent of USGS assessment units and hydraulically, fractured wells.