Impact of Geothermic Well Temperatures and Residence Time on the - - PowerPoint PPT Presentation

Impact of Geothermic Well Temperatures and Residence Time on the In-situ Production of Hydrocarbon Gases from Green River Formation Oil Shale

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Mark White*, Larry Chick, Gary McVay

Pacific Northwest National Laboratory mark.white@pnl.gov

Colorado School of Mines, Colorado Energy Research Institute, 30th Oil Shale Symposium 7.1 In Situ Process Modeling

Environmental Stewardship

• Radionuclide migration and remediation
• Nuclear waste tank leakage
• Vegetated surface barrier design
• Freeze-wall technology

Environmental Remediation

• Carbon tetrachloride in deep vadose zone environment
• Trichloroethylene in arid climate
• Petrol-processing waste in shallow water table environment

Geologic CO2 Sequestration

• Deep sedimentary saline formations
• Deep basaltic saline formations
• Methane hydrate formations with co-production

Hydrocarbon Production

• Alaska Northslope gas hydrate accumulations
• Suboceanic gas hydrate accumulations
• Piceance Basin oil shale
• Enhanced oil recovery technologies

Subsurface Simulation PNNL

Subsurface Transport Over Multiple Phases

Operational Modes

• STOMP-W, -WA, WAE -- Water-Air-Energy Operational Modes
• STOMP-WO, -WOA, WOAE -- Water-Oil-Air-Energy Operational Modes
• STOMP-WS, -WSA, WSAE -- Water-Salt-Air-Energy Operational Modes
• STOMP-WCS, -WCSE -- Water-CO2-Salt-Energy Operational Modes
• STOMP-WCMSE -- Water-CO2-CH4-Salt-Energy Operational Modes

Implementations

• Sequential (Fortran 90)
• Scalable (Fortran 90/Global Arrays/PETSc)

Licensing and Quality Assurance

• Academic, U.S. Gov., Foreign Gov., Industrial
• Documentation (Guides, Website, Publications)
• Short Courses (University Sponsored)
• DOE Order 414.1C (System Safety Software)

Future

• Geologic CO2 sequestration
• Hydrocarbon production
• Petascale computing and beyond

STOMP Overview

• 500-ft kerogen-rich interval

above the water table

• Fischer-Assay of 19 gal/ton
• Geothermic well temperatures of

450˚, 550˚, and 650˚ C

• Geothermic well power density of

2 kW/m

• Hexagonal pattern spacings of

45 ft, 10 m, and 5 m.

• Intrinsic porosity 0.22
• Intrinsic permeability 1 darcy
• Induced fracture density 0.05
• Matrix compressibility 1.e-9 Pa-1
• Maximum induced fracture

porosity 0.10

Problem Description

• Conservation equations
• Thermal energy (temperature)
• Heavy oil (HO volu. molar density)
• Light oil (LO volu. molar density)
• Hydrocarbon gas (CHx volu. molar density)
• Methane (CH4 volu. molar density)
• Phases
• Nonaqueous phase liquid (mobile-compositional)
• Gas (mobile-compositional)
• Kerogen (immobile-single component)
• Coke (immobile-single component)
• Char (immobile-single component)
• Constitutive equations
• Physical properties
• Chemical reactions
• Phase equilibrium
• Transport properties
• Fracture model

Newton-Raphson Iteration Molar Density Equilibrium to Eliminate Primary Variable Switching (system pressure)

Mathematical Model

• Heat transport by advection, gaseous diffusion/dispersion, phase

transformations, component appearance and disappearance, heat of kerogen dissociation, but ignoring oil cracking heat of reaction.

• Darcian advection
• Fickian advection

Algebraic form

Conservation of Energy

• Model #1
• Thermal energy, Oil, H2, CO, CO2, CH4, C2Hx, C3Hx
• Campbell et al. (1980a, 1980b) reaction network
• Kerogen pyrolysis only, no oil cracking reactions
• Simulations yielded high residual NAPL saturations
• Model #2
• Thermal energy, C50Hx, C30Hx, C18Hx, C12Hx, C8Hx, C3Hx, CH4, H2, CO2
• Fan et al. (2009) reaction network
• Simulations yielded oil production lower than consistent for Green

River Formation oil shales with Type 1 kerogens

• Model #3
• Thermal energy, Heavy Oil, Light Oil, Hydrocarbon Gas, Methane
• Modified Braun and Burnham (1993) reaction network
• Kerogen pyrolysis and oil cracking reactions
• Producing coke and char
• Oil production consistent with Type 1 kerogens

Model Development

• Peng-Robinson cubic equation of state
• Modified version of Michelsen’s (1985) flash procedure
• No binary interaction terms
• Temperature dependent pure component parameters
• Fugacity coefficients functions of phase composition, pressure

and temperature

• Michelsen’s scheme requires solution of three independent

variables:

• Modified scheme yielded increased stability and more rapid

convergence by adding two equations:

Phase Equilibria

• Matrix Permeability
• Induced Fracture Permeability
• Dual-Continuum Permeability

Rock Permeability

• Gas Relative Permeability
• Nonaqueous Phase Liquid Relative Permeability

Phase Relative Permeability

• Linear combination of Arrhenius reaction rate equations

Chemical Reaction Model

• Chemical Reactions and Component Species
• 7 chemical species, 4 reactions (13 species, 10 reactions)
• No H2O, H2, CO2, CO
• Water vaporization ignored
• Geomechanics
• Empirical model that allowed fracture aperture to increase with

pore pressure

• Fracture permeability dependent on fracture aperture, absolute

fracture roughness, and fracture density

• Hydrologic Properties
• Empirical model of matrix permeability as a function of kerogen,

char, and coke saturations

• Matrix and fracture moisture retention characteristics
• Symmetry and Boundary Effects
• Two-dimensional horizontal domain ignores end effects
• Symmetry assumption requires active adjacent hexaagons

Approximations and Assumptions

45-ft Hex 650˚C Geothermic Well

45-ft Hex 650˚C Geothermic Well

45-ft Hex 550˚C Geothermic Well

45-ft Hex 450˚C Geothermic Well

10-m Hex 650˚C Geothermic Well

10-m Hex 650˚C Geothermic Well

10-m Hex 550˚C Geothermic Well

10-m Hex 450˚C Geothermic Well

1 year 2 years 3 years 4 years 5 years 6 years

Temperature, color scaled from 40˚ to 440˚C

10-m Hex 450˚C Geothermic Well

1 year 2 years 3 years 4 years 5 years 6 years

Kerogen saturation, colored scaled from 0.0 to 1.0

10-m Hex 450˚C Geothermic Well

1 year 2 years 3 years 4 years 5 years 6 years

Liquid oil saturation, color scaled from 0.0 to 1.0

10-m Hex 450˚C Geothermic Well

1 year 2 years 3 years 4 years 5 years 6 years

Coke saturation, color scaled from 0.0 to 1.0

10-m Hex 450˚C Geothermic Well

5-m Hex 450˚C Geothermic Well

5-m Hex 450˚C Geothermic Well

Geothermic Well Power

• Reaction networks that only consider the primary

kerogen decomposition process will yield residual liquid

• il in the formation, which is not consistent with

laboratory or field observations.

• Char and coke formation are important pore filling

processes that are required for accurate calculation of pore pressure and fluid expulsion.

• Oil and gas recovery predictions are strongly dependent
• n the accuracy and appropriateness of the chemical

reaction network, stoichiometry, and kinetics.

Conclusions Reaction Networks

• Oil production in terms of percent of Fischer Assay is

strongly related to formation temperatures and residence time; where higher temperatures and longer residence times lower oil production, but favor gas production.

• The production period is strongly related to geothermic

well spacing, where larger spacings yield longer production periods.

• Temperature limits on the geothermic wells cause the

power required for these wells to decline during production.

Conclusions Numerical Simulations

• Maximum heater well temperature of 450˚C
• 16 electric heaters in concentric patterns
• Outer hexagon spacing of 19.5 ft
• Intermediate hexagon spacing of 14.0 ft (rotated 90˚)
• Inner diamond spacing of 8.5 ft
• 113-ft heated interval between 280 to 393 ft bgs
• 540-day experimental period
• 1806 barrels of liquid oil recovered
• 861 additional BOE of gas recovered
• 2 simulations with STOMP-OS
• 20 gal/ton Fischer Assay oil shale
• 12 gal/ton Fischer Assay oil shale
• Modified Braun and Burnham (1993) reaction network

Shell Oil Field Experiment MDP[s]

Temperature, color scaled from 40˚ to 440˚C

MDP[s] Calibration Study (12 gal/ton FA)

Kerogen saturation, color scaled from 0.0 to 1.0

MDP[s] Calibration Study (12 gal/ton FA)

Liquid-oil saturation, color scaled from 0.0 to 1.0

MDP[s] Calibration Study (12 gal/ton FA)

Coke saturation, color scaled from 0.0 to 1.0

MDP[s] Calibration Study (12 gal/ton FA)

Shell Oil MDP[s] Calibration Study