2019

R E S E A R C H H I G H L I G H T S

The effect of supercritical CO2 on matrix permeability in unconventional reservoirs

Scientific Achievement The impact of supercritical CO2 on matrix permeability was experimentally evaluated on rocks with a wide range of mineral composition.

Significance and ImpactThe carbonate and clay content has a significant influence on how scCO2 can affect permeability. Interaction of supercritical carbon dioxide with injection reservoir is important to understand their transport characteristics over time.

Arash Kamali-Asl, Mark Zoback, Arjun Kohli

Research Details Matrix permeability experiments performed using argon and scCO2. The argon permeabilities were

made before and after CO2 permeability to evaluate the effects of dissolution and sorption. The most significant change in matrix permeability for carbonate-rich samples, while moderate

change was observed in carbonate-poor, clay-rich samples due to sorption-induced swelling ofclay/organic content.

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Simple Effective Pressure, CP-PP (MPa)

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CO2

Post-CO2 (using argon)

Pore Pressure = 10 MPa

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C3

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Simple Effective Pressure, CP-PP (MPa)

Pre-CO2 (using argon)

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Post-CO2 (using argon)

Pore Pressure = 10 MPa

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Simple Effective Pressure, CP-PP (MPa)

Pre-CO2 (using argon)

CO2

Post-CO2 (using argon)

Pore Pressure = 10 MPaC1

C2

C325% Clay

4% Carb.

34% Clay

8% Carb.

73% carbonate

86% carbonate

Molten-media methane pyrolysis for generation of solid carbon

Scientific Achievement Integrated design optimization and

technoeconomic analysis is conducted for a novel

methane pyrolysis technology

Significance and ImpactMolten-media methane pyrolysis may be

competitive at oil refineries, yielding a solid

carbon feedstock at low-costs

Gregory Von Wald, Mohammad S. Masnadi, D. Chester Upham, Adam R. Brandt

$0.80 $1.30 $1.80 $2.30

$5 $6 $7 $8 $9 $10 $11 $12 $13 $14 $15 $16

Levelized cost of hydrogen ($/kg)

Levelized cost of energy ($/MMBTU)

Natural gas price

IRR

Lang factor

Carbon black value

Carbon tax (av.) - comb.

Carbon tax (av.) - ref.

Carbon tax (seq.)

Lifetime

Capacity factor

Electricity price

$3/MMBTU $9/MMBTU

10% 20%

104

$250/tonne -$10/tonne

$50/tonne

$50/tonne $0/tonne

$0/tonne

20 y 10 y

70%90%

$80/MWh$20/MWhBase case

Research DetailsEconomics of molten-media

methane pyrolysis systems

are less sensitive to capital

cost estimates but benefit

from low natural gas prices.

At current pricing for LCFS

credits, low-carbon hydrogen

may be viable at $0.34/kg H2

Breakdown Pressure of Green River Shale With sc-CO2and Water Monitored Using X-ray Computed Tomography

Scientific AchievementBehavior of sc-CO2 as a fracturing agent wasinvestigated for Green River shale samplessubjected to reservoir-like conditions.

Significance and ImpactMineral composition —which is neglected inmost studies— plays a major role on breakdownpressure behavior for different fluids.

Talal Al Shafloot, Tae Wook Kim and Anthony Kovscek

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l-CO2 (Li et. al., 2016)

water (Li et. al., 2016)

sc-CO2 (our experiment)

Water (our experiment)

H-11 fracture (sc-CO2) H-12 fracture (water)

Research Details A high pressure high temperature (HPHT) cell was used to measure breakdown pressure for 1

inch plugs with the help of CT scanner to confirm fracture initiation.

A general trend of large breakdown pressure for sc-CO2 treated samples was observed.Reactivity to kerogen is suspected to be the reason behind that.

Unstable fracture propagation is captured when fracturing with sc-CO2 with slight branching.Unfortunately, cores dimensions limit the investigation of fracture complexity.

50 µm

Multiscale Study of CO2 Impact On Fluid Transport and Carbonate Dissolution in Nano-Darcy Shale

Scientific Achievement Exposure to carbonic water dissolves calcite in

carbonate-rich shale; however, water moisture in CO2

vapor does not

Dissolution extends roughly 100µm from contact

surface (max. 250µm)

Significance and Impact All investigations confirm inaccessibility of carbonic

water to enhance flow within shale matrix in reasonable

time frame; however, dissolution proves non-uniform

etching of fracture surface once exposed to carbonic

water which could be beneficial in the field with a much

larger fracture network

Carbonate and in particular, calcite content, in sealing

rock could be essential long-term in securing CO2 in

solution in the subsurface

Research Details EDS SEM and µ-CT were used to investigate micron scale

changes in shale mineralogy after exposure to carbonic

water and water saturated CO2 vapor

Six months exposure to carbonic water at 1700psi and 50ºC

resulted in no matrix enhancement on a core scale

Medical CT depicted CO2 recovery of oil in fractured core

with no observable contribution from rock matrix

Youssef Elkady

Before After

Silica-Rich Matrix

Carbonate-Rich Matrix

The impact of small scale rock heterogeneity on CO2 plume migration

Scientific Achievement The impact of mm-cm scale rock heterogeneity on CO2 plume migration is quantified and incorporated into a larger scale reservoir model.

Significance and ImpactSmall scale rock heterogeneity can increase or reduce plume migration depending on the direction of the heterogeneity.

Maartje Boon, Hailun Ni, and Sally M. Benson

Research Details Multiphase flow parameters are measured on heterogeneous rock cores of the Paraatte Fm at

reservoir conditions with the use of a medical X-ray CT scanner. Heterogeneity in the capillary pressure - saturation relationship results in flow-rate dependent

relative permeability. Flow-rate dependent relative permeability is derived using numerical and analytical models for

each of the 15 rock types that comprises the Paraatte Fm.

Multiphase flow experiments

Numerical and analytical models

Melbourne University

As part of the GeoCquest Project – funded by BHP

Viscous dominated (60 ml/min)Capillary dominated (3 ml/min)

Data mining using unsupervised learning to characterize capillary flow and residual trapping

Scientific Achievement Cluster analysis on

coreflooding experiment data

identifies how heterogeneity

affects capillary flow.

Significance and ImpactFlow regimes and different

trapping behaviors can be

easily recognized in this novel

workflow we developed.

Research Details Under capillary dominated flow

regime, permeability determines

the CO2 saturation time series

concaving behaviors.

Flow regimes can be identified

using the Gap value.

Hailun Ni and Sally M. Benson

How permeability affects capillary flow

Visualizing capillary heterogeneity trapping

Voxel-level CO2 saturation seriesVoxel-level capillary pressure

It has been demonstrated that CO2 saturation can increase during imbibition due to

trapping of displaced CO2 from upstream.

Specific capillary heterogeneity trapping regions inside the core can be identified.

F = 0.9 F = 0.6 F = 0.3 F = 0.1

The long-term redistribution of residually trapped CO2by Ostwald ripening

Scientific Achievement The time scale of residual CO2redistribution by Ostwald ripening has been accurately predicted at any stage during the equilibration.

Significance and ImpactOstwald ripening can redistribute and potentially re-aggregate residual CO2, which is relevant to the long-term security of geological CO2 sequestration.

Research Details Ostwald ripening can redistribute residual CO2

between heterogeneous sections within a reservoir.

An analogous retardation factor is developed to give a mathematically rigorous explanation to the time scale of equilibration.

An approximate solution is derived to accurately predict the time scale of equilibration of residual CO2 redistribution by Ostwald ripening at any stage.

Yaxin Li, Charlotte Garing, Sally M. Benson

Multiphase Flow Prediction with Deep Neural Networks

Scientific Achievement A deep neural network is developed for a CO2 storage multiphase flow problems that involves the complex interplay of gravity, capillary, and viscous forces.

Significance and ImpactThis model provides fast and accurate CO2 saturation plume predictions given heterogeneous permeability maps, injection duration, rate, and location.

Gege Wen, Meng Tang, and Sally M. Benson

Research Details• The trained neural network model has an excellent ability to interpolate and to a limited

extent, the ability to extrapolate beyond the training data ranges.

• A transfer learning procedure is introduced that can improve a model’s performance when extrapolating without massive data collection.

• Based on this trained neural network model, a web-based tool is provided that allows users to perform CO2-water multiphase flow calculations online.

The role of carbon capture and storage in decarbonizing California's electricity grid

Scientific Achievement Utilizing gas power plants with carbon capture storage (CCS) can help California reach its zero-carbon grid goals by 2045 cost –effectively.

Significance and ImpactThe analysis demonstrates the role of CCS in a deeply decarbonized grid, and the results can be applied to other electricity grids aiming to decarbonize.

EJ Baik, Kais Siala, Thomas Hamacher, Sally M. Benson

Research Details A capacity expansion and dispatch model is used to assess least-cost pathways to decarbonize

California's electricity grid. Despite its high capital cost, gas power plants equipped with CCS can help decarbonize cost-

effectively by providing valuable night-time power and avoiding over-generation of solar. Gas with CCS will need to be able to operate flexibly and at low capacity factors in a

decarbonized grid.