Geological Sequestration of C
Carbon SequestrationCarbon Sequestrationin Sedimentary Basinsin Sedimentary Basins
Module VIII: Biosolids Module VIII: Biosolids Injection – LA TIRE Injection – LA TIRE
ProjectProjectMaurice Dusseault
Department of Earth SciencesUniversity of Waterloo
Geological Sequestration of C
Deep Injection of Deep Injection of Biosolids…Biosolids… Injection deep below GW level Gets rid of sewage biosolids, animal
biosolids without environmental risk Permanent isolation of bioactive
agents, heavy metals, etc. CH4 is generated, and quite rapidly at
higher temperatures Extra C is sequestered permanently,
mostly as an anthropogenic coal!
Geological Sequestration of C
Comparison of MethodsComparison of MethodsCurrent Methods Straightforward Soil enhancement Highly local (short
transport distance)
Risks to water, soil
Odors …
DBI “New” technology True disposal Central facility No odors No water risks CH4 generated for
beneficial use Carbon sequestered Waste co-disposal
Geological Sequestration of C
Based on Actual ExperienceBased on Actual Experience
Injection facility in Alberta, 1997
Geological Sequestration of C
Risks and CostsRisks and Costs The “true” cost of waste disposal…
Includes primary costs Must also include risk costs Must also include beneficial side effects
The “true” risks of waste disposal Neutralizing bacteria, prions, viruses Water contamination potential Related risks (heavy metals in soils…) The chances (risks) of abuse
Geological Sequestration of C
Conditions for SitingConditions for Siting
Deep, well below potable water sources In horizontal strata of great lateral extent Stratum must be sufficiently thick & porous Permeability must meet certain standards Thick ductile overlying shales are desirable At least one overlying permeable bed Formation water briny, flowing horizontally No exploitable resources to be impaired
Geological Sequestration of C
Ideal LithostratigraphyIdeal Lithostratigraphy
surficial depositsmudstone
silty shaleblanket sand ina thick shale
channel sands ina silty shalecontinuousblanket sandlimestone
limestone stringer
possible SFI™ well locations
3000
-10,
000’
5-30 km
flat or gently inclined strata
not to scale
Geological Sequestration of C
Steps in ImplementationSteps in Implementation Siting: geological and reservoir study Interaction with regulatory agencies Reservoir analysis: capacity, injection
strategy, k, compressibility, etc… New wells or old well recompletion? Design & install monitoring systems Approach based on waste type, studies,
siting… Reporting, QC, regulatory interaction
Geological Sequestration of C
Slurry and Injection UnitSlurry and Injection Unit Screening, mixing, controlling, injecting,
monitoring are the functions of the system Mixing assures a uniform slurry: mobile unit
includes auger mixing, washing through a screen, and density control in an auger tank
All systems are operated by hydraulic motors
Pumping is by a triplex PDP, supercharged with a centrifugal pump (hydraulic)
Geological Sequestration of C
Flow-Through SystemFlow-Through System
hopper
ground wastes
conveyor
screen(5x8 mm)
auger
mixtank
spray jets,auger-mixer
centrifugalchargertriplex pump
high pressure lineinjectionwell
make-up water
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
Geological Sequestration of C
View of SFI SystemView of SFI System
Geological Sequestration of C
SFI in the FieldSFI in the Field
Typical Processing and Injection Equipment
Operations can be fully enclosed for severe weather or odor control
Geological Sequestration of C
Typical Surface UpliftTypical Surface Uplift
10 cm uplift max slope ~1:5,000
no uplift at1.5 km distance
V ~ 16,000 m3
700 m deep
waste site, 100-150 mradius maximum
~symmetric
Geological Sequestration of C
Well CapacityWell Capacity
Proper formation choice is required To date, the maximum injected in a single
well is ~30,000 m3 sand, 200,000 H2O Water dissipates into the sediments rapidly We believe 106 m3 of slurry is quite feasible
for a biosolids injection well Monitoring and analysis allow continuous
re-evaluation of capacity and well performance
Geological Sequestration of C
Solids Injection AdvantagesSolids Injection Advantages Wastes are permanently entombed Proper stratum choice gives exceptionally
high environmental security (minimal risk)
No chance of “repository” impairment No chance of surface H2O contamination Generated gases can be collected Costs are reasonable, even for difficult
wastes Technology is “well-established”
Geological Sequestration of C
Injection CyclesInjection Cyclespressure
time
v = 11.4MPa
initial pore pressure = 4.6 MPa
24-hr cycle
sandinj.
reposeperiod5
67
8
9
10
1
24
3
45 6
7
1
2
38
Geological Sequestration of C
Environmental HusbandryEnvironmental Husbandry
Geological Sequestration of C
Current TechnologyCurrent Technology
Geological Sequestration of C
Deep Biosolids InjectionDeep Biosolids Injection
Inject biosolids into old O&G reservoirs
Metals, bacteria, viruses, are isolated
CO2 generation does not take place
Anaerobic decomposi-tion forms CH4
CH4 can be used Small footprint Solid C is sequestered
Gas to Energy Biosolids InjectionFacility
Methane
BiosolidsInjection
MethaneProduction
Geological Sequestration of C
A Brief HistoryA Brief History Massive sand injection developed 1992-97 Biosolids disposal plus CH4 generation plus
CO2 sequestration concept in 1997 Vancouver assesses, declines (2000) City of Los Angeles approached in 1999 Land spreading court case lost in 2001 DBI passes all permitting needs (late 2001) EPA letter of acceptance (Sept 2003) Etc., etc., etc., etc., hearings, etc., Project initiation date (Jan 2007) First biosolids injection (Sept 2008!!!)
Geological Sequestration of C
Why Los Angeles?Why Los Angeles?LA Basin oilfields are excellent geologic targets with known trapping mechanisms
close to major LA sanitation plants
LA lost a court case (2001), and will have to almost eliminate sludge spreading on fields
(e.g. Kern County) by 2004-2005*
With CH4 at $12 MBTU, DBI and gas recovery is substantially cheaper than secondary and
tertiary treatment, & spreading*California keeps on giving temporary extensions…
Geological Sequestration of C
Los Angeles O&G FieldsLos Angeles O&G Fields
Hyperion
TerminalIsland OCSD
Plant
Carson JWPC
Site completed in summer 2008
Geological Sequestration of C
View of SFI SystemView of SFI System
Geological Sequestration of C
A DBI SystemA DBI System
Geological Sequestration of C
DBI AdvantagesDBI Advantages
landfarms
Fresh water sand
Fresh water sand
Brine filled sand
Brine filled sand
Sealing shale
Sealing shale
Mud/shale
CH4, CO2Gas to EnergyFacility
1. Improve groundwater protection
2. Reduce greenhouse gas emissions
3. Long-term carbon sequestration
4. Reduce transport costs
5. Clean energy
Geological Sequestration of C
UncertaintiesUncertainties
0
500
1000
1500
2000
2500
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00
Years
Pro
duc
ed G
as (M
MsC
f)
0
20
40
60
80
100
Landfill Gas Deepwell InjectionGas
% G
as R
ecov
ered
90% CH4
45% CO2
55% CH4
10% CO2
1. How much gas will be produced, and how fast?
2. How much CO2 will be absorbed by formation water, and for how long?
3. How best to control or eliminate H2S ?
4. What are optimum injection parameters?
Estimated gas production for 5 yrs of biosolids injection at 200 wt tons/day
Injection Period
Geological Sequestration of C
Formation ResponseFormation Response Liquid bleed-off is rapid, allowing pressure decay and
strain relaxation between injection episodes Large target stratum provides necessary storage Overlying shales provide hydrologic isolation from
fresh water and stress barriers to minimize vertical migration
Solid wastes remain close to injection point due to high permeability induced fracture leak-off
Natural temperature, pressure, fluids, provide a good environment for anaerobic biodegradation
water flowwaste pod
Geological Sequestration of C
Typical Injection Typical Injection ParametersParameters
Slurry density 1.15-1.35 Injection rates 1-2 m3/min Injection period 6-12 hours Interval period 12-40 hours Daily volumes 600-1200
m3/dThese rates are sufficient to handle a city
of 300,000 – 450,000 at a single site!
Geological Sequestration of C
Some DBI DetailsSome DBI Details CO2, H2S stripped from gas by dissolving in
the water (CH4 has low solubility in H2O) Carbohydrates have a 40% surplus of C;
this is left behind: sequestered elemental carbon
No sludge ponds, no digesters … Sealed DBI unit, no odor, no spray May have to inoculate the biosolids with
optimum bacteria for the T, pH conditions Based on oilfield skills and technology
Geological Sequestration of C
Initial Compaction, Initial Compaction, TT Biosolids slurry ( ~ 1.2) is injected for 8-
10 hours each day, for several years… Tslurry ~ 15°C, Tfmn ~ 40-50°C Pore pressures dissipate, massive
compaction occurs (non-linear behavior) Formations are cooled by injectate Gradual re-heating takes place as the
geothermal regime is re-established T effects, organics are compressible…
Geological Sequestration of C
Compaction of BiosolidsCompaction of Biosolids
log(t)
poro
sity
rapid slurry dewatering phase
“classical” consolidation
“creep” of organic material
+T effects
biodegradation phase
2 yrs(?)
50
40
30
20
10
0
Geological Sequestration of C
T Gradients - InjectionT Gradients - Injection
T
T
T
d
AA
B
B
low k
high k
conductive heat flux
convective heat flux
Cold fluid injection
shale
sandstone
shaleTo
To
Geological Sequestration of C
Methanogenesis PhaseMethanogenesis Phase Biowastes are essentially complex
carbohydrates and fats… CxHyOz, plus small amounts of S, N
Anaerobic, methanogenic bacteria break these molecules down Available O becomes CO2 Available H becomes CH4 Perhaps traces of H2S if pH is right Excess C remains as solid carbon (coal!)
This is accelerated coal & gas generation
Geological Sequestration of C
Forming of CarbonForming of CarbonC
ompl
ex c
arbo
hydr
ate
CxH
yOz (
N,S
)
C-richremnants
CH4
CO2
NOx
H2S
Evolved gases
(N can form nitrates, S other sulfur compounds) ~16% of mass of CHO converted to CH4
Geological Sequestration of C
T, Biological Activity, T, Biological Activity, Higher T accelerates biodegradation Biodegradation = more compaction The cold region must warm with time Water viscosity is also affected (small) Thus, a complex coupling exists
among the compaction behavior with time and Fourier and Darcy diffusion with changing diffusivity parameters
It is rendered more complex yet…
Geological Sequestration of C
Gas GenerationGas Generation Initially, there is no free gas, Sg = 0 With time, Sg increases in the biosolid,
decreasing water relative perm, kw CH4 generation builds pressure until
fracturing takes place (po > 3) Gas is lighter than water, so -driven
gravitational segregation occurs Gas flows upward through the biosolid
and the porous medium (sandstone)
Geological Sequestration of C
Gas Migration, SegregationGas Migration, Segregation
Shale caprock
Sandstone
Base rock
Biosolids
Gas cap
Gas bubbles
Injection well, later converted to a gas production well
Geological Sequestration of C
Chromatographic Gas Chromatographic Gas Cleaning…Cleaning…
CH4 (75%), CO2 (25%), a bit of H2S, NOx These gases start to bubble upward But, the aqueous phase absorbs gas
until it is saturated with each specie CH4 is very insoluble (< 0.01 v/v/atm) CO2 & H2S are highly soluble As gases migrate upward, these are
stripped by dissolution, but not CH4 Slow moving H2O carries CO2, H2S away
Geological Sequestration of C
More Coupling…More Coupling… CO2, H2S gases dissolve in the water Gravity segregation occurs, displacing
water from the system; this requires a gravity drainage flow model
Liquid flux carries dissolved gases away Cleaned CH4 gas is produced through
the well (p-V-T reservoir effects) Excess carbon remains sequestered, As well as the CO2 dissolved in water
Geological Sequestration of C
Los Angeles ProjectLos Angeles Project Began in 1999 All parties on board 2001 except EPA EPA gave the go-ahead in Sept 2003 Project plan filed in Dec 2003 Final approval Jan-Feb 2007 Biosolids injection started in 2009?
LA sludge after primary biodegradation Sludge will be non-hazardous Inoculate sludge with methanogenic
thermophilic bacteria species? No…
Geological Sequestration of C
Los Angeles O&G FieldsLos Angeles O&G Fields
Hyperion
TerminalIsland OCSD
Plant
Carson JWPC
Geological Sequestration of C
Approach to AnalysisApproach to Analysis The process is highly complex…
Moving boundaries (injection, compaction) Thermal effects (heating and cooling) Pore pressure effects (fracturing…) Biological decomposition Gas generation and chromatographic
effects …
Currently, processes are treated in an uncoupled manner, approximate only
Geological Sequestration of C
Comments on Biosolids Inj.Comments on Biosolids Inj. Complicated coupled processes are
typical in geomechanics DBI concepts evolved from petroleum
geomechanics Formal simulation remains
excessively challenging at present… Massive non-linearities Phase changes, biological activity Many simultaneous diffusion, stress
effects Moving boundaries…
Geological Sequestration of C
ApplicationsApplications Los Angeles will be first (2009) Vancouver is watching, others will
follow Geology appears ideal in Oklahoma,
Iowa, Kansas, Dakotas, Alberta, Saskatchewan, for animal wastes DBI
India, China, Indonesia, …: Little secondary/tertiary treatment Massive contamination issues DBI avoids expensive treatment plants ……