Download - Carbon Sequestration in Sedimentary Basins Module VIII: Biosolids Injection – LA TIRE Project

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


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!


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


Based on Actual ExperienceBased on Actual Experience

Injection facility in Alberta, 1997


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


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


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


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


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)


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


View of SFI SystemView of SFI System


SFI in the FieldSFI in the Field

Typical Processing and Injection Equipment

Operations can be fully enclosed for severe weather or odor control


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


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


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”


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


Environmental HusbandryEnvironmental Husbandry


Current TechnologyCurrent Technology


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


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!!!)


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…


Los Angeles O&G FieldsLos Angeles O&G Fields

Hyperion

TerminalIsland OCSD

Plant

Carson JWPC

Site completed in summer 2008


View of SFI SystemView of SFI System


A DBI SystemA DBI System


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


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


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


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!


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


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…


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


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


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


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


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…


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)


Gas Migration, SegregationGas Migration, Segregation

Shale caprock

Sandstone

Base rock

Biosolids

Gas cap

Gas bubbles

Injection well, later converted to a gas production well


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


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


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…


Los Angeles O&G FieldsLos Angeles O&G Fields

Hyperion

TerminalIsland OCSD

Plant

Carson JWPC


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


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…


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 ……

Download - Carbon Sequestration in Sedimentary Basins Module VIII: Biosolids Injection – LA TIRE Project

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