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

Maurice Dusseault Department of Earth Sciences University of Waterloo

Geological Sequestration of C

Deep Injection of Biosolids…

     Injection deep below GW level Gets rid of sewage biosolids, animal biosolids without environmental risk Permanent isolation of bioactive agents, heavy metals, etc.

CH 4 is generated, and quite rapidly at higher temperatures Extra C is sequestered permanently, mostly as an anthropogenic coal!

Geological Sequestration of C

Comparison of Methods

DBI

 “New” technology   True disposal Central facility    No odors No water risks CH 4 generated for beneficial use  Carbon sequestered  Waste co-disposal

Geological Sequestration of C Current Methods

 Straightforward      Soil enhancement Highly local (short transport distance) Risks to water, soil Odors …

Based on Actual Experience

Risks 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 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 Lithostratigraphy

possible SFI™ well locations 5-30 km

Geological Sequestration of C

flat or gently inclined strata surficial deposits mudstone limestone stringer silty shale blanket sand in a thick shale channel sands in a silty shale continuous blanket sand limestone not to scale

Steps 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 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 System

ground wastes conveyor hopper screen (5x8 mm) auger make-up water spray jets, auger-mixer mix tank triplex pump centrifugal charger injection well high pressure line

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 System

Geological Sequestration of C

SFI 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 Uplift

10 cm uplift ~symmetric max slope ~1:5,000 waste site, 100-150 m radius maximum no uplift at 1.5 km distance 700 m deep  V ~ 16,000 m 3

Geological Sequestration of C

Well Capacity

     Proper formation choice is required To date, the maximum injected in a single well is ~30,000 m 3 sand, 200,000 H 2 O Water dissipates into the sediments rapidly We believe 10 6 m 3 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 Advantages

       Wastes are permanently entombed Proper stratum choice gives exceptionally high environmental security (minimal risk) No chance of “repository” impairment No chance of surface H 2 O contamination Generated gases can be collected Costs are reasonable, even for difficult wastes Technology is “well-established”

Geological Sequestration of C

Injection Cycles

pressure 5 2 4 3 1 repose period 6 7 8 9 10 24-hr cycle initial pore pressure = 4.6 MPa 2 4 3 sand inj.

5 1 s v = 11.4MPa

6 7 8 time

Geological Sequestration of C

Environmental Husbandry

Geological Sequestration of C

Current Technology

Geological Sequestration of C

Deep Biosolids Injection

Gas to Energy

       Inject biosolids into old O&G reservoirs Metals, bacteria, viruses, are isolated CO 2 generation does not take place Anaerobic decomposi tion forms CH 4 CH 4 can be used Small footprint Solid C is sequestered

Methane Production Biosolids Injection Facility Biosolids Injection

Methane

Geological Sequestration of C

A Brief History

 Massive sand injection developed 1992-97          Biosolids disposal plus CH 4 CO 2 generation plus 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?

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 CH 4 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 Fields

Hyperion Carson JWPC Terminal Site completed Island in summer 2008 OCSD Plant Geological Sequestration of C

View of SFI System

Geological Sequestration of C

A DBI System

Geological Sequestration of C

DBI Advantages

4. Reduce transport costs

Gas to Energy Facility

5. Clean energy

CH 4 , CO 2 landfarms Fresh water sand Mud/shale Fresh water sand Sealing shale Brine filled sand Sealing shale Brine filled sand

2. Reduce greenhouse gas emissions 1. Improve groundwater protection 3. Long-term carbon sequestration

Geological Sequestration of C

Uncertainties

1. How much gas will be produced, and how fast?

2 5 0 0

2. How much CO 2 be absorbed by will formation water, and for how long?

2 0 0 0 1 5 0 0

3. How best to control or eliminate H 2 S ?

4. What are optimum injection parameters?

1 0 0 0 5 0 0 0 0 . 0 0

Geological Sequestration of C

Estimated gas production for 5 yrs of biosolids injection at 200 wt tons/day Injection Period 2 . 0 0 4 .0 0 6 . 0 0 100 80 60 40 20 0 55% CH 4 45% CO 2 90% CH 4 8 . 0 0

Y e a r s

10% CO 2 Landfill Gas 1 0 . 0 0 1 2 . 0 0 Deepwell Injection Gas 1 4 . 0 0 1 6 . 0 0

Formation 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

waste pod water flow Geological Sequestration of C

Typical Injection Parameters

     Slurry density Injection rates Injection period Interval period Daily volumes 1.15-1.35

1-2 m 3 /min 6-12 hours 12-40 hours 600-1200 m 3 /d These rates are sufficient to handle a city of 300,000 – 450,000 at a single site!

Geological Sequestration of C

Some DBI Details

      CO 2 , H 2 S stripped from gas by dissolving in the water (CH 4 has low solubility in H 2 O) 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,



T

      Biosolids slurry (  ~ 1.2) is injected for 8-10 hours each day, for several years… T slurry ~ 15°C, T fmn ~ 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 Biosolids

rapid slurry dewatering phase 50 40 30 20 10 0

Geological Sequestration of C

“classical” consolidation “creep” of organic material +  T effects biodegradation phase 2 yrs(?) log(t)

T

T Gradients - Injection

A Cold fluid injection A low k

shale

conductive heat flux convective heat flux T o  T B high k

sandstone shale

T o  T B d

Geological Sequestration of C

Methanogenesis Phase

   Biowastes are essentially complex carbohydrates and fats…  C x H y O z , plus small amounts of S, N Anaerobic, methanogenic bacteria break these molecules down     Available O becomes CO 2 Available H becomes CH 4 Perhaps traces of H 2 S if pH is right Excess C remains as solid carbon (coal!) This is accelerated coal & gas generation

Geological Sequestration of C

Forming of Carbon

CH 4 Evolved gases CO 2 ~16% of mass of CHO converted to CH 4

Geological Sequestration of C C-rich remnants

NO x H 2 S (N can form nitrates, S other sulfur compounds)

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 Generation

     Initially, there is no free gas, S g With time, S decreasing water relative perm, k CH 4 g increases in the biosolid, generation builds pressure until fracturing takes place (p o > s 3 ) = 0 w 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, Segregation

Injection well, later converted to a gas production well Gas bubbles Gas cap Shale caprock Sandstone Biosolids Base rock

Geological Sequestration of C

      

Chromatographic Gas Cleaning…

CH 4 (75%), CO 2 (25%), a bit of H 2 S, NO x These gases start to bubble upward But, the aqueous phase absorbs gas until it is saturated with each specie CH 4 CO 2 is very insoluble (< 0.01 v/v/atm) & H 2 S are highly soluble As gases migrate upward, these are stripped by dissolution, but not CH 4 Slow moving H 2 O carries CO 2 , H 2 S away

Geological Sequestration of C

More Coupling…

      CO 2 , H 2 S 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 CH 4 gas is produced through the well (p-V-T reservoir effects) Excess carbon remains sequestered, As well as the CO 2 dissolved in water

Geological Sequestration of C

     

Los 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 Fields

Hyperion Carson JWPC Terminal Island OCSD Plant Geological Sequestration of C

Approach 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.

   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

Applications

    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  ……

Geological Sequestration of C