GEOL40310_LectureD3_Sequestration3_2023.pdf

Geol 40310 Fossil Fuels and Carbon Capture & Storage (CCS) Lecture D3: CO2 sequestration in saline aquifers and depleted reservoirs Autumn 2023 T. Manzocchi, UCD 1 Lecture D3: CO2 sequestration in saline aquifers and depleted reservoirs CO2 Storage in saline aquifers - Structural and stratigraphic...

Geol 40310 Fossil Fuels and Carbon Capture & Storage (CCS) Lecture D3: CO2 sequestration in saline aquifers and depleted reservoirs Autumn 2023 T. Manzocchi, UCD 1 Lecture D3: CO2 sequestration in saline aquifers and depleted reservoirs CO2 Storage in saline aquifers - Structural and stratigraphic trapping - Capillary seal failure, fracture seal failure - CO2 plume migration and trapping mechanisms. Structural / stratigraphic trapping, Residual trapping, solubility trapping, mineral trapping - Examples: - Sleipner - Modelling CO2 sequestration: The Utsira Formation the Garn and Ile formations - Northern Lights CO2 Storage in depleted oil reservoirs - HyNet Project CO2 Storage inventories 2 Geol 40310 Lecture D3 1 Global CO2 volumes sequestered 1970 - 2022 Million tonnes of CO2 / year operational In construction Dedicated geological storage 1972: Val Verde USA 1996: Sleipner, Norway Enhanced oil recovery Data from Global Status of CCS 2022; Global CCS Institute 3 CO2 Storage in saline aquifers After IPCC (2005) 4 Geol 40310 Lecture D3 2 Structural and Stratigraphic trapping: Like conventional oil and gas reservoirs these need a reservoir rock, a trap and a seal Anticline Pinchout Unconformity Fault NPD CO2 Storage Atlas Norwegian Continental Shelf 5 Pressure build-up in a CO2 accumulation CO2 injector Pressure Depth Pressure increase required to inject at the target rate 6 Geol 40310 Lecture D3 3 Injection from a well CO2 PWH PR Pwf Reservoir Pressure build up (𝑃𝑤𝑓 − 𝑃𝑅 ) Well Head 0 0 Flow out of well: 𝑞𝐶𝑂2 = II(𝑃𝑤𝑓 − 𝑃𝑅 ) Flow rate (Tonnes / hr) Injectivity index is a function of the formation permeability, the fluid viscosity and the thickness of permeable interval. 7 Pressure build-up in a CO2 accumulation Datum case: stable CO2 column in trap CO2 injector Pressure Additional Pressure increase due to CO2 column buoyancy Depth Pressure increase required to inject at the target rate 8 Geol 40310 Lecture D3 4 Pressure build-up in a CO2 accumulation CO2 injector Higher injection rate: Greater pressure increase can promote top-seal leakage risk due to fracturing Pressure Additional Pressure increase due to CO2 column buoyancy Depth CO2 Pressure > Fracture pressure: risk fracturing the top seal and leaking CO2 Pressure increase required to inject at the target rate 9 Pressure build-up in a CO2 accumulation Datum case: stable CO2 column in trap CO2 injector Pressure Additional Pressure increase due to CO2 column buoyancy Depth Pressure increase required to inject at the target rate 10 Geol 40310 Lecture D3 5 Pressure build-up in a CO2 accumulation Thicker CO2 column: greater capillary pressure can cause leakage (capillary seal failure). CO2 injector Additional Pressure increase due to CO2 column buoyancy Pressure Depth Capillary pressure > Capillary threshold pressure: leakage of non-wetting phase CO2 possible through top-seal. Pressure increase required to inject at the target rate 11 Principle of CO2 trapping (same as the principle of oil and gas trapping) Reservoir rocks Capillary pressure 100 10 1 1 0.1 0.01 10000 1000 100 10 1 0.1 0.01 0.001 0.0001 0.00001 0.000001 FWL 1000 0.0000001 Depth Reservoir Seal Maximum capillary pressure Capillary threshold pressure (bars) Efficient seals Pressure Permeability (mD) • Capillary pressure in the accumulation is a function of the density contrast between the fluids and the height above the free water level. • If the capillary pressure matches the capillary threshold pressure of the seal, it will begin to leak CO2. 12 Geol 40310 Lecture D3 6 CO2 Storage in saline aquifers Structural and stratigraphic trapping • CO2 injection that is too fast, or CO2 columns that are too thick, can lead to top-seal failure and risk of leakage. • Over time, structural and stratigraphic trapping gives way to residual trapping, solubility trapping and mineral trapping After IPCC (2005) 13 CO2 migration plume mobile, residual and dissolved CO2 Peter et al (2022) 14 Geol 40310 Lecture D3 7 1. CO2 injection phase Buoyancy-driven CO2 migration updip Impermeable seal Injection of supercritical CO2 Mobile CO2 plume (not trapped) Permeable reservoir unit 15 2. CO2 plume migration, residual trapping Mobile CO2 plume (not trapped) Residual trapping CO2 CO2 water Back of plume Steady-state plume migration. water Front of plume 16 Geol 40310 Lecture D3 8 2. CO2 plume migration, residual trapping Capillary pressure Capillary pressure: (PCO2 – Pwater) Steady-state plume migration. 0 Water saturation 1 Residually trapped CO2 Residually trapped CO2 CO2 CO2 water Back of plume: Spontaneous Imbibition Steady-state plume migration. water Front of plume: Drainage 17 3. Plume migration is arrested by a seal: Structural or stratigraphic trapping Trapped CO2 (strutural or stratigraphic) Residual trapping 18 Geol 40310 Lecture D3 9 4. Throughout the process: solubility trapping CO2 disolves in the formation water. CO2-saturated water is denser than the formation water and will sink Residual trapping Trapped CO2 (strutural or stratigraphic) Dissolution trapping 19 5. Finally (perhaps): mineral trapping The CO2-rich water reacts with the rock to precipite new calcite minerals CO2-saturated formation water Time (lots of it!) Mineral trapping as cements on rock grains or new diagenetic minerals 20 Geol 40310 Lecture D3 10 Sleipner CO2 Storage Project • Equinor (formally Statoil) have been sequestering 1 million tonnes of CO2 per year from the Sleipner platform since 1996. • Produced gas contains about 9% CO2 which must be reduced to < 2.5% before sale. • CO2 is separated from the gas on the platform, and injected into the Utsira formation at a depth of 800 – 1000 m. • The operation is cost-effective, as the Norwegian taxation liable on venting the CO2 to atmosphere would exceed the costs of injection and monitoring. 21 Sleipner CO2 Storage Project • The Utsira Formation: 200 m thick sands near the injection site, but has a laterally variable thickness. • The Utsira Sand is capped by mudstone and has thin mudstone layers within the succession. • Injection takes place along a 40 m perforated interval in a deviated (horizontal) well. • The CO2 rises through time to towards the top of the aquifer. • No evidence of leakage or escape from the aquifer has been detected to date. 22 Geol 40310 Lecture D3 11 Tune Seismic amplitude display to highlight CO2 filled sands Acoustic impedance softer harder Depth Amplitude tuned to gas-sand response Bacon et al (2003) 23 CO2 Plume on Sleipner – rapid vertical migration, then lateral spreading Time-lapse seismic sections 1994 2001 2004 2006 2008 Top Utsira Base Utsira 24 Geol 40310 Lecture D3 12 The Utsira Formation Depth to top Utsira Formation 700m Suitable areas Sleipner Simulation area NPD CO2 Storage Atlas Norwegian Continental Shelf 25 The Utsira Formation CO2 injection simulation • Up to 200 million tCO2 injection possible in area, using 4 or 5 wells. • 8000 years after injection the CO2 migrates and follows the topography and accumulates in surrounding structures. NPD CO2 Storage Atlas Norwegian Continental Shelf 26 Geol 40310 Lecture D3 13 Modelling CO2 sequestration in the Garn and Ile formations Garn and Ile study 5km Garn and Ile formations: Good quality, thick aquifers dipping ca. 2° towards the shore. Sleipner NPD CO2 Storage Atlas Norwegian Continental Shelf 27 Sector model of injection into the Garn and Ile aquifer • • • Based on simulation results, about 400 million tons CO2 can be stored in the Garn and Ile aquifers (8 mill tons/year over 50 years). This will require 4 injection wells (2 mill tons/year per well) and yield an acceptable pressure increase (< 20 bar). After 10,000 years most of the gas will have gone into solution with the formation water or will be residually trapped. NPD CO2 Storage Atlas Norwegian Continental Shelf 28 Geol 40310 Lecture D3 14 Northern Lights CCS project First exploitation license for CO2 storage awarded to Equinor, Shell and Total in January 2019. Gas field Oil field Garn and Ile study EL001 Sleipner License EL001 Halland, 2019, GeoExPro 16 (6) 29 Northern Lights CCS project • • • • The 31/5-7 confirmation well (Eos) was drilled and tested from 2 December 2019 to 7 March 2020. May 2020: Plan for development and operation (PDO) submitted for approval. CO2 will be injected ca. 20 km south of the Troll Structure in the underlying Cock and Johansen Formations at a depth of ca. 2700m. At least 1.5 million tonnes of CO2 per year will be sequestered for 25 years. Plume at 25 years after 1.5 mt / year Source: Equinor 30 Geol 40310 Lecture D3 15 CO2 storage efficiency Storage efficiency (ε) = Actual volume of CO2 stored Theoretical pore volume available • CO2 Storage efficiency is low due: An unfavourable CO2 - water mobility ratio (low CO2 viscosity). High sensitivity of CO2 movement to permeability heterogeneity. • Typically, storage efficiencies of ca. 5% are assumed for regional storage assessments for saline aquifers. • Filling a structural or stratigraphic trap could result in a local storage efficiencies of ca. 50%, but this has yet to be tested. Ringrose et al. (2021); Annu. Rev. Chem. Biomol. Eng. 12:471-494. 31 CO2 storage Options (IPCC Report, 2005): Ocean Storage • Dissolution type • Lake type Mineral carbonation • Subsurface mineralisation • Surface waste materials, soils Geological storage • Enhanced Oil Recovery (EOR) • Unminable coal seams • Depleted oil/gas fields • Saline aquifers 32 32 Geol 40310 Lecture D3 16 CO2 Sequestration in depleted oil or gas reservoirs • Proven traps • Well understood geological and engineering characteristics • Potential re-use of existing infrastructure Depleted Frigg Gas Reservoir, Norwegian Sea. A candidate for CO2 storage NPD CO2 Storage Atlas Norwegian Continental Shelf 33 The greatest leakage risk for sequestration in depleted hydrocarbon fields is often the integrity of existing wells. • Carbonic acid (CO2 dissolved in water) is very corrosive to materials such as cement and steel. This situation can over time cause damage to downhole tubulars and mechanical barrier elements and lead to degradation of well integrity. Between cement and outside of casing Between cement and inside of casing Through the cement Through the casing Through fractures in the cement Between cement and formation NPD CO2 Storage Atlas Norwegian Continental Shelf 34 Geol 40310 Lecture D3 17 HyNet Project, NW England Picture Source: Offshore magazine • Blue hydrogen production from natural gas with carbon capture. • H2 to be stored in underground in salt cavities (Holford Brinefield, Cheshire): storage concept development study initiated by Costain, October 2021. • CO2 storage in disused gas fields, East Irish Sea Basin (Hamilton, Hamilton North and Lennox fields): 6-year appraisal license granted to ENI in 2020 to assess feasibility. 35 Planned CCS Hubs - Europe 36 Geol 40310 Lecture D3 18 Global CO2 storage projects- operational and planned Global Status of CCS 2022; Global CCS Institute 37 Theoretical storage capacity by region 38 Geol 40310 Lecture D3 19 Theoretical storage capacity and cumulative storage in the sustainable development scenario Theoretical capability far exceed the required storage 39 CO2 storage Options (IPCC Report, 2005): Lecture D1 Ocean Storage • Dissolution type • Lake type Mineral carbonation • Subsurface mineralisation • Surface waste materials, soils Geological storage Lecture D2 • Enhanced Oil Recovery (EOR) • Unminable coal seams • Depleted oil/gas fields • Saline aquifers Lecture D3 Lecture D4: Module wrap-up. 40 40 Geol 40310 Lecture D3 20