Technical results series

CO2 injection across three scales

Three CO2 injection problems were modeled in Terra. They cover pressure-controlled injection into a 10 m sample, long-term radial injection into a 10 km aquifer, and a fully coupled aquifer-caprock system.

3 solved .tflux models Two-phase CO2-water flow Cartesian and axisymmetric Flow and coupled hydromechanics

Three model problems

CO2 injection from a sample to an aquifer-caprock system

Each problem is presented as a separate Terra model with its geometry, physics, loading schedule, mesh, solved fields, and physical interpretation.

Problem 1Solved

A pressure-controlled well drives CO2 through a compact aquifer beneath a low-permeability caprock.

Model state: Solved
Horizon: 5 h
Mesh: 240 nodes / 208 quads

Problem 2Solved

A full-height well injects CO2 into a 10 km aquifer, resolving density, pressure, and saturation over 370 days.

Model state: Solved
Horizon: 370 d
Mesh: 572 nodes / 510 quads

Problem 3Solved

Two-phase flow, stress, strain, porosity, and displacement evolve together beneath a deformable caprock.

Model state: Solved
Horizon: 7 d after equilibration
Mesh: 519 nodes / 439 quads

Setup and assumptions

The lower 10 x 10 m domain is aquifer rock and the upper 10 x 10 m domain is caprock. The two-dimensional Cartesian model solves water and gas component balances with dissolved CO2 at 320 K. Mechanical equilibrium and heat transport are disabled.

Rock porosity0.10

Caprock porosity0.01

Rock permeability rows10^-11, 10^-13 m2

Caprock permeability rows10^-16, 10^-18 m2

Condition	Location / interval	Value
Bottom liquid pressure	Line 1, y = 0 m	10.1 MPa
Top liquid pressure	Line 4, y = 20 m	9.9 MPa
Initial liquid pressure	All domains	P_l = 10.1 - 0.01y MPa
Initial gas pressure	All domains	0.1 MPa
Equilibration	0-1 h	No injection
Pressure ramp	Well line, 1-2 h	Gas pressure increases to 11 MPa
Constant injection pressure	Well line, 2-5 h	11 MPa

Six Terra field plots at five hours for Problem 1: gas pressure, liquid pressure, liquid saturation, gas flux, liquid flux, and dissolved CO2 — **Six-field result atlas at 5 h.** Nodal pressures and dissolved concentration are smoothly interpolated. Saturation and fluxes retain their element association. Colour limits remain fixed across panels so the spatial changes are easy to read. Data: solved Terra result store.

Liquid saturation contours at two and five hours showing expansion of the CO2 plume in Problem 1 — **Plume growth from 2 h to 5 h.** The area below full liquid saturation grows from 1.768 m2 to 44.444 m2. The caprock's much lower permeability restricts upward migration.

Gas entry creates a moving saturation front, while dissolved CO2 changes the brine density behind it.

Gas pressure first rises around the short well section. Where gas pressure overtakes liquid pressure, the aquifer desaturates. Liquid flow weakens inside the gas-rich region and becomes concentrated around the advancing front.

At 5 h, Terra gives 0.1-10.9998 MPa gas pressure, 9.9-10.9377 MPa liquid pressure, 0.12849-1.0 liquid saturation, and 0.000244444-0.0268885 kg/kg dissolved CO2. The brine density range is 1087.44-1091.93 kg/m3.

Setup and assumptions

The homogeneous aquifer runs from r = 0.15 m to 10,000 m and from y = -100 m to 0 m. A 100 m gravel strip extends the outer radius to 10,100 m. The model is axisymmetric around y and solves isothermal water and gas balances with dissolved CO2 at 320 K. Mechanics is disabled.

Rock porosity0.15

Gravel porosity0.30

Full well rate79.1681 kg/s

Scheduled input2.493226 Mt by day 370

Condition	Location / interval	Value
Outer liquid pressure	Buffer line 2	10.0 MPa
Initial liquid pressure	All domains	P_l = 10 - 0.01y MPa
Initial gas pressure	All domains	0.1 MPa
Equilibration	0-5 d	No injection
Flow ramp	Well wall, 5-6 d	0 to 0.84 kg m^-2 s^-1
Constant wall flux	6-370 d	0.84 kg m^-2 s^-1
Axisymmetric conversion	2 pi r h = 94.2478 m2	79.1681 kg/s

Full-domain and near-well CO2 density contours at day 370 for Problem 2 — **CO2 density at global day 370.** The full 10.1 km view and the first-kilometre detail share one colour scale. The solved density range is 1.66018-711.255 kg/m3.

Gas pressure, liquid pressure, and liquid saturation history at radius 50 metres and elevation minus 10 metres — **Point history at r = 50 m, y = -10 m.** At day 370, liquid pressure is 14.27910 MPa, gas pressure is 14.30787 MPa, and liquid saturation is 0.156493. The curves show the stored Terra quantities at every written time.

Pressure controls gas density and mobility, so the plume evolves under a constant imposed mass flux.

CO2 density is highest near the pressurised well and falls sharply across the plume boundary. Liquid saturation drops after gas pressure exceeds liquid pressure. The long radial domain keeps the far boundary separate from the near-well response.

The later pressure decline follows from the gas phase having much lower viscosity than brine. As gas occupies more pore space, mobility increases and the imposed wall flux requires less pressure support.

Setup and assumptions

The aquifer occupies r = 0.15-2,000 m and y = -100-0 m. A gravel strip extends to r = 2,100 m. The caprock occupies r = 0.15-2,100 m and y = 0-100 m. The axisymmetric model is isothermal at 59.5 degrees C and solves radial and vertical displacement together with liquid and gas pressure.

Initial porosityAquifer 0.10 / caprock 0.01 / gravel 0.30

Top traction-28 MPa

Production wall rate16.4934 kg/s

Prescribed day-7 input9,903.93 t

Condition	Location / interval	Value
Vertical rollers	Bottom lines 4 and 5	u_y = 0; penalty 10¹⁵
Radial rollers	Outer lines 3 and 9	u_r = 0; penalty 10¹⁵
Top load	Caprock top	sigma_y = -28 MPa
Outer liquid pressure	Gravel top, r = 2000-2100 m	15 MPa
Initial liquid pressure	All domains	14 MPa at y = 100 m to 16 MPa at y = -100 m
Initial normal stress	All domains	(-19.6, -28, -19.6) to (-22.4, -32, -22.4) MPa
Equilibration	-5 to 0 d	Coupled equilibrium
Ramp / constant wall flux	0-0.1 d / 0.1-7 d	0 to 0.175 / 0.175 kg m^-2 s^-1

Four coupled Terra fields at day seven for Problem 3: gas pressure, liquid pressure, porosity, and vertical displacement increment — **Coupled day-7 field atlas.** Injection raises gas and liquid pressures near the well. The same calculation updates porosity and displacement. Data: solved persistent Terra result store.

Aquifer and caprock porosity contours at day seven for Problem 3 — **Pressure-dependent porosity.** The solved aquifer range is 0.0999988-0.100076. The caprock range is 0.00999087-0.0100212. Both cell-associated fields show the strongest change near the injection well.

New Terra result Aquifer-caprock interface uplift profile and prescribed cumulative injection through day seven

Interface uplift and prescribed source. Day-7-minus-equilibrium uplift falls monotonically from 4.12072 mm at the well to 0.06099 mm at 2,000 m. The mass curve is the exact integral of the prescribed wall source, not a solved global CO2 inventory.

Pressure build-up expands the porous skeleton and lifts the aquifer-caprock interface.

Near the well, gas pressure reaches 17.3362 MPa, liquid pressure reaches 17.3134 MPa, and the minimum liquid saturation is 0.626713. Volumetric response changes porosity in both the aquifer and the lower-permeability caprock.

The equilibrium-relative uplift is 4.12072 mm at r = 0.15 m, 1.30126 mm at 514.397 m, 0.58368 mm near 1,000 m, and 0.06099 mm at 2,000 m. The response decays smoothly with radial distance.

Reference: CODE_BRIGHT Tutorial manual (2026).

Study the complete multiphysics response

The three solved models open in Terra with their geometry, physics, mesh, study, and result definitions preserved.

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CO2 injection across three scales

CO2 injection from a sample to an aquifer-caprock system

CO2 injection into a sample

Setup and assumptions

CO2 injection into an aquifer

Setup and assumptions

CO2 injection beneath a caprock

Setup and assumptions

Study the complete multiphysics response