Reservoir flow (geobrain.physics.flow)

Differentiable two-phase flow with wells: the forward model behind history matching, well placement and closed-loop reservoir management.

Piece	What is there
Grid and rock	CartGrid, Rock
Operators	TransientFlowOperator, FlowEvolutionOperator, ParametricFlowOperator
Wells	Well, WellGroup, Perforation, BHPControl, RateControl, WellObservationOperator
Time stepping	TimeStepScheduler, AdaptiveTimeStepper
Configuration	FlowExecutionConfig, FlowHistoryConfig, FlowModelSchema, FlowFieldSpec
Diagnostics	FlowConvergenceDiagnostics, discover_flow_capabilities

The fluid and rock property models live one level down:

geobrain.physics.flow.models.OilWaterModel, geobrain.physics.flow.properties.relperm.RelPermCorey, ...properties.pvt.PVTAnalytic, ...properties.fluid.OilWaterFluid, and ...wells.compute_well_index gives the Peaceman well index from the cell geometry.

Why differentiable matters here

The time march is an implicit Newton solve at every step. Taping it would store every Newton iteration of every timestep; instead the operator carries an implicit-function adjoint, so one backward pass returns

\[\frac{\partial\,\text{cumulative oil}}{\partial \log k}\]

for every cell in the model, at the price of one extra simulation rather than one per cell.

Read that map as economics, not as physics. Permeability is worth having near the injector, where it buys injectivity, and worth not having along a streak that runs straight to one producer, because that spends the water on one well. It is the first step of a history match or a well-placement study.

The working rule it demonstrates

Sweep is decided by the permeability field, not by the well pattern. Four producers arranged symmetrically around one injector produce four different histories, because the high-permeability streaks between them are not symmetric.

Note

Well rates follow the canonical source convention: injection positive, production negative. Displays negate production, and the axes say so.

A five-spot waterflood, the water cut it produces well by well, and the adjoint sensitivity that prices every cell. From examples/03_physics/07_reservoir_flow.py.

See also

• examples/03_physics/07_reservoir_flow.py: a five-spot waterflood, the water cut per well, and the adjoint that prices every cell.