Coupled Well Card Options (EOR)

The coupled well model for STOMP-EOR allows the specification of both injection and production type wells. Injection wells can be either mass or volumetric type wells and production wells can be either liquid production or fluid production type wells.

Well Trajectories

Well trajectories are specified using straight-line segments, in the natural drilling direction. The individual well sections can be screened or unscreened and have associated radii and skin factors. The trajectories of well sections are specified via a starting (i.e., first transition point) x, y, z point in the global coordinate system and an ending (i.e., second transition point) x, y, z point in the global coordinate system. Well trajectories are not permitted that coincide with a grid-cell surface. The only portions of the well trajectories that are active are those within a grid-cell volume. The translation of well trajectories into well nodes and connections between well nodes and field nodes will require computational time at the start of the simulation. For large domains and large well counts this initialization stage will require some time to complete, but is only required at the start of the simulation.

Injection Mass Well

The injection mass well is used to specify the injection of a fluid at a particular mass rate. Fluid will be injected from the well into the field grid cells across the screened interval. The distribution of fluid crossing the well surface depends on the resistance to flow as defined by the local well index, fluid mobility, and driving force across the well surface. The fluid injection rate is additionally bound by a pressure limit at the top of the screened interval; where the screened interval is assumed to be located at the point where the well trajectory crosses into the computational domain. Injection mass wells can be time varying and the composition of the injected fluid can additionally be time varying. Fluid compositions are defined as being in one of three states as shown in Table 1. The injection schedule is divided into time periods and time points. The thermodynamic state, as defined by the options in Table 1, of the injected fluid is fixed during time points. The composition of the fluid within a time period (i.e., between time points can vary), but its state is fixed. The thermodynamic state of the fluid can only vary between time periods.

Injection Volumetric Well

The injection volumetric well is used to specify the injection of a fluid at a particular volumetric rate. Fluid will be injected from the well into the field grid cells across the screened interval. The distribution of fluid crossing the well surface depends on the resistance to flow as defined by the local well index, fluid mobility, and driving force across the well surface. The fluid injection rate is additionally bound by a pressure limit at the top of the screened interval; where the screened interval is assumed to be located at the point where the well trajectory crosses into the computational domain. Injection volumetric wells can be time varying and the composition of the injected fluid can additionally be time varying. Fluid compositions are defined as being in one of three states as shown in Table 1. The injection schedule is divided into time periods and time points. The thermodynamic state, as defined by the options in Table 1, of the injected fluid is fixed during time points. The composition of the fluid within a time period (i.e., between time points can vary), but its state is fixed. The thermodynamic state of the fluid can only vary between time periods.

State Identifier	Aqueous Saturation	Nonaqueous Saturation
CW1	s_l = 1.0	s_n + s_g* = 0.0*
CW2	s_l < 1.0	s_n + s_g* > 0.0*
CW3	s_l = 0.0	s_n + s_g* = 1.0*

Table 1. Phase conditions for specifying the thermodynamic state of fluids injected into the well.

Liquid Production Well

The production liquid well is used to specify the production of only liquids (i.e., aqueous and nonaqueous-liquid) from the screened intervals of the well. Gas phase is not produced via the production liquid type well. Liquids enter the well based on the resistance to flow as defined by the local well index, liquid mobility, and driving force across the well. Liquids are not permitted to flow from the production well into the field domain. Pressure within the production well is based on the specified pressure at the bottom, in reference to the natural drilling direction, screened interval of the well, and the local density of the produced liquids. Local liquid density is computed as an average of the locally produced liquids.

Production Well

The production well is used to specify the production of all fluids (i.e., aqueous, nonaqueous-liquid, and gas) from the screened intervals of the well. Fluids enter the well based on the resistance to flow as defined by the local well index, fluid mobility, and driving force across the well. Fluids are not permitted to flow from the production well into the field domain. Pressure within the production well is based on the specified pressure at the bottom, in reference to the natural drilling direction, screened interval of the well, and the local density of the produced fluids. Local liquid density is computed as an average of the locally produced fluids.

Component Order

Coupled-well states CW2 and CW3 require the specification of total mole fractions of the petroleum components. For these inputs the components are not named but listed by the petroleum component order. The petroleum component order is CO₂, CH₄, and then the specified petroleum components in the order specified on the Petroleum Component Properties Card.