Coupled Well Card Options (e-W)

The coupled well model for eSTOMP-W allows the specification of both mass injection and mass production (withdrawal) type wells, with or without solutes. By including the key words “write aqueous flux” and “write solute flux” in the coupled well card, the total aqueous and solute fluxes generated by each well at every time step will be outputted to files “well_aqueous_flux.dat” and “well_solute_flux.dat” respectively. If the user chooses to not report those variables, one can just leave the space for these key words empty in the input file. The user can select either or both of the flux files to be written by the code.

Well Trajectories

Well trajectories are specified using straight-line segments. The trajectories of well sections are specified via a starting (i.e., first transition) x, y, z point in the global coordinate system and an ending (i.e., second transition) x, y, z point in the global coordinate system.  However, eSTOMP-W well segments cannot span over multiple grid cells, and cannot extend beyond the model domain. Therefore, it is best practice to specify well segment end points to be coincident with the grid cell edges.

When listing the well segments in the eSTOMP-W Coupled Well Card, it is critical to have the sequence correct for different types of wells. For injection wells, the segments should be ordered from the top to the bottom of the well, and for extraction wells the order is bottom to top. If the segments are not listed in the appropriate order, convergence issues may occur. In addition, wells are currently assumed to be vertically oriented and each well segment must correspond to a single computational grid block in the model domain. These restrictions are specific to eSTOMP and are due to domain-decomposition considerations and Global Array memory storage choices that were made during parallelization of the code.

Aqueous Mass Injection Well

The injection well is used to specify the injection of water at a particular mass rate.  Water will be injected from the well into the field grid cells across the screened interval.  The distribution of water 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 aqueous injection rate is additionally bounded by a pressure limit specified at the top of the screened interval and a maximum mass limit. The maximum pressure specified for the well will be case dependent. One general rule of thumb is to set the maximum pressure to a large value (for example, 100 bar). Likewise, the maximum mass should also usually be set to a large number, as once the maximum mass limit is exceeded, the injection rate will be reduced to zero. Injection mass wells can be time varying. The injection schedule is divided into time periods and time points. For aqueous injections, solute concentrations can be specified.

Aqueous Mass Production Well

The production well is used to specify the production of water from the screened intervals of the well.  Water enters the well based on the resistance to flow as defined by the local well index, fluid mobility, and driving force across the well. Water is not permitted to flow from the production well into the field domain.  It is good practice to specify the minimum pressure to be negative (for example. -1.0 bar). Additionally, if a solute is present in the model domain, whether it be introduced through a source, boundary condition, initial condition, or injection well, then the source concentration option should be specified for all production wells.