##### Page tree
Go to start of banner

# Total sandface flowrate = qt

Go to start of metadata

Total produced or injected flowrate of all fluids across the well-reservoir contact with the volumes measured at the sandface temperature and pressure conditions.

Usually abbreviated as $//$ or $//$ (with the latter does not imply a product) or specifically $//$ for production and $//$ for injection.

The concept applies both to producing and injecting wells.

The main purpose of describing the intakes and offtakes in terms of the Total sandface flowrate $//$ is that it measures the actual flowing volumes in porous and as such directly relate to reservoir pressure.

For volatile oil fluid model the total sandface flowrate is related to surface flowrates of fluid components as:

 (1)
 (2)

where

 $//$, $//$, $//$ water sandface flowrate, oil sandface flowrate, gas sandface flowrate $//$, $//$, $//$ produced water surface flowrate, oil surface flowrate, gas surface flowrate $//$, $//$ injected water surface flowrate,  gas surface flowrate $//$ formation volume factors for water, oil, gas $//$ Solution GOR and Vaporized oil ratio at sandface pressure/temperature conditions

The total sandface flowrate $//$ of production is related to
Liquid production rate $//$ as:

 (3)

where

$//$ Production Water Cut Production Gas-Oil-Ratio = GOR

Starting with definition of Total sandface flowrate (1) and substituting the expression of Oil surface flowrateGas surface flowrateWater surface flowrate through Liquid production rate one arrives to (3).

It simplifies for the
Black Oil model ($//$) to:

 (4)

or

 (5)

It simplifies further down to production from
undersaturated reservoir as:

 (6)

and even simpler for single-phase fluid (water, dead oil or dry gas) with  surface flow rate $//$ and formation volume factor B as below:

 (7)