Very often the production reports give the data in terms of daily (or some other fixed frequency) produced volume. So, for a well producing at 1000 STB/D for 12 hrs and then shut-in for 12 hrs, would have a 24 hr reported production rate as 500 STB/D

The objective of Uptime correction is to determine the exact production duration during the day after the detection of the shut ins on the pressure history and correct the production history in order to respect the shut in and the real production rate. The uptime correction result is as follows:

If the option is on, the rates will be set to 0 during shut-ins.

Additional option And Nowhere Else is activated. If checked, you can select to replace zero rates outside shut-ins periods to either with constant value or with the last non null rate value.

Type the constant values you want to use in the specified fields.

If the option is on, the rates prior shut-ins will be corrected to become equal to the previous step rates. The reason behind this is often the same as with the uptime correction, when rates before shut-in are daily averaged and less in values than real ones. However, there are other reasons when rates before shut-ins are conservative.

If Always Replace With Previous Step is selected, then all the last rates prior shut-ins are replaced to previous step rates that are higher without exceptions.

If Replace With The Previous Step If Difference > is selected, the rates before shut-ins are replaced to the previous step rates that are higher only if a certain rate difference threshold is reached.

The threshold is defined by a user and can be set in Fractions or in Percentages.

Select Use Pressure For Last Rate Correction if you want to apply additional criteria on pressure difference to replace the rates before shut-ins.

Select Pressure by using the drop-down list, or by clicking on Browse.

For steady-state flow, if the rate difference is 0.1 (10%) then ΔP difference is also 0.1 (10%); so, for steady state flow ΔP difference multiplier equals to 1, and the complex rate-pressure criteria means that the algorithm replaces the rate before shut-in only if rate difference is more than 0.1 (10%) and ΔP difference is less than 0.1 (10%).

For unsteady-state flow, the pressure difference for fixed rate difference is a complex function of reservoir parameters and periods’ durations. By default, the ΔP difference multiplier is 0.8 but can be changed by a user.

When the option is enabled, the algorithm corrects (modifies) single, isolated spikes above or below the trend.  If the production is continuously spikey, then the algorithm will not do anything.

IQR (interquartile range) multiplier is used to determine what the outlier spike is.  The higher the value of the IQR multiplier, the wider the tolerance ‘band’ around the trend and only large outliers will be smoothed; the lower the IQR multiplier, the narrower the tolerance band and more spikes will be corrected.

If the option is on the rates will be simplified with honoring of cumulative if the difference between neighboring rate steps is less than a certain rate value (Absolute ΔY) or a Fraction/% (Relative ΔY).

Type your values if necessary or accept default ones.

If the option is on the rates prior shut-in will be kept unchanged. This is useful when applying the rates simplification that can distort the rate values prior shut-ins.

The option can be useful when injection rates are recorded as positive values.