Unsteady State Wellbore Simulator

Production Well Optimization

Liquid Loading prediction

Gas lift modelling

Low Introductory Pricing



Full Wellbore Segment simulations more powerful than nodal analysis

Solves mass balance equations for the segments of the pipes in a well to obtain pressure, saturation and rate profiles.

Calculates changing pressures, saturations, rates in wellbore as reservoir influx or well offtake/injection changes with time

Co-current and counter-current multiphase flow in vertical/inclined/horizontal pipe using Beggs-Brill multiphase correlation

Black Oil/ Gas Condensate/ Gas-Water PVT data

Oil/Gas/Water Formation Volume Factors and Viscosities, Solution Gas-Oil Ratio, Condensate-Gas Ratio

Wellbore is divided into segments of user specified length

Using well deviation survey, well trajectory is divided into segments for flow/mass calculation

Multiple pipes of varying diameter, concentric and also side by side.

Segments can be perforated/plugged for reservoir and inter-pipe flow.

Transient calculation of Pressure, Oil/Water/Gas Rates and Saturations in wellbore segments.

Reservoir Connection

Multiple wellbore segments can be connected to reservoir at different times

Multiple attached reservoirs can be defined with varying Pressure, oil/water/gas saturations, PVT tables, Relative Permeability tables for variable influx calculation.

Reservoir influx rates can be also be specified directly and changed with time.

Multiple pipe offtake/injection points.

Time dependent pressure and maximum production/injection rate constraints.

Produce reservoir fluid from one pipe and inject into another pipe of the well ( eg Gas lifting)

Pump head curves, inline chokes, Flow Control Devices

Position, size or modify with time to optimize well flow



Detailed analysis of wellbore flow for different pipe configurations and operating conditions as a function of time. Obtain pressure, saturations, flow rates and direction of flow for individual segments of discretized pipes. Optimize number of pipes, pipe sizing, and perforations by analysis of pressure drop and rates.

Position and size inline choke, flow control devices and pumps

Estimate when liquid loading occurs by changing reservoir pressure, gas-liquid ratios, offtake pressures with time until well stops flowing.

Model gas lift injection to unload liquid water or condensate. Simulate varying gas lift rates, tubing string sizes and pressures.

Multiple reservoir zones - Multiple wellbore segments may be joined to reservoir model a well producing from several reservoirs of different PVT properties, commingled into the same producing tubing or with packers separating flow into annuli and production tubing.

Model a long horizontal well with many wellbore segments producing from several reservoir zones or hydraulic fracs as function of time.


Easy to Use Graphical Interface

Data File Builder

       Create new, modify and save data sets

       Tab identified Input forms with Spreadsheets, List boxes, error checking

       Specify Timestep size and output intervals, restart file writes

       Black Oil PVT data from Correlation

       Import Wellbore survey to discretize well

       Specify pipe sizes, perforations, chokes, pumps- change with time

       Enter Reservoir pressures, saturations, or fixed rates as function of time

       Specify offtake points with pressure and maximum withdrawal rates, injection points with pressure and injection rates

       Pump head curve

Run Data Files

       Select a list of data files to run 2 at a time.

       Review simulator messages

       Open Data File or Results file of selected run file

Review Results

       Select pipes, series, and times for spreadsheet report of segments.

       Report rates, cumulatives at production/injection points

       Report reservoir rates and cumulatives

       Graph reports

       Wellbore schematic of report parameters colored and animated with time

Help PDF documentation

Tutorial Movies

         How to use videos

YouTube Channel

       Videos of simulation of Wellbore with Time for Liquid Loading and Gas Lift



USWS Overview

Overview of the User Interface of the Unsteady State Wellbore Simulator (USWS) with Black Oil PVT properties

Click to watch


USWS - Gas Bubble Rising in a Pipe filled with Water

Shows multiphase counter current flow of gas and water in a vertical pipe.

Gravity segregation of gas and water.

Click to watch


USWS - Gas water loading then add gaslift tubing

Decline reservoir pressure until upward gas-water flow stops and water loading occurs.

Add gas lift tubing and inject gas rate to extend production period.


USWS Oil Well Depletion with Gas Lift

Oil Well Reservoir Pressure declines until well stops flowing. Gas Lift injection to extend production. Increase gas lift rate with time.


USWS - Gas Condensate Loading with gas lift

Depletion of gas condensate reservoir, showing well condensate and gas rates as reservoir pressure decreases with time. Shows condensate loading when pressure drops too low to flow. Adding gas lift to maintain production. Too much gas lift gas restricts condensate recovery.


USWS Oil Well depletion - add a pump to extend production

Well producing oil and water decline reservoir pressure until well stops flowing. Add a tubing string with pump and size head curve to extend production of well.

USWS Liner FCDs and Inline choke

How to place liner chokes and inline chokes to control production




For more information, contact:-

T.T. & Associates Inc

C/o PetroStudies Consultants Inc

#204, 4603 Varsity Drive NW

Calgary, Alberta, T3A 2V7, Canada

Phone: 403-265-9722