Contents
GasPal Short and Long Term Simulations
General
Functions
For storage or production reservoirs
GasPal can
1.
Accurately predict performance of gas
production or storage reservoir-compressor-pipeline systems.
2. Simulate injection and production or a
mixture of the two, providing full
storage scheduling flexibility
3. Simulate complex surface network
including splits, loops and multiple offtake points
4. Simulate injection and production
or a mixture of the two, providing full
storage scheduling flexibility
5.
Model 1, 2, 3 phase flow in
formation, tubing and surface lines
6.
Computing speed that allows
sensitivity planning runs “w/o limit”; for storage hourly/daily scheduling of
compressors for production and injection. Schedules obtained are efficient and
economic.
7.
Provide a convenient interface for
inputting data, cut & paste history match data from Excel, smoothly manage
restart files.
8.
Generate a full gamut of output
graphs and tables to export results to Excel
9.
Storage database allows operations to
be quickly rescheduled in response to new opportunities or unexpected changes
in available equipment and/or supply/demand requirements
Special
Production Modes
GasPal has
the following special production modes for European gas providers
1.
Nomination Run:
Both constrained and unconstrained potentials (capacities) are calculated
first. GasPal then nominates a
production rate for each month with margin and well work considered.
2.
DCQ Run: GasPal
calculates the Daily Contract Quantity with required swing for each month.
Users can specify DCQ length to be 3, 6 or 12 months.
GasPal
Short and Long Term Simulations
- Short-term operation: hourly time steps for two weeks. Useful for
immediate injection/withdrawal planning.
- Mid-term planning: daily time step for one year. Useful for
overall storage planning.
- Long-term production: weekly time for 7 years or monthly time step
for 30 years. Useful for regular gas reservoir production or blowdown.
Simulation
Cells
GasPal uses GRIDDER to divide a reservoir into arbitrary simulation
cells. Faults can be incorporated in the simulation grids.
Flow Rate Modeling
- Regular k/h Darcy and psuedo pressure for formation,
multiple phase flow for tubing
- Empirical method C/n for formation and multiple
phase flow for tubing
- Empirical methods for both formation and tubing,
AFBC option
Backout
Calculations
When gas from a new source (e.g. wells from other
reservoirs) is interjected into a surface network, the new gas causes
additional pressure drop through the network. The higher pressure propagates to
the wellheads of existing wells to cause rate drop from those wells. GasPal
dynamically calculates the rate and pressure at every surface pipe and vertical
tubing string. The rate reduction because of new gas is accurately calculated
and displayed.
In the following example, reservoir JUN joins the
network at month 36. The new gas causes a higher pressure at node 1.
Consequently, higher wellhead pressures at wells of reservoir SEN cause a rate
reduction in the same reservoir.
Compressor
Modeling
A compressor can be installed
at any node in the surface network. A compressor installation schedule controls
how compression is available at any given time. The following example shows
that a compressor installed at month 18 causes lower wellhead pressure and
higher production rate.
Storage
Modeling
GasPal models both withdrawal
and injection for storage reservoirs.
The following example shows the injection /withdrawal rates and
reservoir pressure for 365 days. Users specify injection, withdrawal or idle
for every time step (hourly, daily, weekly or monthly.) Daily time step is good for general, annual
planning; hourly time step can be used for tactic (weeks) operation planning.
