1 October 2004 Cutting-Edge Software for Managing Gas Production and Storage Operations

2 1.Goal of forthcoming initial release targeted for 1 st Quarter, 2005: Accurate prediction of performance of gas storage reservoir/compressor/pipeline systems with a speed that allows hourly/daily scheduling of compressors for production and injection. Schedules obtained are efficient and economic. Given a complete database GasPal allows operations to be quickly rescheduled in response to new opportunities or unexpected changes in available equipment and/or supply/demand requirements. GasPal, focusing on operational planning, is a logical counterpart to Maraco’s GasTop software, which performs optimal investment planning for storage operations.

3 GasPal Characteristics GasPal: foundation is a PC-based gas reservoir simulator. GasPal: complex surface network may include splits, loops and multiple offtake points. GasPal: each of several reservoirs may have up to 5 producing layers GasPal: GRIDDER™ preprocessor inserts arbitrary number of computing cells into each reservoir. GasPal: simulates injection and production or a mixture of the two, providing full storage scheduling flexibility. GasPal: hourly, daily or monthly time steps accommodate short-, mid- and long-term planning needs. GasPal: optimizes service allocation and size of possible compressor configurations.

4 Operational Planning Scope 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 : monthly time step for 30 years. Useful for regular gas reservoir production or blowdown.

5 Surface Flow Capabilities: Splits, Loops & Offtake Points Produce against or inject with a given back pressure Produce or inject a requested rate profile Split flow at node Choke total flow or either flowline

6 Surface Line Capabilities: Multiple Reservoirs Choke each producing cell and/or reservoir to produce requested rate Each cell in each reservoir may have different characteristics

7 Surface Line Capabilities: Compressor Optimization Compressor locations and sizes optimized to maximize withdrawal, injection and inventory revenues Work is now underway on GasPal’s compressor scheduling capability

8 Reservoir: Arbitrary Number Of Simulation Cells Faults Computing mesh generated by GRIDDER

9 Reservoir: Multiple Layers

10 Results From Current Development Version Of GasPal October 2004

11 Interface Layout Surface network Output Results Reservoirs Offtake points

12 Reservoir Output

13 Flow Rate Through Each Pipe

14 Pressure Drop Across Each Pipe

15 Offtake Rate: Fixed Back Pressure

16 Pressure: With Offtake Rate Fixed

17 Bi-directional Flows Gas flow direction is determined by system pressure distribution

18 Reverse Flow Dictated by pressure at end nodes, flow can be reversed Reversed flow displayed as “negative”