Transient Pressure Testing

ScanWell Acoustic Metering provides a cost-effective solution for gathering critical late-time pressure data, enabling extended monitoring without the need for intrusive interventions. This approach is essential for understanding complex reservoir characteristics such as boundaries, heterogeneities, and dual-porosity effects in low-permeability gas reservoirs.

Benefits of Extended Monitoring with ScanWell

• Enhanced Reservoir Characterization: Obtain accurate estimates of reservoir permeability and porosity.
• Boundary Identification: Detect reservoir boundaries and heterogeneities with precision.
• Fracture Analysis: Gain insights into fracture network behavior and the effectiveness of well stimulation.
• Optimized Reservoir Management: Access valuable data to refine production strategies and improve long-term reservoir performance.

ScanWell’s technology ensures accurate, reliable results while reducing operational costs and minimizing downtime, empowering operators to maximize the value of their assets.

Key Considerations for Low-Permeability Reservoirs

1. Pressure Propagation Time:
   • In low-permeability formations, pressure disturbances from production or shut-in propagate very slowly through the reservoir.
   • Observing pressure responses at later times is essential to capture radial flow and reservoir boundary effects.
   • Shut-in durations can range from several days to weeks, depending on the reservoir’s permeability and size.
2. Late-Time Data Requirement:
   • For low-permeability reservoirs, late-time pressure data is critical to understanding reservoir characteristics such as boundaries, heterogeneities, and dual-porosity effects (if present).
   • Without sufficient monitoring, key insights into reservoir limits or connectivity may be missed.
3. Challenges with Gas Compressibility:
   • Gas compressibility amplifies the effect of low permeability, as gas expansion and storage within the formation can further slow the pressure stabilization process.
   • Monitoring must continue until the pressure response transitions from wellbore storage to radial or pseudo-steady-state flow.
4. Skin and Near-Wellbore Effects:
   • Low-permeability gas wells are often hydraulically fractured to enhance production. Early-time data reflects wellbore storage and fracture behavior, while extended monitoring is needed to observe the true reservoir response beyond the fracture zone.
5. Extended monitoring helps identify:
   • Reservoir boundaries (e.g., faults or pinch-outs).
   • Dual-porosity systems where pressure is influenced by both matrix and fracture flows.
   • Pseudo-steady-state flow, providing reliable estimates of permeability and porosity.

Operational Considerations

1. Extended Shut-In Period:
   • In very low-permeability reservoirs, shut-in durations can extend significantly, particularly for large reservoirs or those with complex boundary behaviours. Wireline resources maybe required on site during the whole shut-in period.
   • The exact duration depends on the time needed to observe stabilization and late-time pressure trends.
   • While extended monitoring provides valuable data, it increases operational costs due to deferred production.
   • Reservoir simulation models should guide the duration of testing to balance data needs and economic constraints.