Injection well operators are responsible for the safety of the people and the environment surrounding the well during and after the injection process. Injection well testing is one method of ensuring optimum and safe well operations and waste disposal.
Injection is commonly used in oil fields for:
- Underground waste disposal
- Water flooding
- Enhanced Oil Recovery (EOR)
- CO2 sequestration…
…And other applications.
The two areas of concern during slurry injection are:
- Containment of injected materials
- Prevention of perceived seismic activity
Liquids and slurries are injected into target formations where they are expected to remain stored until removal. But what happens if the injection misses or damages the formation? Hydraulic fractures, which can be created depending on the reservoir properties and the pressure of the injection.
Risks of Fracture and Containment Loss
The fracture of a containment formation may cause the injection zone to breach through the overlying containment layers. If you lose containment, you risk waste escaping the target disposal formation. Injected fluids can breach to the surface through unconfined vertical fracture growth.
Prevent Containment Loss through Well Testing
The best way to prevent containment loss is through real-time monitoring of well performance and well injection testing, both during and after injection.
The least expensive methods for estimating reservoir and fracture parameters are well testing and pressure transient analysis. Both methods are required to fully evaluate the properties of the injection formation as well as the existence and characteristics of any hydraulic fractures that occur during the injection operation.
Production Well Tests
Production well tests estimate a variety of formation parameters to provide data for visualizing the reservoir model and behavior.
|Drill Stem Test||
During drilling phase.
|Draw Down Test||
After well is in production at constant flow rate after long shut-in.
|Pressure build-up Test||
By shutting in a production well that produces at a constant rate.
|Well Interference Test||
By observing the change of pressure while changing the flow rate.
Injection Well Tests
Injection well tests determine the pressure at which the adjacent rock breaks down, to estimate formation characteristics, and define fracture propagation.
During well completion.
During well completion.
After well is put on injection at constant flow rate after long shut-in.
|Pressure Fall-off Test||
By shutting down an injector that injects at constant flow rate.
|Step Rate Test||
By stepping up injection flow rate and recording injection pressure at each step.
Pressure Transient Analysis
Pressure Transient Analysis is conducted quarterly or annually. The goal is to determine fracture and formation properties including:
- Fracture closure pressure
- Fracture dimensions
- Formation conductivity
- Fracture linear flow
Regular monitoring enables safe, sustainable, long-term injection operations. Maintaining safe injection well operations requires real-time testing and monitoring to detect and assess potential formation fractures and prevent environmental contamination and overt seismic activity.
Advantek’s assists companies with long term well assurance and compliance through intelligent injection monitoring. In addition to standard techniques, we use our patent pending simulator @IPTTM, the world’s most advanced model for fall of test analysis of fractured completions.