Advances in Diagnostic Fracture Injection Testing for Exploration and Development Applications in Unconventional Reservoirs

Diagnostic Fracture Injection Tests (DFITs) have become the most popular well-testing method for unconventional reservoir evaluation. The conventional DFIT (or “mini-fracture test”) consists of a sequence of injection, to initiate and propagate a mini-fracture, followed by a shut-in period. The pressure falloff period after shut-in is interpreted for important information used in hydraulic-fracture design such as instantaneous shut-in pressure (ISIP), closure pressure (a proxy for minimum in-situ stress), reservoir pressure and reservoir transmissibility. However, reservoir properties from after-closure reservoir flow regimes may require days or even weeks to obtain using the conventional (pump-in/falloff) DFIT. As an alternative, the author and his research group have proposed a modified DFIT to accelerate the time to reach closure pressure and reservoir information. The new test, referred to as ‘DFIT-FBA’ involves the sequence of pump-in/flowback where reservoir information is obtained from flowback data using classic rate-transient analysis (RTA) methods. Initial field trials indicate DFIT-FBA can be used to obtain reservoir information (e.g. reservoir pressure) in typically < 2 hours, in contrast to days or weeks for conventional DFITs.

In this webinar, the conventional and DFIT-FBA methods are compared and advantages/disadvantages discussed. The speed of DFIT-FBA compared to the conventional DFIT opens up new avenues for application of DFITs. Use of the DFIT-FBA for selecting targets for horizontal wells in an exploration program is demonstrated, as is the first-time application of DFIT-FBA (and DFITs in general) for characterizing along-well reservoir quality variability in a horizontal well. The webinar should be of interest to engineers involved in hydraulic-fracture stimulation design and reservoir characterization.

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