Selection of the Flowback Rate for DFIT-Flowback Test

Abstract

The DFIT-flowback test has shown some advantages in terms of running time and accuracy over typical injection tests such as DFITs specially in very low permeability formations. However, the success of the test depends largely on choosing an appropriate flowback rate to achieve acceptable results. The hidden assumption behind analysis is assuming uniform closure of fractures at the last step of the tests. Basically, the uniform closure is the only considered form of fracture closure in all the existing analyses for this test. Here, we show how adjusting flowback rates may change fracture closure mode and how to interpret field data accordingly. Often abnormality in the data acquired from pump-in/flowback tests have posed challenges in the widespread application of this test. Here, we use scaling analysis verified by numerical simulations to describe different situations may occur during this test and how to interpret abnormal data. Using scaling analysis does not require running complicated simulations and can provide quick solutions in field operations. Using this method can hopefully make DFIT-flowback more popular in the field.