In this paper, we summarize interpretations of 225 Diagnostic Injection Tests (DFITs) from the Montney Shale – all of the Montney datasets available from the Alberta Energy Regulator (AER). There are at least two commonly-used procedures for estimating stress from a DFIT – the ‘compliance method’ and the ‘tangent method.’ Both methods utilize plots of pressure versus G-time and estimate stress from the shape of the curve. However, the methods are based on different conceptual models, and they usually yield different results. We estimated stress using both procedures. We found that the compliance method stress estimate is average of 3638 kPa higher. The compliance method ‘net pressure’ estimate is an average of 2.26x lower. The difference between the two methods becomes greater when stress and pore pressure are further apart. When using the compliance method, it is sometimes not possible to estimate stress, depending on the shape of the pressure transient curve. To assess, we categorized each transient as having a ‘clear,’ ‘adequate,’ ‘weak,’ or ‘no’ compliance closure response. Of the DFITs reviewed, 84% had a clear response, 11% had an adequate response, 1% had a weak response, and 4% had no response. In contrast, a prior study by different investigators reviewed 80 of the Montney AER DFITs, a subset of the DFITs reviewed in this study, and reported a much lower percentage of tests – fewer than half – had a clear or adequate response. The discrepancy is evidently caused by differences in interpretation procedure. We have posted plots of all 225 tests, along with our annotations and interpretations, to an online data repository.
