In this study, we propose a new method for estimating average fracture compressibility (cf¯) during flowback process, and apply it on flowback data from thirty multi-fractured horizontal wells completed in Eagle Ford, Horn River, Montney and Woodford formations. We conduct complementary diagnostic flow regime analyses and calculate cf¯ by combining a flowing material balance equation with rate-decline analysis.

We observe two production signatures during flowback: (1) single-phase water production followed by hydrocarbon breakthrough and (2) immediate production of hydrocarbon with water. Water rate-normalized-pressure plots show pronounced unit slopes, suggesting pseudo-steady state flow. Water decline curves follow a harmonic trend during multiphase flow; from which we forecasted ultimate water production as an estimate of initial fracture volume. The cf¯ estimates are within the range of 7 – 200 × 10-6 psi-1, and are generally lower than the values previously estimated using Aguilera’s type curves and DFIT data. Also, cf¯ estimates for deeper dry gas wells are relatively higher than those for shallower oil wells.

Keywords:
Upstream Oil & Gas, flowback data, shale gas, compressibility, complex reservoir, average fracture compressibility, hydraulic fracturing, Aguilera, flowback, flowback data analysis
Subjects:
Hydraulic Fracturing, Formation Evaluation & Management, Unconventional and Complex Reservoirs, Drillstem/well testing, Shale gas
Copyright 2019, Society of Petroleum Engineers
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