Measuring hydraulic fracture apertures: a comparison of methods

摘要: Abstract. Hydraulic fracture apertures predominantly control fluid transport in fractured rock masses. Hence, the objective of current study is to investigate and compare three different laboratory-scale methods to determine hydraulic (Fontainebleau and Flechtinger) sandstone samples with negligible matrix permeability. Direct measurements were performed by using a flow-through apparatus a transient-airflow permeameter. In addition, microscope camera permitted measuring mechanical from which corresponding hydraulic indirectly derived applying various empirical correlations. Single fractures sample cores generated artificially either axial splitting or saw cut resulting in hydraulic that ranged between 8 66  µ m. Hydraulic apertures, accurately determined apparatus, are used results obtained other methods. The transient-airflow permeameter delivers accurate values, particularly when repeated measurements along full width are performed. this case, mean excellent quantitative agreement. When calculated indirectly from optically empirical equations, they show larger variations difficult the flow-through-derived results. Variations as observed between methods almost certainly related differences sampled fracture volume. Overall, direct a reference, this study demonstrates applicability portable to determine at both laboratory outcrop scales.