Experimental study of hydraulic fracture containment in layered reservoirs

摘要

This paper presents the results of an experimental study of hydraulic fracture containment carried out with an analogue layered reservoir constructed from transparent materials. These experiments include (i) abrupt stress contrasts between layers; (ii) weak interfaces; and (iii) contrast of material properties between the reservoir and bounding layers. Different geometries, including the propensity for height growth and/or "T-shaped" growth have been observed. There are four observed cases: containment, height growth, T-shape growth and the combination of height growth and T-shape. The results indicate that these cases fall within distinct regions when plotted in a two-dimensional parametric space defined by: 1) horizontal confining stress difference between the reservoir and barriers ("stress jump") normalized by the difference between the measured fluid pressure and the horizontal stress in the reservoir ("net pressure"); and 2) difference between horizontal barrier stress and vertical stress normalized by the net pressure. Besides providing data for benchmarking numerical models, these experiments show that the observed height growth for the zero-toughness cases with no T-shaped growth is substantially less than the prediction from the conventional equilibrium height growth models.