Using Umbrella Deconstruction & Energy Dispersive Spectrometer (UD-EDS) technique to quantify the anisotropic elements distribution of Chang 7 shale and its significance

This study utilizes the experimental technique named Umbrella Deconstruction & Energy Dispersive Spectrometer (UD-EDS) method to quantify the anisotropic element distribution of shale which has been proved significant in the stimulation of shale. Direct quantification of anisotropic distribution of element in shale from the Triassic Yanchang formation in the HJS district was carried out to ensure both observational resolution and sample representativeness. Results show that many types of elements distribution vary in eight directions. The element contents are similar in three directions - 90 degrees (270 degrees), 112.5 degrees (292.5 degrees) and 135 degrees (315 degrees), they are quite different from which in other five directions, which has obvious significance in shale stimulation. Results also prove that the evidence of dominant fracture direction in fracturing can be found in brittle minerals. As to Chang 7 shale, the dominant fracture direction of shale reservoir is distributed in a specific area instead of overall extending along a single direction. In this specific area the best dominant fracture direction can be found. The subsequent results would offer the microscopic evidences for the shale fracturing and point to an innovative direction for research on exploration and development of the unconventional oil and gas. (C) 2019 Elsevier Ltd. All rights reserved.