A quadruple packer tool for conducting hydraulic stress measurements in mines and other high stress settings

摘要

The new high capacity tool for hydraulic stress measurements, the VQJPT, has successfully been developed. This tool consists of four inflatable packer elements, with a configuration that allows pressurization of the inner test section of up to about 70MPa in a 76 mm borehole. The tool may also be employed in larger-diameter boreholes, but at a reduced pressurization level. However, it is also possible to replace existing packer elements with larger-diameter elements. Testing of the new equipment was unproblematic, with —exception of the leakage problem of the test tube during the second set of the laboratory tests. As a result, the tool was not tested to its maximum level. Nevertheless, the functionality was proven, which was also later verified in the field campaign at the Malmberget mine of LKAB. The observed pressures were relatively moderate (maximum recorded pressure was 42MPa), but this level justifies the development of the tool as testing with a conventional straddle packer would not have been successful.