Instrumentation for determining rock mass permeability by hydro-pneumatic pressure testing

In order to eliminate the problems encountered with existing pressure test equipment, a downhole control unit was designed for conducting tests in NX boreholes. The unit maintains a preset minimum differential pressure between the packers and the test section, and controls inflation and deflation of the packers. The packer response to inflation and deflation commands is greatly increased in deep borings since the control unit is located downhole, and inflation is accomplished with the testing fluid (which is normally either water or air). For increased flexibility, the control unit was designed with the capacity for operating as either a single- or double-packer system by the use of simple ground surface control commands