Patent ID: 8230918

Claim:
A method of analyzing formation fractures in formation rock of interest in a subsurface hydrocarbon reservoir to characterize the petrophysical properties of the fractures based on measurements obtained from magnetic instrumentation in a well tool assembly having inflatable packers therewith, comprising the steps of: lowering the well tool assembly in a well borehole in the reservoir to a position adjacent the formation rock of interest; isolating a formation test section of the formation rock of interest adjacent the well borehole in the reservoir from fluid flow from other portions of the reservoir by inflation of at least one of the inflatable packers of the well tool assembly at the position adjacent the formation rock of interest; obtaining base magnetic readings from the isolated formation test section with the magnetic instrumentation in the well tool assembly; determining a base magnetic parameter of the formation rock of interest based on the obtained base magnetic readings from the isolated formation test section; injecting a volume of a magnetic fluid into the isolated formation test section to enhance the magnetic parameters of the isolated formation test section while the well tool assembly is in position in the well borehole isolating the formation test section; obtaining enhanced magnetic readings with the magnetic instrumentation in the well tool assembly from the isolated formation test section containing the injected volume of magnetic fluid; determining an enhanced magnetic parameter of the formation rock of interest based on the enhanced magnetic readings obtained from the isolated formation test section with the volume of injected magnetic fluid therein; and determining from the base magnetic parameter, the enhanced magnetic parameter of the formation rock of interest, and the injected volume of magnetic fluid a characterization of the petrophysical properties of the formation fractures in the formation rock of interest in the subsurface hydrocarbon reservoir.