Patent ID: 8661888

Claim:
A method of studying properties of a rock mass, the method comprising: thermally disturbing the rock mass or a part thereof by circulating a fluid through a borehole using a tubing, wherein a temperature of the circulation fluid is different from a temperature of the rock mass, recording temperature along the borehole using temperature transducers, recording differential electrical signals that are proportional to a temperature difference between two points along the borehole before, during, and after the thermal disturbance, wherein the recording is performed continuously or periodically at time intervals of a pre-selected duration determined based on (i) properties of temperature noise in the borehole and (ii) a degree of possible deviation of thermal properties of the rock mass and the recording is performed by at least one pair of differential temperature transducers located along an axis of the borehole, so that a depth range of the location of the differential temperature transducers covers an area of the rock mass and distances between the transducers in the pairs and a number of the pairs are selected in advance based on (i) a required accuracy of determining a location of boundaries of rock mass areas with different properties, (ii) a minimum possible length and a maximum possible length of the rock mass areas, and (iii) the properties and a degree of the temperature noise in the borehole, comparing the differential electrical signals measured by the pairs of the differential temperature transducers before the thermal disturbance of the rock mass with the differential electrical signals measured by the same pairs of the differential temperature transducers during the thermal disturbance, comparing the differential electrical signals measured by different pairs of the differential temperature transducers located along the borehole axis, characterizing differences between the rock mass areas by their properties based on the results of the comparison of the differential electrical signals, and identifying boundaries between the rock mass areas with different thermal properties.