Apparatus and methods for monitoring a core during coring operations

A formation core analysis method, comprising:

• measuring resistivity of a formation core while the core displaces into a core barrel assembly, the measuring being performed with multiple longitudinally spaced apart first sets of transmitters and receivers;
• measuring resistivity of a formation external to the core barrel assembly while a coring bit penetrates the formation, the measuring being performed with multiple longitudinally spaced apart second sets of transmitters and receivers, wherein a speed of displacement of the coring bit into the formation is indicated by differences between measurements taken via the second sets of transmitters and receivers as the coring bit penetrates the formation;
• and
• determining a speed of displacement of the core into the core barrel assembly, based at least in part on differences between measurements taken via the first and second sets of transmitters and receivers as the core displaces into the core barrel assembly, wherein a collapse of the core is indicated by a difference between the speed of displacement of the core and the speed of displacement of the coring bit.

A method of determining a speed of displacement of a formation core into a core barrel assembly as the core is being cut, the method comprising:

• transmitting electromagnetic waves into the core as the core is being cut and measuring the resistivity of the core with longitudinally spaced apart sets of transmitters and receivers;
• measuring resistivity of a formation external to the core barrel assembly by transmitting electromagnetic waves into the formation as the formation is being cut by a coring bit;
• comparing the resistivities measured by the longitudinally spaced apart sets of transmitters and receivers;
• and
• determining the speed of displacement of the core into the core barrel assembly relative to a speed of displacement of the coring bit into the formation, based at least in part on the comparing.