T2-cutoff determination using magnetic susceptibility measurements

摘要

Systems and methods for determining T2 cutoff are described. T2 cutoff can be derived from magnetic susceptibility measurements. By providing a depth curve of T2cutoff, improved permeability estimations from NMR can be generated. By combining a magnetic susceptibility tool and an NMR tool, a dynamic T2cutoff can then be provided, together with the standard NMR log, according to some embodiments. According to some embodiments the improved permeability estimations can be provided automatically and in real time at the wellsite.

主权项

1. A method of determining T2 cutoff in a subterranean rock formation comprising:
receiving, from a first downhole tool positioned proximate a rock medium in the subterranean rock formation, magnetic susceptibility data representing magnetic susceptibility measurements made of the rock medium; utilizing the received magnetic susceptibility data of the rock medium as a proxy in order to calculate over time an estimated value of a T2 cutoff; receiving from a second downhole tool, also positioned proximate the rock medium, a T2 distribution of data representing NMR measurements of the rock medium; and applying the estimated value of the T2 cutoff to the T2 distribution of data representing NMR measurements of the rock medium, in order to thereby derive one or more of:
a permeability of the rock medium; anda location of a non-moveable fluid in the rock medium; wherein one or more of the permeability of the rock medium and the location of the non-moveable fluid in the rock medium is provided as an output to a user.