Use of PNC tools to determine the depth and relative location of proppant in fractures and the near borehole region

A method for determining the location and height of gravel-pack particles placed in a gravel-pack zone inside a casing of a cased borehole within a subterranean formation as a result of a gravel-pack procedure, comprising:

• utilizing a gravel-pack slurry comprising a liquid and gravel-pack particles to hydraulically place the particles into a region of the cased borehole, wherein all or a fraction of such gravel-pack particles includes a thermal neutron absorbing material;
• obtaining a post-gravel-pack data set by:
• (i) lowering into the borehole traversing a subterranean formation a pulsed neutron capture logging tool comprising a pulsed neutron source and a detector,
• (ii) emitting pulses of neutrons from the last-mentioned neutron source into the borehole and the subterranean formation,
• (iii) detecting in the borehole thermal neutrons or capture gamma rays resulting from nuclear reactions in the borehole and the subterranean formation, and
• (iv) measuring a capture cross-section of a borehole component and a time gated count rate from borehole and formation decay, wherein the time gated count rate from borehole and formation decay is measured within a time gate interval more than 400 μsec after the end of the neutron pulse;
• utilizing the post-gravel-pack data set to determine the location of the gravel-pack particles;
• and
• correlating the location of the gravel-pack particles to a depth measurement of the borehole to determine the location, height, and/or percent fill of gravel-pack particles placed in the gravel-pack zone inside the casing.

A method for determining the quality and consistency of a gravel-pack placed inside a casing of a cased borehole within a subterranean formation as a result of a gravel-pack procedure, comprising:

• modeling a percent fill of gravel pack particles in the cased borehole based on a simulation utilizing conditions of the borehole and the casing to provide a gravel-pack model;
• utilizing a gravel-pack slurry comprising a liquid and gravel-pack particles to hydraulically place the particles into a region of the cased borehole, wherein all or a fraction of such gravel-pack particles includes a thermal neutron absorbing material;
• obtaining a post-gravel-pack data set by:
• (i) lowering into the borehole traversing a subterranean formation a pulsed neutron capture logging tool comprising a pulsed neutron source and a detector,
• (ii) emitting pulses of neutrons from the last-mentioned neutron source into the borehole and the subterranean formation, and
• (iii) detecting in the borehole thermal neutrons or capture gamma rays resulting from nuclear reactions in the borehole and the subterranean formation,
• utilizing the post-gravel-pack data set to determine the location of the gravel-pack particles;
• correlating the location of the gravel-pack particles to a depth measurement of the borehole to provide a gravel-pack measurement;
• and
• comparing the gravel-pack measurement with the gravel-pack model to determine the quality and/or percent fill of the gravel-pack particles placed inside the casing.

A method for determining the location and height of frac-pack particles placed inside a casing of a cased borehole and in fracture(s) in a subterranean formation as a result of a frac-pack procedure, comprising:

• utilizing a frac-pack slurry, comprising a liquid and frac-pack particles to hydraulically fracture the subterranean formation to generate a fracture and to place the particles into the fracture and also into a frac-pack zone portion of the cased borehole in the vicinity of the fracture, wherein all or a fraction of such frac-pack particles includes a thermal neutron absorbing material;
• obtaining a post-frac-pack data set by:
• (i) lowering into the borehole traversing the subterranean formation a pulsed neutron capture logging tool comprising a pulsed neutron source and a detector,
• (ii) emitting pulses of neutrons from the last-mentioned neutron source into the borehole and the subterranean formation,
• (iii) detecting in the borehole thermal neutrons or capture gamma rays resulting from nuclear reactions in the borehole and the subterranean formation
• utilizing the post-frac-pack data set to determine the location of the frac-pack particles inside the casing;
• and correlating the location of the frac-pack particles to a depth measurement of the borehole to determine at least one selected from the group consisting of the location, axial distribution, radial distribution, and height of frac-pack particles placed inside the casing borehole region in the vicinity of the fracture and to assist in determining the location and height of fracture(s) in the formation.

A method for determining the location and height of gravel-pack particles placed in a gravel-pack zone inside a casing of a cased borehole within a subterranean formation as a result of a gravel-pack procedure, comprising:

• utilizing a gravel-pack slurry comprising a liquid and gravel-pack particles to hydraulically place the particles into a region of the cased borehole, wherein all or a fraction of such gravel-pack particles includes a thermal neutron absorbing material;
• obtaining a post-gravel-pack data set by:
• (i) lowering into the borehole traversing a subterranean formation a pulsed neutron capture logging tool comprising a pulsed neutron source and a detector,
• (ii) emitting pulses of neutrons from the last-mentioned neutron source into the borehole and the subterranean formation,
• (iii) detecting m the borehole thermal neutrons or capture gamma rays resulting from nuclear reactions in the borehole and the subterranean formation,
• utilizing the post-gravel-pack data set to determine the location of the gravel-pack particles;
• and
• correlating the location of the gravel-pack particles to a depth measurement of the borehole to determine the location, height, and/or percent fill of gravel-pack particles placed in the gravel-pack zone inside the casing.