Evaluation of liquid-containing samples using nuclear magnetic resonance

Claim 1

A method of evaluating the potential production characteristics of a zone of a subterranean formation which extends between a first depth and a second depth comprising: (a) obtaining at least one sample of the formation from the zone; (b) substantially saturating the sample with a saturating liquid comprising water; (c) subjecting the thus saturated sample to a static magnetic field, oriented in a first direction and along a reference frame axis, so as to substantially align the nuclear magnetization of the saturating liquid with the static magnetic field; (d) subjecting the sample during step (c) to at least one radio frequency pulse, at a resonant frequency with respect to preselected nuclei in the saturating liquid, so as to substantially invert the magnetization of such preselected nuclei to an orientation in a second direction substantially opposite to the first direction; (e) detecting, at a predetermined delay time following the radio frequency pulse of step (d), a component of the magnetization of the preselected nuclei which is parallel to the reference frame axis; (f) repeating steps (d) and (e) for at least one other delay time; (g) determining, from the magnetization component values and corresponding delay times obtained in (e) and (f), the delay time at which the magnetization component is about 0, hereinafter referred to as the NMR zero time; and (h) determining if the zone is potentially productive of hydrocarbons which are substantially free of water based on the NMR zero time obtained in step (g).

Claim 2

A method of evaluating the potential production characteristics of a zone of a subterranean formation which extends between a first depth and a second depth comprising: (a) obtaining at least one sample of the formation from the zone; (b) substantially saturating the sample with a saturating liquid comprising water; (c) subjecting the thus saturated sample to a static magnetic field, oriented in a first direction and along a reference frame axis, so as to substantially align the nuclear magnetization of the saturating liquid with the static magnetic field; (d) subjecting the sample during step (c) to at least one radio frequency pulse, at a resonant frequency with respect to preselected nuclei in the saturating liquid, so as to substantially invert the magnetization of such preselected nuclei to an orientation in a second direction substantially opposite to the first direction; (e) detecting, at a predetermined delay time following the radio frequency pulse of step (d), a component of the magnetization of the preselected nuclei which is parallel to the reference frame axis; (f) repeating steps (d) and (e) for at least one other delay time; (g) determining, from the magnetization component values and corresponding delay times obtained in (e) and (f), the delay time at which the magnetization component is about 0, hereinafter referred to as the NMR zero time; and (h) determining if the zone is potentially productive of hydrocarbons which are substantially free of water based on the NMR zero time obtained in step (g).

Claim 11

A method of determining the residual saturation of a sample of a porous media with respect to a saturating liquid, comprising: (a) substantially saturating the sample with the saturating liquid; (b) subjecting the thus saturated sample to a static magnetic field, oriented in a first direction and along a reference frame axis, so as to substantially align the nuclear magnetization of the saturating liquid with the static magnetic field; (c) subjecting the sample during step (b) to at least one radio frequency pulse, at a resonant frequency with respect to preselected nuclei in the saturating liquid, so as to substantially invert the magnetization of such preselected nuclei to an orientation in a second direction substantially opposite to the first direction; (d) detecting, at a predetermined delay time following the radio frequency pulse of step (c), a component of the magnetization of the preselected nuclei which is parallel to the reference frame axis; (e) repeating steps (c) and (d) for at least one other delay time; (f) determining, from the magnetization component values and corresponding delay times obtained in steps (d) and (e), the delay time at which the magnetization component is about 0, hereinafter referred to as the NMR zero time; and (g) determining the residual saturation of the sample with respect to the saturating liquid based on the NMR zero time obtained in step (f).

Claim 12

A method of determining the residual saturation of a sample of a porous media with respect to a saturating liquid, comprising: (a) substantially saturating the sample with the saturating liquid; (b) subjecting the thus saturated sample to a static magnetic field, oriented in a first direction and along a reference frame axis, so as to substantially align the nuclear magnetization of the saturating liquid with the static magnetic field; (c) subjecting the sample during step (b) to at least one radio frequency pulse, at a resonant frequency with respect to preselected nuclei in the saturating liquid, so as to substantially invert the magnetization of such preselected nuclei to an orientation in a second direction substantially opposite to the first direction; (d) detecting, at a predetermined delay time following the radio frequency pulse of step (c), a component of the magnetization of the preselected nuclei which is parallel to the reference frame axis; (e) repeating steps (c) and (d) for at least one other delay time; (f) determining, from the magnetization component values and corresponding delay times obtained in steps (d) and (e), the delay time at which the magnetization component is about 0, hereinafter referred to as the NMR zero time; and (g) determining the residual saturation of the sample with respect to the saturating liquid based on the NMR zero time obtained in step (f).