Method for determining formation characteristics with enhanced vertical resolution

Claim 1

A method for determining the density of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors in response to the signal from the signal source received by the at least two signal sensors; (d) generating the individual density responses from the at least two sensor signals; (e) matching the vertical resolution of the generated densities from the at least two signals; (f) determining an environmentally compensated density from the at least two resolution matched individual densities; (g) determining the differences between the compensated density of step (f) and the resolution matched density from the sensor spaced the least distance from the signal source; and, (h) combining the result of step (g) with the unmatched density response, from step (d), of the sensor placed nearest the source to determine the density wherein the vertical resolution of the density is enhanced.

Claim 2

A method for determining the density of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors in response to the signal from the signal source received by the at least two signal sensors; (d) generating the individual density responses from the at least two sensor signals; (e) matching the vertical resolution of the generated densities from the at least two signals; (f) determining an environmentally compensated density from the at least two resolution matched individual densities; (g) determining the differences between the compensated density of step (f) and the resolution matched density from the sensor spaced the least distance from the signal source; and, (h) combining the result of step (g) with the unmatched density response, from step (d), of the sensor placed nearest the source to determine the density wherein the vertical resolution of the density is enhanced.

Claim 6

A method for determining the porosity index of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors, in response to the signal from the signal source received by the at least two signal sensors; (d) generating the individual porosity index responses from the at least two sensor signals; (e) matching the vertical resolution of the generated porosity index responses from the at least two signals; (f) determining an environmentally compensated porosity index from the at least two resolution matched porosity index responses; (g) determining a continuous calibration factor utilizing the environmentally compensated porosity index of step (f) and the resolution matched porosity index responses, from step (e), of the signal sensor spaced the least distance from the signal source; and (h) determining a porosity index wherein the vertical resolution of the porosity index is enhanced, by applying the continuous calibration factor from step (g), to the unmatched porosity index response from step (d), for the sensor spaced nearest the source.

Claim 7

A method for determining the porosity index of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors, in response to the signal from the signal source received by the at least two signal sensors; (d) generating the individual porosity index responses from the at least two sensor signals; (e) matching the vertical resolution of the generated porosity index responses from the at least two signals; (f) determining an environmentally compensated porosity index from the at least two resolution matched porosity index responses; (g) determining a continuous calibration factor utilizing the environmentally compensated porosity index of step (f) and the resolution matched porosity index responses, from step (e), of the signal sensor spaced the least distance from the signal source; and (h) determining a porosity index wherein the vertical resolution of the porosity index is enhanced, by applying the continuous calibration factor from step (g), to the unmatched porosity index response from step (d), for the sensor spaced nearest the source.

Claim 13

A method for determining a characteristic of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors in response to the signal from the signal source received by the at least two signal sensors; (d) determining individual formation characteristics from the signals from the at least two sensors; (e) matching the vertical resolution of the generated formation characteristic responses from the at least two signal sensors; (f) determining an enrivonmentally compensated characteristic of the subsurface geological formation from a combination of the resolution-matched individual characteristic responses; (g) determining a continuous calibration factor by utilizing the environmentally compensated characteristic of step (f) and the resolution matched formation characteristic response from the signal sensor spaced the least distance from the signal source; and (h) determining the desired characteristic by combining the unmatched characteristic response from step (d), of the sensor spaced the least distance from the source with the continuous calibration factor of step (g) wherein the vertical resolution of the desired characteristic is enhanced.

Claim 14

A method for determining a characteristic of a subsurface geological formation traversed by a borehole, comprising the steps of: (a) passing a logging tool through the borehole, the logging tool having associated therewith a signal source and at least two signal sensors spaced from the signal source by different distances; (b) transmitting a signal from the signal source into the subsurface geological formation; (c) generating sensor signals from the at least two signal sensors in response to the signal from the signal source received by the at least two signal sensors; (d) determining individual formation characteristics from the signals from the at least two sensors; (e) matching the vertical resolution of the generated formation characteristic responses from the at least two signal sensors; (f) determining an enrivonmentally compensated characteristic of the subsurface geological formation from a combination of the resolution-matched individual characteristic responses; (g) determining a continuous calibration factor by utilizing the environmentally compensated characteristic of step (f) and the resolution matched formation characteristic response from the signal sensor spaced the least distance from the signal source; and (h) determining the desired characteristic by combining the unmatched characteristic response from step (d), of the sensor spaced the least distance from the source with the continuous calibration factor of step (g) wherein the vertical resolution of the desired characteristic is enhanced.