# US 8,274,288 B2 · Multi-transient DC resistivity measurements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,274,288 B2 - Document ID: US8274288B2 - Status: Granted - Kind: B2 - Application number: 11/990,035 - Filed: 2006-08-04 - Published: 2010-12-16 - Granted: 2012-09-25 - Earliest claimed: 2005-08-05 - Assignees: MTEM Ltd - Inventors: Antoni Marjan Ziolkowski; Bruce Alan Hobbs - Web page: https://patentgrep.com/patent/US8274288B2 ## CPC - G01V 3/02: operating with propagation of electric current - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract A method for measuring resistivity variations in the earth comprising passing a transient current between two source electrodes; measuring the transient current at the source electrodes; measuring the resultant transient voltage between at least one pair of receiver electrodes; estimating one or more processing functions for applying to the measured input current to provide a step current profile, and applying the same one or more processing functions to the measured voltage to provide an estimate of the step response voltage between the receivers, using both the step current and the estimated step response voltage to determine the resulting apparent earth resistance, and using the apparent earth resistance to determine the resistivity of the earth. ## Claims ### Claim 1 A method for measuring resistivity variations in the earth comprising passing a transient current between two source electrodes; measuring the transient current at the source electrodes; measuring the resultant transient voltage between at least one pair of receiver electrodes; estimating one or more processing functions for applying to the measured input current to provide a step current profile, and applying the same one or more processing functions to the measured voltage to provide an estimate of a step response voltage between the receivers, using both the step current and the estimated step response voltage to determine a resulting apparent earth resistance, and using the apparent earth resistance to determine the resistivity of the earth. ### Claim 2 (depends on 1) A method as claimed in claim 1 wherein the step of applying the estimated processing function to the measured voltage involves convolution of the received voltages with the estimated processing function to find the corresponding step responses. ### Claim 3 (depends on 1) A method as claimed in claim 1 wherein the processing function is a filter for converting the measured input current to the step profile. ### Claim 4 (depends on 1) A method as claimed in claim 1 wherein the one or more processing functions comprise a filter for converting the measured current to an impulse and means for integrating the result to obtain the step input profile. ### Claim 5 (depends on 1, 2, 3, 4) A method as claimed in any of claims 1, 2, 3 or 4 comprising removing cultural noise. ### Claim 6 (depends on 1, 2, 3, 4) A method as claimed in any of claims 1, 2, 3 or 4 comprising estimating a steady state voltage from a step response. ### Claim 7 (depends on 1, 2, 3, 4) A method as claimed in any of claims 1, 2, 3 or 4 wherein the source and receiver electrodes are provided in a marine environment. ### Claim 8 A system for measuring resistivity variations in the earth comprising a source for passing a current between two source electrodes; a measurement device for measuring the transient current at the source electrodes; a voltage measurement device for measuring the resultant transient voltage between at least one pair of receiver electrodes; and a processor configured to estimate one or more processing functions for applying to the measured input current to provide a step current profile; apply the same one or more processing functions to the measured voltage to provide an estimate of a step response voltage between the receivers, use both the step current and the estimated step response voltage to determine a resulting apparent earth resistance, and use the apparent earth resistance to determine the resistivity of the earth. ### Claim 9 (depends on 8) A system as claimed in claim 8 wherein the processor is operable to apply the estimated processing function to the measured voltage by convolution of the received voltages with the estimated processing function to find the corresponding step responses. ### Claim 10 (depends on 8) A system as claimed in claim 8 wherein the processing function is a filter for converting the measured input current to the step profile. ### Claim 11 (depends on 8) A system as claimed in claim 8 wherein the one or more processing functions comprise a filter for converting the measured current to an impulse and means for integrating the result to obtain the step input profile. ### Claim 12 (depends on 8, 9, 10, 11) A system as claimed in any of claims 8, 9, 10 or 11 wherein the processor is operable to remove cultural noise. ### Claim 13 (depends on 8, 9, 10) A system as claimed in any of claims 8, 9, 10, or 11 wherein the processor is operable to estimate a steady state voltage from a step response. ### Claim 14 (depends on 8, 9, 10, 11) A system as claimed in any of claims 8, 9, 10 or 11 wherein the source and receiver electrodes are provided in a marine environment.