# US 7,609,169 B2 · Electromagnetic telemetry apparatus and methods for minimizing cyclical or synchronous noise > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,169 B2 - Document ID: US7609169B2 - Status: Granted - Kind: B2 - Application number: 11/468,868 - Filed: 2006-08-31 - Published: 2008-03-20 - Granted: 2009-10-27 - Earliest claimed: 2006-08-31 - Assignees: Precision Energy Services, Inc. - Inventors: Robert Anthony Aiello - Web page: https://patentgrep.com/patent/US7609169B2 ## CPC - E21B 47/13: by electromagnetic energy, e.g. radio frequency - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract An electromagnetic well borehole telemetry system for transmitting information between a downhole transceiver, disposed preferably within a borehole assembly in the borehole, and a surface transceiver positioned at or near the surface of the earth. A trigger and cooperating strobe are used to define strobe increments. Synchronous telemetry measurements made during the strobe increments are algebraically summed to identify a synchronous cyclical noise component in a composite electromagnetic telemetry signal. Any non cyclical noise components occurring during the strobe increments algebraically cancel in the algebraic summing operation. The cyclical noise component is then removed from the composite signal thereby increasing the signal to noise ratio of the telemetry system. The system is particularly effective in minimizing electromagnetic noise generated by the rotation of a rotating element such as the rotary table or top drive of a drilling rig. ## Claims ### Claim 1 An electromagnetic telemetry system comprising: (a) a surface transceiver for measuring a composite signal; (b) a trigger sensitive to a stimulus and cooperating with a strobe to define a plurality of strobe increments; and (c) a processor cooperating with said surface transceiver (i) to algebraically sum increment composite noise signals measured during said plurality of strobe increments to define a cyclical noise component, and (ii) to combine said cyclical noise component with said composite signal to obtain a signal component. ### Claim 2 (depends on 1) The electromagnetic telemetry system of claim 1 wherein said stimulus comprises a predetermined azimuth point on a rotating element. ### Claim 3 (depends on 1) The electromagnetic telemetry system of claim 1 wherein said stimulus comprises a signal generated by a clock. ### Claim 4 A method for determining a signal component contained within a composite electromagnetic signal, the method comprising the steps of: (a) measuring said composite signal; (b) defining a plurality of strobe increments with a trigger sensitive to a stimulus and cooperating with a strobe; (c) measuring, during said plurality of strobe increments, increment composite noise signals; (d) summing algebraically said increment composite noise signals to define a cyclical noise component; and (e) combining said cyclical noise component with said composite signal to obtain said signal component. ### Claim 5 (depends on 4) The method of claim 4 comprising the additional step of defining said stimulus as a predetermined azimuth point on a rotating element. ### Claim 6 (depends on 4) The method of claim 4 comprising the additional step of defining said stimulus as signal generated by a clock. ### Claim 7 An MWD logging system comprising: (a) a downhole electromagnetic transceiver for transmitting a signal component from a downhole sensor; (b) a surface electromagnetic transceiver for measuring a composite signal comprising said signal component; (c) a trigger responsive to an azimuth point on a rotating element of a drilling rig and cooperating with a strobe to define a plurality of strobe increments; and (d) a processor cooperating with said surface transceiver (i) to algebraically sum increment composite noise signals measured during said plurality of strobe increments to define a cyclical noise component, and (ii) to combine said cyclical noise component with said composite signal to obtain said signal component. ### Claim 8 (depends on 7) The logging system of claim 7 wherein said cyclical noise component is normalized as a function of said definition of said plurality of said strobe increments. ### Claim 9 (depends on 7) The logging system of claim 7 further comprising a predetermined relationship for converting said signal component into a parameter of interest. ### Claim 10 (depends on 9) The logging system of claim 9 further comprising a recorder cooperating with said processor to generate a log of said parameter of interest. ### Claim 11 A method for determining a parameter of interest while drilling a borehole, the method comprising the steps of: (a) transmitting, with a downhole electromagnetic transceiver, a signal component from a downhole sensor; (b) receiving, with an electromagnetic surface transceiver, a composite signal comprising said signal component; (c) defining a plurality of strobe increments with a trigger responsive to an azimuth point on a rotating element of a drilling rig and cooperating with a strobe; and (d) algebraically summing increment composite noise signals measured during said plurality of strobe increments to define a cyclical noise component; (e) combining said cyclical noise component with said composite signal to obtain said signal component; and (f) converting said signal component into said parameter of interest using a predetermined relation. ### Claim 12 (depends on 11) The method of claim 11 comprising the additional step of normalizing said cyclical noise component as a function of said definition of said plurality of said strobe increments. ### Claim 13 (depends on 11) The method of claim 11 further comprising the step of generating a log of said parameter of interest. ### Claim 14 (depends on 11) The method of claim 11 wherein said strobe increment comprise equal arcs. ### Claim 15 (depends on 11) The method of claim 11 wherein said strobe increments are contiguous.