# US 10,308,861 B2 · Methods of logging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,308,861 B2 - Document ID: US10308861B2 - Status: Granted - Kind: B2 - Application number: 15/400,438 - Filed: 2017-01-06 - Published: 2017-07-13 - Granted: 2019-06-04 - Earliest claimed: 2016-01-07 - Assignees: M-I L.L.C. - Applicants: M-I L.L.C. - Inventors: Balakrishnan Panamarathupalayam; Amr Essawi - Web page: https://patentgrep.com/patent/US10308861B2 ## CPC - C09K 8/52: Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning - C08F 220/54: Amides {, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide} - C08F 220/56: Acrylamide; Methacrylamide - C09K 8/035: Organic additives - C09K 8/12: containing synthetic organic macromolecular compounds or their precursors - C09K 8/5083: {obtained by reactions only involving carbon-to-carbon unsaturated bonds} - C09K 8/512: containing cross-linking agents - E21B 21/003: {Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138)} - E21B 37/00: Methods or apparatus for cleaning boreholes or wells (E21B21/00 takes precedence) - E21B 37/08: cleaning in situ of down-hole filters, screens, {e.g. casing perforations,} or gravel packs (E21B37/06 takes precedence) - E21B 43/082: {Screens comprising porous materials, e.g. prepacked screens} - E21B 43/10: Setting of casings, screens, liners {or the like} in wells - E21B 43/25: Methods for stimulating production {(by vibrating earth formations E21B43/003)} - G01V 3/20: operating with propagation of electric current - G01V 3/24: using AC - G01V 3/34: Transmitting data to recording or processing apparatus; Recording data - C08F 228/02: by a bond to sulfur - C09K 2208/26: Gel breakers other than bacteria or enzymes - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - 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 of electrically logging a section of a wellbore includes circulating a wellbore fluid within the wellbore, the wellbore fluid including a base fluid; and a crosslinked and branched polymeric fluid loss control agent formed from at least an acrylamide monomer and a sulfonated anionic monomer; wherein the fluid loss control agent has an extent of crosslinking that is selected so that the fluid loss control agent has a viscosity that is within a peak viscosity response of the viscosity response curve; placing within the wellbore a wellbore logging tool capable of applying an electrical current to the wellbore; applying electrical current from the logging tool; and collecting an electrical log of the portion of the wellbore that has had electrical current applied thereto. ## Claims ### Claim 1 A method of electrically logging a section of a wellbore, comprising: circulating a wellbore fluid within the wellbore, the wellbore fluid comprising: an aqueous base fluid; and a crosslinked and branched polymeric fluid loss control agent formed from at least an acrylamide monomer and a sulfonated anionic monomer; wherein the fluid loss control agent has an extent of crosslinking that is selected so that the fluid loss control agent has a viscosity that is within a peak viscosity response of a viscosity response curve, wherein the wellbore fluid exhibits a low end rheology that does not deviate by more than 30 percent under a temperature up to 300° F. when compared to low end rheology of the fluid at temperatures below about 250° F.; placing within the wellbore a wellbore logging tool capable of applying an electrical current to the wellbore; applying electrical current from the logging tool; and collecting an electrical log of the portion of the wellbore that has had electrical current applied thereto. ### Claim 2 (depends on 1) The method of claim 1, further comprising: moving the wellbore logging tool within the wellbore while continuously applying electrical current and collecting an electrical log. ### Claim 3 (depends on 1) The method of claim 1, further comprising: transmitting the electrical log to the surface. ### Claim 4 (depends on 1) The method of claim 1, wherein the acrylamide monomer is at least one selected from unsubstituted acrylamide, alkylacrylamides, N-methylol acrylamide, N-isopropyl acrylamide, diacetone-acrylamide, N-alkyl acrylamide, where alkyl is C1 to C14, N,N-dialkyl acrylamides, where alkyl is C1 to C14, N-cycloalkane acrylamides. ### Claim 5 (depends on 1) The method of claim 1, wherein the sulfonated anionic monomer is selected from 2-acrylamide-2-methyl-propanesulfonic acid, vinyl sulfonate, and styrene sulfonic acid. ### Claim 6 (depends on 1) The method of claim 1, wherein the wellbore fluid exhibits temperature stability up to 300° F. ### Claim 7 (depends on 1) The method of claim 1, wherein, after aging the wellbore fluid for at least 5 days at a temperature of at least 300° F., the wellbore fluid at 3 rpm, tested at 120° F., has a rheometer measured value of at least 5. ### Claim 8 (depends on 1) The method of claim 1, wherein the fluid loss control agent is present in the wellbore fluid at a concentration of about 0.5 to 15 lb/bbl. ### Claim 9 (depends on 1) The method of claim 1, wherein the fluid loss control agent has a percentage of intermolecular crosslinking that ranges from 0.25 to 10%. ### Claim 10 (depends on 1) The method of claim 1, wherein the peak viscosity response is defined as having an amount of crosslinker that correlates to the peak viscosity amount plus or minus the amount of crosslinker that correlates to up to 75% of the area under the viscosity response curve. ### Claim 11 (depends on 1) The method of claim 1, wherein the peak viscosity response is defined as having an amount of crosslinker that correlates to the peak viscosity amount plus or minus the amount of crosslinker that correlates to up to 75% of the area under the viscosity response curve. ### Claim 12 (depends on 1) The method of claim 1, wherein the electrical log consists of microresistivity measurement of one or more vertical segments of at least one selected from a wall of the wellbore and a formation structure associated with the wellbore. ### Claim 13 A system for electrically logging a section of a wellbore, comprising: a wellbore containing a wellbore fluid, the wellbore fluid comprising: a base fluid; and a crosslinked and branched polymeric fluid loss control agent formed from at least an acrylamide monomer and a sulfonated anionic monomer; wherein the fluid loss control agent has an extent of crosslinking that is selected so that the fluid loss control agent has a viscosity that is within a peak viscosity response of a viscosity response curve, wherein the acrylamide monomer is at least one selected from unsubstituted acrylamide, alkylacrylamides, N-methylol acrylamide, N-isopropyl acrylamide, diacetone-acrylamide, N-alkyl acrylamide, where alkyl is C1 to C14, N,N-dialkyl acrylamides, where alkyl is C1 to C14, N-cycloalkane acrylamides, wherein the sulfonated anionic monomer is selected from 2-acrylamide-2-methyl-propanesulfonic acid, vinyl sulfonate, and styrene sulfonic acid, wherein, after aging the wellbore fluid for at least 5 days at a temperature of at least 300° F., wellbore fluid at 3 rpm, tested at 120° F., has a rheometer measured value of at least 5; and a wellbore logging tool capable of applying an electrical current to the wellbore. ### Claim 14 (depends on 13) The system of claim 13, further comprising: a cable attached to the wellbore logging tool, the cable being capable of suspending the tool within the wellbore; and a winch attached to the cable, the winch being capable of reversibly moving the wellbore logging tool, via the cable, vertically and horizontally within the wellbore. ### Claim 15 (depends on 13) The method of claim 13, wherein the wellbore fluid exhibits a low end rheology that does not deviate by more than 30 percent under a temperature up to 300° F. when compared to low end rheology of the fluid at temperatures below about 250° F. ### Claim 16 (depends on 13) The method of claim 13, wherein the fluid loss control agent is present in the wellbore fluid at a concentration of about 0.5 to 15 lb/bbl. ### Claim 17 (depends on 13) The method of claim 13, wherein the fluid loss control agent has a percentage of intermolecular crosslinking that ranges from 0.25 to 10%. ### Claim 18 (depends on 13) The system of claim 13, wherein the polymeric fluid loss control agent has an average molecular weight range from 250 Da to 1,000 kDa. ### Claim 19 (depends on 18) The system of claim 18, wherein a ratio of the acrylamide monomer to the sulfonated anionic monomer is from 0.5:1 to 10:1. ### Claim 20 (depends on 19) The system of claim 19, wherein the ratio is from 1:1 to 5:1. ### Claim 21 A method of electrically logging a section of a wellbore, comprising: circulating a wellbore fluid within the wellbore, wherein the wellbore fluid comprises an aqueous base fluid and exhibits low end rheology that does not deviate by more than 30 percent under a temperature up to 300° F. when compared to low end rheology of the fluid at temperatures below about 250° F.; placing within the wellbore a wellbore logging tool capable of applying an electrical current to the wellbore; applying electrical current from the logging tool; and collecting an electrical log of the portion of the wellbore that has had electrical current applied thereto. ### Claim 22 (depends on 21) The method of claim 21, further comprising: moving the wellbore logging tool within the wellbore while continuously applying electrical current and collecting an electrical log. ### Claim 23 (depends on 21) The method of claim 21, further comprising: transmitting the electrical log to the surface.