Methods of logging

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.

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.