Systems and methods of logging in a well include utilizing a solidifying fluid, such as magnetorheological fluid, in at least one annulus surrounding a logging tool. Given production tubing may remain in the well during the logging as desired for efficiency, space between the production tubing and a casing string may form the annulus. Filling the annulus with the solidifying fluid and selective activation of the solidifying fluid to a solidified state during the logging limits interference in data collected as a result of transmitting across the annulus. Deactivation of the solidifying fluid to a liquefied state enables recovery of the solidifying fluid from the well after the logging. Embodiments employ the logging in various applications, such as assessing a cemented casing string in well abandonment operations.