Patent ID: 9074988
Filing Date: 2015-07-07
Classification: E21B,G01N,G02B

Abstract:
1. A system for controlling hydrogen concentration in optical sensing systems in subsurface wells, comprising: a. at least one optical fiber line; b. at least one tubular conduit, the at least one optical fiber line being positioned within the at least one tubular conduit; c. a hydrogen gas system for flowing a hydrogen flush gas of known concentration from the surface side of the subsurface well into the subsurface well through the at least one tubular conduit; d. wherein the at least one optical fiber line has a known optical attenuation per unit length vs. wavelength, and a known downhole total optical attenuation; e. wherein the at least one tubular conduit is positioned from the surface side of the subsurface well in a first direction to a prescribed subsurface distance and then is reversed through a 180 degree turnaround into an opposite direction and returned the surface; f. wherein the at least one optical fiber line is single ended and deployed only to the 180 turnaround; and g. wherein the controlled concentration hydrogen gas is flowed downhole in the at least one tubular conduit and returns to the surface.