Abstract: A gamma ray logging system and a method of calibrating a detected gamma radiation spectrum. The gamma ray logging system includes a gamma ray detector for detecting gamma radiation, an analyzer for generating a detected gamma radiation spectrum from the detected gamma radiation, and a processor which is configured to perform a calibration of the detected gamma radiation spectrum. The method of calibrating the detected gamma radiation spectrum includes selecting at least two data points from the detected gamma radiation spectrum, determining a mathematical relationship from the selected data points, and using the mathematical relationship to generate a calibrated gamma radiation spectrum from the detected gamma radiation spectrum.

Abstract: A tubing plug is adapted for insertion into a tubing string for sealing the tubing string. The tubing plug is comprised of a housing having an outer surface, wherein the housing is adapted for insertion in the tubing string such that an annulus is defined between the tubing string and the outer surface of the housing and wherein the housing defines a fluid passage therethrough, the fluid passage having an upper end and a lower end. A sealing mechanism is associated with the housing for sealing the annulus and a two-way fluid bypass is provided for selectively permitting a flow of a fluid across the sealing mechanism. Finally, a one-way valve is located at the lower end of the fluid passage for selectively permitting a flow of a fluid in a first direction from the upper end to the lower end of the fluid passage and for preventing a flow of a fluid in a second direction from the lower end to the upper end of the fluid passage.