Abstract: A method for logging a subsurface formation includes acquiring neutron capture data using a pulsed neutron tool at a plurality of locations along a borehole penetrating the subsurface formation, wherein the plurality of locations include a formation zone that contains water; comparing an apparent water salinity or an apparent water sigma value estimated from the neutron capture data acquired in the formation zone that contains water with a water salinity or water sigma value of a water sample from the subsurface formation to produce a calibration parameter for the neutron capture data; and correcting the neutron capture data, based on the calibration parameter, to produce corrected neutron capture data. The method may further include determining a water saturation from the corrected neutron capture data.

Abstract: A method for logging a subsurface formation includes acquiring neutron capture data using a pulsed neutron tool at a plurality of locations along a borehole penetrating the subsurface formation, wherein the plurality of locations include a formation zone that contains water; comparing an apparent water salinity or an apparent water sigma value estimated from the neutron capture data acquired in the formation zone that contains water with a water salinity or water sigma value of a water sample from the subsurface formation to produce a calibration parameter for the neutron capture data; and correcting the neutron capture data, based on the calibration parameter, to produce corrected neutron capture data. The method may further include determining a water saturation from the corrected neutron capture data.

Abstract: Disclosed is a method to increase the bonding forces of a hydraulic cement to a subterranean pipe (such as a casing) by the addition of at least one cementitious expansive agent to increase the bulk volume of the cement plug and a latex. The method includes positioning a platform in a downhole pipe below the desired cement plug interval, positioning a plug dump bailer tool comprising a chamber for cement slurry and a valve to discharge the cement slurry on and above the platform, and discharging the cement slurry. The cement slurry includes an expansive agent and latex to increase the shear-bond between the downhole pipe and the cement plug.

Abstract: The present invention relates to a method to increase the bonding forces of a hydraulic cement to a subterranean pipe (such as a casing) by the addition of at least one cementitious expansive agent to increase the bulk volume of the cement plug and a latex. The method of the invention includes positioning a platform in a downhole pipe below the desired cement plug interval, positioning a plug dump bailer tool comprising a tubular storing chamber for a cement slurry and a valve to discharge the cement slurry on and above the platform and discharging a cement slurry that comprises an expansive agent and a latex in quantities enough to increase the shear-bond between the downhole pipe and the cement plug. The invention allows a significant reduction of the height of the cement plug and therefore of the number of dump-bailer operations required for placing a plug.

Abstract: The combination of the cement contamination laboratory measurements and the field log measurement allows to perform the evaluation of cement placement and quality related to the designed percentage cement displacement coverage and set-up times in the casing annulus. Since the logging time after the cement job is completed is known, a comparison between the acoustic impedance or compressive strength measured using the USI log and the acoustic impedance or the compressive strength measured in the laboratory, a level of mud contamination can be derived at every point across the wellbore. From the laboratory correlations, cement strength prediction with time can be established. This new product will give the operator an accurate tool to recommend performing remedial cementing with a higher success rate.

Abstract: A tool for use in analyzing a subsurface formation for the presence of hydrocarbon includes a neutron generator capable of generating a burst of neutrons at a high energy level, some of which will collide inelastically with atomic nuclei in the subsurface formation to produce inelastic gamma rays and then will be captured by atomic nuclei to produce capture gamma rays. The tool also includes at least one radiation detector to detect the inelastic and capture gamma rays, and counting circuitry configured to produce a count of detected inelastic gamma rays and a count of detected capture gamma rays. Processing circuitry in the tool generates a numerical output by dividing the count of inelastic gamma rays by the count of capture gamma rays and then provides the numerical output to an output device for use in analyzing the subsurface formation for the presence of hydrocarbon.