Abstract: The disclosure provides methods of measuring an intrinsic CO ratio in a geological formation by disposing, proximate the formation, a petrophysical tool including at least one gamma-ray detector, reading a carbon gamma-ray peak for the geological formation and an oxygen gamma-ray peak for the geological formation, determining a measured CO ratio of the geological formation from the carbon gamma-ray peak and the oxygen gamma-ray peak, and correcting the measured CO ratio by applying a corrective algorithm specific for the petrophysical tool or the type of petrophysical tool to obtain an intrinsic CO ratio of the geological formation. The corrective algorithm is derived by a mathematical analysis of measured CO ratios of a sample with a known intrinsic CO ratio using the same petrophysical tool or a petrophysical tool representative of a same type of petrophysical tool. Additional methods and systems using this method are provided.

Abstract: Provided here are compositions and improved methods for recovering portion of irreducible water saturation in a porous rock sample. Compositions used here contain a displacement fluid and a surfactant, and lead to an increased recovery of the irreducible water from the porous rock sample.

Abstract: In one possible implementation, a computer-readable tangible medium includes instructions that direct a processor to access one or more wellbore properties and a plurality of well fluid properties. Instructions are also present that direct the processor to access a distance between a proposed location of an inlet to a multiphase production logging tool and an emulsion generation location in a wellbore. Further instructions instruct the processor to predict a drop size distribution of emulsified water in the well fluid at the proposed location of the inlet to the multiphase production logging tool. Additional instructions instruct the processor to compute an estimated error in water holdup detected by the multiphase production logging tool based on the drop size distribution, and recommend deployment of a pulsed neutron logging tool in the wellbore when the estimated error in the water holdup is above a preset threshold.

Abstract: Provided here are compositions and improved methods for recovering portion of irreducible water saturation in a porous rock sample. Compositions used here contain a displacement fluid and a surfactant, and lead to an increased recovery of the irreducible water from the porous rock sample.

Abstract: Provided in some embodiments are systems and methods for monitoring cement quality of a cased well. Embodiments include conducting a cement-bond logging and a first pulsed neutron (PN) logging to generate a cement-bond log (CBL) and first pulsed neutron log (PNL) for the well, determining a first cement quality index (CQI) for the well based on the CBL and the first PNL, in response to determining that mud effects for the well have dissipated, conducting a second PN logging to generate a second PNL for the well, determining a second CQI for the well based on the CBL and the second PNL, determining a tuned CQI for the well based on the first CQI and the second CQI, conducting a follow-up PN logging to generate a follow-up PNL for the well, and determining a cement quality log for the well based on the tuned CQI and the follow-up PNL.

Abstract: In one possible implementation, a computer-readable tangible medium includes instructions that direct a processor to access one or more wellbore properties and a plurality of well fluid properties. Instructions are also present that direct the processor to access a distance between a proposed location of an inlet to a multiphase production logging tool and an emulsion generation location in a wellbore. Further instructions instruct the processor to predict a drop size distribution of emulsified water in the well fluid at the proposed location of the inlet to the multiphase production logging tool. Additional instructions instruct the processor to compute an estimated error in water holdup detected by the multiphase production logging tool based on the drop size distribution, and recommend deployment of a pulsed neutron logging tool in the wellbore when the estimated error in the water holdup is above a preset threshold.