Abstract: Methods, systems, and computer program products for correcting cased hole neutron porosity logs provide a “residual” correction that substantially accounts for potential coupling between casing thickness and other environmental parameters. The residual correction may be used to derive a casing thickness response function that is customized for the particular well under consideration. The customized casing thickness response function may then be used to adjust cased hole neutron porosity logs for the well in a manner that more accurately accounts for potential coupling of the effects of casing thickness and other environmental parameters, in contrast to existing solutions that tend to ignore such potential coupling.

Abstract: Methods, systems, and computer program products for identifying annular space materials calculate a near-to-far (“N/F”) neutron count ratio from neutron count rates detected by detectors located near to and far from a neutron source, respectively. The N/F neutron count ratio may then be used along with formation porosity to provide an estimation of the type of material that may be present in the annular space.

Abstract: Methods, systems, and computer program products for correcting cased hole neutron porosity logs provide a “residual” correction that substantially accounts for potential coupling between casing thickness and other environmental parameters. The residual correction may be used to derive a casing thickness response function that is customized for the particular well under consideration. The customized casing thickness response function may then be used to adjust cased hole neutron porosity logs for the well in a manner that more accurately counts for potential coupling of the effects of casing thickness and other environmental parameters, in contrast to existing solutions that tend to ignore such potential coupling.

Abstract: Methods, systems, and computer program products for identifying annular space materials calculate a near-to-far (“N/F”) neutron count ratio from neutron count rates detected by detectors located near to and far from a neutron source, respectively. The N/F neutron count ratio may then be used along with formation porosity to provide an estimation of the type of material that may be present in the annular space.

Abstract: A method and system for estimating native hydrocarbons from oil-based drilling muds with the aid of NMR data. Adaptive echo stacking may be used to balance between precision and sensitivity to changes in the fluid composition. Apparent T2 decay time and effective diffusion constants derived from the NMR data may be transformed into an indication of native hydrocarbon type, using known diffusion constants, fuzzy logic, and neural networks.