摘要:
Determining a parameter associated with a formation corrected for neutrons produced. At least some of the illustrative embodiments are methods including: disposing a logging tool within a borehole, the borehole penetrates a formation; producing neutrons by a neutron source within the logging tool; detecting neutrons produced by the neutron source, the detecting by a neutron detector; creating an indication of a number of neutrons produced by the neutron source, the indication based only on neutrons detected that have not interacted with other elements before entering the neutron detector; obtaining a count rate of a gamma detector responsive to the production of neutrons by the neutron source; and determining a parameter associated with the formation based on the count rate and on the indication of the number of neutrons produced.
摘要:
Determining a parameter associated with a formation corrected for neutrons produced. At least some of the illustrative embodiments are methods including: disposing a logging tool within a borehole, the borehole penetrates a formation; producing neutrons by a neutron source within the logging tool; detecting neutrons produced by the neutron source, the detecting by a neutron detector; creating an indication of a number of neutrons produced by the neutron source, the indication based only on neutrons detected that have not interacted with other elements before entering the neutron detector; obtaining a count rate of a gamma detector responsive to the production of neutrons by the neutron source; and determining a parameter associated with the formation based on the count rate and on the indication of the number of neutrons produced.
摘要:
Determining a value indicative of gas saturation of a formation. At least some of the illustrative embodiments are methods including obtaining an inelastic count rate and a capture count rate of a gamma detector for a particular borehole depth, calculating a ratio of an inelastic count rate to a capture count rate for the particular borehole depth, determining a value indicative of gas saturation based on the ratio of the inelastic count rate to the capture count rate for the particular borehole depth, repeating the obtaining, calculating and determining for a plurality of borehole depths, and producing a plot of the value indicative of gas saturation of the formation as a function of borehole depth.
摘要:
Determining a value indicative of gas saturation of a formation. At least some of the illustrative embodiments are methods including obtaining an inelastic count rate and a capture count rate of a gamma detector for a particular borehole depth, calculating a ratio of an inelastic count rate to a capture count rate for the particular borehole depth, determining a value indicative of gas saturation based on the ratio of the inelastic count rate to the capture count rate for the particular borehole depth, repeating the obtaining, calculating and determining for a plurality of borehole depths, and producing a plot of the value indicative of gas saturation of the formation as a function of borehole depth.
摘要:
Casing condition is an important concern to oilfield operators. Systems and methods are disclosed herein for using neutron logging tools to measure casing condition, using windows in the gamma energy spectrum that are sensitive and insensitive to casing condition to obtain a ratio having a value that ranges between one extreme representative of completely absent casing and an opposite extreme representative of casing in good condition. The sensitive (“divergence”) window may be positioned at or near 7.65 MeV, the characteristic energy of gamma rays from a neutron capture event by an iron nucleus. The insensitive (“consistency”) window is preferably adjacent to the divergence window with a comparable size to the divergence window. A suitable division point between the windows may be about 6.25 MeV.
摘要:
Predicting gas saturation of a formation using neural networks. At least some of the illustrative embodiments include obtaining a gamma count rate decay curve one each for a plurality of gamma detectors of a nuclear logging tool (the gamma count rate decay curves recorded at a particular borehole depth), applying at least a portion of each gamma count rate decay curve to input nodes of a neural network, predicting a value indicative of gas saturation of a formation (the predicting by the neural network in the absence of a formation porosity value supplied to the neural network), and producing a plot of the value indicative of gas saturation of the formation as a function of borehole depth.
摘要:
Downhole fluid typing with pulsed neutron logging. A method comprises obtaining gamma count rates at a particular borehole depth; calculating a fluid type indicative response value for the borehole depth; determining at least one fluid type based on the response value for the particular borehole depth; and producing a display of the at least one fluid type corresponding to the borehole depth. A system comprises a downhole tool comprising a neutron source and at least one gamma detector; gamma count rates produced due to gamma arrivals at the gamma detector(s); and a processor coupled to a memory, wherein the memory stores a program that, when executed by the processor, causes the processor to: calculate a fluid type indicative response value for a particular borehole depth based on the gamma count rates; and determine at least one fluid type based on the response value for the particular borehole depth.
摘要:
Various apparatus or methods are arranged to operate a tool downhole in a well, where the tool has a detection package operable to detect gamma rays. Deviation of energy spectra of detected gamma rays in each selected energy window of a set of selected energy windows with respect to reference energy spectra of the respective selected energy window can be detected. One or more properties of one or more regions around the tool can be determined from the deviations, the regions being between the tool and a source of the detected gamma rays in a formation around the well. Additional apparatus, systems, and methods having a gamma ray detection package can operate in a variety of applications.
摘要:
Predicting gas saturation of a formation using neural networks. At least some of the illustrative embodiments include obtaining a gamma count rate decay curve one each for a plurality of gamma detectors of a nuclear logging tool (the gamma count rate decay curves recorded at a particular borehole depth), applying at least a portion of each gamma count rate decay curve to input nodes of a neural network, predicting a value indicative of gas saturation of a formation (the predicting by the neural network in the absence of a formation porosity value supplied to the neural network), and producing a plot of the value indicative of gas saturation of the formation as a function of borehole depth.
摘要:
Determining a value indicative of fracture quality. At least some of the illustrative embodiments are methods including: obtaining or measuring gas saturation of a formation to create a value indicative of pre-fracture gas saturation; and after a fracturing process measuring gas saturation of the formation to create a value indicative of post-fracture gas saturation; and creating a value indicative of fracture quality based on the value indicative of pre-fracture gas saturation and the value indicative of post-fracture gas saturation.