Baker Hughes, a Ge Compnay, LLC

Baker Hughes Holdings LLC

Hao Zhang

John Longo

Quming Zhou

Freddy Mendez

Wei Han

Alberto Mezzatesta

Xiaochu Yao

Qiong Zhang

Eliseo Rodriguez

Methods and devices for estimating at least one property of a volume of interest of an earth formation from a radiation based measurement. Methods include using an optimization procedure to determine an optimal mineralogical model in dependence upon a secondary dependence relation between tool measurements, the mineralogical model including a mineralogical composition of the volume. The secondary dependence relation may include a relation between a plurality of estimated elemental concentrations for the volume. The mineralogical composition may include a concentration of each mineral of a plurality of minerals of the volume. The relation may include a ratio of a first elemental concentration of the plurality of estimated elemental concentrations and a second elemental concentration of the plurality of estimated elemental concentrations. Methods may include using at least one cost function to determine the optimal mineralogical model, wherein the at least one cost function is determined using the relation.

Geological constraint using probability functions in stochastic mineralogy modeling

Examples of techniques for generating a high-resolution lithology model for subsurface formation evaluation are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes determining, by a processing device, a low-resolution lithology volumetric model. The method further includes comparing, by the processing device, the low-resolution lithology volumetric model to a high-resolution imaging log. The method further includes calculating, by the processing device, a dynamic boundary curve for each of a plurality of moving windows. The method further includes generating, by the processing device, the high-resolution lithology model based at least in part on the calculated dynamic boundary curve for each of the plurality of moving windows. The method further includes controlling a drilling operation based at least in part on the high-resolution lithology model.

Generating a high-resolution lithology model for subsurface formation evaluation

Estimating a correction factor from logs of compensated thermal neutron porosity measurements, including modeling each measurement of the compensated thermal neutron porosity measurements of the log as resulting from at least: i) a first contribution correlated to an absorbance of a first portion of neutrons produced by irradiation of the volume attributable to interactions in the volume indicative of pore space in the matrix, and ii) a second contribution correlated to an absorbance of a second portion of the neutrons attributable to trace elements of at least one dominant neutron absorber in the formation; iii) a third contribution correlated to an absorbance of a third portion of the neutrons attributable to dry minerals in the matrix other than dominant neutron absorbers; and estimating the second contribution and determining the correction factor from the second contribution; and correcting a compensated thermal neutron porosity measurement using the correction factor.

Compensated neutron correction for contributions outside the petrophysical model

Systems, devices, and methods for evaluating a volume of interest of an earth formation. Methods include estimating a parameter of interest of a volume of the formation using a value of a signal property (frequency amplitude) for a second harmonic mode signal component of a detected acoustic signal from the volume. Methods may include activating a transmitter to propagate an acoustic wave through the volume; producing the detected acoustic signal at a receiver responsive to the acoustic wave; and identifying the fundamental mode signal and the second harmonic mode signal associated with the detected acoustic signal. Methods include estimating an acoustic wave non-linearity parameter (&#x3b2;) for the volume using a relationship between the value of the signal property of the second harmonic mode signal component and a value of the signal property for a fundamental mode signal component of the detected acoustic signal.

Non-linear acoustic formation evaluation

Systems, methods and devices for evaluating an earth formation intersected by a borehole. Method embodiments may include using a downhole tool in the borehole to generate a plurality of signal pulses responsive to detected radiation; using at least one signal quality characteristic of each pulse of the plurality of pulses to classify each pulse as belonging to at least one subset of a plurality of pulse subsets; and using one of more of the plurality of pulse subsets to estimate a value of a parameter of interest. The signal quality characteristic may be indicative of a pulse pile-up condition being associated with the respective pulse. The signal quality characteristic may include at least one of: i) rising time (slope) of the respective pulse; ii) time between a peak of the respective pulse and a peak of a closest following pulse; iii) pulse width; and iv) skewness of the pulse.

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The Woodlands, TX, United States of America

Hao Zhang