Schlumberger Technology Corporation

Halliburton Energy Services, Inc.

Jiaxin Wang

Libai Xu

Christian Stoller

Jeffrey James Crawford

Lei Wang

Wei Yang

In some examples, a computer-readable medium stores executable code which, when executed by a processor, causes the processor to obtain a threshold pulse rate that is based on an average pulse rate of a gamma radiation detector tool and on a desired probability that the threshold pulse rate will not be exceeded by the gamma radiation detector tool. The code also causes the processor to identify instances of pulse from the gamma radiation detector tool that do not exceed the threshold pulse rate, and output an indication of the identified instances of pulses for use in a measurement-while-drilling application.

Probabilistically distinguishing between true and false scintillator pulses

A method includes receiving a drilling parameter, a tool characterization parameter, and a formation model. The method includes generating a forward model of a tool response at a bed boundary using the one drilling parameter, the tool characterization parameter, and the formation model. The method includes predicting at least two azimuthal gamma logs using the forward model. The method includes determining that a difference between the at least two azimuthal gamma logs generates a confidence level that is greater than a confidence threshold. In response to determining that the difference between the at least two azimuthal gamma logs generates the confidence level that is greater than the confidence threshold, the method includes generating a well plan. The method includes outputting a command for controlling a trajectory in directionally drilling a wellbore within a formation associated with the formation model using the well plan.

Trajectory control for directional drilling using azimuthal gamma ray measurements

Methods of elemental imaging of a formation include acquiring spectral gamma ray measurement, acquiring a total gamma ray image, deriving structure information of the formation from the total gamma ray image, and applying the structure information to the spectral gamma ray measurement to form an elemental image. In the present methods, the structure information of the formation is derived from comparing the total gamma ray logs for each azimuthal sector to a derived total gamma ray log. The derived total gamma ray log is acquired from the total gamma ray image by summing over all azimuth bins or the spectral gamma ray measurement by summing over all energy bins.

Methods of elemental imaging of formations and systems for producing the same

A method for correcting natural gamma ray measurements includes processing an acquired gamma ray spectrum in combination with elemental standard spectra and at least one standard mud activation spectrum to compute corrected natural gamma ray measurements. The gamma ray spectrum is acquired using a logging string employing a neutron source and a natural gamma ray sensor.

Method for correcting natural gamma ray logging measurements

A method for estimating a drilling fluid flow rate in a subterranean wellbore includes processing an acquired gamma ray spectrum in combination with standard elemental spectra and at least one standard oxygen activation spectrum to compute an oxygen activation yield. The oxygen activation yield is further processed to estimate a drilling fluid flow rate and or to infer a borehole diameter change or a lost circulation event. The gamma ray spectrum is acquired using a logging string employing a neutron source and a natural gamma ray sensor.

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Katy, TX, United States of America

Jiaxin Wang