Halliburton Energy Services, Inc.

Other

Woodside Energy (Deepwater) Inc.

Joakim Oscar Blanch

Georgios L Varsamis

Jennifer Anne Market

Sven G Holmquist

Batakrishna Mandal

Vimal Vinod Shah

Eugene J Linyaev

Abbas Arian

Denis P Schmitt

Gary Lee Fickert

Calvin W Kessler

Arthur C H Cheng

Alexander Vladimirovich Kostin

Christopher Andrew Hurren

Jonathan DeWitt Jarvis

Neil Gavin Evans

The following disclosure relates to a system for generating velocity models of salt and subsalt formations. The system provides accurate velocities for both salt and subsalt formations. In some embodiments, the disclosure relies on the combination of three elements: the 'long offset' between seismic source and seismic receiver node, the use of multiple seismic signals at different geographic locations, and the refraction of the seismic wave off of the “basement” of the earth's crust. By combining the multiple seismic signals with the “fast basement,” which is accessible due to the long offset of sources and receiver nodes, it is now possible to determine a more accurate seismic propagation velocity for salt and subsalt formations by using FWI-based refraction tomography.

System for generating velocity models of subsalt formations

An attenuation apparatus, system, and method are disclosed. The attenuator is attached to a pipe and includes a housing that includes an inner sleeve and an outer sleeve. The attenuator includes one or more masses, to resonate when exposed to waves including acoustic frequency components.

Low frequency acoustic attenuator

Methods and apparatus are provided for reducing and/or substantially eliminating sensitivity mismatch of acoustic receivers used with acoustic sources to determine acoustic properties of geologic formations as a logging tool traverses the formations. Methods are directed to detecting waveform arrival times at receivers, determining places in a well where arrival times of waves are substantially the same at a plurality of receivers, and estimating effective receiver sensitivities and equalization factors using Stoneley wave amplitudes and windowed deconvolution of Stoneley waves. Methods are further directed to correcting wave amplitudes using estimated effective receiver sensitivities and equalization factors for receivers.

Adaptive equalization of downhole acoustic receivers

A self-adaptable data compression technique includes compressing the digital data points of a waveform according to at least a first protocol and a second protocol, and various comparing the compressed data under various protocols to determine which would require the least memory for storage.

Self-adaptable data compression technique

The specification discloses a system and related method for determining characteristics of earth formations traversed by a borehole. An acoustic transmitter mounted on a tool, whether that tool is a wireline tool or a logging-while-drilling tool, imparts acoustic energy into the formation, and a plurality of receivers spaced apart from the transmitter and from each other receive acoustic energy responsive to the transmitter firing. Portions, or all, of each received signal are used to estimate source signals using an assumed transfer function. Each of those estimated source signals are then compared in some way to determine an objective function. This process is repeated for multiple assumed transfer functions, and at multiple starting times within the received signals. By searching for minimas of a plot of the objective function, characteristics of the earth formation may be determined.

Acoustic logging apparatus and method

The patent discloses a signal processing technique for determining the fast and slow shear wave polarizations, and their orientation, for acoustic waves in an anisotropic earth formation. The signal processing method decomposes composite received waveforms a number of times using a number of different strike angles. The decomposed signals are used to create estimated source signals. The estimated source signals are compared in some way to obtain an objective function. Locations in a plot where the objective function reaches minimum values are indicative of the acoustic velocity of the fast and slow polarizations within the formation.

Acoustic logging apparatus and method for anisotropic earth formations

The specification discloses a signal processing technique applicable in acoustic logging devices. The method involves receiving a set of acoustic signals and converting those received signals to their frequency domain representation. Values of the frequency domain representations along constant frequencies are correlated to produce a correlation matrix. Eigenvectors and eigenvalues of the correlation matrix are determined, and the eigenvectors corresponding to signals of interest are removed to create a subspace. Thereafter, a series of test vectors, which test vectors embody a series of estimated slowness values, are applied to the subspace vector. If the test vector maps to or may be represented by the subspace, then the estimated slowness embodied in the test vector maps to noise of the system and is not the correct value for the formation. If, however, the test vector does not map to the subspace, then the slowness embodied in the test vector approximates the actual formation slowness.

High resolution dispersion estimation in acoustic well logging

A method for creating a frequency domain semblance for use in conjunction with acoustic logging tools is disclosed. Such a frequency domain semblance may be obtained by transforming an acoustic signal received at multiple depths into the frequency domain, combining the received waveforms corresponding to the different depth, and expressing the result in a graph with slowness and frequency axes. This graph shows the frequency-slowness location for the acoustic signal, as well as for other related signals that may inadvertently be generated by the acoustic logging tool. This information may then be used to more clearly measure the slowness of the received acoustic signal. Another aspect of the invention is the treatment of two or more time domain semblances as probability density functions of the slowness for an acoustic signal. This enables the combination of time domain semblances from the same depth in the wellbore.

Processing for sonic waveforms

A method for creating a frequency domain semblance for use in conjunction with acoustic logging tools is disclosed. Such a frequency domain semblance may be obtained by transforming an acoustic signal received at multiple depths into the frequency domain, combining the received waveforms corresponding to the different depth, and expressing the result in a graph with slowness and frequency axes. This graph shows the frequency-slowness location for the acoustic signal, as well as for other related signals that may inadvertently be generated by the acoustic logging tool. This information may then be used to more clearly measure the slowness of the received acoustic signal. Another aspect of the invention is the treatment of two or more time domain semblances as probability density functions of the slowness for an acoustic signal. This enables the combination of time domain semblances from the same depth in the wellbore. Once combined, the time domain semblances more accurately depict the slowness of an acoustic wave through the formation at the selected depth. In addition, a related self-adaptation method to compress the waveform data downhole for storage or transmission is also disclosed.

Growing community of inventors

Houston, TX, United States of America

Joakim Oscar Blanch