Abstract: Automatic detection and accurate time picking of weak events embedded in strong noise such as microseismicity induced by hydraulic fracturing is accomplished by: a noise reduction step to separate out the noise and estimate its spectrum; an events detection and confidence indicator step, in which a new statistical test is applied to detect which time windows contain coherent arrivals across components and sensors in the multicomponent array and to indicate the confidence in this detection; and a time-picking step to accurately estimate the time of onset of the arrivals detected above and measure the time delay across the array using a hybrid beamforming method incorporating the use of higher order statistics. In the context of hydraulic fracturing, this could enhance the coverage and mapping of the fractures while also enabling monitoring from the treatment well itself where there is usually much higher and spatially correlated noise.

Abstract: A multimode acoustic source device for disposition in a borehole formed in a subterranean formation is aligned along an axial axis of the borehole and has a plurality of radiating plates circumferentially disposed about the axial axis. A drive mechanism is proposed to independently and reversibly move each radiating plate from a first position to a second position in a direction transverse to the axial axis. This enables the multimode source to generate each of several azimuthal modes for logging a subterranean formation.

Abstract: Methods and related systems are described for modified semblance criterions based on the approach of thresholding the signal energy. A first criterion is derived by posing the problem as that of detecting a signal with energy (or amplitude) greater than the specified threshold and deriving the generalized likelihood ratio test statistic. A second criterion is derived using the same method by posing the problem as that of rejecting any signal with energy (or amplitude) below a specified threshold and detecting it if its energy is above another threshold greater than or equal to the first. These appropriately modify the original semblance criterion which is shown to be equivalent to the GLRT test statistic in the absence of any threshold on the signal amplitude. In addition simpler modifications are also described. Tests on synthetic data illustrate the effectiveness of all these modifications which perform comparably well at suppressing unwanted arrivals while accurately processing the desired signals.

Abstract: Slowness dispersion characteristics of multiple possibly interfering signals in broadband acoustic waves as received by an array of two or more sensors are extracted without using a physical model. The problem of dispersion extraction is mapped to the problem of reconstructing signals having a sparse representation in an appropriately chosen over-complete dictionary of basis elements. A sparsity penalized signal reconstruction algorithm is described where the sparsity constraints are implemented by imposing a l1 norm type penalty. The candidate modes that are extracted are consolidated by means of a clustering algorithm to extract phase and group slowness estimates at a number of frequencies which are then used to reconstruct the desired dispersion curves. These estimates can be further refined by building time domain propagators when signals are known to be time compact, such as by using the continuous wavelet transform.

Abstract: Methods and related systems are described for use for determining orientation of a measurement tool in a cased borehole. The measurement tool is deployed in a cased section of a borehole. The tool includes a volume containing a reference fluid having a first density, and a marker within the fluid having a different density. The position of the marker within volume containing the reference fluid is senses, and orientation information of the measurement tool is determined based at least in part on combining information relating to the position of the marker with prior recorded data representing orientation measurements made while the section of the borehole was not yet cased.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: This invention pertains to the extraction of the slowness dispersion characteristics of acoustic waves received by an array of two or more sensors by the application of a continuous wavelet transform on the received array waveforms (data). This produces a time-frequency map of the data for each sensor that facilitates the separation of the propagating components thereon. Two different methods are described to achieve the dispersion extraction by exploiting the time frequency localization of the propagating mode and the continuity of the dispersion curve as a function of frequency. The first method uses some features on the modulus map such as the peak to determine the time locus of the energy of each mode as a function of frequency. The second method uses a new modified Radon transform applied to the coefficients of the time frequency representation of the waveform traces received by the aforementioned sensors.

Abstract: An integrated framework is described for automating some or all of mud slowness estimation for both fast and slow formations. An estimation of fluid slowness based on monopole radial profiling is calculated if conditions permit. Alternatively, an estimation of fluid slowness based on Scholte wave slowness is estimated if conditions do not permit calculation based on monopole radial profiling. Tool standoff may also be estimated based on monopole radial profiling.

Abstract: A method for acquiring and analyzing time-series data using singularities is described. This method allows for the analysis of data over a wide spectrum of frequencies. Once the data is acquired in an oil field, singularities of the data are extracted; and the extracted singularities are utilized to interpret the formation properties related to the data.

Abstract: A method facilitating radial profiling of acoustic slowness of a formation traversed by a borehole is disclosed. According to some aspects of the invention, a 3D image of near, far, and intermediate formation slowness is provided.

Abstract: Methods and apparatus facilitating radial profiling of acoustic slowness of a formation traversed by a borehole are disclosed. According to some aspects of the invention, a radial slowness profile is imaged, including an image of altered region slowness.

Abstract: A method for acquiring and analyzing time-series data using singularities is described. This method allows for the analysis of data over a wide spectrum of frequencies. Once the data is acquired in an oil field, singularities of the data are extracted; and the extracted singularities are utilized to interpret the formation properties related to the data.

Abstract: This invention pertains to the extraction of the slowness dispersion characteristics of acoustic waves received by an array of two or more sensors by the application of a continuous wavelet transform on the received array waveforms (data). This produces a time-frequency map of the data for each sensor that facilitates the separation of the propagating components thereon. Two different methods are described to achieve the dispersion extraction by exploiting the time frequency localization of the propagating mode and the continuity of the dispersion curve as a function of frequency. The first method uses some features on the modulus map such as the peak to determine the time locus of the energy of each mode as a function of frequency. The second method uses a new modified Radon transform applied to the coefficients of the time frequency representation of the waveform traces received by the aforementioned sensors.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: A method and system for fluid characterization in an underground formation surrounding a borehole are provided. Acoustic signals are transmitted and received in the borehole. The received acoustic signals are processed to obtain at least one attribute of formation mobility. Formation fluid is characterized based on a change of the at least one attribute. A decision is made based on the characterization output.

Abstract: A method of determining the sonic slowness of a formation traversed by a borehole comprising generating tracks from sonic waveform peaks received at a plurality of depths wherein the peaks that are not classified prior to tracking is set forth. A method for generating a slowness versus depth log is generated for waveform arrivals by classifying long tracks, classifying small tracks; classifying tracks that overlap; filling in gaps; and creating a final log is disclosed. In further improvements, non-classified tracks and interpolation are used to fill in gaps.

Abstract: Methods and systems are provided for downhole analysis of formation fluids by deriving fluid properties and associated uncertainty in the predicted fluid properties based on downhole data, and generating answer products of interest based on differences in the fluid properties. Measured data are used to compute levels of contamination in downhole fluids using an oil-base mud contamination monitoring (OCM) algorithm. Fluid properties are predicted for the fluids and uncertainties in predicted fluid properties are derived. A statistical framework is provided for comparing the fluids to generate, in real-time, robust answer products relating to the formation fluids and reservoirs thereof. Systematic errors in measured data are reduced or eliminated by preferred sampling procedures.

Abstract: Methods and apparatus facilitating radial profiling of acoustic slowness of a formation traversed by a borehole are disclosed. According to some aspects of the invention, a radial slowness profile is imaged, including an image of altered region slowness.

Abstract: The present invention is directed to methods and systems for taking measurements relating to subterranean formations. The methods and systems effectively compress data and thus facilitate more efficient data transmission. The methods and systems are capable of automatically varying data compression rates during a measurement operation. The variable data compression capability facilitates reliable collection of measurement data at faster and/or constant logging speeds. The data compression methods and systems may be applied to any measurement operation relating to subterranean formations, including, but not limited to: acoustic wireline logging measurements, acoustic logging-while-drilling measurements, electromagnetic measurements, nuclear magnetic resonance measurements, and resistivity measurements.