Geokinetics Inc.

United States

Geokinetics Inc.

United States
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Babalola A.,University of Houston | Hilterman F.,Geokinetics Inc. | Stewart R.B.,University of Houston
SEG Technical Program Expanded Abstracts | Year: 2015

Abstract AVO processing workflows are designed to preserve relative amplitude between offset gathers making them ideal for reservoir characterization. But in the event where the traces are not aligned, post-processing techniques predicated on windowed cross-correlation are employed to adequately condition seismic data. A new application of dynamic time-warping algorithm, a technique used for speech recognition by matching similarities in two discrete time series that are out of phase is applied to non-linearly correct for time mis-alignment. A case study with time-lapse dataset from the Norne field, Norwegian Sea is presented showing significant improvement in Bayesian inversion for elastic properties as the traces are warped prior to the Inversion process. © 2015 SEG.

Qi C.,University of Houston | Hilterman F.,Geokinetics Inc.
SEG Technical Program Expanded Abstracts | Year: 2015

In highly cyclic sedimentation with large impedance contrasts, such as coal beds, peg-leg multiples make seismic ties with primary-only synthetics difficult (Qi and Hilterman, 2013b). A processing technique based on time-varying matched filters is presented for removing the effects of peg-leg multiples. Within the coal beds in particular, we calculate time-evolving seismic wavefields with the contribution of all multiples using the reflectivity method. Then based on the seismic wavefields, time-varying matched filters that are S/N weighted are generated that compensate for the apparent time delay introduced by the peg-leg multiples. A synthetic seismic line based on well-log curves from a highly cyclic coal-bed area has been built and processed to illustrate the fidelity and effectiveness of this method. Lastly, the method is applied to field data from Cooper Basin, Australia to resolve the base of the coal-bed sequence. © 2015 SEG.

Qi C.,University of Houston | Hilterman F.,Geokinetics Inc.
Geophysics | Year: 2017

Stratigraphic filtering (SF), or short-period multiples, is prominent in cyclically stratified sedimentation with large impedance contrasts that result in normal-incident reflection magnitudes greater than 0.5. Because SF attenuates and delays the propagating wavelet, similar to the effects of Q attenuation, the integrity of well ties is often jeopardized. A method is proposed to obtain better well ties in areas with severe SF. Starting with a well-log acoustic impedance curve, two-way transmitted wavefields and their equivalent inverse filters are generated at each time sample. Because a time-varying convolution of the transmitted wavefields with the primary-only reflectivity yields the multiple reflectivity, a time-varying deconvolution of the multiple synthetic with the inverse filters yields the primary-only reflectivity. In essence, when the multiple synthetic matches the near-angle stack at a well location, the near-angle stack is deconvolved in a time-varying fashion to match the primary-only synthetic, which then constitutes a correlation with the acoustic impedance yielding a good well tie. This new well-tie technique preserves the integrity of the lithologic interpretation because stretching and squeezing the time scale of the primary- only synthetic to force a seismic match are avoided. Our well-tie method is applied to the synthetic and field data from Cooper Basin, Australia, where more than 30 coal beds are observed within a 1000 ft (304 m) interval. © 2017 Society of Exploration Geophysicists.

Nicholson F.,Beach Energy | Bourne J.,Beach Energy | Hilterman F.,Geokinetics Inc.
Leading Edge | Year: 2017

With improved seismic data quality, prestack inversion has become a routine process for quantitative seismic interpretation. However, direct products from traditional seismic inversion usually are P-impedance (PI), S-impedance (SI), and, in some cases, density. These elastic properties are only an indirect description of subsurface geology. A bridge must be established from inverted PI, SI, and density to more understandable reservoir properties: lithology, porosity, and water saturation. Reservoir-property inversion is a model-based inversion process to transform PI, SI, and density to lithology, porosity, and water saturation. The inversion is performed in two steps: (1) well-log inversion on log data to estimate optimal elastic properties of rock-grain constituents and (2) reservoir-property inversion to estimate reservoir properties from PI, SI, and density. The underlying rock-physics models are the same for both inversions including mass-balance equation, Gassmann equation, Voigt-Reuss-Hill average, and Krief's relationship, or, optionally, the Xu-White velocity model. The solution of the inversion is considered as optimal in terms of minimum misfit of PI, SI, and density modeled with inverted reservoir properties compared to the input PI, SI, and density. The inversion results honor all the interrelationships between various elastic properties, reservoir properties, and rock-grain properties. A limitation of the proposed inversion includes a requirement for lithology with only two solid constituents, such as sand mixed with shale. It also requires a density volume as one of the primary input data for the inversion. Due to the inversion's sensitivity to fluid contents, estimated water saturation in many cases may not be reliable. This paper presents the inversion methodology and the inversion results from a set of modeled data as well as a real case study to demonstrate the inversion's capability.

Zhou Z.,University of Houston | Hilterman F.J.,Geokinetics Inc.
Geophysics | Year: 2010

Three seismic attributes commonly used to predict pore fluid and lithology are the fluid factor (ΔF), Poisson impedance (PI), and lambda-rho (γρ). We evaluated the pore-fluid sensitivity of these attributes with both well-log and seismic data in Tertiary unconsolidated sediments from the Gulf of Mexico where sand and shale are the only expected lithologies. While the sensitivity of one attribute versus another to discriminate pore fluid is often debated in the literature, the sensitivities of the three attributes are not independent but can be traced back to the fluid factor, which is a function of the P- and S-wave normal-incident reflection coefficients. Interestingly, the fluid factor, which is a reflectivity attribute, at the top of a hydrocarbon-saturated reservoir, is basically independent of the shale properties above the reservoir. It is a function of the brine and hydrocarbon impedances of the reservoir. The next attribute, Poisson impedance, is thenequal to the fluid factor times the sum of the brine and hydrocarbon impedances. Finally, the lambda-rho attribute is equal to the Poisson impedance multiplied by the same impedance sum. Essentially, the same scale factor differentiates these attributes, which does not significantly affect the sensitivity of the attributes. PI is the basis of the sensitivity for these attributes. As a means of testing their sensitivity for predicting pore fluid, we generated the three attributes along with their statistical distributions for different pore fluids for 183 reservoirs. The well-log statistical descriptions were then used to calibrate the seismic amplitude in a 3D survey to reflectivity values, thus allowing pore-fluid classification schemes based on Bayes' decision rules. In essence, seismic-amplitude quantification was based on regional statistics rather than individual wells within the 3D seismic survey to delineate the portions of the reservoir that were saturated with oil, gas, or brine. © 2010 Society of Exploration Geophysicists.

Pramik B.,Geokinetics Inc.
SEG Technical Program Expanded Abstracts | Year: 2011

Our ability to process and deliver proper broadband seismic data to our colleagues and customers is dependent on the selection of appropriate seismic acquisition parameters. Inadequate survey design can result in insufficient signal to noise ratios in the final data which will lead to an inferior product. Consideration of all seismic events present in the recorded data with respect to proper spatial sampling in all appropriate domains relevant to the seismic processing will help ensure that the broadband signal that is imparted into the earth, detected by the receivers and delivered to the processing center can be faithfully preserved throughout data processing. © 2011 Society of Exploration Geophysicists.

Gaiser J.E.,Geokinetics Inc.
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

It is well established that similar vertical wavelength ranges must be preserved in multicomponent data and that wavelengths of P- and S-waves must match in order to sample reflectivity in an equivalent manner. Conversion of a wavefield to another time or depth domain is described by transformation functions that depend on average VP/VS ratios and velocity. Although these functions align corresponding stratigraphic events of different wavefields, they distort the seismic wavelet because global average velocity properties are independent of local interval properties that define wavelength. In this study we develop a theory of velocity-based wavelet corrections for domain transformations, which are expressed as functions of interval and average VP/VS and velocity, to match wavelength of multicomponent wavefields. We examine the effects for both land and marine data examples and find that land surveys are affected more than marine, and may require spectral broadening of the wavelet. Data from the Marcellus shale in northeast Pennsylvania, USA, shows significant bandwidth improvements for C-waves when wavelet corrections based on velocity match their wavelengths with P-waves. Application of these wavelet corrections should benefit registration fidelity, joint AVO/A (offset and azimuth) inversions and attribute analyses.

A method for spatial sampling of a seismic wavefield at the bottom of a water layer at an effective spatial sampling denser than the physical layout of the sensors. The sensors comprise a sensing element for vertical particle motion and a sensing element for rotational motion around a horizontal axis. Stress and wavefield conditions allow the rotational sensing element to yield the transverse horizontal gradient of the vertical particle motion wavefield, used in ordinate and slope sampling to yield improved transverse spatial sampling of the vertical particle motion wavefield.

Wang J.,University of Houston | Stewart R.R.,University of Houston | Dyaur N.I.,University of Houston | Lee Bell M.,Geokinetics Inc.
Geophysics | Year: 2015

Marine guided waves are strongly dispersive and commonly observed in seismic surveys worldwide in areas of shallow water with a hard seafloor. They are energetic and can obscure deeper reflection signals. We have conducted several ultrasonic physical modeling experiments to observe marine guided waves. The guided-wave dispersion curves from these surveys fit theoretical calculations very well. We next developed a new method to extract the subbottom S-wave velocity and density from water column guided waves using least-squares inversion. We have also developed a dispersion-curve filter, in the velocityfrequency domain, to attenuate the guided waves. We then applied these techniques to the physical modeling data, which have different water depths and different subbottom materials. The extracted results (S-wave velocity, density, and water depth) match the actual values well. The dispersion-domain filter clarifies reflections by attenuating the guided waves, which benefits further processing and interpretation. © 2016 Society of Exploration Geophysicists.

News Article | November 30, 2016

ANCAP and Geokinetics Agree on a Regional Seismic Program, Onshore Uruguay HOUSTON, TX (23 November, 2016) – The Administración Nacional de Combustibles, Alcoholes y Portland (ANCAP) has authorized Geokinetics Inc.

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