Category Archives: News and Events

Latest CRGC-related News and Events.

Seminar: Seismic dispersion, attenuation, and frequency-dependent anisotropy of fractured reservoirs

Mr. Junxin Guo, PhD candidate, Exploration Geophysics, Curtin University

Title: Seismic dispersion, attenuation, and frequency-dependent anisotropy of fractured reservoirs

Held: Wednesday 28 March, 3PM–4PM

ABSTRACT:

Seismic characterisation of fractures is of great importance for the oil and gas production. For this purpose, in this thesis, I explore the mechanisms for the seismic dispersion, attenuation, and frequency-dependent anisotropy in fractured reservoirs.

Two important mechanisms are investigated, one is the wave-induced fluid flow (WIFF) and the other is the wave scattering by fractures. This study provides numerically validated theoretical models, which lays the basis for developing seismic attributes for fractured reservoir characterisation.

Workshop: Seismic Anisotropy short course, Overview of seismic anisotropy: Theory and applications

Ilya Tsvankin of Colorado School of Mines delivered a two-day Seismic Anisotropy short course, Overview of seismic anisotropy: Theory and applications, at the Australian Resources Research Centre (ARRC) on 26-27 March 2018.

 Prof. Tsvankin is Co-Leader of the Centre for Wave Phenomena (CWP) at the Colorado School of Mines and is known for his research in seismic anisotropy, elastic wave propagation, and characterisation of fractured reservoirs. His monograph ‘Seismic Signatures and Analysis of Reflection Data in Anisotropic Media’ is a comprehensive text covering both basic and applied aspects of seismic anisotropy.

The course covered the following topics:

  1. Anisotropic wave propagation
  2. Anisotropic ray tracing
  3. Notation and seismic signatures for vertical transverse isotropy (VTI)
  4. Normal-moveout (NMO) velocity for 2D anisotropic models
  5. 3D description of NMO velocity and NMO ellipse
  6. Nonhyperbolic reflection moveout
  7. P-wave time-domain signatures in VTI media
  8. Inversion of dip and nonhyperbolic moveout
  9. Time and depth processing of P-wave data for VTI and TTI models
  10. Moveout of mode-converted PS-waves and the “PP+PS=SS” method
  11. Joint inversion of PP and PS data and multicomponent tomography for TI media
  12. Case studies of multicomponent (PP+PS) processing
  13. Notation and signatures for orthorhombic and HTI media
  14. Anisotropic amplitude-variation-with-offset (AVO) analysis
  15. Inversion of vertical seismic profiling (VSP) data for anisotropy parameters

Seminar: Novel analysis of borehole and airborne radiometrics

Dr. Anton Kepic, Professor, Exploration Geophysics, Curtin University, Boart Longyear Chair in Geophysical Instrumentation

Title: Novel analysis of borehole and airborne radiometrics

Held: Wednesday 21 March, 3PM–4PM

ABSTRACT:

Gamma ray spectroscopy has been in use in the mineral exploration industry for decades, with much pioneering work done in the 1970’s to 1980’s.  The ability to collect good quality gamma ray energy spectra with 256 or more channels has been implemented and the computational resources for better data processing are now abundant. Despite such advances there hasn’t been much change in 30 years in the way natural gamma spectra are analysed, in the borehole or in airborne radiometrics.

Recent research by the Curtin University Geophysical Instrumentation Group, which includes myself, Dr Michael Carson and Ida Hooshyari-Far (PhD graduate student) have demonstrated that analysing the scattered gamma rays in the earth may be used to see changes in soils and rocks non-invasively using natural gamma radiation.  Additionally, a measure of these changes, the Heavy Mineral Indicator (HMI), is generally related to the iron content of the material.

Monte Carlo gamma-particle simulations, laboratory scale models, and field experiments all demonstrate that the natural gamma ray spectrum recorded during borehole drilling (Logging-While-Drilling) can be used to track changes in heavy element concentrations with the Heavy Mineral Index, and this HMI measure correlates well with iron-rich zones.  Advances in airborne gamma ray spectrometers and the implementation of low-level surveys also provide high quality spectra similar to logging while drilling approaches.  Thus, similar analyses were performed on a well-studied radiometrics data set from Elashgin, Western Australia.  Maps of HMI produced from the raw gamma spectra show very clearly that iron-rich soils and surface formations are well mapped.  Thus, using the same approach in analysing natural gamma from boreholes allows maps of Fe and K, U, Th to be made simply by reprocessing legacy data.

These findings represent a significant advance in how we may use spectral gamma measurements in the earth sciences, creating a basis for a new generation of safe logging-while-drilling tools plus changing the way we will analyse airborne radiometrics in the future.

Seminar: New developments in anisotropic processing of seismic data: An overview

Dr. Ilya Tsvankin, Professor, Department of Geophysics  Centre for Wave Phenomena, Colorado School of Mines

Title: New developments in anisotropic processing of seismic data: An overview

Wednesday 28 February 2018, 3PM–4PM

ABSTRACT:

I will give a brief overview of the research program of my research group, the A(nisotropy)-Team at the Centre for Wave Phenomena (CWP). The group’s portfolio includes a wide range of projects on modelling, inversion, and imaging of seismic reflection and borehole data from anisotropic media.

The team also works on seismic fracture characterisation and collaborates with the Reservoir Characterisation Project at the School of Mines on time-lapse monitoring of unconventional reservoirs. Among the topics discussed in the talk are:

  •  ray-based and wave-equation migration velocity analysis for anisotropic media
  • elastic full-waveform inversion (FWI) of reflection and microseismic data
  • estimation of attenuation anisotropy from multicomponent wavefields
  • application of anisotropic models in time-lapse seismic

Seminar: Evolution of Effluent Chemist at Crystal Geyser, Green River, Utah

Dr. Weon Shik Han, Associate Professor, Department of Earth System Sciences Yonsei University, Seoul, Republic of Korea

Title: Evolution of Effluent Chemist at Crystal Geyser, Green River, Utah

Thursday 1 February 2018, 3PM–4PM

ABSTRACT:

At CO2 injection sites, CO2 leakage from the storage formation
could be catastrophic. CO2 is a highly compressible fluid, typically injected at high pressure and temperature conditions. If this compressed CO2 reaches highly permeable conduits such as faults and fractures, CO2 could leak unabated to other formations (e.g. fresh water aquifers) and/or to the surface.

Assuming a fast-flow path to the surface, CO2 escaping from the storage formation instantaneously reaches the surface while experiencing adiabatic expansion, which results in Joule-Thomson cooling. The addressed eruptive mechanisms are analogues to natural CO2 eruption mechanisms, which are found in CO2-driven cold-water geysers around the world. A notable example of a CO2-driven cold-water geyser is the Crystal Geyser in central Utah. The fluid mechanics of this regularly erupting geyser was investigated by instrumenting its conduit with pressure, temperature, pH, EC, and dissolved oxygen sensors, measuring every 1 minute during and between eruptions.

Results of these measurements suggest that the time-scale of a single-eruption cycle is composed of four successive eruption types with two recharge periods ranging from 30 to 40 hours. Current eruption patterns exhibit a bimodal distribution although previous measurements and anecdotal evidence suggests that this pattern was different prior to recent seismic activity. This cold geyser’s eruptions are regular and predictable, and reflect pressure, temperature, EC, pH, and dissolved oxygen changes resulting from Joule-Thomson cooling, endothermic CO2 exsolution, and exothermic CO2 dissolution. Specifically, the perturbation of pressure and temperature data observed at the Crystal Geyser suggested the possibility of using temperature sensing technology within the observation well at the engineered CO2 sequestration site.

Seminar: An introduction to latest full-waveform sonic measurements

Dr. Baichun Sun, Curtin University Graduate

Title: An introduction to latest full-waveform sonic measurements

Held on Thursday 25 January 2018, 3PM–4PM

 ABSTRACT:

Borehole sonic logging tools have long been used to measure formation geophysical properties. I will talk about industry latest development of the sonic logging tool for open hole applications, including answer-product developments.

  1.  brief introduction about sonic logging,
  2. Capability of latest sonic logging tool,
  3. Tool  QC algorithms
  4. Velocity logs, including subarray examples
  5. VTI and HTI log examples.