COLORED INVERSION HAMPSON RUSSELL MANUAL
COLORED INVERSION HAMPSON RUSSELL PLUS

Model Building Seismic data does not contain the low frequencies needed for to recover absolute impedances through inversion. NOT to change the sonic log, but only the depth-time curve. в—¦ Possibly repeat the previous two steps. в—¦ Extract a new wavelet using the well logs. в—¦ Stretch/squeeze the logs to tie the seismic data. Wavelet is very important Procedure: в—¦ Use statistical wavelet extraction to determine a preliminary wavelet. Wavelets are used for 4 types of processes: в—¦ в—¦ в—¦ в—¦Д¬reating synthetics. decreasing bandwidth with increasing depth в—¦ Inter-bed multiples в—¦ NMO stretch в—¦ Offset or angle Wavelets in the earth vary in space (including by offset/angle) and in time for a several reasons: в—¦ Near surface effects в—¦ Frequency-dependent absorption i.e. These wavelets both have the same amplitude spectrum, but different (constant) phase spectra:

Over a limited frequency range, the phase spectrum may often be approximated by a straight line. The wavelet is defined completely by its amplitude spectrum and its phase spectrum:

COLORED INVERSION HAMPSON RUSSELL MANUAL

Log correlation is the process of applying a manual correction to the well depth-time curve to optimize the correlation between well depths and seismic times. в—¦ The events on the seismic data may be mispositioned due to imperfect processing. в—¦ Noise in the sonic log velocities produce cumulative errors in the calculated travel-times. в—¦ The shallowest velocities are not logged.

The default depth-time table calculated from the sonic log is never exactly correct because: в—¦ The seismic datum and log datum may be different. A critical step is correlation of well-depth to seismic-time: The impedance log model must be measured in 2way travel time but the original logs are measured in depth. The initial guess model for each trace consists of an impedance log, usually derived by multiplying a real sonic log by a real density log. Using values determined in the Analysis QC areal variations Create data slices QC Inversion results at well locations Use well logs and horizons to replace the low frequencies not recorded by the seismic. Select Inversion Type and Parameters Scale model and seismic. Load wells Import seismic Import or pick seismic horizonsД«uild low frequency model: Inversion Analysis: Perform Inversion: Interpret Result Model Based Inversion Flow Gather necessary inputs: п‚— Theoretically, inversion attempts to recover these lost regions. п‚— As we can see from these plots, the effect of the wavelet is to remove both high and low frequencies from the trace spectrum. The effect of convolving the wavelet with the reflectivity is to remove much of the high frequency detail:Д¬onvolution in the time domain is multiplication in the frequency domain. Frequency-dependent absorption is ignored. Transmission loss and geometric spreading are ignored.

COLORED INVERSION HAMPSON RUSSELL PLUS

Seismic = Wavelet convolved with Reflectivity plus noise. General Forward Model for Inversion Reflectivity Impedance Displays Post-stack seismic inversion transforms an input seismic volume into a volume of acoustic impedance. п‚— Current inversion technology has shifted attention to the quality of the input seismic data, and the model building. п‚— In recent years, inversion has been combined with pre-stack AVO analysis, known as Simultaneous Inversion. Inversion history Early inversions were limited to poststack data. Lithology Separation with Simultaneous Inversion Simultaneous Inversion of AVO Seismic Data Low frequency AI model (0-10Hz) Seismic + Low Frequency Trend (0-3Hz) AI Model (0-60Hz) Tie Wells to Seismic & Wavelet Estimation Which Inversion Acoustic Impedance Inversion (full stack) п‚— Simultaneous AVO inversion (pre stack) п‚— Geostatistical Inversion (full /prestack) п‚— P-Imp to Recoverable Oil/GasвЂ¦ п‚— Porosity to Permeability? If the relationship exists! п‚— P-Imp to Net HC Pore Volume ( in Oil sands): п‚— P-Impedance is also known as acoustic impedance (AI)Д¬ommon P-Impedance Relationships P-Imp to Porosity (in clean carbonates) п‚— P-Imp to Net Pay (in gas sands) п‚— Measure for the hardness of the rock Density * Velocity The Seismic Experiment Interaction of Geology & GeophysicsД®ND пѓ Structure пѓ Velocity пѓ Rock, Fluid, Lithology tДЄI and Seismic Data in Time and Frequency DomainДЇrom Rock Properties to Reservoir Properties QAB 4013 Rock Physics and AVO Analysis - Seismic InversionDr.

Colored inversion hampson russell