250 likes | 425 Views
Reconditioning Seismic Data to Improve Carbonate Stratigraphic Interpretation and Reservoir Characterization, Fullerton Field, West Texas. by Hongliu Zeng Bureau of Economic Geology John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin.
E N D
Reconditioning Seismic Data to Improve Carbonate Stratigraphic Interpretationand Reservoir Characterization,Fullerton Field, West Texas by Hongliu Zeng Bureau of Economic Geology John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin
Carbonate Earth Mode:How Much Can Seismic Data Help? Seismic Data Earth Model H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Presentation Outline • Value of seismic data as seen in petrophysical analysis • Why seismic data needs reconditioning before interpretation? • Basic seismic data conditioning (phase adjustment and high-frequency enhancing) • Advanced seismic data conditioning (progressive, model-based inversion) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Fullerton Seismic Data (2-D & 3-D) Labrador Phase 1 Phase 2 Southful 2 km H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Synthetic Seismogram (Cal/Mon 1) Tubb Abo H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Log Velocity vs. Log Porosity(FCU2723) Porosity 0 10 20 Velocity (ft/s) 15000 25000 Tubb Depth (ft) Zone1 Velocity (ft/s) Zone2 Wichita Abo Porosity H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Original Seismic Poorly Tied toLog Lithology/Porosity f f f DT Tubb Up. St. Zone 1 Zone 2 Wichita Abo 1 km H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Basic Data Conditioning • High-frequency enhancing - Original data are dominated by low frequencies - Boosting high-frequency components improves seismic resolution (even in a price of reducing S/N ratio) • Adjust seismic phase to 90º - Standard zero-phase wavelet is not ideal for lithologic interpretation of seismically thin beds - 900-phase data resemble the impedance section, which conditions amplitude to lithology H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Interpretive Advantage of90º-Phase Wavelet(Fullerton Carbonates) 200 300 400 500 600 700 800 900 100 00 Tubb Zone 1 Zone 2 Wichita H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
High-frequency Enhancing(Spectral Balancing) 0 60 120 Hz Tubb Zone 1 Zone 2 Wichita H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Data Conditioning Improves Resolution and Well-Seismic Tie Tubb Up. St. Zone 1 Original data Zone 2 Wichita Abo Tubb Reconditioned Data after phase Shifting and high- Frequency enhancing Up. St. Zone 1 Zone 2 Wichita Abo H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Amplitude as Indicator of PHIH (L2100/Wichita) PHIH (well) Amplitude H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Amplitude as Indicator of PHIH(L2200/Zone 2) PHIH (well) Amplitude H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Advanced Data Conditioning • Seismic data are limited in frequency (<100 Hz) and Resolution (10 ms or 100 ft) • The only source of high-frequency information beyond seismic is well logs • Use of well logs as soft constrain may significantly improve resolution (2 ms or 20 ft) • Tool: model-based inversion (Hampson-Russell, Jason, CGG, etc.) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Model-Based Inversion Impedance Logs Initial Model Inverted Impedance Seismic H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Challenges in Building Initial Model • Impedance values between wells are interpreted • Correlation of well logs are characterized by uncertainties of various degrees • Correlation surfaces may not be accurate beyond wells • First initial model is always not optimal H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Well Correlation vs. Real Seismic H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Progressive Inversion • Build multiple initial models and do multiple inversions • Start from the most prominent and reliable geologic boundaries and seismic horizons, adding additional horizons from intermediate inversion results • Use more and more horizons to build better initial model, resulting in better inversion with higher resolution. H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Start from Best Horizons Abo H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Progressive Inversion(First Round) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Progressive Inversion(Second Round) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Progressive Inversion(Third Round) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Improvement in Resolution Seismic 3rd-Round Inversion 100 ft H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology
Summary • Original seismic data are often not optimal for geologic interpretation and need reconditioning • Basic data conditioning (1) corrects seismic phase and (2) enhance high-frequency components in the data, improving resolution to 100 ft • Advanced data conditioning combines geologic interpretation and seismic data in a progressive, model-based inversion procedure, further improving resolution to 20 ft H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology