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

Carbonate Earth Mode: How Much Can Seismic Data Help? Earth Model Seismic Data 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 Southful Phase 1 Phase 2 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

Velocity (ft/s) Porosity Depth (ft) Velocity (ft/s) Porosity Tubb Wichita Zone1 Zone2 Abo Log Velocity vs. Log Porosity (FCU2723) H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology

Zone 2 Zone 1 Wichita Tubb Abo Up. St. Original Seismic Poorly Tied to Log Lithology/Porosity DT  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 phase data resemble the impedance section, which conditions amplitude to lithology H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology

Interpretive Advantage of 90 º -Phase Wavelet (Fullerton Carbonates) Zone 2 Zone 1 Wichita Tubb H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology

High-frequency Enhancing (Spectral Balancing) Hz Zone 2 Zone 1 Wichita Tubb H. Zeng; UL/PTTC May 2003 Workshop, Bureau of Economic Geology

Data Conditioning Improves Resolution and Well-Seismic Tie Original data Reconditioned Data after phase Shifting and high- Frequency enhancing Zone 2 Zone 1 Wichita Tubb Abo Up. St. Zone 2 Zone 1 Wichita Tubb Abo Up. St. 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

PHIH (well) Amplitude Amplitude as Indicator of PHIH (L2200/Zone 2) 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 Initial ModelImpedance Logs SeismicInverted Impedance 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 Seismic3 rd -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