Shuqian Dong and Sherif M. Hanafy February 2009 Interpolation and Extrapolation of 2D OBS Data Using Interferometry

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

Problems Problem 2: Near offsets are (sometimes) missing Solution: Interferometric extrapolation Problem 1: Receiver interval is (sometimes) too large Solution: Interferometric interpolation Water

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

OBS Interpolation G(B|A) Interpolated OBS Data Sea bed Reflectors Ocean Surface x B A G(x|A) Natural OBS Green’s Function Sea bed Reflectors Ocean Surface x A G o (x|B)* Model based Green’s Function B Sea bed Ocean Surface x A Dong S. and G. T. Schuster, 2008, Interferometric interpolation and extrapolation of sparse OBS and SSP data: UTAM 2007 annual meeting, 39 – 48.

Workflow Input Field Data Water Layer Thickness Generate GF for Water Multiples Interpolate/Extrapolate M issing D ata Max. Itr (MF ) Get Virtual CSG Max Iter Intr/Extr Final CSG N Matching Filter N Y Y Time (s) 03.0 X (km) 04.5 Sea bed Ocean Surface x Time (s) 03.0 X (km) 04.5 Time (s) 03.0 X (km) 04.5 Input Data Unfiltered Virtual Filtered Virtual G(x|B) G(B|A) G(x|A)

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

Time (s) 03.0 X (km) 04.5 Time (s) 03.0 X (km) 04.5 Local Matching Filter

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

Z (km) 04.5 X (km) shots dx = 30 m 800 receivers dx = 7.62 m Velocity Model

Interpolation Goal Given 80 Traces Trace interval = 76.2 m Goal 800 Traces Trace interval = 7.62 m Sparse geometryDense geometry

X (km) Time (s) Input CSG dx = 76.2 m traces: 80 X (km) Time (s) Virtual CSG dx = 7.62 m traces: 800 X (km) 06.0 Time (s) Filtered Virtual CSG dx = 7.62 m traces: 800 X (km) Time (s) Real CSG dx = 7.62 m traces: 800 Sparse OBS Interpolation

Z (km) 04.5 X (km) 06.0 Migration of sparse OBS data Sparse OBS Interpolation Z (km) 04.5 X (km) 06.0 Migration of interpolated OBS data

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

GoM Field Data Gulf of Mexico OBS marine data A total of 896 CSGs 179 traces/CSG Trace interval = 25 m 2501 samples/trace sec sample interval Total time = 10 s

Interpolation Goal Given 101 Traces Trace interval = 100 m Goal 401 Traces Trace interval = 25 m Sparse geometryDense geometry

Field Data: Interpolation 0 10 Time (s) 0 X (km) Original OBS data Trace’s number = 401 Trace interval = 25 m 10 0 Time (s) 0 X (km) Sparse OBS data Trace’s number = 101 Trace interval = 100 m 10 0 Time (s) 0 X (km) Virtual OBS data Trace’s number = 401 Trace interval = 25 m 10

Trace Comparison Green are virtual traces and yellow are true traces

Field Data Extrapolation Example

Extrapolation Goal Given 48 Traces at far offsets Shot – first trace offset is 250 m Goal 58 Traces at near and far offsets Extrapolate for the 250 m at the near offset Dense geometrySparse geometry

Field Data: Extrapolation Time (s) X (m) Input CRG Time (s) X (m) Real CRG Time (s) X (m) Virtual CRG

Outline Problem: Missing and Sparse Traces in OBS Theory of Interferometric Interpolation and Extrapolation Matching Filter Numerical Examples –Synthetic Example: SEG/EAGE Velocity Model –Field Data: Gulf of Mexico Summary and Conclusions

OBS field data and generated water multiples are used to interpolate or extrapolate missing traces The proposed technique is successfully tested on synthetic and field data Iteration over interferometric and matching filter will improve the final results

Acknowledgement We would like to thank the UTAM 2008 sponsors for their support. Thank You