Migration of intermediate offset data from two-boat-survey Zongcai Feng Nov 3, 2015

Outline  Motivation  Extended aperture by two shot boat survey  Interferometric interpolation  Predict intermediate offset using multiples  Theory  Filling the gap of intermediate offset data  Numerical test

Motivation Surface-related multiples are treated as noisy conventionally. RAW Data SRME Data Multiples can provide different illumination area from primary.

Motivation Surface-related multiples are treated as noisy conventionally. RAW Data SRME Data Multiples can provide different illumination area from primary Increase the illumination area (Xin Wang)

Original Two-source-boat Survey (The CLO technique) LL water Near-offset shot Far-offset shot Streamer length: L is 2 L ahead of

Original Two-source-boat Survey (The CLO technique) LL water Near-offset shot Far-offset shot Streamer length: L Is L ahead of The CLO technique. In CLO acquisition, an extra source array system is deployed on a smaller vessel, sailing one spread-length ahead of the main seismic vessel. (Piet Van Mastrigt, 2002) Advantages of CLO are: increased efficiency that results from doubling the streamer count (typically 8-km offsets with 4-km streamers) Offset: 0~L + L~2L

Extended Aperture with Two-source-boat Survey for Primary and Multiples (Schuster and Wang, 2012) L2L water Near-offset shot Far-offset shot Streamer length: L is 2 L ahead of

Extended Aperture with Two-source-boat Survey for Primary and Multiples (Schuster and Wang, 2012) L2L water Near-offset shot Far-offset shot Streamer length: L is 2 L ahead of

Extended Aperture with Two-source-boat Survey for Primary and Multiples (Schuster and Wang, 2012) L2L Near-offset shot Far-offset shot Streamer length: L is 2 L ahead of Rec # Near offset shot Sor # Rec # Far offset shot Sor # Rec # Intermediate offset are missing Sor # water Offset: 0~L Offset: 2L~3L Offset: L~2L?

2L~3L All offset data (wave equation) 0~L L~2L Far Offset Near OffsetInter Offset part Primary Multiple Far offset multiple Inter offset primary predict

Outline  Motivation  Extended aperture by two shot boat survey  Interferometric interpolation  Predict intermediate offset using multiples  Theory  Filling the gap of intermediate offset data  Numerical test

Interferometric interpolation s g water layer x

Predict intermediate offset using multiples (Hanafy and Schuster, 2013) water layer L2L sxg Data based Model based Assume know: water velocity, location and reflectivity of water bottom

Reiceiver side intermediate offset primary water layer L2L s xg

Reiceiver side intermediate offset primary water layer L2L s xg

Source side intermediate offset primary water layer L2L sxg

Source side intermediate offset primary water layer L2L sxg

Stationary Phase Analysis water layer sxg g s'

Stationary Phase Analysis water layer s x g’ g x' g’ s' s’g & s’g’ straight

Stationary Phase Analysis water layer s x g x' g’ s' s’g & s’g’ straight

Intermediate offset aperture analysis L2L sxg Near Offset: 0~L Intermediate Offset: L~2L ? Offset =5L Far Offset: 2L~3L

Intermediate offset aperture analysis L2L sxg Near Offset: 0~L Intermediate Offset: L~2L ? Offset =1.5L Far Offset: 2L~3L For flat ocean bottom, predict Intermediate Offset: L ~ 1.5L For deeper structure, predict Intermediate Offset > L ~ 1.5L e.g: = 1.1L ~ 1.5L or 1.8L~2.2L (1.8L~2.0L )

Outline  Motivation  Extended aperture by two shot boat survey  Interferometric interpolation  Predict intermediate offset using multiples  Theory  Filling the gap of intermediate offset data  Numerical test

Numerical Test water layer L2L sxg

2L~3L All offset data (wave equation) 0~L L~2L Far Offset Near OffsetInter Offset part Primary Multiple Far offset multiple Inter offset primary predict

Far offset data (2L~3L) Primary + Multiple Assume deeper water, primary can be easily mute

Predict Primary Part inter offset data (1.5L~2L) Born modeling for water bottom reflection True Primary For deeper structure, predict Intermediate Offset > L ~ 1.5L Non stationary

water layer L2L sx g Numerical Test

2L~3L 0~L L~2L Far Offset Near OffsetInter Offset part Far offset multiple Inter offset primary predict All offset data (wave equation) Primary Multiple

Primary + Multiple Far offset data (2L~3L) Assume deeper water, primary can be easily mute

Inter offset data (L~2L) Born modeling, Cross correlation, Deconvolution True inter offset data L~2L Pre inter offset data

True inter offset data Inter offset data filter (L~2L) Cross correlation, Slank stack, Filter (angle) P M Pre inter offset data

Source side intermediate offset primary water layer L2L sxg

Intermediate offset data filter Local Slank Stack Filter (angle)

g T Slank Stack Use Local Slank Stack to Calculate Filter F(g)

g T

g T when (g,t) is stationary Use Local Slank Stack to Calculate Filter F(g)

Intermediate offset data By Local Slank Stack Filter

Zoom in Intermediate offset data By Local Slank Stack Filter

Inter offset data zoom in True data Predict data after filtering

Use Local Slank Stack to Calculate Filter F(g) g T Slank Stack Extent slank stack:

g T Use Local Slank Stack to Calculate Filter F(g)

Inter offset data aftering filtering Cross correlation, Local slank stack, Filter (angle) Zoom in new old

Local Slank Stack Compare Zoom

Primar + Multiple Predict intermediate offset data using predicted multiple Multiple x F(t) predict

Predict offset data (L~2L)

Source side intermediate offset primary water layer L2L sxg Intermediate offset multiple

Next step  More complex model + RT to separate multiples  Compare intermediate offset image with near and far offset  Migration  Add noise