Beach Energy Ltd Lake Tanganyika 2D Transition Zone Seismic Survey Data Processing, 2015 Matching Filter to match Transition Zone Airgun Source Wavelet to the Modeled Marine Airgun Source Signature (minimum-phased and de-bubbled) Line BST14A-02 Revised Feb 27, 2015

Lake Tanganyika 2D Transition Zone Seismic Survey Location of Lines

Derivation of Matching Filter Operator

 The Matching Filter to match the Transition Zone Airgun Source wavelet to the Marine Source Signature (with no bubble):  Input the modeled Marine Source Signature wavelet that was modeled by Fugro and the Transition Zone Source Signature modeled by BGP.  Create the Minimum Phase Equivalent of the Marine Source Signature and taperr the amplitudes to remove the gun bubble pulse which adds low frequencies to the data.  Using the Weiner Matching Filter, create an operator that matches the Transition Zone Source wavelet to the tapered Minimum Phase Equivalent of the Marine Source Signature.  This operator is the Matching Filter Operator.  Test the Matching Operator by applying it to the Transistion Zone Source wavelet and check for similarity with the Minimum Phased Marine Source Signature.

Match Filter Derivation 1. Transition Zone Modeled Signature 2.Marine Source Sig (min. phs. debubbled)

Match Filter Derivation 3. Match Filter Operator 4.Convolution Output (check against #2)

Shot Gather Before Match-Filter Applied First break 674 msec

Shot Gather After Match-Filter Applied (matching Vibroseis source wavelet to Marine) First break 670 msec

Stack Displays Sequence Input field data/Reformat Add Geometry: (from SPS files) Spherical Divergence Correction: (V**2)(T**1.2) Ensemble Balance: entire record scaled Low-cut filter: 4 Hz Airgun Data: Match Filter Vib Data: Match Filter, reverse polarity NMO correction: preliminary velocities Trace Balance: 7 windows Stack Static Shift to lake level High-cut: 83 Hz Trace Balance: 7 windows Display: -ve = blue, +ve = red Note: positive reflection co-eff. = -ve number or blue color

Stack Before Match-Filter Applied

Stack After Match-Filter Applied (matching Vibroseis source wavelet to Marine)