Horizon based target orientated beam demultiple with examples from the North West Shelf, Australia

Abstract

Complex inter-bed multiple in the North West Shelf, Australia, is a problem for depth velocity modelling and imaging of Jurassic reservoirs. Traditional Radon & 3D-SRME (3D Surface Related Multiple Elimination) demultiple techniques are now standard processes for removing long period and waterbottom related multiples. However, throughout the Browse Basin, deeper multiple generators and the small velocity discrimination between primary have rendered these techniques ineffective against inter-bed multiples. Beam Migration has specific advantages in its speed and high signal-to-noise levels that make it suitable for depth velocity modelling and final imaging. Wavelets can, based upon a combination of criteria, be weighted down or excluded from reconstruction. It is possible to reject wavelets that match a multi-dimensional multiple model. This model is based upon a combination of interpretation, normal moveout and spatial & temporal location. Data examples from the North West Shelf, Australia, illustrate the flexibility of this approach and demonstrate its effectiveness in the complex inter-bed multiple area of Browse Basin. Close interaction and good understanding of the objectives, especially between the imagers and the asset team is required for the project' success. Interactive or quick testing of multiple model scenarios (through combined depth velocity model building software) is necessary to aid this interaction.