Abstract

While wide-azimuth seismic surveys represent a routine in land environments, in marine environments things go differently. Conventional offshore 3D acquisition is still being performed mainly using narrow azimuth streamer configurations, even in structurally complex areas. Attempts at breaking this paradigm have been recently made by the industry with good results, through the acquisition of some unconventional "Multi Azimuth" (MAZ), "Wide Azimuth" (WAZ), "Rich Azimuth" (RAZ) and Coil Shooting marine surveys. Here we are presenting planning, acquisition and processing results of the advanced marine surveys, a Multi-Azimuth and a Coil shooting (Full azimuth), recently acquired by Eni e&p in Indonesia. We are also presenting a 2D test and successive 3D acquisition of a broad bandwidth (dual sensor) seismic in West Timor area, aimed at exploiting sub thrust geology. At the end we demonstrate that advanced acquisition techniques effectively provide improved geophysical images and more geological insight for exploration compared to traditional techniques.

Introduction

Towed Streamer Marine seismic acquisition generates a dataset with a limited azimuth range, of the order of 10o. In areas of complex geology, this limited azimuth collection, can result in very poor illumination of the reservoir by the seismic wave-field, due to bending and scattering of the ray-paths in the over-burden. Over the last five years, efforts to mitigate this poor illumination effect, with marine towed streamer surveys, have focused on acquisition solutions to generate seismic datasets with better azimuth distribution. The efforts included multi-direction and multi-vessels geometries to acquire surveys rich in azimuth. These techniques have proven to provide significant value in complex imaging environments; however they are constrained by the cost and availability of the multi-pass, multi-vessel operations.

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