Connolly, David L.¹, Fred Aminzadeh¹, Herald Ligtenberg²
(1) dGB-USA, Sugar Land, TX
(2) dGB Earth Sciences, Enschede, Netherlands

ABSTRACT: Reducing Seal and Charge Risk by Detecting Fluid Migration Pathways Using Seismic Data

Large scale vertical fluid migration, dominating the Gulf of Mexico, Niger delta, North Sea, and many other basins has been known for years from geochemical maturity data. This vertical migration often occurs via gas clouds or chimneys related to fault zones or fractures. Detecting and confirming such vertical migration has been very difficult. Gas chimney processing offers the opportunity to highlight these vertical disturbances in the seismic record, map fluid migration pathways, and thus predict favorable traps or fault blocks for gas or oil accumulation.
Gas chimney processing approach uses the "meta-attributes" concept to highlight vertical chaotic seismic disturbance in 3-D data. It is comprised of properly trained neural network with a number of seismic attributes as well as geologist’s insight and interpretation as its input. This leads to creation of a "Chimney Cube". Similar approach can be used to detect other features such as faults, fractures, salt bodies, sand-filled channels as well as other lithofacies and stratigraphic features.
Chimney interpretation is a key component of integrated workflow for reducing seal and charge risk in hydrocarbon exploration and prospect ranking. Seal and charge risk can be significantly reduced when this migration path data is combined with other independent indications of hydrocarbon migration and entrapment. These include basin modeling, geochemical analysis, piston coring, remote sensing, pressure prediction, and seismic inversion. With examples from GOM, Niger delta, North Sea and South Africa we show how different types of chimneys are related to different seal characteristics.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.