Discrete Frequency Ant Tracking: Method and Application

Abstract

This paper uses the integrated application of ant tracking and spectral decomposition to detect minor faults and fractures based on 3D seismic data in fractured carbonate reservoirs. A new method is developed to improve imaging of faults and fractures using “discrete frequency ant tracking (DFAT)”. DFAT data is computed using discrete frequency phase data obtained from spectral decomposition. We detect fracture zones in the DFAT cubes, then, using diverse diagrams we correlate FMI data with the fractures extracted from DFAT. The different DFAT attribute maps show that the high-frequency ant tracking data is more effective at detecting small faults and fractures. After the interpretation of multi-scale frequency data, DFAT data that reveal faults and fractures distribution better were selected to create a new data cube by means of reconstruction. When compared with conventional data, the reconstructed ant tracking data produces more detailed images of small faults and fractures.

We applied this method to a carbonate reservoir located in Bohaiwan basin of Northeast China. It is a carbonate buried hill, and the main rock types are limestone and dolomite. The matrix porosities of carbonate exhibit lower and impermeable, and they are not the mainly reservoir. The late-formed unfilled tectonic fractures and faults are the dominant reservoir space for oil migration and accumulation. After integrated study of the seismic attributes, well logs and production data, we determined the favourable zones for a fractured reservoir and a reservoir model for the carbonate buried hill. The main factor controlling the carbonate reservoir is the small faults and fractures. The hydrocarbon reservoirs are located at high position in the buried hill along the large fault and the hydrocarbon is also clustered around small faults and fractures. 5 wells were drilled based on the results of this study and very productive in the regions predicted to be enriched in hydrocarbons. The results of our case study shows, this has the potential to be a highly effective and very valuable seismic method.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018