Fluid Discrimination of Poststack Britght Spot unsing Amplitude Variation with Offset(AVO) analysis and Model-Based Iversion In Abasi Field.Onshore Western Niger Delta,Nigeria.
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Date
2015
Authors
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Journal ISSN
Volume Title
Publisher
Obafemi Awolowo University
Abstract
Fluid discrimination of poststack bright spots in Abasi Field, Onshore Western Niger Delta, Nigeria was investigated using Amplitude Variation with Offset (AVO) Analysis and Model-Based Inversion. This was with a view to distinguishing genuine poststack bright spots from false bright spots using AVO effect.
A dataset of 3-D seismic partial angle stack data (near, far and full offset), and a suite of digital logs from five wells were provided by Shell Petroleum Development Company of Nigeria Limited (SPDC). The OV-001, OV-002 and OV-003 well logs were used to identify and correlate the reservoirs across the field for subsequent analysis. The structural features within the study area were identified using the full offset seismic data. The bright spots were enhanced using RMS attributes. AVO attributes were generated for amplitude extraction using the horizon slices. The dataset was inverted into an acoustic impedance volume for the analysis of fluid distribution across the study area.
Depth maps generated revealed two fault-independent closures located at approximately 8750 ft (prospect 1) and 9250 ft (prospect 2) on horizons 1 and 2 respectively. Amplitude maps generated for the horizons showed a bright spot on prospect 1 while there was no bright spot on prospect 2. The Pseudogradient crossplot and Far minus Near times Near attribute indicated that the hydrocarbon sands within the study area were associated with Class III type AVO anomaly. One of the sands (Prospect 1) had approximately 2 km lateral extent. Prospect 1, which displayed a good AVO anomaly, bright spot effect and low acoustic impedance as shown by the inversion results was a potential hydrocarbon reservoir. Prospect 2, with no AVO anomaly, no bright spot effect and high acoustic impedance was a wet reservoir. This interpretation was supported by the resistivity log of ID-001 well. Two genuine bright spots and three false bright spots were distinguished within the study area.
The study concluded that prospect 1 was a potential hydrocarbon reservoir.
Description
xv,127
Keywords
Fluid Discrimination, Poststack Bright Spot, Amplitude Variation, Model Based Inversion, Abasi Field, Onshore, Western Niger Delta, Nigeria
Citation
Mfon King Saviour(2015)Fluid Discrimination of Poststack Britght Spot unsing Amplitude Variation with Offset(AVO) analysis and Model-Based Iversion In Abasi Field.Onshore Western Niger Delta,Nigeria.