Improving Petroleum System Analysis With Better Understanding of Seismic Input Uncertainties
Duan, Ling1 and Liu, Jianchang
Seismic data serves as the primary Input for basin model construction and petroleum system analysis. The seismic data quality and interpretation directly impact basin model quality through providing inputs regarding a basin’s formation depth, geometry, depositional and lithological information. Understanding seismic data and the associated uncertainties will allow for effective incorporation of seismic information into basin models to enhance the model’s geologic content and predictive capability.
The scheme employs integrating seismic data within a 3D basin model as the basis of analysis. During the model building process, seismic attributes are extracted and interpreted in order to use these variables to optimize the basin’s geologic elements and populate the litho-facies. The seismic sections or cube inserted into the 3D basin model provide visual and dynamic connections between the seismic data and the basin model. This allows for optimization in establishing correlations and interactions between petroleum system components and seismic characteristics.
Uncertainty analysis is performed using the integrated model. The analysis covers the uncertainties of seismic velocity model building, time / depth conversion, amplitude characteristics and their implication on the lithological composition of formations, attribute geometry variations and their impact on the depositional environment. Another topic of interest involves an investigation of the relative magnitude of the seismic input uncertainties and the intrinsic uncertainties in basin model regarding the "trade-off" effect in modeling uncertainties. Some of the uncertainties in seismic data may be so overwhelming that the uncertainties of the exploration are primarily determined by the seismic data, while some uncertainties may have strong correlations with those in basin model such that the overall uncertainties of modeling may be inflated or reduced by these correlations.
Case studies from deepwater basins of the northern margin of South Atlantic area show that this uncertainty analysis influences the selection of modeling methodologies, improves the source rock maturity prediction, provides clearer understanding of hydrocarbon migration patterns, and incorporates estimates of the nature and volume of hydrocarbon accumulations.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013