Case story
Discovery well validates reservoir-focused gather conditioning and interpretation
Client: Harbour Energy
Location: Indonesia
Challenge
Harbour Energy identified amplitude supported exploration prospects in multi-client 3D data but had concerns about data fidelity and suitability for quantitatively evaluating the prospects.
Harbour Energy had identified a number of amplitude supported exploration prospects using multi-client 3D seismic data.
However, observed differences in event alignment, noise level and bandwidth between contractor processed angle stacks gave rise to concerns about the prestack amplitude fidelity of the data and its suitability for quantitatively evaluating the prospects.
Solution
Sharp Reflections provided prestack gather QC, post-migration conditioning, and AVA attribute generation to aid exploration drilling planning.
Sharp Reflections was brought in to perform full-volume prestack gather QC, post-migration gather conditioning and AVA attribute generation. The aim was to provide reservoir-focused, quality assured prestack gathers and derivative attributes to aid exploration drilling planning.
The team used iterative full-volume QC attributes at each step of the conditioning process to assist with algorithm parameterization and to address spatial and temporal variations in data quality. Interpretation of the results was assisted through extensive 3D parametric modelling of possible reservoir, seal and fluid scenarios, utilizing data from offset wells to identify key Extended Elastic Impedance (EEI) angles for reservoir and fluid prediction.
Impact
Sharp Reflections workflow improved amplitude fidelity across the angle stacks, resulting in enhanced resolution and confident calibration against pre-drill scenarios.
The workflow resulted in improved amplitude fidelity across the angle stacks, specifically in terms of S:N, bandwidth consistency and event alignment, with Class IIp events clearly preserved and enhanced. Resulting AVA attributes and EEI volumes demonstrated enhanced resolution of the prestack signal and allowed Harbour Energy to confidently calibrate the observed responses against pre-drill scenarios.
The play-opening discovery well was drilled by Harbour Energy in Q2 2022, providing valuable calibration for prestack inversion work to follow.
Sharp Reflections full-volume prestack data QC – health-checks – provide spatial, temporal and angle dependent insights into prestack data quality and fitness-for-purpose and inform decisions for gather conditioning processes and parameterization.
Global AVA compliance
RMO/gather
flatness
S:N ratio
Spectral
bandwidth
Phase
stability
Multi-client processed angle stacks
Near angle stack
Data courtesy of PGS
Ultra-far angle stack
Data courtesy of PGS
Reservoir-focused conditioned angle stacks
Near angle stack
Data courtesy of PGS
Improved S:N on near angle stack
Ultra-far angle stack
Data courtesy of PGS
Alignment time-shifts, increased bandwidth and improved S:N on far angle stack
Impact of conditioning on AVA response – intercept-gradient cross-plots
Data courtesy of PGS
Discovery well-tie (resistivity log) with EEI fluid volume validates the conditioning and AVA attribute results
