The scope of work includes, but is not limited to the provision of 3D Survey APSDM Strategic Imaging Project, associated tools and highly qualified specialist personnel.
Interested companies must be able to provide the following 3D Survey APSDM Strategic Imaging Project:
A. General Project Description
- The Project is best described as an Integrated Imaging Study with a primary objective to develop the best methodologies to solve fault related imaging problems that are common in the block and other areas across the Niger delta.
- Anisotropic prestack depth migration in combination with advanced velocity model building and tomographic techniques are essential technologies for the project. Success will require strong collaboration between specialized experts from the contractor and the company, as well as an iterative, integrated, creative and highly interpretive approach.
- Fault surfaces will need to be depth interpreted and become surfaces that separate velocity contrasts within the model. Anisotropic parameters will need to be constrained by available well control and checkshots (VI and Walkaway) as well as geological surfaces. Finding the proper combination of depth imaging algorithms and model building will require some trial and error testing.
- Ultimately, the imaging objectives for the block are to improve fault sag and fault shadow related imaging problems to reduce the structural and stratigraphic uncertainty for several deeper (>10,000ft) exploration leads as well as at Yoho and adjacent fields.
B. Input Data and Area
- Input data for the project will be the block 2003 3D survey that was acquired in a 10 streamer/dual source configuration covering ~1230 km2 (full fold). The data were acquired E-W into 12.5m xline bins with 6km streamers with a 18.75m flip/flop source yielding 80 fold. Due to surface obstructions in the area some 1500m offset box-in data was also acquired in 2003. Additional vintage streamer data (different shooting direction) will also be used to supplement near offset gaps around obstructions
- The Imaging Program area includes the entire 2003 3D survey extent (~1230 km2 full-fold). Based on technical and business needs a priority area of ~262 full-fold sq.-km (~125 sq,-km image area) is planned to be branched off later in the velocity model building phase
C. Generalized breakdown
The services can be broken down into these three general categories;
- Hi-end preprocessing from navigation merged field tapes. Noise mitigation, multiple suppression and signal enhancement are critical, particularly in fault shadow areas. Bin and regularize the data prior to migration
- Iterative Anisotropic Velocity Model Building to accurately resolve lateral velocity contrasts across faults for the entire the block. Contractor must have a full suite of proven prestack depth migration algorithms (Kirchhoff, Beam, WEM, RTM) as well as proven tomography with ability to constrain input rays based on model surfaces. Contractor must have the ability to incorporate the geological surfaces and other geophysical data into the velocity/anisotropic model
- Hi-end post-migration processing and noise reduction as required with a suite of angle stacks and specified derivative volumes