Assets
Technologies
Enovation is deploying selected advanced, proven geophysical technologies to capture valuable opportunities in hydrocarbon exploration, development, production and reservoir management
Enovation is currently targeting the following technologies :
Multi 4 Component Seismic (4C)
Four-component (4C) seismic data are typically acquired using three orthogonally-oriented geophones or accelerometers and a hydrophone within an ocean-bottom sensor. The system can be deployed in node-type systems or as cables. The addition of geophones/accelerometers allows measurement of shear (S) waves, as well as compressional (P) waves
4C seismic has a number of potential advantageous over conventional seismic:
Improved Imaging
- Imaging through gas clouds and gas charged sands where the P wave image is blurred, noisy, non existent or distorted, 4C can illuminate previously hidden prospects and reservoirs
- Imaging weak P impedance contrast (transparent) reservoirs
- Imaging where there is a strong P multiple, by better survey geometry, a broader frequency band and dual sensor summation
- Imaging beneath salt and imaging in complex structural areas to improve illumination and resolution of sub-salt prospects
Improved Lithology/Fluid prediction in reservoirs
- Bright Spot anomaly analysis
- Reservoir characterization for exploration pre-drilling and delineation phase through seismic attributes (Vp/Vs etc.)
- Lateral extent of oil bearing sands away from well control
- Saturation mapping
Seismic Anisotropy (Directionally dependent) determination
- Estimating Vertical Transverse Isotropy (VTI) parameters for use in processing
- Fracture density and direction; optimize drilling campaigns for field development and production phase through the use of the full azimuthal coverage
4C Seismic can potentially therefore:
- Produce clearer pictures of complex Oil and Gas fields
- Provide more information about reservoir rocks
- Reduce development risks and enhance Oil recovery
Marine Electromagnetic seabed surveys are used to map subsurface resistivity in order to locate hydrocarbon reservoirs which are normally highly resistive
The controlled source (CSEM) technique employs a powerful low frequency (typically 0.1-10Hz) source close to the seafloor with an array of detectors lying on the seabed, to map subsurface resistive layers
In resistive layers, such as a hydrocarbon reservoir, the magnetic and electric field attenuation is lower than in the surrounding water saturated sediments. Electromagnetic surveys can therefore potentially distinguish between water filled and hydrocarbon filled reservoirs, and can also be used to detect Basalt, Carbonates and Salt. EM complements information derived from seismic methods
Water depth has a strong influence on the measured signal due to the airwave effect generated at the sea-air interface. Shallow water provides a technical challenge for CSEM techniques due to this airwave effect
New acquisition and processing methods are however being developed for shallow water applications and also to improve the vertical and lateral resolution of the EM method
Multi-Azimuth seismic is a technique primarily used to improve illumination of the subsurface in areas of complex structures. In such areas velocity overburden effects and ray bending can mean that illumination is not even at a particular target horizon. Illumination of complex structural geology or structures below complex salt bodies are examples. By acquiring seismic data on a number of different source receiver azimuths improved illumination can be achieved
Other potential advantages of Multi-Azimuth/Wide Azimuth surveys are:- Improved multiple diffraction attenuation
- Improved signal to noise ratio
- Measurement of azimuthal anisotropy
- More reliable and detailed amplitude maps to map reservoir systems.
Typically a marine streamer survey would be acquired a number of times with different survey azimuths and the processed results combined
Ocean bottom surveys offer another way of achieving a more complete azimuth distribution
Wave Equation Pre Stack Depth Migration (PSDM)
3-D prestack depth migration (PSDM) constitutes the ultimate seismic imaging technology whereby each of the elemental prestack raypaths is individually imaged. The precursor to this imaging process is the calculation of travel-time trajectory maps through a given velocity depth model. Travel times must be computed for distances along the ray path segments from shot and receiver locations to the target element. A Kirchhoff algorithm can then be used to effect the prestack imaging. Wave equation migration is an accurate and robust alternative to Kirchhoff migration when multi-pathing and other complex wave modes occur
Pre-stack migration is often applied when the layers being observed have complicated velocity profiles, or when the structures are just too complex to see with post-stack migration. Pre-stack is an important tool in modelling salt diapirs because of their complexity
The combination of tectonically complex overburden with variable lithologies in the Southern North Sea is one area that lends itself to the application of 3-D PSDM. Sub-salt imaging in the Gulf of Mexico is another
Enovation is investigating the potential of Geochemical Imaging which involves detection of minute levels of hydrocarbon compounds emanating from a reservoir that migrate to the surface. Typically samples are taken at the surface via modules inserted in the soil. Offshore samples can be taken via ocean bottom cores
Differentiation of petroleum phases including gas, condensate and oil is possible with advanced analytical techniques
The method is suitable for either Frontier or Prospect evaluation and looking for by-passed pay
The technique can be combined with Seismic or EM techniques to reduce risk
Normally onshore acquisition is more cost effective
Other
Enovation is interested in hearing from providers of developing technology that would provide reduced risk and /or improved information
Please refer to the Opportunities section under New Technologies
