Well Log Guided Processing. Interpretive Processing
Sonic logs, possibly with associated Check Shot data, may be used to guide velocity picking, associating lithologies with specific interval velocities and possibly velocity gradients. Synthetic seismographs may be used to aid selection of deconvolution parameters. Offset synthetics, utilizing shear velocities, may be used to identify AVO behaviour. All of these may be used to guide the processing in an interpretive rather than an aesthetic sense to deliver more geologically plausible results. We at GeoVectra seek to take advantage of all external information available in our aim to make the seismic data better relate to the underlying geology.
In common with well log guided processing VSP data can provide very useful information to guide the processing of surface seismic data as well as providing a generally more accurate local image of the geology close to the well than is possible with surface seismic data. Amongst the useful information available from VSP surveys are; velocity, frequency dependent loss, multiple reflection identification and potentially attenuation, deconvolution, polar anisotropic parameters and azimuthal anisotropic parameters with multiple azimuth surveys.
Modelling. Feasibility studies
It has often been said that the most expensive surveys are those that don't meet their objectives; this is true for all seismic surveys, 2D, 3D, land, towed streamer or OBC. The obvious first step is to define and agree upon what these objectives are, obvious but not too common in practice. From this basis a complete process from survey design through acquisition, processing and interpretation may be designed. This involves analyzing all available data, wells, production, reservoir engineering, petrophysics, geology, geophysics including prior seismic data. An investment in this procedure generally pays dividends in delivering value from the seismic data. A value of information study, to find an optimal solution, may also be used as the final step in this process to aid management decision making.
High Resolution Plains data
GeoVectra Ltd., has the tools and expertise to deliver high precision imaging enabling, for instance, interpretation of thin but laterally extensive channels. Where there is variable weathering thickness surface referenced NMO can aid in defining subtle lateral variations in velocity.
GeoVectra Ltd., has substantial experience in imaging data in structurally complex settings be it through pre-stack time, or pre-stack depth imaging. Well data, check shot data and/or VSP data may be used to guide the process to deliver a structurally precise image. Surface referenced NMO brings significant advantages in imaging data from such areas where the source and receiver are often at very different elevations.
Surface Referenced NMO
Surface referenced move out is a technique that treats the downgoing wavefield from the source and the upgoing wavefield to the receiver separately in terms of static and velocity handling. This is particularly beneficial in the case of areas of extreme topography where the source and receiver may be at considerably different elevations. It is also beneficial with OBC surveys where the source is near the water surface and the receivers are on the sea floor and for converted wave surveys where the receiver side Shear wave statics are often radically different from source P wave (compressional) statics. Surface referenced NMO is also beneficial where weathering changes substantially across a survey, bringing a closer relationship between interval velocities of geological formations and stacking velocities
Pre-Stack Depth Migration
GeoVectra Ltd., has many years of experience in velocity model building for pre-stack depth migration. This has been, and may in the future be, applied to relatively simple as well as complex structural areas where anisotropic parameters may yield useful information related to rock properties. This can be especially beneficial for resource plays in tight formations.
Converted Wave data
GeoVectra Ltd., has several years of knowledge and experience in processing converted wave data plus tools within VISTA dedicated to this purpose, whether the survey be 2D and 3D. Once again surface referenced NMO is a valuable tool in treating the source and receiver wave fields separately.
We offer processing of OBC data, both 2C and 4C. Surface referenced NMO is very beneficial in this area as the sources and receivers are at different elevations leading to a shift in the midpoint that this process deals with naturally. Wavefield separation is handled though algorithms in VISTA.
Towed Streamer 2D
In addition we also offer processing of towed streamer data. VISTA contains the required algorithms for processing such data including bandwidth expansion common in today's marine processing.
Wide Line Processing
GeoVectra Ltd., has expertise in processing wide line profile data. Such data tends to be acquired in areas of rugged land terrain with severe geological structure but may also be ocean bottom data from geologically complex areas. Careful combination of the data from the adjacent CMP tracks generally results in much improved imaging compared to a simple 2D profile that is adversely affected by cross-dip and cross-line noise. Such data may be imaged in time or depth.
Front-Ending. Geometry QC. Field QC
VISTA has robust attribute-based capabilities for performing field data QC as well as Geometry QC and front-ending.