Largeo
Processing 2D/3D
Time Processing of 2D/3D Seismic Data
The seismic processing workflow in LARGEO is always geologically guided and directed by the
imaging objectives, with identification of all challenges and constrains to overcome. We carefully
select the most adequate processing techniques and apply integrated seismic solutions in order
to develop the best possible image from our clients data. The LARGEOs experienced seismic
processing team makes every effort to extract more subsurface information and, therefore,
more value from seismic data.
We apply innovative processing techniques for land and marine data, acquired in challenging
environments and under intricate geological conditions, where rapid changes in geology or
complex sub-surface structure makes conventional processing difficult. Using industry first-class
programming tools, our team has developed its own depth modeling and imaging solutions,
including static corrections, noise and multiple removal and others.
LARGEO computer centre provides adequate processing power for application of complex
resource-intensive and time-consuming algorithms. In order to enhance the value of seismic
data and increase the confidence level of seismic exploration for our clients our processing
team applies interactive velocity analysis, 3D SRME, HR Radon, tau-p deconvolution etc.
Interpretive Processing
The main goal of data processing is to produce an accurate image of geologic targets, and data
migration is the key element of this phase. Migration requires the building of a velocity model to
evaluate and represent the acoustic properties of the subsurface.
The success of seismic processing in LARGEO is based to a large extent on cooperation
between geophysicist and geologist. LARGEO uses supplementary geological information in
seismic data processing combining processing and interpretation workflows into one integrated
process.
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Depth Imaging
In order to obtain accurate structural image and to recover from seismic data angle-dependent
reflectivity information, we always perform amplitude-preserving migration. This information is
used then for future seismic attribute analysis, including AVO/AVA analysis, lithological
interpretation and reservoir characterization.
Based on the problems addressed our specialists apply a variety of processing tools including
those by GXTechnology recognized leader in advanced seismic data processing, GeoDepth
(Paradigm Geophysical), Tsunami Imaging (Tricon Geophysics).
Pre-Stack Time Migration
When the relative simplicity of the subsurface does not warrant depth migration, pre-stack time
migration (PreSTM) solutions will often suffice.
We use an amplitude-preserving Kirchhoff PreSTM routine developed by GXT group that is
ideal for imaging complex geologic conditions or velocity fields, yet without a requirement to
employ pre-stack depth migration (PreSDM).
Pre-Stack Depth Migration
Pre-stack depth migration (PreSDM) is a processing technique that moves seismic reflections to
their correct locations in space. It is critical in areas where there are significant and rapid lateral
or vertical changes in velocity that distort images acquired in the time domain.
LARGEO applies comprehensive toolkit of PreSDM technologies developed by GXT, including:
- Shot-based wave equation depth migration, to provide the best imaging results for
complex geological environments. GXTs wave equation PreSDM solution does not suffer from
problems typically associated with conventional wave equation implementations, such as
numerical dispersion, azimuthal anisotropy, or limited dips. GXTs shot-based wave equation
migration can also be applied to extract true 3D reflection angle gathers.
- Amplitude preserving GXT Kirchhoff depth migration algorithms capable of
accommodating turning rays (for imaging very steep dips and overhangs), and able to account
for anisotropic conditions. A key benefit is that GXTs Kirchhoff solutions are significantly faster
than most other Kirchhoff-based tools employed by the industry.
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Reverse Time Migration
Current migration methods face limitations in the presence of complex, steeply dipping
reflectors such as those found on salt flanks. Reverse time migration (RTM) overcomes these
constraints, enabling structures with dips greater than 90 degrees to be properly imaged.
Duplex Wave Migration (using Tetra Seis Inc. processing technology)
3D Duplex Wave Migration is a practical tool developed by Tetra Seis Inc., to delineate vertical
boundaries that are invisible to conventional PSDM. The imaging of vertical boundaries has
become extremely important for solving complex exploration and production challenges. These
include salt wall imaging, zero or near zero throw faults within the reservoir, zones of fracturing,
locating diagenetic reservoirs formed by basinal hydrothermal fluid flow along vertical faults,
identification of bypassed reserves (enhanced recovery) and the delineation of the edge
boundaries of oil or gas interfaces.
Interpretation
Interpretation and Reservoir Characterization
LARGEO has developed the interdisciplinary processing and interpretation workflow using
seismic attributes and AVO analysis, seismic inversion and spectral decomposition for reliable
reservoir characterization. The interpretation workflow sequence applied by LARGEO
specialists includes AVO/AVA analysis and multi-attribute analysis, seismic inversions,
spectral decomposition.
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Structural interpretation includes
- Geological interpretation of well data
- Well-to-seismic ties and structural interpretation of seismic data sets
- Seismic sequence analysis, identification, positioning and detailed mapping of faults,
subsurface geological mapping of target are
Seismic reservoir characterization includes:
- Sequence stratigraphic analysis and integrated interpretation of seismic, geological and
well data
- Development of reservoir model including spatial distribution of important petrophysical
parameters, such as lithology, permeability, porosity, saturation etc.
- Assessment of reservoir parameters and volumetric through integrated reservoir studies
using seismic facies classification, seismic inversions, AVO and seismic attribute analysis
- Risk assessment and volumetric estimation of petroleum prospects
On-board Processing
On-board Processing and QC of seismic Data
Full 2D/3D processing onboard of seismic vessels has become an industry standard in marine
seismic operations. It is proved to be more cost effective, considerably improves quality of data,
facilitates preliminary interpretation and accelerates project turnaround.
LARGEO provides turn-key on-board processing services, which include experienced
personnel, onboard seismic processing facilities and software for high-quality seismic data
processing and QC.
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Our customized easy-scalable processing systems can be used for comprehensive data QC or
generate a fully processed 2Dor 3D dataset onboard within the timeframe of the acquisition
project. The basic configuration of the on-board cluster allows performing standard QC
workflow and conventional 2D processing. The cluster can be easily scaled for sophisticated
QC and full 3D production processing on-board of a seismic vessel.
Seismic QC Services
Seismic acquisition QC services
LARGEO has carried out numerous QC jobs on client's behalf for the upstream oil and gas
industry. The company's qualified geophysical consultants will guarantee seismic and
geophysical data QA/QC and ensure that geophysical targets are met, HSE issues are
observed and acquisition projects are executed in accordance with contract requirements and
technical specifications. We offer geophysical consultants for seismic and navigation data QC,
health, safety and environment, crew efficiency and acquisition techniques quality control. Our
qualified Acquisition Supervisors will provide real-time feedback and ensure accurate and timely
delivery of technical results to the client.
LARGEO seismic acquisition QC services for land and marine operation include:
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- Technical audits and assessment of the contractors equipment and personnel
- Real time quality control and supervision of field operations
- Plane, geodetic and topographic land surveys
- Health, Safety and Environmental Quality Control based on international principles and
performed to international standards
- Field processing and QC of acquired data
- Processing flow and parameter design
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The results and conclusions are supported by comprehensive reports that outline the problems
encountered and detail the actions, decisions taken during the course of operations
Survey Design
2D/3D Seismic Survey Design
Constructing the right survey plan is a critical part of each acquisition project. Using all
available information and specialized programming tools, our survey design specialists can
optimize the acquisition efforts, given all geophysical, logistical and budget constraints. This
information comes from previous seismic data and available well logs, from a conceptual
geological model and surface geology. LARGEO also provides project management and
monitoring of field operations in order to balance geophysical and financial issues and to
achieve best results at the lowest possible cost. The company offers the following consulting
services:
Survey design, fold, offset and azimuth modeling and evaluation of other survey parameters,
including assessment of operational cost and safety constraints;
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- Analysis of existing geological and geophysical data, resolution, noise and coverage
analysis;
- Project management and technical support, continuous tracking and control of acquisition
progress;
- Preparation of tender documents, supported by detailed survey and equipment
specifications and data quality requirements, contract appraisal and negotiations.
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