COURSE OVERVIEW:

Seismic velocities and depth conversion constitute the vital process of transforming seismic data from the time domain, where it is recorded, into the depth domain, where drilling occurs. Accurate depth conversion is perhaps the most high-stakes task in geophysics, as even minor errors in velocity estimation can lead to significant miscalculations in structural elevation, gross rock volume, and well placement. This course explores the various types of velocities—such as stacking, interval, and average velocities and how each is utilized to build a representative model of the subsurface.

The scope of this course covers the spectrum of depth conversion methodologies, ranging from simple layer-cake models to complex velocity-depth functions and geostatistical approaches. Participants will learn how to derive velocity information from diverse sources, including checkshot surveys, VSP data, sonic logs, and seismic processing velocities. The curriculum places a heavy emphasis on identifying and correcting for pitfalls such as velocity pull-ups, push-downs, and lateral velocity gradients caused by salt bodies, gas clouds, or varying lithology.

Coverage includes the practical application of depth conversion workflows in various tectonic settings and the quantification of depth uncertainty. The course teaches participants how to validate velocity models against well tops and how to use blind-well tests to assess the reliability of the depth maps. By mastering these techniques, geoscientists can ensure that structural maps are accurate, reservoir volumes are correctly estimated, and the risks associated with "drilling into the unknown" are minimized.

COURSE OBJECTIVES:

After completion of this course, the participants will be able to:

• Differentiate between NMO, Stacking, RMS, Interval, and Average velocities.
• Explain the physical relationship between rock lithology, compaction, and seismic velocity.
• Utilize checkshot and VSP data to calibrate time-to-depth relationships.
• Construct velocity models using various methods, including constant velocity and $V_0 + k$ functions.
• Apply layer-cake depth conversion for basins with distinct stratigraphic units.
• Identify and mitigate seismic imaging artifacts like velocity pull-ups and push-downs.
• Convert stacking velocities to interval velocities using the Dix equation and its limitations.
• Evaluate the impact of anisotropy on depth conversion accuracy.
• Perform map-based and volume-based depth conversion workflows.
• Validate depth maps by comparing predicted depths with actual well markers.
• Quantify depth uncertainty and its effect on gross rock volume (GRV) estimations.
• Build complex velocity models for Pre-Stack Depth Migration (PSDM).
• Formulate a risk-managed depth conversion strategy for exploration and development.

TARGET AUDIENCE:

Geophysicists, Geologists, Reservoir Engineers, and Technical Support Staff responsible for structural mapping and volumetric analysis.

TRAINING COURSE METHODOLOGY:

A highly interactive combination of lectures, discussion sessions, and case studies will be employed to maximise the transfer of information, knowledge, and experience. The course will be intensive, practical, and highly interactive. The sessions will start by raising the most relevant questions and motivating everybody to find the right answers. The attendants will also be encouraged to raise more of their questions and to share in developing the right answers using their analysis and experience. There will also be some indoor experiential activities to enhance the learning experience. Course material will be provided in PowerPoint, with necessary animations, learning videos, and general discussions.

The course participants shall be evaluated before, during, and at the end of the course.

COURSE CERTIFICATE:

National Consultant Centre for Training LLC (NCC) will issue an Attendance Certificate to all participants completing a minimum of 80% of the total attendance time requirement.