# Seismic time-depth conversion using geostatistics| Training course

Learn how to perform depth conversion and quantitative uncertainty analysis on depths, spill-points, traps, and reservoir volumes applying geostatistics.

## Learning objectives

• Understand and master the use of geostatistics for seismic time-to-depth conversion.
• Explore many possible conversion scenarios.
• Perform comprehensive risk analysis on depths and reservoir volumes to inform your decision-making.

## Outlines

• Half of the course is devoted to theoretical and methodological presentations, the second half to practical exercises on real-life cases to deepen the understanding of concepts. The focus is on illustrations and practical contributions of the covered concepts.
• Computer exercises with Isatis.neo Petroleum Edition.
• Course material provided.

## Who should attend?

Geophysicists or geomodelers involved in seismic data interpretation and horizon mapping.

## Course content

#### DAY 1: THE FUNDAMENTALS OF GEOSTATISTICS FOR TIME-DEPTH CONVERSION

• Validate well and seismic data
Use univariate and bivariate statistics and probabilities for in-depth data analysis and quality control (distributions, mean, variance, correlation coefficient, linear regression).
• Quantify the spatial variability and correlation of well and seismic data (including depth, velocity, or any available seismic attribute)
Calculation, interpretation, and modeling of simple and cross-variograms.
• Map time and depth horizons
Understand the principles and properties of 2D kriging and implement the technique for surface mapping.
Learn how to apply kriging with external drift to refine maps in multivariate cases.
Identify and model trends in non-stationary cases. Compute residuals.
• Perform uncertainty analysis from conditional simulations
Understand the difference between kriging and conditional simulations.
Learn how to apply the simulations to generate heterogeneity models.

#### DAY 2: GEOSTATISTICAL TIME-TO-DEPTH CONVERSION USING ISATIS.NEO’S “CONVERSIONS & UNCERTAINTIES” WORKFLOW

Going through all the steps of Isatis.neo depth conversion’s workflow

• Understand the added-values and principles of geostatistical depth conversion
Why using geostatistics for depth conversion?
Illustration on a simple reservoir (with conformable horizons) and a layer-cake reservoir.
What to do when well data is sparse and insufficient? Introduction to Bayesian kriging.
• Prepare your data to depth conversion
Achieve mis-ties correction
Map the time uncertainty derived from a prior data processing (seismic filtering, mis-ties correction, merge of 2D and 3D datasets)
Generate a fault model from fault sticks
• Quantify potentially recoverable resources
Define different conversion scenarios for sensitivity analysis of the resulting reservoir morphology to input data, computation methodologies, and parameters.
Achieve depth conversion using depth modeling or velocity modeling and considering or not uncertainties associated with the seismic time and fault positions.
Generate and analyze spill point locations
Generate and analyze potential reservoir traps
Generate the optimistic, mode, and pessimistic values of key reservoir volumes.

#### DAY 3: ISATIS.NEO WORKSHOP (OPTIONAL)

Put your new knowledge into practice using your favorite dataset and gain confidence and efficiency when using Isatis.neo.

## Prerequisites

This course does not require prior knowledge in geostatistics. Some basic knowledge of statistics is an asset.