Unlocking reliable subsurface insights requires more than a single “best guess.” In collaboration with Geovariances, we demonstrate how combining Petrosys PRO and Isatis.neo creates a powerful workflow for stochastic time-depth conversion and probabilistic volumetrics.
Petrosys PRO is trusted worldwide for seismic mapping, faulted surface modelling, and integration with interpretation projects, making it the ideal platform to prepare high-quality time surfaces.
Isatis.neo, developed by Geovariances, is a leading geostatistics software solution designed to quantify uncertainty, generate multiple realizations, and deliver probabilistic insights into subsurface geometry and reservoir potential.
By integrating these tools, exploration teams can quantify uncertainty in depth conversion, generate probabilistic gross rock volume (GRV) estimates, and make smarter, risk-aware exploration decisions.
Stochastic Time-Depth Conversion with Petrosys PRO and Isatis.neo
Abstract
Subsurface interpretation and volumetric assessment are often limited by deterministic workflows that provide only a single “best estimate” of depth and gross rock volume. This underrepresents the true geological uncertainty inherent in seismic interpretation, sparse well control, and velocity modelling.
In this study we present a workflow that integrates Petrosys PRO and Isatis.neo to deliver a more robust and risk-aware approach to time–depth conversion and volumetric analysis. Petrosys PRO is used to construct and refine complex faulted time surfaces directly from seismic interpretation projects. These QC’d and validated time grids form the foundation for subsequent stochastic modelling.
The workflow then applies geostatistical methods in Isatis.neo, specifically Bayesian kriging with external drift and multiple realizations, to condition depth horizons exactly to well markers while honouring seismic time data as continuous auxiliary information. This process quantifies and propagates uncertainty from velocity model parameters and spatial variability into multiple stochastic depth scenarios. For each realization, reservoir spill-points and gross rock volumes are calculated, producing probabilistic GRV distributions instead of single deterministic numbers.
By combining Petrosys PRO for surface building with Isatis.neo for stochastic geostatistical modelling, exploration teams can generate a clearer, more complete picture of subsurface potential. This enables better risk quantification, more targeted data acquisition, and improved exploration decision-making.
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