Reservoir Modeling and Geostatistics
An important aspect of modern production geology involves the building of 3-D geological models, particularly for large fields. These models have many practical uses. They help the geologist and the rest of the subsurface team to locate the remaining hydrocarbons in mature producing fields. The trajectories for new wells can be planned to find the optimal well path relative to the reservoir geology.
Geostatistical methods are used to build these 3-D models. Although these were originally developed as tools to analyze the spatial distribution of rocks and rock properties, there is often not enough data available from oil fields to do this properly. More typically, the tools are used in production geology as a means of making a 3-D model that replicates the geological scheme. A lithofacies model can be produced, which honors the statistical distribution of rock properties for the individual lithofacies.
3-D geological models are used to estimate the inplace hydrocarbon volumes. It is important to understand the uncertainty involved in estimating these volumes. This can be a difficult job to do reliably, although there are several methods available that allow the geologist to do this in a rigorous way.
One of the main uses of 3-D models is to provide a framework for the reservoir engineer’s simulation model. The simulation model is used to estimate reserves and to help with managing the field, and is the basis for economic forecasting within an oil company.
Figures & Tables
Oil Field Production Geology
This book was written for students, new professionals in oil companies, and for anyone with an interest in reservoir geology. It explains the background to production geology in the context of oil field subsurface operations. It also gives practical guidelines as to how a production geologist can analyze the reservoir geology and fluid flow characteristics of an oil field with the aim of improving hydrocarbon recovery. Advice is given on how to search for the remaining oil volumes in a producing field, where these pockets are typically found, and then how to plan wells to target these volumes.