In the oil and gas industry, reservoirs are rock formations that hold natural hydrocarbons like oil and gas. In order to extract these resources, engineers drill into the rocks and use various production techniques to bring them to the surface. Reservoir characterization is a crucial process that requires an understanding of how hydrocarbons behave within the formation, how well they are stored, and what obstacles can hinder their flow. Additionally, reservoir characterization must be conducted with a strong emphasis on regulatory compliance in Alberta, as adhering to local regulations is vital for ensuring safe and efficient operations. In this article, we’ll dig deeper into reservoir characterization as it becomes a pivotal aspect of well completion and workover, especially within the framework of Alberta’s regulatory standards.

Reservoir characterization is the process of obtaining detailed information about a subsurface reservoir, such as its size, shape and characteristics. It involves integrating data from different sources, including well logs, cores, seismic biostratigraphic data and analogues. Using this information, a 3D computer model is created that represents the subsurface reservoir.

This model can then be used to simulate fluid flows and predict the behavior of the reservoir under a variety of conditions. This information can help determine optimal production techniques, minimize risk and maximize the recovery of hydrocarbons.

Seismic reservoir characterization is the process of estimating the rock and fluid properties, such as velocities, density, porosity, mineral fractions and fluid saturations, from seismic and well log data. This is achieved through an inverse problem that attempts to solve for the observed seismic responses with optimization algorithms.

The key to successful reservoir characterization is to have accurate data and an up-to-date model. This is why it’s important to update the model as new petrophysical, seismic and production data become available. This is called a dynamic reservoir model and is a preferred approach over a static model.

Porosity and permeability are two important characteristics that affect fluid flow in a reservoir. Porosity is the ability of a rock to store a certain amount of fluid, while permeability measures how easily a phase like water or hydrocarbon moves through the pore spaces of a rock.

Another important property that affects fluid flow is relative permeability. This describes how well a phase such as water flows in comparison to a phase like oil within a reservoir. The higher the relative permeability, the more oil can be produced from a reservoir.

Hydraulic Fracturing Pressures

The pressure differential in a reservoir is a critical factor that influences how easy it is to produce hydrocarbons from the formation. It is determined by the depth of the reservoir, rock porosity and permeability, as well as any barriers to fluid flow. Knowing the reservoir pressure can help engineers optimize hydraulic fracturing technique and avoid damage to the reservoir or wellbore.

The first fine reservoir characterization study should include the following: fine stratigraphic classification and correlation, fault system interpretation, sedimentary microfacies analysis, comprehensive reservoir evaluation and geological modeling. The second fine reservoir characterization study should also include secondary fine well-log interpretation, interlayer analysis and percolation barrier study. A thorough and robust reservoir characterization study should be completed for every project. This will help to ensure that the right decisions are made and that the production plan is implemented successfully. Learn how to achieve this by attending a Regional Masterclass on Integrated Petrophysics for Reservoir Characterization. This course, developed over 25 years of petrophysical consulting and training, demonstrates how to get robust answers through the logical integration of diverse data sets.