Labeled Water Will Help Model Complex Oil Deposits
Russian scientists have proposed to improve the accuracy of 3D models of carbonate reservoirs using the tracer method.
Perm Polytechnic University scientists have developed an approach that increases the reliability of modeling complex oil deposits. It makes it possible to qualitatively assess the actual filtration flows through which the liquid moves to the well. The Devon News Agency learned about this from the PNRPU message.
Rocks have small voids and cracks through which oil or gas flows. For productive field development, it is important to understand how many resources lie in the formation and how they move within the rock.
To do this, scientists conduct various geophysical and hydrodynamic studies of wells. With their help, they collect information about the porosity, permeability, and structure of the formation, as well as about pressure, temperature, and fluid movement inside it. Based on this, a 3D model of the field is being built, reflecting the entire oil production situation.
The model must fully reproduce all the real filtration processes of the reservoir. However, in the case of carbonate reservoirs, it is not always possible to reliably display them. Their structure is complicated by a large network of channels, cracks and voids. Because of this, the properties of such a formation are heterogeneous. Therefore, it is difficult to accurately predict how the liquid will behave during extraction.
In such conditions, the quality of modeling can be improved with the help of additional research. Scientists at Perm Polytechnic University propose using the method of tracing mountain channels.
It consists in adding a special indicator to a liquid (water, oil or gas). It can be a chemical compound, a dye, or a radioactive isotope that is easy to detect. The labeled liquid is pumped into a well or reservoir and sensors are used to monitor where and how quickly the substance appears in other wells.
“This method has long been widely used to study the structure of the reservoir and the movement of groundwater,“ says Inna PONOMAREVA, Professor of the Department of Oil and Gas Technologies at PNRPU. “Despite this, the results of its implementation are not taken into account when creating a hydrodynamic model.“
A complex oil deposit, characterized by heterogeneity of the void space and high viscosity, was chosen as the main object of the polytechnic. At first, its hydrodynamic model was constructed without taking into account tracer studies.
Then the indicator was pumped into five injection wells and its appearance was tracked in 17 producing wells. The results confirmed the complex structure of the collector, expressed in the branched structure of real filtration flows.
“Based on the new data, we have fine-tuned the existing model and performed simulation calculations of oil production,“ explains Dr. Ponomareva. “Its additional adaptation using the tracer method allowed for at least a 10% improvement in the convergence of estimated and actual production figures.“
This affects the planning of new, more productive ways to develop the field. This approach improves the accuracy of the 3D model by revealing information about the actual location of channels in the rock structure. This makes it possible to improve the quality of forecasting the behavior of minerals and optimize their extraction processes.
