Maximum oil production by a mathematical method

Efficient oil recovery is important, as the demand for energy grows. Linda Wiegman found a solution that can better predict Shell's oil production.

Linda Wiegman: "By injecting chemicals in present oil reservoirs, more oil can be recovered faster. " (Photo: Sam Rentmeester)
Linda Wiegman: "By injecting chemicals in present oil reservoirs, more oil can be recovered faster. " (Photo: Sam Rentmeester)

Oil supplies will eventually run out. There are only few left and oil recovery has gotten increasingly difficult. "It is important to get the most out of existing oil reservoirs," said Wiegman (26, Applied Mathematics). She graduated at the Department of Enhanced Oil Recovery at Shell, on assignment for the Faculty of Electrical Engineering, Mathematics and Computer Science. She found that how the mathematical method for the prediction model for oil recovery is approached, has a large impact on the prediction itself. Due to her work, predictions about oil recovery are more accurate.

Even oil trapped in porous rocks is forced out

"When oil is found, an opening in the ground will simply make the oil flow out of the reservoir. As soon as the pressure inside the reservoir is equal to the outside, the outflow will stop," Wiegman said. "Therefore, the second step is to inject water at one side, to force the oil to flow out at the other side. But water, unlike oil, flows easily, leaving almost 50% of oil in the reservoir," she said. Thus, a more efficient way of water flooding is necessary. By injecting chemicals in present oil reservoirs, like polymer and surfactant, more oil can be recovered faster. These chemicals make the water more viscous and change the chemical properties between oil and water. Even oil trapped in porous rocks is forced out.

The model equations need to be accurate

The effect of these chemicals on the water and oil flow is simulated in a reservoir simulator. In order to predict and optimize the oil production based on the quantity of chemicals, the model equations need to be accurate. Wiegman researched the best way to discretize the transport of chemicals via a numerical method. Her main finding was the high impact of the accuracy of the numerical method on the prediction model of oil recovery. The more accurate the method, the better the prediction. This will not only affect costs, but her method contributes to maximizing the oil recovery in existing reservoirs.

Wiegman graduated cum laude and is already hired by Shell. Her tip for other graduates is: "Do not be afraid to try things yourself and be creative."

Title: Numerical aspects of transport modelling in Enhanced Oil Recovery

Grade: 9