Numerical Simulation

Numerical simulation is one of the most powerful reservoir engineering tools. Its strength lies in the fact that all assumptions are tested at the same time and must consistently work with each other, all the laws of physics, and the known facts. Because of its power to constrain and calibrate assumptions, it can also be used in the early stages of exploration with natural state models. In early, as well as later, production stages it can used to see where the pressure support is coming from and identify areas of expansion. Depending on how simulations are built, they can diagnose individual well contributions and problems, and how these play out over the life of the field. It can be the ultimate field management tool -- testing large or small changes that allow the field to be produced to its maximum level while managing decline.

A major use of numerical models is for financial loans. Simulations for financial reasons may not work for field management, but simulations built for field management are always useful, and better, for use in the financial area. GRG has experienced situations where a bank was going to call in loans based on their financial model, which would have caused the project to fail, but due to a field management model built by our reservoir engineers, the operator was able to show the banks that there was a solution with enhancement as well, which convinced the banks to continue the project. The management plan was executed, resulting in field performance exactly as the model predicted, producing more than 40X (and counting) the amount forecasted in the financial model.

Our models are built from an operator’s perspective and are totally integrated with the geology and conceptual model, with the maximum amount of constraints. Our models are more useful and will save you more! We can model in both of the most common geothermal simulation programs, TOUGH2 and TETRAD.

Wellbore Simulation

Wellbore simulation is used to understand the flow up a wellbore during production. Geothermal fluids lose pressure as they come up the wellbore and any liquid in the stream can flash from 0 to 100% as it comes up the wellbore, causing the fluid to sometimes pass through several flow regimes with different pressure loss and flow properties. Understanding what is happening in the wellbore allows the operator to design and optimum the size of the well, which can be wellbore limited, and also too large to flow. If liquid is present in the flow the velocity must be sufficient to lift the water or liquid fallback will kill the well flow. Wellbore problems such as collapse or even scale buildup can be detected with wellbore simulation. Scale thickness can be estimated with a clean and scaled simulation and production gain from a proposed scale cleanout, optimizing cleaning cycles. Production losses from alternate wellbore repairs can also be done to optimize the best economic path. It can also resolve issues form different enthalpy zones producing in the same well. In exploration, it allows for a cheaper, smaller diameter well to be used to test, and then determine the flow that development size wells would produce, and optimize to the most economic development. Each of these examples lower risk and increase the overall economics.