What is Flow Simulation?

"Flow Simulation" is a technique used by Reservoir Engineers to understand the flow behavior of a hydrocarbon reservoir. It uses a special computer software to mathematically represent the reservoir, the wells penetrating it and then they study the change of different fluids concentrations and pressure through out the reservoir as fluid is withdrawn and introduced from/to it.

"Flow Simulation" involves several steps, namely...

• Model Construction
• Model Initialization
• History Matching
• Prediction or Forecasting

During "Model Construction", the mathematical model is prepared. It involves generating a 3D grid system as shown in Figure-1 that represents the reservoir and populate it with various provide various static rock and fluid properties Figure-2.

Figure-1: The Grid / Skeleton

Figure-2: The Grid populated with properties.

In "Model Initialization" stage the model is given the initial properties like various fluid saturation and pressure as it was before any production or injection started. The engineer attempts to match field observations recorded at newly drilled wells to the model as shown in Figure-3.

Figure-3: Illustration of Initialization

Once a satisfactory history match is achieved, the next step of the process is "History Matching". At this stage, historical data or observed data are attempted to match with the model output (Figure-4A and Figure-4B). The parameters usually used to match are flow rates like total liquid, oil rates, ratios like water-cut, gas-oil-ratio (GOR) and pressure. The purpose of the history match exercise is to make sure the model is behaving exactly like the actual reservoir.

Figure-4A: Not History Matched

Figure-4B: "Reasonably" History Matched

Once a satisfactory history match has been achieved, we can assume the model is behaving like the actual reservoir and hence should be able to give a reliable prediction. At this stage, the model is run beyond present time into future time to understand how the reservoir would respond to different production and injection scenario (Figure-5). This exercise is called "Prediction" or "Forecasting"

Figure-5: Prediction