Anchoring in Legacy Models
Related Topic:
Anchoring in Advanced Analytical Models
Anchoring is a technique for improving the efficiency of the history-matching process. You can specify a measured pressure and WellTest will calculate the initial synthetic pressure, which results in the model line going through that specified pressure. This specified measured pressure is known as the anchor point.
The legacy suite of models within WellTest, which are accessible via the Models menu, provide three possible anchor options: initial pressure, final flowing pressure, or any other specified pressure.
1. Initial Pressure Anchor: This selection is used when analyzing drawdown data with a known (measured) initial pressure. The synthetic initial pressure is set to the reservoir pressure specified in pressure, volume, temperature (PVT) properties.
2. Final Flowing Pressure Anchor: This anchor point is convenient when analyzing buildup or falloff data. The initial pressure is usually not measured, and with anchoring to the final flowing pressure, you can focus on history matching the good quality, shut-in data, and then checking to ensure the synthetic initial pressure is reasonable.
3. Specified Pressure Anchor: In situations where neither the initial pressure nor the final flowing pressure is known, it is possible to specify any other measured pressure.
An anchor point is selected by clicking one of three icons on the model’s toolbar.
An anchor point is set automatically if the pi or pf option is selected. If the general anchor option is chosen, you select an anchor point by clicking the desired pressure on the History plot.