Pressure transient analysis (PTA) is typically performed on pressure BU data acquired over a period from a few hours to a few days, while production data analysis (PDA) is performed with production data acquired over a period of a few days to several years. Recent approaches to extending a pressure BU response by deconvolving production data seem promising, but simple rate-normalized pressure (RNP) and its derivative may be more straightforward provided redundant data and artifacts are eliminated in the RNP processing.
This paper offers a unified PTA-PDA analysis combining pressure BU deconvolution with the RNP. Using the RNP as the indicator of the late-time behavior, the unified PTA-PDA analysis can provide a virtual constant rate drawdown response for the duration of the production data including the early time response from a selected pressure BU transient. The virtual pressure change and, in particular, its derivative provide trends easily identified as flow regimes suggesting model features that must be included in a simulated drawdown intended to match the unified response.
A model match with the virtual drawdown resulting from the unified PTA-PDA analysis offers a model consistent with the entire production history that can be used to forecast future production behavior and reserves for the well. Synthetic and field examples illustrate the approach.