Analyzing well performance and making decisions based on it is a core part of a reservoir and production engineer’s role. This paper, an extension of the universal type curve approach, will assist technical professionals in understanding the performance of their wells and help them make quick and reliable decisions by employing a novel set of type curves for evaluating well performance. The new set of diagnostic type curves is an amalgamation of multiple techniques, but mainly employs the modified Power-Law-Exponential (PLE) equation and the modified Arps equation. The two sets of diagnostic type curves presented in this paper were shown to be useful in evaluating and predicting performance for unconventional horizontal wells, especially those with frac hits, excessive interference, and downhole issues. The results also provide guidance for decline parameters to use in performance predictions.


With the advent of unconventional reservoirs, many conventional forecasting techniques needed to be modified to account for different flow regimes and other changing well properties. Joshi & Lee (2013) compared various decline techniques and the conclusion was that none of the decline curve models could predict long-term performance accurately with less than 18 months of monthly data. Recently, Muralidharan & Joshi (2018) simplified the type curve process by employing a universal type curve (UTC) approach that removes biases when conducting decline curve analysis while narrowing uncertainty in the EUR. In brief, the UTC approach was validated using a robust workflow, starting with petrophysical analysis, progressing to flowing material balance and rate transient analysis, followed by history matching using a numerical simulator. In total, 147 wells with a minimum of two years of production and pressure history was used for an EUR analysis. The result of the UTC approach was a rule of thumb: On average, the technical EURs are about 3 times the 1-year cumulative production, with an expected range of 2.5 to3.5.

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