Production Decline Curves of Tight Oil Wells in Eagle Ford Shale

TLDR

Well productivity in the Eagle Ford shale varies widely in initial rate, decline curvature, and lifetime, and longer time series or probabilistic modeling are needed for realistic multi‑well estimates. The study derives typical production curves for tight oil wells in the Eagle Ford shale using monthly production data from multiple horizontal wells. Initial production rates and decline rates were recorded and estimated ultimate recoveries were calculated with hyperbolic and stretched‑exponential decline‑curve models. Average initial production is ~500 bbl/d, giving an EUR of 150–290 kbbl; a hyperbolic model with IP = 500 bbl/d, D = 0.3, b = 1 predicts 250 kbbl over 30 years, though extrapolation is uncertain.

Abstract

This study derives typical production curves of tight oil wells based on monthly production data from multiple horizontal Eagle Ford shale oil wells. Well properties initial production (IP) rate and production decline rate were documented, and estimated ultimate recovery (EUR) was calculated using two empirical production decline curve models, the hyperbolic and the stretched exponential function. Individual well productivity, which can be described by IP level, production decline curvature and well lifetime, varies significantly. The average monthly IP was found to be around 500 bbl/day, which yields an EUR in the range of 150–290 kbbl depending on used curve, assumed well lifetime or production cutoff level. More detailed analyses on EUR can be made once longer time series are available. For more realistic modeling of multiple wells a probabilistic approach might be favorable to account for variety in well productivity. For less detailed modeling, for example conceptual regional bottom-up production modeling, the hyperbolic function with deterministic parameters might be preferred because of ease of use, for example with the average parameter values IP = 500 bbl/day, D = 0.3 and b = 1 resulting in an EUR of 250 kbbl with a 30-year well lifetime, however, with the recognition that this extrapolation is uncertain.