In less than 10 years, the shale oil & gas revolution has allowed the United States to become gas independent and reduce their oil dependency by half. However, this unexpected influx of hydrocarbons caused a successive collapse in gas (2012) and oil prices (2014) with a significant impact on drilling and fracturing activities. As a matter of fact, between late 2014 and early 2016, the number of operating rigs was divided by four. Many analysts predicted that this downturn would lead to a rapid and significant slowdown in production.
Nevertheless, the retrospective analysis of big shale gas plays over the 2008-2015 period shows that the aggregate production of the three major gas plays (Barnett, Haynesville and Marcellus) has not stopped increasing. Over the past two years, and with 4 times less operating rigs, this growth has been even more significant than that observed before the collapse of gas prices.
Total developed a specific model to understand this resilience, which results from three factors: (1) the drilling of a large portfolio of wells at different maturities; (2) the improvement of operational performance; and (3) the increase in reserves per well thanks to innovative completion and fracturing technologies as well as the identification of sweet areas. Maintaining a production plateau requires a critical activity that declines with the number of wells put on stream, the improvement of operational performance and the reserves per well. The model shows that at the end of a development, the critical activity can be 5 to 10 times lower than that required during the ramp-up phase.
The same model was used to simulate the production history of 5 big plays (Barnett, Haynesville and Marcellus for gas; and Bakken and Eagle Ford for oil). The history match is performed by calculating the best decline curve per well using a least squares algorithm. The method achieves an excellent match of production history with a good coherence between calculated and actual reserves per well.
To test the resilience of the plays, the production history was extended over 10 years (2015-2025) to pursue a decline strategy (no new wells put on stream during that period). The results show that resilience differs from one play to another depending on its maturity and the size of its well portfolio.
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