Refracturing, or a so-called ‘refrac’, involves restimulating a well after an initial period of production. The objective of a refrac is to tap unstimulated parts of the reservoir with higher pore pressure. A refrac is typically performed after the flowing bottomhole pressure is below the saturation pressure, hence rigorously accounting for multiphase flow effects is important in the evaluation. In this paper, we utilize a multiphase flowing material balance (FMB) technique to evaluate refracs in the Eagle Ford.
The multiphase flowing FMB method by Thompson & Ruddick (2022) are used to evaluate both successful, and unsuccessful refracs in the Eagle Ford. The multiphase FMB method is unique as it does not require relative permeability curves, which is highly uncertain in tight unconventioanls. In this study, the method is leveraged to quantify the difference in contacted pore volume pre- and post a refrac. The results, and associated analysis, are backed by simulated cases to enhance our understanding of the problem in general.
Refracs are typically characterized by rapid changes in flowing pressures and rates. Hence, leveraging techniques that rigorously account for superposition and multiphase flow effects are important, as relying solely on rates (i.e., decline curve analysis) is not sufficient to capture the complexity a well is exposed to during a refrac. This paper provides a workflow to quantify the successfulness of a refrac.
We present complete details to both synthetically generated and actual field data sets. Contributions include a technical framework to perform refrac evaluations in tight unconventionals, incorporating both changing pressures and rates. We also compare results of our analysis to results obtained from interpreting multiphase production data using single-phase techniques.
Devon Energy have performed 46 so-called ‘refracs’ in the Eagle Ford. A ‘refrac’, or refracturing, refers to the process of performing hydraulic fracturing again on a well that has already undergone the process in the past. It involves pumping a fluid at high pressure into the well to create new fractures, or to re-stimulate existing ones that have become less productive over time due to factors such as natural depletion or clogging of the fractures with minerals, or other materials.
