Flowback data are defined as the early time-pressure-rate (TPR) data which are taken immediately following the completion and stimulation of a given well. Although typically discounted or even ignored, this data has a wealth of well/reservoir information. Analysis can provide forward-looking indications of long-term well deliverability as well as an early diagnosis of any potential production problems. Effective analysis of early TPR data, however, requires the utilization of all data sources and data types — for example: phase rates, pressures, choke settings, sand production, chlorides content, etc.
The purpose of this paper is to provide a comprehensive workflow for early-time flowback data which provides a unique visualization of these data, as well as a correlative and integrated analysis of these data (i.e., comparing different data types and functions, correlating one data type with another, etc.). The major steps in a generic "flowback" workflow include:
Collection and quality control of TPR and other well performance/completion data. Construction/calibration of a base well/reservoir model (including well completion and stimulation parameters). Construction/application of specialized plots to identify features in the data at a very basic level (i.e., water unloading). Correlation of flowback data using empirical and non-parametric models. Extrapolation of parametric and non-parametric models to provide predictive estimates of early-time well performance. Implementation of an assessment loop to guide future production/completion practices.
The proposed methodology is demonstrated using case studies of wells completed in tight/shale gas reservoir systems. Extensive discussion is provided for the analysis/interpretation of flowback data; as well as our efforts to identify and quantify factors which affect and control production. The approach used in this work is that of a "dashboard" of (static) diagnostic plots as well as correlations/plots for multiple-well sets of flowback data. While the focus of this workflow is the diagnostic analysis of flowback data, we also provide guidance towards the use of flowback and long-term well performance data in "model-based" analyses.