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Journal of Australian Energy Producers
RESEARCH ARTICLE (Non peer reviewed)

Engineered flowback and reservoir evaluation for unconventional wells

Andrew Fontenot A * and Chau Nguyen A
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A Oilfield Data Services Inc., Houston, TX, USA.

The APPEA Journal 63 S173-S176 https://doi.org/10.1071/AJ22238
Accepted: 10 March 2023   Published: 11 May 2023

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of APPEA.

Abstract

A flowback procedure is presented that uses a wellbore model coupled with thermal and fluid modelling to calculate the bottomhole pressure (BHP) and maximise the safe initial production/drawdown without over-stressing and damaging the fracture system. After obtaining the BHP, it is then possible to determine the fractured reservoir volume, fracture-dominated volume, and matrix contribution. The paper presents a case history validating the model calculations in an unconventional well. Two methods of decline analysis are presented, ‘Conventional’ and ‘Thermodynamic Transient Analysis’ (TTA), and together, these methods provide insights into the fracture system and overall reservoir volumes by recognising and applying the appropriate equation for the proper reservoir flow regime. The early flowback period can be used to determine the frac volume, while later periods will begin showing the increasing amount of matrix contribution. The wellbore flow model and decline analysis calculations are verified by a case history presented in the paper, where this flowback process was utilised on a hydraulically fractured East Texas well. The wellhead pressures (WHPs) in this case study highlight the need to accurately calculate BHPs based on the WHP and rates, due to significant differences between the trends and decline rates of the respective pressures.

Keywords: flowback, hydraulic fracturing, reserves, reservoir, reservoir management, reservoir flow regime, East Texas, Thermodynamic Transient Analysis, unconventional.

Andrew Fontenot has a wide variety of experience in domestic and international oil and gas exploration, production operations and petroleum engineering consulting. After graduating from Louisiana State University with a BS in Petroleum Engineering, he spent time evaluating hydraulic fracturing completions using microseismic monitoring and recommending ways to optimise field and asset development, well spacing, and treatment design. Andrew is currently working with Oilfield Data Services, helping operators identify their reservoir volumes and estimated ultimate recovery, and recommending ways to optimise production.

Chau Nguyen is a Reservoir and Production Engineer with Oilfield Data Services. Her current research interests include real-time well surveillance, completion evaluations, production optimisation, and reservoir management. Nguyen holds a Bachelor’s degree in Petroleum Engineering from the University of Houston. She is a member of SPE and SPWLA.


References

Fair C, Flores R, Hakim B, Nande S (2014) Using the Results from Automated Petroleum Engineering Calculations to Accelerate Decision Workflows. Paper presented at the SPE Asia Pacific Oil & Gas Conference and Exhibition, October 2014, Adelaide, Australia. (Society of Petroleum Engineers)
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