The Eagle Ford Shale Laboratory (EFSL) Project
The Eagle Ford Shale Laboratory: A Field Study of the Stimulated Reservoir Volume, Detailed Fracture Characteristics, and EOR Potential
OBJECTIVES
The ultimate objective of this project is to help improve the effectiveness of shale oil production by providing new scientific knowledge and new monitoring technology for both initial stimulation/production as well as enhanced recovery via refracturing and EOR. This project will develop methodologies and operational experience for optimized production of oil from fractured shale, an end result that would allow for more production from fewer new wells using less material and energy.
For this, our team utilizes newly-developed monitoring solutions based on distributed fiber-optic sensing and permanently installed rotary seismic sources to provide continuous surveillance before, during and after fracturing. The project targets three important stages of unconventional oil production from shales: (1) a Refracturing Stage where a previously fractured legacy well will be re-stimulated for improved production, (2) a new Stimulation Stage where the most advanced hydraulic fracturing and geosteering technology will be applied in two new production wells, and (3) a Gas-EOR (enhanced oil recovery) Phase where the refractured well will be later tested for the efficiency of Huff and Puff gas injection as an EOR method. Field monitoring will be complemented by laboratory testing on cores and drill cuttings, and coupled modeling for design, prediction, calibration, optimization, and code validation.
The main scientific/technical objectives of the proposed project are:
- Develop and test new breakthrough monitoring solutions for hydraulic fracture stimulation, production, and EOR. In particular, for the first time in unconventional reservoirs, use active seismic monitoring with fiber optics in observation wells to conduct: (1) real-time monitoring of fracture propagation and stimulated volume, and (2) 4D seismic monitoring of reservoir changes during initial production and EOR from the refractured well.
- Improve understanding of the flow, transport, mechanical and chemical processes during and after stimulation (both initial and refracturing) and gain insights into the relationship between geological and stress conditions, stimulation design, and stimulated rock volume
- Assess spatially and temporally resolved production characteristics and explore relationship with stimulated fracture characteristics.
- Evaluate suitability of refracturing to achieve dramatic improvements in stimulation volume and per well resource recovery.
- Evaluate suitability of gas-based EOR Huff and Puff methods to increase per well resource recovery.
- Optimize drilling practices in the Eagle Ford shale based on surface monitoring and near-bit diagnostic measurements during drilling.
- Conduct forward and inverse modeling to test reservoir and fracture models and calibrate simulations using all monitored data. Ultimately, provide relevant guidance for optimized production of oil from fractured shale.
- Disseminate research and project results among a broader technical and scientific audience, and ensure relevance of new findings and approaches across regions/basins/plays.
SCOPE OF WORK
The project will start with the refracturing of a legacy well that was initially stimulated using now outdated fracturing technology (Task 2). A monitoring well, strategically located on both sides of the legacy well, will be drilled, completed, and instrumented to allow for real-time monitoring of evolving fracture characteristics and stimulated volume. These monitoring well will also be used for the other two main project stages, involving a new state-of-the art stimulation effort (Task 3) and a Huff and Puff EOR test (Task 4). Task 3 will be conducted in two new wells of opportunity drilled; these wells will be situated parallel to the horizontal observation well on the other side of the refracturing well. Task 4 will be conducted in the refractured legacy well, testing the efficiency of a Huff and Puff process with natural gas injection for EOR. As described below, each main task comprises various field activities complemented by laboratory testing and coupled modeling for design, prediction, calibration, and code validation. In addition to the three main tasks aligned with refracturing, new stimulation, and EOR, the work plan comprises Task 1 (Project Management and Planning) and Task 5 (Integrated Analysis, Lessons Learned, Products, and Reporting).
Seismic feasibility modeling with 3D finite difference and ray simulations for a surface orbital vibrator (SOV) source. NRMS of S-wavefield difference shows large amplitude change due to frac-refrac.
