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A Comprehensive Methodology for Investigating Cocurrent Spontaneous Imbibition in Coal.
Yuejian Lu1,2, Dameng Liu3,4, Yidong Cai3,4
1School of Civil and Architecture Engineering, Nanchang Institute of Technology, Nanchang 330099, China.
ACS Omega
|November 11, 2024
Summary
This study visualizes fluid flow in coalbed methane reservoirs using nuclear magnetic resonance and X-ray microcomputed tomography. It reveals three imbibition types and four dynamic stages, crucial for optimizing hydraulic fracturing.
Area of Science:
- Geosciences
- Petroleum Engineering
- Materials Science
Background:
- Understanding fluid distribution and dynamic wettability in coalbed methane (CBM) reservoirs is crucial for optimizing hydraulic fracturing.
- Spontaneous imbibition at the nano-micro scale governs fluid flow and gas-water exchange efficiency in CBM systems.
Purpose of the Study:
- To visualize and quantify fluid distribution during spontaneous imbibition in CBM reservoirs.
- To analyze gas-water exchange efficiency and dynamic wettability using combined NMR and μ-CT technologies.
- To establish a fundamental basis for optimizing hydraulic fracturing parameters in CBM exploration.
Main Methods:
- Combined use of nuclear magnetic resonance (NMR) and in situ X-ray microcomputed tomography (μ-CT) for fluid distribution and flow behavior analysis.
- Investigation of spontaneous imbibition stages to determine gas-water exchange efficiency.
- Calculation of dynamic wettability during spontaneous imbibition using NMR data.
Main Results:
- Imbibition characteristics were categorized into three types (I, II, III) based on NMR, differing in fluid distribution within nanopores and micro pore-fractures.
- Spontaneous imbibition dynamics were delineated into four stages via μ-CT, with the third stage showing peak imbibition efficiency due to fluid exchange in fractures.
- A negative correlation between contact angle and T2g was observed, indicating hydrophobic samples have smaller T2g values. Wettability dynamically decreased with imbibition time.
Conclusions:
- The study provides a multi-scale visualization and quantification of fluid dynamics in CBM reservoirs during spontaneous imbibition.
- The identified imbibition types and dynamic stages offer insights into gas-water exchange and wettability alterations.
- Findings contribute to a better understanding of fluid flow mechanisms, essential for enhancing CBM recovery and optimizing hydraulic fracturing.
