Mechanisms of Water-Lock Removal by a Nanoemulsion/Mud Acid Composite System in Low-Permeability Sandstone Reservoirs: Insights from Pore-Scale Characterization in the MB Block
- 1Key Laboratory of Enhanced Oil Recovery (Northeast Petroleum University) , , , ,
- 2Clausthal University of Technology , ,
- 3University of Louisiana at Lafayette , , ,
Abstract
Water-lock damage in low-permeability sandstone reservoirs is primarily caused by small pore-throat structures, strong capillary forces, and hydrophilic rock surfaces. Conventional treatment methods mainly target either fluid-interface modification or pore blockage problems separately. In this study, a nanoemulsion/mud acid composite system was developed to achieve a combined effect of fluid interfaces and localized mineral dissolution. Interfacial tension (IFT) measurements, contact angle analysis, constant-rate mercury intrusion (CRMI), nuclear magnetic resonance (NMR), and high-temperature high-pressure core flooding experiments were conducted to investigate the water-lock removal performance and underlying mechanisms of the composite system. The results demonstrate that the optimized 0.20 wt % nanoemulsion/mud acid system reduced the oil–water interfacial tension to 0.486 × 10–3 (mN·m–1) and increased the contact angle to 116.4°. The combined CRMI–NMR characterization revealed that fluid mobility in low-permeability sandstone can be classified into bound, transition, and movable zones, rather than being described by a single flow threshold. Increasing the production pressure differential intensified deep water-phase invasion and retention, weakened the production enhancement effect caused by increased driving force, and further aggravated water-lock damage. Mineralogical analysis, NMR measurements, and permeability-recovery experiments collectively indicate that water-lock removal is associated with coupled interfacial regulation and localized pore–throat modification. These findings provide a pore-scale theoretical basis for optimizing treatment-agent concentration and production pressure differential, while further field-scale validation remains necessary.
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BibTeX
@article{qu2026mechanisms,
title = {{Mechanisms of Water-Lock Removal by a Nanoemulsion/Mud Acid Composite System in Low-Permeability Sandstone Reservoirs: Insights from Pore-Scale Characterization in the MB Block}},
author = {Guohui Qu and Jingxuan Wu and Michael Zhengmeng Hou and Yikun Liu and Louis Osei Twum and Ning Liu},
journal = {ACS omega},
year = {2026},
month = sep,
doi = {10.1021/acsomega.6c07390},
url = {https://europepmc.org/article/PMC/PMC13670283},
note = {CC BY},
}
RIS
TY - JOUR
TI - Mechanisms of Water-Lock Removal by a Nanoemulsion/Mud Acid Composite System in Low-Permeability Sandstone Reservoirs: Insights from Pore-Scale Characterization in the MB Block
AU - Guohui Qu
AU - Jingxuan Wu
AU - Michael Zhengmeng Hou
AU - Yikun Liu
AU - Louis Osei Twum
AU - Ning Liu
PY - 2026
DA - 2026/09/29
JO - ACS omega
DO - 10.1021/acsomega.6c07390
UR - https://europepmc.org/article/PMC/PMC13670283
AB - Water-lock damage in low-permeability sandstone reservoirs is primarily caused by small pore-throat structures, strong capillary forces, and hydrophilic rock surfaces. Conventional treatment methods mainly target either fluid-interface modification or pore blockage problems separately. In this study, a nanoemulsion/mud acid composite system was developed to achieve a combined effect of fluid interfaces and localized mineral dissolution. Interfacial tension (IFT) measurements, contact angle analysis, constant-rate mercury intrusion (CRMI), nuclear magnetic resonance (NMR), and high-temperature high-pressure core flooding experiments were conducted to investigate the water-lock removal performance and underlying mechanisms of the composite system. The results demonstrate that the optimized 0.20 wt % nanoemulsion/mud acid system reduced the oil–water interfacial tension to 0.486 × 10–3 (mN·m–1) and increased the contact angle to 116.4°. The combined CRMI–NMR characterization revealed that fluid mobility in low-permeability sandstone can be classified into bound, transition, and movable zones, rather than being described by a single flow threshold. Increasing the production pressure differential intensified deep water-phase invasion and retention, weakened the production enhancement effect caused by increased driving force, and further aggravated water-lock damage. Mineralogical analysis, NMR measurements, and permeability-recovery experiments collectively indicate that water-lock removal is associated with coupled interfacial regulation and localized pore–throat modification. These findings provide a pore-scale theoretical basis for optimizing treatment-agent concentration and production pressure differential, while further field-scale validation remains necessary.
SN - 2470-1343
ER -