# Development and Interfacial Mechanism of Epoxy Soybean Oil-Based Semi-Liquid Gel Materials for Wellbore Sealing Applications

## TL;DR

A new semi-liquid gel material was developed for sealing oil wellbores, offering high strength, injectability, and degradability.

## Contribution

The novel semi-liquid gel material combines epoxy resin, soybean oil, and additives for tunable gelation and strong interfacial adhesion.

## Key findings

- The gel system achieves compressive strength over 112.5 MPa and a breakthrough pressure gradient exceeding 50 MPa/m.
- Interfacial adhesion is enhanced with OTS, increasing adhesion layer thickness nearly 10-fold.
- The material degrades completely within 48 hours at 120 °C using a γ-valerolactone and p-toluenesulfonic acid solution.

## Abstract

In this study, a novel semi-liquid gel material based on bisphenol A-type epoxy resin (E51), methylhexahydrophthalic anhydride (MHHPA), and epoxidized soybean oil (ESO) was developed for high-performance wellbore sealing. The gel system exhibits tunable gelation times ranging from 1 to 10 h (±0.5 h) and maintains a low viscosity of <100 ± 2 mPa·s at 25 °C, enabling efficient injection into the wellbore. The optimized formulation achieved a compressive strength exceeding 112.5 ± 3.1 MPa and a breakthrough pressure gradient of over 50 ± 2.8 MPa/m with only 0.9 PV dosage. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of a dense, crosslinked polyester network. Interfacial adhesion was significantly enhanced by the incorporation of 0.25 wt% octadecyltrichlorosilane (OTS), yielding an adhesion layer thickness of 391.6 ± 12.7 nm—approximately 9.89 times higher than that of the unmodified system. Complete degradation was achieved within 48 ± 2 h at 120 °C using a γ-valerolactone and p-toluenesulfonic acid solution. These results demonstrate the material’s potential as a high-strength, injectable, and degradable sealing solution for complex subsurface environments.