High-strength PVA-based carboxymethyl cellulose hydrogel enabling adaptive plugging of cracks of varying widths

Drilling fluid loss is a major challenge facing oil and gas drilling operations worldwide and often results in significant economic losses. Although traditional liquid-crystal materials (LCMs) offer key advantages such as self-adaptive crack plugging capabilities and adjustable gelation times. However, due to its limited pressure resistance, its range of applications remains limited. In this study, a simple freeze-thaw strategy was employed to innovatively develop a PVA-based plugging hydrogel. This method leverages physical cross-linking properties to reduce the need for chemical cross-linking agents and improve the material's rheological properties. The 15% PVA hydrogel achieved a tensile strength of 6.99 MPa. Its compressive strength was 4 MPa at 80% strain. Furthermore, it exhibited excellent fatigue resistance, with compressive strength decreasing by only 21% after 50 cycles. Simulated plugging tests demonstrated that the prepared hydrogel exhibits excellent sealing performance under a water pressure of 5 MPa. This study provides an economically viable and environmentally friendly solution for preventing drilling fluid loss, making it a highly promising candidate material for deep-sea drilling applications.