Research on performance and action mechanism of polyhydroxy high-efficiency shale inhibitor

Abstract:

To address the challenge of wellbore instability in drilling deep shale formations and overcome the shortcomings of conventional shale inhibitors， such as insufficient temperature resistance and limited anti-swelling efficiency， a highly efficient polyhydroxy shale inhibitor was synthesized under mild conditions using triethanolamine and 1，2-dibromoethane as raw materials. Its performance was systematically evaluated through tests including anti-swelling rate， temperature resistance， core linear expansion， and hot-rolling recovery. The structure and action mechanism were characterized using Fourier transform infrared （FT-IR） spectroscopy， scanning electron microscopy （SEM）， and X-ray photoelectron spectroscopy （XPS）. The results indicate that the inhibitor achieves a synthesis yield of 98.7%， exhibits good water solubility， and features a mild synthesis process， demonstrating great potential for industrialization. A 23% aqueous solution of the inhibitor exhibits an anti-swelling rate of 96.7% at room temperature and maintains 92.3% after aging at 140 ℃. Furthermore， the hot-rolling recovery of shale cores reaches 92.5% at 140 ℃， with a significantly reduced linear expansion. All indicators are markedly superior to those of conventional inhibitors. Mechanism analysis reveals that the multiple hydroxyl groups in the molecule form hydrogen bonds with the hydroxyl groups on shale mineral surfaces， while the protonated amino groups generate electrostatic adsorption. Together， they form a dense adsorption film on the shale surface， blocking the invasion of drilling fluid filtrate. Simultaneously， the hydroxyl groups in the molecule undergo condensation reactions with the silanol groups on the shale surface to form chemical bonds， further enhancing the compactness and stability of the adsorption film. These synergistic effects endow the inhibitor with strong adsorption and long-lasting film-forming capabilities on the shale surface. This study provides a novel technical approach for the development of inhibitors used in drilling deep and complex shale formations， showing promising application prospects.