Inhibition performance of amidocyanogen silanol in water-based drilling fluid

Abstract In this study, a series of amidocyanogen silanols (HASes) modified by methacryloxy propyl trimethoxyl silane (MPS) with polyethylene polyamine was introduced as potential shale inhibitors, thus providing the development and application of high-temperature resistant shale inhibitors in water-based drilling fluids. One shale inhibitor was selected based on cuttings dispersion tests. The results indicated that the shale inhibitor prepared with tetraethylenepentamine and MPS with the mole ratio of 1:2 (named HAS-8) was the best. The inhibition performance of HAS-8 was evaluated with the cuttings dispersion test, linear swelling test, and bentonite inhibition test, and was compared with the performance of currently available polyamine inhibitors. The results indicated that HAS-8 can effectively inhibit the hydration swelling and dispersion of clay, and that its temperature resistance is significantly better than that of polyamine inhibitors. The inhibition mechanism of HAS-8 was investigated with X-ray diffraction, adsorption measurement, and thermogravimetric and transmission electron microscope analysis. The mechanism is the adsorption on the clay surface and the intercalation of the interlayer, which inhibited the surface hydration and osmotic hydration of the clay. In field application of Bei 9 well, the HAS-8 effectively inhibits the hydration of water-sensitive cuttings and maintains the wellbore stability of the shale formation, providing a guarantee for safe and fast drilling.