Inhibition performance and mechanism of Horsetail extract as shale stabilizer

The Horsetail extract was used as shale stabilizer, its inhibition performance was studied by laboratory experiments and compared with potassium chloride and polyamine, and its anti-swelling mechanism was analyzed. Bentonite inhibition test, sodium bentonite sedimentation test, dynamic linear swelling test, and hot rolling cutting dispersion test were employed. The results show that: the bentonite is not capable of being hydrated or dispersed in solution with the Horsetail extract; the Horsetail extract can reduce the swelling of the bentonite and prevent disintegration and dispersion of cuttings in aqueous medium; the extract is well comparable and competitive with potassium chloride and polyamine in inhibition performance. The constituents of the Horsetail extract have active hydroxyls which are capable of forming hydrogen bounding with surfaces of bentonite particles, leading to decrease of the water absorption on bentonite particles' surfaces which results in bentonite swelling reduction. Besides having good anti-swelling ability, Horsetail extract is ecofriendly, readily available and inexpensive. Key words: Horsetail extract, water-based drilling fluid, shale hydrated swelling, shale stabilizer, anti-swelling mechanis