Preparation and performance of amine-tartaric salt as potential clay swelling inhibitor

A series of small molecular clay swelling inhibitor was prepared with tartaric acid and amines, presented as amine-tartaric salts (ATS). The inhibitor was screened based on the linear expansion rate of bentonite. The results show that the inhibitor prepared with tartaric acid and triethylenetetramine with the mole ratio of 1:1 (named as ATS-4) is the best inhibitor of the hydration expansion and dispersion of bentonite. The inhibitive properties of ATS-4 were evaluated by various methods, including clay linear swelling tests, anti-swelling tests, mud ball immersing tests, mud-making inhibition experiments and particle distribution measurements etc. The results show that ATS-4 has superior performance to inhibit the hydration swelling and dispersion of clays by controlling the particle size of clay. On the other hand, the bentonite linear expansion rate in 0.5% ATS-4 aqueous solution is much lower than that of others, and the hydration expansion degree of the mud ball in ATS-4 aqueous solution is appreciably weaker than the control test, and it is compatible with the conventional additives in water-based drilling fluids. Then, the inhibition mechanism of the amine-tartaric salt was well discussed based on thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray diffraction analysis (XRD), single crystal X-ray diffraction and ion exchange tests.