A Novel Environment-Friendly Natural Extract for Inhibiting Shale Hydration

This paper reports the first use of Tribulus terrestris extract (TTS), a newly developed nonionic surfactant, as an inhibitor for shale hydration. The critical micelle concentration of TTS was determined using the surface tension method, while its inhibition properties were evaluated with a variety of inhibition assessment methods. The sodium bentonite inhibition tests revealed that TTS can significantly inhibit clay pulping. The scanning electron microscopy images of unmodified and TTS-modified shale samples were observed and discussed. The hydrogen bonds between the hydrophilic tail of the TTS molecules and the available oxygen atoms on the clay silica surface led to the formation of a hydrophobic shell on the clay surface, which is considered as the main inhibition mechanism of TTS. The results from the contact angle experiments also validated this conclusion. In addition, the environmental aspects of TTS were measured in this paper. The experimental results suggest that TTS has a better inhibitor performance than either of the more conventional potassium chloride or polyamine and show that it has a good application prospect as an environment-friendly shale inhibitor.