Study of gelatin as biodegradable shale hydration inhibitor

In order to develop a biodegradable and efficient shale inhibitor, gelatin, a biodegradable amino polymer, was introduced as a potential shale inhibitor. The inhibitive properties were evaluated by linear swelling test, hot-rolling recovery test and montmorillonite (MMT) plate soaking test. The results showed that the inhibition of gelatin was better than other common inhibitors. The inhibitive mechanism of gelatin was also investigated via a variety of characterization methods. First of all, gelatin was adsorbed on MMT particles through electrostatic interactions and hydrogen bonds. Then, the negative charge on MMT particles was neutralized and the double electrical layers were suppressed. For the adsorbed gelatin molecules, only a few molecules entered the interlayer space and expelled water. Meanwhile, the main part of gelatin was strongly adsorbed on the surface of MMT particles and formed a polymer film, which made clay surface more hydrophobic. Thus, the polymer formed an effective shield to prevent the invasion of water. Finally, the MMT layers were compressed together in a form of thicker and larger agglomerations and the hydration was well inhibited.