Preparation And Application Of Multi-amine Clay Swelling Inhibitor

In this paper,dimethylamine(diethylamine)and epichlorohydrin were used as raw materials with a molar ratio of 1:1,and piperazine(melamine,glucose and sodium oleate)were used as the third reactant to synthesize a kind of polyamine shale inhibitor.In addition,citric acid and amines were used to synthesize small molecule shale inhibitor in water.With the linear expansion rate of bentonite as evaluation index,the synthetic conditions were optimized,and a suitable inhibitor for bentonite was screened.Properties of the inhibitor were evaluated by anti-swelling experiments,mud ball experiments,drilling fluid properties evaluation experiments,etc.And the inhibition mechanism of the polyamine was studied thoroughly by ion exchange method,scanning electron microscope(SEM),thermogravimetric analysis(TGA)and X-ray diffraction(XRD)etc.(1)With the linear expansion rate of bentonite as evaluation index,the synthetic temperature,the content of cross-linking agent and concentration of inhibitor were optimized.The results show that the inhibitor DEP-7,synthesized from dimethylamine and epichlorohydrin with the mole ratio of 1:1 and 2.0% piperazine under 120 ?,displays the best performance,and linear swelling ratio of bentonite in 0.5% DEP-7 solution after 90 min is 50.0%;The inhibitor DEM-8,synthesized with 0.1% melamine under 90 ?,displays the best multifunctional performance;The inhibitor GGCP-2,synthesized with 0.1% glucose under 60 ?,displays the best performance,anti-swelling rate of 0.8% GGCP-2 reaches up to 94.5%.With the amount of sodium oleate of 1.0%,the properties of the product gets to optimum,and linear swelling ratio of bentonite in 0.5% DESo-2 solution after 90 min is 56.4%.Mud ball experiments,anti-swelling experiments and drilling fluid performance evaluation experiments show that polyamine cationic compounds have stronger inhibitive capability to bentonite hydration swelling and dispersion,and application in the fracturing fluid and the acidizing fluid also shows good inhibition performance.(2)Citric acid and amines were used as raw materials to synthesize a kind of small molecule shale inhibitor in water displayed appropriate performance.The inhibitor CAA-10,synthesized from citric acid and triethanolamine with the mole ratio of 1:1,is better,the linear swelling ratio of bentonite in 0.5% CAA-10 solution after 90 min is 49.8%,and its anti-swelling rate of 1.0% CAA-10 is 71.8%.The screened inhibitors showed thicken ability and goodcompatibility with KD-03 and modified starch in drilling fluid.Especially for modified starch,compared to blank,the apparent viscosity of drilling fluid treated by 0.1% CAA-10 and 2.0%modified starch was increased 2.2 times,and fluid loss was reduced 62.5%.(3)Inhibition mechanism study demonstrates that the polycation compounds inhibit effectively the hydration or swelling of clays mainly owing to electrostatic adsorption,hydrogen bonding,anchoring effect etc.And small molecules amine-tartaric acid salts inhibit effectively the hydration or swelling of clays mainly owing to ion exchange action,in addition,the cation absorption onto clay surface to control the hydration of clay.