Laboratory Study on Environmentally Friendly Polymer Shale Inhibitor

KCl polymer drilling fluids are currently commonly used in Sichuan and Chongqing areas. The KCl polymer drilling fluids used contain high concentration of chlorines which, when reacted with organic compounds in the surrounding environment, will generate chlorinated chemicals having teratogenesis, carcinogenesis and mutagenesis effects. A polyethylenepolyamine, havingdegree of amination of more than 85%, was synthesized through Hofmann Reaction from polyacrylamide. It has LC₅₀(opossum shrimp) of 18,764 mg/L, actually non-toxic, and BOD₅/COD_Cr of 68.2%, easy to degrade. In laboratory evaluation, the polyethylenepolyaminesolution reduced the linear rate of swelling of cores by 56.79%, and increased the rate of recovery of shale cuttings by 61.84%, while KCl solution reduced the linear rate of swelling of cores by 22.75%, and increased the rate of recovery of shale cuttings by 43.03%.This polyethylenepolyamine is also superior to KCl in reducing the capillary suction time (61.84% against 34.62%). These results show that the polyethylenepolyamine is a better shale inhibitor than KCl.