Micro-emulsion viscosity reducer for thick oil, and preparation method thereof

The invention provides a micro-emulsion viscosity reducer for thick oil, and a preparation method thereof. The viscosity reducer comprises, by weight, 33-37 parts of an oil-soluble viscosity reducer, 16-20 parts of a nonionic surfactant, 18-22 parts of a sulfonate anionic surfactant, 2-4 parts of a Tween emulsifier, 3-5 parts of isomeric alcohol and 20-24 parts of water. The micro-emulsion viscosity reducer is prepared through a reaction of above raw materials in a reaction kettle at a certain temperature under a certain rotating speed. The micro-emulsion viscosity reducer is processed by oilfield hot sewage to prepare an aqueous solution, and the aqueous solution injected to the underground, so the micro-emulsion viscosity reducer has the characteristics of high viscosity reduction, strong economy and the like, allows the viscosity of the thick oil to be decreased by above 98%, can substitute high-pressure steam exploitation, realizes a very high economic input-output ratio, fully solves the problems of high thick oil viscosity, difficult exploitation and the like in oilfield exploitation and extraction processes, and has a large-scale popularization value.