Study on in situ viscosity model of tight oil and its measurement method

The change of in situ viscosity in micro-scale of tight oil reservoir has great influence on the seepage process. Due to the imperfection of in situ viscosity model and measuring method, the prediction of development effect and scientific guidance is affected. Here, an in situ viscosity model of seepage fluid in tight reservoirs is established, and the main influencing factors are studied. The in situ viscosity changes linearly with the bulk viscosity; When the average pore radius less than 500 nm, the in situ viscosity increased sharply. The approximate properties of boundary fluid and heavy oil are verified by experiments, and a method for measuring boundary fluid viscosity based on nuclear magnetic resonance (NMR) is found. According to the viscosity property of boundary fluid, the experiment is designed to verify the measurement method of boundary fluid viscosity by NMR.