Solution of thixotropic model parameters during shutdown and restart of gelled crude oil in loop

Thixotropy, an important index to measure the low-temperature fluidity of waxy crude oil, is crucial to the hydraulic characteristics and safety of gelled crude oil during pipeline shutdown and restart. In the existing process of solving the parameter of the thixotropic model, the thixotropic data in the flow recovery stage after start has been taken into consideration, but the fact that the gelled crude oil in pipeline is thixotropic at the initial moment of startup, has been ignored. The startup test for controlling the flow was designed via the loop flow experimental device, and the method for acquiring thixotropic data in the initial flow filling stage was proposed based on the pressure data along the loop at the startup stage. Based on the thixotropic data of the two stages of loop shutdown and restart, the related parameters of the 4-parameter hyperbolic thixotropic model were calculated, and the mathematical model describing the thixotropic characteristics of gelled crude oil was obtained. Compared with the traditional method for calculating the parameters of the thixotropic model of gelled crude oil in the loop, the solved thixotropic model, which has taken the initial filling stage into consideration, is able to better reflect the real thixotropic characteristics of gelled crude oil in the loop.