A Preheating and Production Unsteady Prediction Method for Waxy Crude Oil Long-distance Pipeline

Abstract

The invention discloses a non-steady-state prediction method for preheating and putting into production of a long-distance crude oil pipeline containing waxy crude oil. Based on a body-fitted grid method based on differential equations, a body-fitted grid structure corresponding to the long-distance crude oil pipeline is obtained; based on the Body-fitted grid structure, transforming the heat transfer equation and boundary conditions in the preheating and commissioning mathematical model into calculation heat transfer equations and calculation boundary conditions on the calculation plane; discretizing the calculation heat transfer equation and the calculation boundary conditions , to obtain the discrete equation; use the alternating direction iteration method to solve the discrete equation to obtain the thermal system equation; substitute the hot water parameters into the thermal system equation to obtain the soil heat storage corresponding to the soil corresponding to the long-distance crude oil pipeline; When the heat storage amount in the soil is not less than the preset heat storage amount, the time corresponding to the heat storage amount in the soil is determined as the oiling time.

Description

technical field [0001] The invention relates to the field of crude oil pipeline preheating, in particular to a preheating and production unsteady-state prediction method for long-distance waxy crude oil pipelines. Background technique [0002] The existing waxy crude oil mainly adopts the process of heating and transporting. For the production of long-distance pipelines for transporting waxy crude oil, if the crude oil is directly put into the cold pipe, the temperature drop of the crude oil is too fast during the flow, which will lead to The frictional resistance rises sharply and the transportation is difficult, and even leads to serious accidents in the condensation pipe. Therefore, in order to avoid this situation, in actual production, most of the long-distance pipelines for waxy crude oil are usually firstly equipped with high heat capacity, Preheat the pipeline with low-viscosity medium (hot water is generally used). After the temperature field of the soil around the ...

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Problems solved by technology

[0002] The existing waxy crude oil mainly adopts the process of heating and transporting. For the production of long-distance pipelines for transporting waxy crude oil, if the crude oil is directly put into the cold pipe, the temperature drop of the crude oil is too fast during the flow, which will lead to The frictional resistance rises sharply and the transportation is difficult, and even leads to serious accidents in the condensation pipe. Therefore, in order to avoid this situation, in actual production, most of the long-distance pipelines for waxy crude oil are usually firstly equipped with high heat capacity, Preheat the pipeline with low-viscosity medium (hot water is generally used), and after the temperature field of the soil around the pipeline is fully preheated, the temperature field basically meets the requirements, and the temperature of the preheated fluid enters the station is high enough, then the crude oil is put in at an appropriate time to realize normal transportation

[0003] In the prior art, the preheating and commissioning of long-distance waxy crude oil pipelines usually uses hydraulic systems and thermal systems for coupled calculations, using unstructured grids, which do not fit well at the boundaries, especially at the pipelines. Segmented calculations make the calculation amount larger and the calculation speed slower, and there is a problem of longer calculation time

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