Method for calculating temperature, pressure and dryness of injected steam and nitrogen mixture

Abstract

The invention provides a method for calculating temperature, pressure and dryness of an injected steam and nitrogen mixture. The method comprises the steps as follows: calculating initial temperature, initial gaseous dryness and initial steam dryness of a mixture after steam is mixed with nitrogen; calculating wellhead temperature, wellhead pressure and wellhead dryness distribution of a surface pipeline wellhead with randomly set step length by using the outlet of a steam boiler as an initial calculating point; calculating wellbore temperature, wellbore pressure and wellbore dryness distribution with randomly set step length by using the wellhead as an initial calculating point; and providing guidance for the implementation of the corresponding technology in an oil field site based on the wellbore temperature, the wellbore pressure and the wellbore dryness distribution. The method of the invention has excellent computational stability and higher computational accuracy, and provides reliable calculation means for optimal design of wellbore injecting parameters of a stream and nitrogen mixed system.

Description

technical field [0001] The present invention relates to the field of steam injection development in thermal recovery of heavy oil, in particular to the calculation of the relevant parameters of injected steam and nitrogen mixture in surface pipelines and well bores in heavy oil thermal recovery, specifically, the temperature, temperature and temperature of injected steam and nitrogen mixture. Calculation method of pressure and dryness. Background technique [0002] Steam injection is an effective and economical method for producing heavy oil. However, the steam injection technology itself has some shortcomings: the cost of simple steam injection is high; The steam in the reservoir channeled along the high-permeability layer, resulting in a large loss of injected steam and a decrease in volumetric sweep coefficient. Therefore, a thermal oil recovery process using nitrogen assisted steam injection is proposed. The process can reduce steam heat loss, improve steam injection e...

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Problems solved by technology

[0004] The invention provides a method for calculating the temperature, pressure and dryness of the injected steam and nitrogen mixture. Under the condition that the steam temperature, steam pressure and steam dryness at the outlet of the steam boiler are known, the steam+nitrogen binary system is deduced. The calculation formula and calculation process of the temperature, pressure, and dryness distribution of the two-phase mixture in the surface pipeline and the wellbore solve the problem that the existing steam injection parameter calculation model cannot calculate the temperature field, pressure field, and dryness of the nitrogen and steam mixture in the wellbore. Problems with correct calculation of fields

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