Shaft heat loss determining method

Abstract

The invention provides a shaft heat loss determining method. The shaft heat loss determining method comprises the steps that calculating parameters are read in; thermal resistance values at all positions in the radius directions in a shaft and a radial upper heat loss limit value of a shaft unit are calculated; a radial initial heat loss value of the shaft unit is set; a first current value and a second current value are set; a current total thermal resistance value and a third current value are calculated in a circulatory mode, and the first current value and the second current value are updated until the updated second current value is larger than or equal to the depth of the shaft; the obtained third values are summed, and the result obtained after summation is determined to be the shaft heat loss value. By the adoption of the shaft heat loss determining method, heat loss calculation is conducted on the shaft in a sectional mode, so that the shaft heat loss result worked out is more accurate.

Description

technical field [0001] The invention relates to the field of steam injection oil recovery, in particular to a method for determining heat loss of a wellbore. Background technique [0002] In the oil extraction technology, the unprocessed oil extracted directly from the oil well is crude oil, and the viscosity of different types of crude oil is generally different. Among them, heavy oil refers to crude oil with high asphaltene and colloid content and high viscosity. Practice shows that the viscosity of heavy oil generally changes significantly with the change of temperature. As the temperature rises, the viscosity of heavy oil generally decreases, so the exploitation and transportation of super heavy oil generally requires the use of thermal means to reduce the viscosity of super heavy oil, such as the use of steam injection recovery technology for the production of super heavy oil. At present, the main method of heavy oil production is steam injection, including steam huff...

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Problems solved by technology

However, the above calculation method continues to calculate the entire depth of the wellbore as a whole, without considering that with the different depths of the wellbore, factors such as steam temperature in the wellbore will change, and the heat loss of the wellbore will also change accordingly. Therefore, the above method The calculation result is not accurate

At the same time, after three or four iterations of this calculation method, the temperature of the outer wall of the insulation layer will be lower than the temperature of the inner wall of the casing. This phenomenon does not conform to the natural law, and the iteration will not converge, and the iterative calculation cannot be continued.

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