Horizontal gas well liquid holdup calculation method based on flow pattern conversion limit

Abstract

The invention provides a horizontal gas well liquid holdup calculation method based on a flow pattern conversion limit, which comprises the following steps of: constructing a three-parameter equation according to the change trend of the liquid holdup along with the gas flow velocity, substituting the calculated liquid holdup of the annular flow-stirred flow transition point, the stirred flow-slug flow transition point and the slug flow-bubble flow transition point in the drooping pipe under the normal pressure / normal temperature condition at a certain wellbore liquid flow rate and the corresponding gas flow speed into an equation, and iteratively solving the coefficient of the three-parameter equation; then, correcting the liquid holdup of the vertical section by adopting an angle correction term to obtain a new normal-temperature and normal-pressure liquid holdup model with a certain inclination angle, and converting the airflow velocity under high pressure into the corresponding airflow velocity under normal pressure by utilizing dimensionless norm based on a flow similarity criterion; and finally, substituting the converted corresponding airflow velocity under normal pressure into the new model to obtain the liquid holdup of the horizontal gas well under a certain pressure condition. The method does not need comparison and optimization of a large number of models and flow pattern judgment calculation, can directly calculate the liquid holdup of the whole shaft of the horizontal gas well according to the apparent velocity of the gas phase, and is simple, convenient and accurate.

Description

technical field [0001] The invention belongs to the technical field of gas well drainage and gas production, and in particular relates to a method for calculating the liquid holdup of a horizontal gas well based on a flow pattern conversion limit. Background technique [0002] Water production rises significantly in the middle and late stages of gas reservoir development, and timely carrying the liquid out of the wellbore is an important measure to maintain normal production and prolong the life cycle of gas wells. Gravity drop dominated by liquid holdup is an important component of wellbore pressure gradient and a key parameter in the design of continuous liquid carryover in gas wells. Therefore, accurate prediction of liquid holdup is the key to clarifying the wellbore pressure drop in gas wells and realizing continuous liquid carrying in gas wells. [0003] At present, there are many calculation methods for liquid holdup, including mechanism model method, empirical formu...

AI Technical Summary

Problems solved by technology

The mechanism model selects the corresponding calculation method after identifying the flow pattern. However, the flow pattern discrimination standards established by different scholars are different, resulting in large differences in the accuracy of the calculation results and poor engineering applicability.

[0004] In addition, the above calculation methods are mostly established based on vertical wells, while horizontal wells are divided into vertical section, inclined section and horizontal section. The influence of factors such as diameter change is more obvious. At present, for horizontal wells, three flow pattern diagrams describing horizontal pipes, inclined pipes and vertical pipes are generally used for segmental processing. For gas wells with extremely small water production, the gas-liquid ratio is extremely high, and it is easy to exceed the coordinate value range of the gas-liquid two-phase pipe flow pattern diagram commonly used in engineering, resulting in a large error in predicting the gas-liquid two-phase flow pattern of horizontal gas wells

It can be seen that there is currently a lack of a simple and practical unified liquid holdup calculation model for the entire wellbore of horizontal wells.

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