Prediction of annulus liquid level depth in high-temperature and high-pressure gas wells based on sustained casing pressure

Abstract

Annulus liquid level depth is used to describe the variation of sustained casing pressure, calculate the leakage location, and reflect the hydrocarbon content in annulus. There are currently no theoretical prediction methods for it. Thus, a prediction model and numerical solution method for the annulus liquid level depth are established, and this model is then utilized to analyze the effects of various factors on the annulus liquid level depth. The research results show that the wellhead temperature, initial tubing-casing annulus pressure, and the amount of annulus gas released have a significant influence on the annulus liquid level depth by changing the annulus liquid compression and string deformation. The impact of a huge annular pressure change on the annulus liquid compression is noticeable, which is beneficial to improving the prediction accuracy of the annulus liquid level depth. Therefore, this prediction method is better suited to high-pressure wells than the echo-sounding method.