Prediction of Hydrate Formation Risk Based on Temperature–Pressure Field Coupling in the Deepwater Gas Well Cleanup Process

Abstract

Deepwater oil and gas exploitation has become an important field in the petroleum industry development. However, there are still no mature methods for hydrate prevention in the deepwater wells cleanup stage, and the excessive use of inhibitors has severely increased the construction costs. In our study, based on the hydrate phase equilibrium equation, the common influencing factors of hydrate formation were analyzed. Then, combined with the hydrate phase equilibrium equation and heat transfer equation, the temperature–pressure coupling model of the wellbore field during the deepwater gas wells cleanup process is established. Then, taking a deepwater gas well as an example, the temperature distribution and hydrate formation area distribution characteristics along the wellbore are analyzed. The study shows the following: the increase of heavy gas hydrocarbons and hydrogen sulfide content, the decrease of formation water mineralization degree, and the decrease of condensate oil content will promote hydrate formation; alcohol is a better choice as a hydrate inhibitor for deepwater operation; properly increasing the gas–liquid flow rate and increasing the ratio of liquid to gas, the use of high salinity completion liquid will help to reduce the risk of hydrate formation in the process of well cleanup stage. This work can help to reduce the cost of operations while ensuring the security of the deepwater gas testing.

Virtual Special Issue of Recent Research Advances in China: Unconventional Gas

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