A combined linear and sinusoidal empirical model for shale gas wellhead pressure and production rates considering fluctuations in gas–water flow

Abstract

The relationship between wellhead pressure and gas–water flow rate is an important research topic. Nevertheless, a comprehensive theoretical model has not been developed mainly due to complicated field conditions. Finding data-driven models is therefore another crucial direction of research. Despite the development of data-driven models, existing models are not exhaustive. The main disadvantage of the conventional Gilbert model is that it can be used only when both gas and water are produced. Whereas in shale gas production, it is common that only gas or water is produced. To tackle these problems, this study proposes a different type of empirical model considering choke cross-sectional area, volume factors of gas and water, and nonlinearity apart from gas and water rates. In comparison, the Gilbert model only considers choke diameter. The improvements allow the proposed model to only require the existence of one of gas and water, thus expanding the application scope of Gilbert’s model. The applications using field data from 49 shale gas wells indicate the proposed model has the best accuracy among all models compared. The derivation of the proposed model benefits both theoretical and data-driven studies on the relationship between wellhead pressure and gas–water flow rate for hydrocarbon production wells.

Keywords:

• Choke size
• Gilbert model
• shale gas production
• two-phase flow
• wellhead pressure

Disclosure statement

The authors report there are no competing interests to declare.

Data availability statement

The authors do not have permission to share the data.

Additional information

Funding

This work was supported by the Fourteenth Five-Year Major Science and Technology Project of CNPC under Grant No. 2021DJ1505; National Natural Science Foundation of China under Grant No. 12272217.