Open Access

ARTICLE

Temperature and Pressure Profiles during Prolonged Working Fluid Injection in Wellbores: Mechanisms and Key Influencing Factors

Yu Sang¹, Anqi Du¹, Changqing Ye¹, Jianhua Xiang¹, Yi Chen¹, Yazhou Guo², Le Shen^3,*

1 Engineering Technology Research Institute of PetroChina Southwest Oil & Gasfield Company, Chengdu, 610017, China
2Erlian Branch of Huabei Oilfield Company, CNPC, Xilinhaote, 026000, China
3 State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China

* Corresponding Author: Le Shen. Email:

(This article belongs to the Special Issue: Fluid and Thermal Dynamics in the Development of Unconventional Resources III)

Fluid Dynamics & Materials Processing 2025, 21(7), 1623-1639. https://doi.org/10.32604/fdmp.2025.065832

Received 22 March 2025; Accepted 18 June 2025; Issue published 31 July 2025

Abstract

In the context of the global “Carbon Peaking and Carbon Neutrality” initiative, the injection of carbon dioxide (CO₂) into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequestration while enhancing hydrocarbon recovery. However, variations in injection parameters at the wellhead can exert pronounced effects on the temperature and pressure conditions at the bottom of the well. These variations, in turn, influence the geomechanical behavior of reservoir rocks and the displacement efficiency of CO₂ within the formation. Precise prediction of downhole thermodynamic conditions is therefore essential for optimizing injection performance and ensuring reservoir stability. To address this need, the present study develops a robust coupled model to simulate the behavior of CO₂ within the wellbore, incorporating momentum conservation, mass continuity, and steady-state heat transfer equations. Validation against field-measured data confirms the model’s reliability and applicability under real-world operating conditions. Parametric analysis reveals the complex influence of injection conditions on bottom-hole states. Injection pressure primarily affects downhole pressure, exerting minimal influence on temperature. In contrast, low injection temperatures and elevated flow rates lead to reduced bottom-hole temperatures and heightened pressures. Owing to the interplay of convective and conductive heat transfer mechanisms, the relationship between injection rate and bottom-hole temperature exhibits nonlinearity. Notably, injection scenarios characterized by low temperature, high pressure, and high velocity promote a deeper penetration of the CO₂ critical phase transition point within the tubing. Among the parameters examined, injection temperature emerges as the dominant factor affecting the depth of CO₂’s phase transformation, followed by injection rate, with pressure exerting the least influence. A strong correlation is observed between injection rate and the depth of the critical phase transition, offering a practical framework for tailoring injection strategies to enhance both CO₂ storage capacity and recovery efficiency.

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Keywords

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