Wellbore flow field of coiled tubing drilling with supercritical carbon dioxide

Weiqiang Song, Hongjian Ni, Ruihe Wang and Mengyun Zhao

Greenhouse Gases: Science and Technology, 2017, vol. 7, issue 4, 745-755

Abstract: To achieve better well control for supercritical carbon dioxide drilling, a mathematical model was presented to investigate the pressure and temperature profile in both the tubing and the annulus. The closed model fully couples the hydraulics, heat transfer, and compressibility of carbon dioxide, and then the wellbore flow field is presented and analyzed based on field application. The results show that the pressure change of carbon dioxide is 36.7% smaller than that of water along the annulus in the study case. Carbon dioxide changes into supercritical state when the depth equals 700 m ∼830 m in the tubing, and it could maintain in supercritical state in the whole annulus. Both the pressure profile and the temperature profile are highly coupled with the physical properties of carbon dioxide. The density of carbon dioxide is large enough to drive downhole motors and its capacity is much larger than that of air in the wellbore. The pressure increases lightly with increasing mass flow rate in the annulus; however, it is significantly and positively impacted by the outlet pressure. The influence of outlet pressure on temperature profile is negligible in the tubing. The inlet temperature could not impact the pressure profile in the annulus, and its influence on temperature profile mainly lies in the shallow section of the tubing. It is newly validated that supercritical carbon dioxide drilling is more suitable for the exploitation of unconventional reservoirs with narrow pressure windows. The results could lay a theoretical foundation for practical application. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

Date: 2017
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Persistent link: https://EconPapers.repec.org/RePEc:wly:greenh:v:7:y:2017:i:4:p:745-755

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