Title: Study on the wellbore flow and phase transition during formation H₂S invasion

Authors: Liangbin Dou; Gensheng Li; Zhonghou Shen; Zhongwei Huang; Xianzhi Song

Addresses: China University of Petroleum, 18 Fuxue Road, Changping, Beijing, 102249, China ' China University of Petroleum, 18 Fuxue Road, Changping, Beijing, 102249, China ' China University of Petroleum, 18 Fuxue Road, Changping, Beijing, 102249, China ' China University of Petroleum, 18 Fuxue Road, Changping, Beijing, 102249, China ' China University of Petroleum, 18 Fuxue Road, Changping, Beijing, 102249, China

Abstract: Considering the special physical properties of hydrogen sulphide (H₂S) and its phase transition in the wellbore, a mathematical model for wellbore flow and heat transfer during formation H₂S invasion was established. Heat transfer and pressure were calculated along with H₂S physical properties parameters, and a solution method of the model was proposed. The results indicate that liquid H₂S transforms into gas state during its rising process in the annulus when choke pressure is low; the flow above phase transition point is two-phase flow while the flow below phase transition point is single-phase flow in the annulus. The paper exhibits the results and the reasons of the bottom-hole pressure and the depth of phase transition varying with different H₂S influx rate, injection rate, choke pressure, and land surface temperature. The study is of certain significance for improving the safety during the exploration of acidic oil and gas reservoirs. [Received: February 21, 2012; Accepted: June 10, 2012]

Keywords: H2S invasion; hydrogen sulphide; well control; wellbore flow; heat transfer; phase transition; bottom-hole pressure; BHP; mathematical modelling; influx rate; injection rate; choke pressure; land surface temperature; drilling safety; acidic oil and gas reservoirs; natural gas.

DOI: 10.1504/IJOGCT.2013.056666

International Journal of Oil, Gas and Coal Technology, 2013 Vol.6 No.6, pp.658 - 674

Received: 23 Feb 2012
Accepted: 10 Jun 2012
Published online: 29 Jan 2014 *

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