Production forecasting of gas condensate well considering fluid phase behavior in the reservoir and wellbore Juntai Shi a, * , Liang Huang a , Xiangfang Li a , Kamy Sepehrnoori b a MOE Key Laboratory of Petroleum Engineering, China University of Petroleum at Beijing, Beijing 102249, PR China b The University of Texas at Austin, Austin, TX 78712, USA article info Article history: Received 19 November 2014 Received in revised form 20 March 2015 Accepted 22 March 2015 Available online Keywords: Gas condensate wells Deliverability equations Fluid phase behavior Wellbore Pseudo-pressure function Two phase flow abstract Retrograde condensation occurs when the reservoir pressure falls below the dew point pressure in gas condensate reservoirs. Complex fluid phase behavior in the reservoir and the wellbore makes it chal- lenging to predict the productivity of gas condensate wells. To date, the gas rate in the deliverability equation of gas well is assumed the gas rate at surface condition converted from that at the reservoir condition by using the volume factor. However, because of the complex fluid phase behavior in gas condensate wells, the gas rate at the reservoir condition cannot be directly changed to that at surface condition by using volume factor. Hence, the development of a new analytical model to accurately calculate the productivity of gas condensate wells is still required and necessary. In this work, we propose a new deliverability equation of gas condensate wells with a consideration of fluid phase behavior in both the reservoir and the wellbore. Also, several pseudo-pressure functions for different condensate distribution and flow models are examined systematically; these include the model before condensation, the model after condensation, but without condensate flow, the model after condensation and with condensate flow, and the model after re-vaporization. Two synthetic numerical simulation cases and two field case studies are performed to validate these deliverability equations for gas condensate wells. Results show that the phase behavior of gas condensate fluid in the wellbore plays a significant role in the deliverability evaluation and in the forecasting of gas condensate wells. If neglecting its effect on the deliverability, gas and condensate production rates could not be accurately predicted. The data from the proposed model have good agreement with the simulation and field production data of wells in Yakela Gas Condensate Reservoir and Yaha Gas Condensate Reservoir in China. If the conventional deliverability equation neglecting the effect of phase behavior in the wellbore was used, the predicted gas production will be higher than the actual value; even 50% higher than the actual value at high flow rates. Through these case studies, it can be concluded that the effect of condensate-gas phase behavior in the wellbore cannot be ignored in the deliverability equation for gas condensate wells. This work can provide a more accurate method of forecasting the gas and condensate production for condensate gas reservoirs and also guide optimization of single well production rate and gas recovery rate for gas condensate reservoirs. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Gas condensate reservoir is a special complex reservoir. In the production process, the condensate liquid will retrograde, gradu- ally accumulate, and then form condensate blocking in the vicinity of wellbore after the bottom-hole flowing pressure (BHFP) has dropped below the dew point pressure (Muskat and Meres, 1936; Fevang and Whitson, 1995; Whitson et al., 1999; Henderson et al., 2000). The condensate blocking would decrease the productivity of gas condensate well. Many researchers have proposed different types of deliverability equations for gas condensate wells, which can be summarized into four types: the deliverability equation for conventional gas wells (Houpeurt, 1959; Rawlins and Schellhardt, 1935) in which the gas flow rate is assumed the sum of pure gas flow rate and condensate converted gas flow rate (Li, 2008; Shi * Corresponding author. E-mail address: juntai.shi@gmail.com (J. Shi). Contents lists available at ScienceDirect Journal of Natural Gas Science and Engineering journal homepage: www.elsevier.com/locate/jngse http://dx.doi.org/10.1016/j.jngse.2015.03.033 1875-5100/© 2015 Elsevier B.V. All rights reserved. Journal of Natural Gas Science and Engineering 24 (2015) 279e290