Key parameters forecast model of injector wellbores during the dual-well sagd process

Abstract

Based on parameters forecast model of conventional horizontal injector wellbore, combined with coupling calculation of dual-tubing steam mass flow, the mass conservation equation, energy conservation equation and momentum conservation equation of steam flow within injector wellbore under different tubing combinations in preheating and production phases are formulated and the key parameters calculation model of dual-tubing injector wellbore is established. The temperature and pressure along the injector wellbore during the steam-assisted gravity drainage (SAGD) preheating phase of a SAGD well are calculated and compared with the downhole monitored data, which shows good match and verifies the accuracy of the model. Meanwhile, the model calculates that the minimal steam injection rate during SAGD preheating phase is 60 t/d, the longest horizontal length is 564 m under current configuration. Considering the current configuration has disadvantages of two sections of steam imbibition that may result in risk of section/point steam breakthrough at Point A during SAGD production phase, the combination of long tubing and short tubing is optimized: the short tubing is relocated 150 m from Point A and long tubing is located at Point B. Consequently, three sections of steam imbibition could be realized, and the risk of section/point steam breakthrough at Point A is effectively reduced. Key words: dual horizontal wells, SAGD, parallel-tubing, wellbore, temperature, steam quality, pressure