A Coupled Wellbore-Reservoir Simulator utilizing Measured Wellhead Conditions

• Main Author: Halldóra Guðmundsdóttir 1987-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2012
• Subjects: Vélaverkfræði; Borholur; Líkön; Jarðhitakerfi; Hermun; Reykjanes; Iceland
• Online Access: http://hdl.handle.net/1946/13219

Modeling a geothermal system requires simulating the behavior of a reservoir and the flow in production wells, which is usually done individually. The main objective in this study is to develop a coupled wellbore-reservoir simulator to allow for more integrated modeling and to use wellhead conditions to a greater extent than has been done so far by defining them as main inputs to the coupled model. The program TOUGH2 is used to simulate the behavior of a reservoir while a new model, FloWell, is designed to simulate two phase flow in a wellbore. Finally, a detailed numerical model of the Reykjanes geothermal field in Iceland including the coupled FloWell-TOUGH2 model is constructed. FloWell produced simulations in good agreement with pressure logs from wells at Reykjanes and Svartsengi geothermal fields. An inverse estimation with iTOUGH2 was effective in estimating new permeabilities for the Reykjanes reservoir, providing a reasonable match for the natural state of the reservoir as well as the observed pressure drawdown. Predicting the response of Reykjanes reservoir in 2012-2027, for a production to maintain 150 MWe power generation with 77.8 kg/s injection, caused the mass being removed at a higher rate than physically possible. Increasing the injection to 220 kg/s resulted in a semi-stable pressure and after 15 years of simulation a total of 18 bar drawdown in pressure was detected in the center of the reservoir and 12 bar at the boundaries. The coupling procedure suggested in this study, with measured wellhead conditions as main inputs, yielded reasonable results for the Reykjanes geothermal field. Therefore, after further validation, the simulator might prove to be a useful tool in future assessments of geothermal resources, both in Iceland and worldwide. Þegar líkan af jarðhitageymi er útbúið er reynt að herma bæði flæði í jarðhitageymi og borholum, venjulega hvort í sínu lagi. Meginmarkmið þessa verkefnis er að þróa líkan þar sem flæði í jarðhitageymi og borholum er hermt í samfelldri keyrslu. Með því ...