The Wellbore Simulator FloWell - Model Enhancement and Verification

Abstract

Since the geothermal industry began, numerous geothermal models have been developed. The simulator FloWell, developed at the University of Iceland in 2012, is a wellbore simulator designed to model liquid, two-phase and superheated steam flows in geothermal wells. FloWell is based on empirical correlations combined with conservation of mass, momentum and energy. It is user-friendly, computationally inexpensive and it has been coupled with the reservoir model TOUGH2 with good results. Now it is being incorporated into iTOUGH2 to enable direct use of wellhead production data for model calibration. In order to thrive in the fast developing industry and stay up-to-date, it is vital that the development of model based design methodologies, and operational decision tools as FloWell, is a continuous process. This paper discusses the enhancement and further verification of FloWell. During first development some general assumptions were made for simplification, such that simulations were restricted to wells with single feedzone and single diameter. In this paper the feasibility and implementation of adding these features to FloWell is discussed. Furthermore, the possibility of integrating curves for the well head valve is analyzed. Such integration allows for simulations with FloWell to be compared to pressure measurements taken before and after the valve. An inverse analysis with iTOUGH2-PEST is performed for parameter estimation in FloWell in order to assess which factors have the most impact during wellbore simulations. A parameter sensitivity analysis in FloWell follows the inverse analysis as well as an evaluation on measurement uncertainty in wellbores.