| Abstract |
This work presents a brief description of the architecture and scope of the wellbore simulator SIMU2000. Its prime application involves the representation of the different flow types and thermodynamic conditions found in geothermal wells. The simulator utilizes a homogeneous flow model that incorporates the fundamental theories of Fluid Mechanics. It allows the handling of two-phase three component mixtures (H2O-NaCl-CO2), which represent the main constituents appearing in the production of geothermal fluids. SIMU2000 uses a new two-phase friction factor developed based on 64 production tests carried out on 45 different wells. More than 324 pressure drop data and 628 temperature measurements were recovered from wells. Mechanical log recorders (Kuster) were mainly used but some electronic logs (Hot Hole and Pruett) were also carried out. The friction factor is calculated using the Reynolds number, steam quality, and fluid pressure, therefore, it is independent of any flow pattern identification. Production data included specific enthalpies from 650 to 2780 kJ/kg, fluid pressures between 0.4 and 14 MPa, and fluid temperatures from 110 to 340 ?C. The computer code of SIMU2000 is written in Fortran 90 and generates an executable file a little bit greater than 1 Mb. This program is divided in four parts: the wellbore simulator; a graphical output to analyze the results on the screen; a separate subroutine to evaluate the mass flow rate of three component flows discharging to the atmosphere at the speed of sound; and a dialog box to calculate the thermodynamic state of a three component mixture for manual calculations. The code incorporated an efficient algorithm to solve the fluid transport phenomena, based on a numerical method of successive approaches. The simulator systematically uses the International System of Units, for data input and for output generation. Everything is realized into a friendly Windows 95 environment for the user. Up to date, SIMU2000 has been applied on multiple wells covering a broad extent of thermal conditions. Results obtained through its use have been good enough from the engineering point of view. Nevertheless, updating of the simulator is not only a continuous task with the purpose of improving the simulator performance, but also looking for extending its application field. |