TEMLOPI: a thermal simulator for estimation of drilling mud and formation temperatures during drilling of geothermal wells

Abstract

This paper describes the development and application of the numerical code TEMLOPI v1.0, a useful tool for estimating the temperature distribution of the fluids employed for drilling geothermal wells. The simulator also allows estimation of the thermal disturbance of the surrounding rock caused by fluid circulation and well shut-in. TEMLOPI v1.0 is based on a mathematical model which considers the main heat transfer mechanisms and the heat exchange between the circulating fluid and the surrounding rock formation that occur during drilling of geothermal wells. The simulator was written in Fortran 77 using modular (block) programming. It runs on most IBM compatible personal computers and can be used in-situ. Input data includes the well geometry, the fluid and flow characteristics and the initial (undisturbed) formation temperature. Output files contain the transient temperature distribution (temperature vs depth) in the fluid flowing down the drill pipe and the annulus, the well inner face and the radial distribution in the surrounding rock. The software code model, architecture, input and output files and the solution algorithm are described in detail. Results obtained were validated by comparison with data published in the specialized literature and with data from well Az-29 from the Los Azufres Mexican geothermal field.