A new model for predicting pressure traverse in two phase flow geothermal well

Abstract

The complexity associated with the two phase or multiphase flow system have been a long-time challenge in the modelling of the flowing pressure in the production channel which includes geothermal well. The flow of hot water and its vapour ensued all throughout the geothermal system producing from the reservoir source to the wellbore and later to the surface. The performance of geothermal system is primarily dependent on the ability to accurately predict the flowing pressure in the production well. Several models derived from the fundamental thermodynamic energy equation to handle the complexity of two-phase flow in geothermal well have demonstrated diverse discrepancy when compared with real time measurement. It has been conceived in the study that the inclusion of pressure drop due to accumulation in the thermodynamic energy equation reduces the discrepancy between the predicted pressure and the field measurement. It is pertinent to the geothermal energy industry to assess the accurate model that consider all constituent terms that impact the two-phase flow behaviour in a geothermal production well. A more exact numerical model for evaluating the flowing pressure in geothermal has been derived in this study where the right constituent terms that practically impact the two-phase flow behaviour in a geothermal vertical well are considered. The present model has the capacity to predict flowing pressure accurately as the flow transit from one regime to another. Likewise, the present model was able to capture the transient period that usually occurs when the geothermal well is put to production. The present model was validated using data from KE1-22 and Mesa 6-1 wells reported in literature. The present model gave the least mean absolute relative error of 0.033 when applied to measured field data from KE1-22 Well while Hassan and Kabir, Ansari, Orkiszewski and Homogenous models gave errors of 0.12, 0.33, 0.41 and 0.38 respectively. Similarly, relative to data from Mesa 6-1 the present model gave a mean absolute relative error of 0.052 while Hassan and Kabir, Ansari, Orkiszewski and Homogenous models gave errors of 0.17, 1.46, 1.37 and 2.53 respectively. The newly derived model is reliable for assessing the performance of the geothermal system and evaluating flowing pressure at every difference transition period.