Performance Productivity Curves in Geothermal Systems: A Case of Los Humeros, MÈxico

Abstract

The mechanisms that have a direct influence on geothermal well productivity, are mainly associated with physicochemical characteristics of the reservoir fluids and/or materials. Among these, the chemical composition of the fluids, the physical structures of the formation, such as faults and fractures, the permeability, are some of the parameters that dominate the flow of fluids from the reservoir to the wellbore. The productivity of the wells is a result of the reservoir energy, which in turn is influenced by the characteristics of the media where it is located.
The Los Humeros geothermal field, located in the Mexican Neo-Volcanic belt is a typical example of a reservoir of volcanic origin. In this field it has been identified that the reservoir physical structures have a direct effect on the overall behavior of the wells. More specifically, those wells that are located within the block limited by the same faults, behave in a particular way, and this behavior differs substantially from another wells located in a different block formation that has another faults as boundaries.
It has also been identified that the behavior of the output or IPR curves and their corresponding productivity indices is correlated with among other parameters: The production time, the decline ratio, the formation permeability and corresponding damage, the reservoir thickness and areal extent.
The high drop pressure in relation with the mass production is correlated with some formation damage. So, it affects to decline ratio and productivity indices. The main effect is the flow restriction by obstruction of permeable channels in the rock matrix.
In this work we analyze the productivity of some wells located at the central portion of the Los Humeros, MÈxico geothermal field. The behavior of their IPR curves at early production time, lead us to confirm the influence of geological structures over the productivity behavior in the different systems.