Effect of Pressure and Temperature on Petrophysieal Characteristics in the Case of Carbonate Reservoirs

摘要

The effect of temperature on petrophysical properties reduction might be one of the main reasons in the failure of thermal enhanced oil recovery pilot tests. The temperature and pressure changes constitute the fundamental elements in controlling fluid circulation. Thus, the conducted study is aimed to investigate this statement in the context of carbonate reservoirs and their petrophysical characteristics. Intensive runs of flooding experiments were performed using carbonate samples from Middle East reservoirs at different effective pressures up to 4000 psi (276 bar) and temperatures reaching 100 °C to investigate fluid circulation behavior. In addition a tex-tural examination of the carbonate samples was conducted using an ordinary microscope and scanning electron microscope (SEM). Results indicated that permeability reduction increases gradually with increasing pressure and temperature. It was found that a permeability reduction of 50% was recorded at temperatures above 50 °C compared with the initial permeability at 25 °C. Furthermore, the permeability reduction reached 59% at an effective pressure of 4000 psi at 100 °C compared to initial permeability at 725 psi (50 bar) and at 25 °C. According to the overall results, the effect of temperature on permeability reduction in the applied carbonate samples is as important as that of the effective pressure. The reduction phenomenon can be explained by the process of packing and compaction leading to rock deformation. In addition, and based on the textural analysis, no formation damage was noticed, and permeability reduction occurred at the applied conditions was reversible.