Reservoir heterogeneity and inter-reservoir communication due to fracturing pose major challenges for our industry in terms of reservoir characterization and fluid flow modeling. Improved understanding and representation of their role in static and dynamic models is becoming a pivotal component for effective field management. Normally, multiple sources of both static and dynamic information are integrated to generate models used to simulate reservoir performance in order to identify optimal practices for efficient production and recovery.
This paper presents a thorough reservoir study focused on the investigation of the use of temperature measurements to inform on fluid flow within and between reservoirs. The study addresses mainly the communication that exists in the reservoir beyond the well-bore, attributed to fracture corridors and faults. The interpretation of temperature measurements are integrated with other sources of dynamic and static information such as open-hole logs, production profiles, fluid losses, and pressure transient analysis. The study area covers a portion of an oil field that has been under peripheral water flooding for more than 30 years, producing mainly from the upper of the two reservoir units. As expected, the injected cold water imposes a significant variation in temperature profile across the reservoir which helps to describe the flood performance and understand the underlying geology. Additionally, we found that the rate of change of temperature with respect to time over the entire area shows that increasing temperatures are correlated with locations showing high structural relief. Our existing mapping shows these areas as being more densely fractured, with high fluid flow capacity. The coincidence of these factors with the temperature anomalies we observed strongly suggests that the faults and fractures in these areas may be responsible for mass and heat transfers between the two reservoirs.
The outcomes of this study are used to optimize development and production plans such as balancing the off-take between high-structure and down-dip areas to prevent undesired water flood advances. They are also fully integrated with other sources of information to construct geological and flow simulation models in order to assess sweep performance and recovery estimation.