Detection of Water or Gas Entries in Horizontal Wells From Temperature Profiles

Abstract

Abstract The temperature profiles in a horizontal oil-producing well can be measured precisely with distributed temperature sensors, which are being increasingly installed in intelligent well completions. With temperature resolution on the order of 0.1 °F, modern temperature-measuring instruments can detect small temperature changes along the wellbore that can indicate the locations of water or gas entries into an oil well. These temperature changes are primarily caused by differences in Joule-Thomson effects for each phase (oil, water, and gas) caused by the pressure drop in the well. In this paper, we illustrate a specific condition for which water entry locations can be identified from the temperature profile of a horizontal well. The criterion for such discrimination is that a measurable change in the slope of the temperature profile occurs at the water entry location. Using a numerical model of temperature and pressure in the reservoir and the wellbore, we calculate time-varying temperature profiles for a bottom water drive reservoir. In these calculations, one section of the well was experiencing a large flow rate, while the rest of the open section of the well produced oil at a smaller rate. We varied the production rate and types of oil to see their effects on the temperature profiles. From these sensitivity studies, we identified the relative water production rates that create identifiable temperature anomalies in the temperature profile along a horizontal well. The results confirm the utility of temperature profiles in identifying water or gas entries if the well rate is large.