LAUSR

Abstract A robust reservoir surveillance program is key to successful management of a steamflood operation and accurate measurement and proper interpretation of temperature surveys is essential for such a surveillance program. The objective of this study was to look at factors that can impact a temperature log by performing an extensive analysis of field data, primarily gathered from a single company's steamflood operations in California, from over 1000 temperature observation wells. Additionally, a simple analytical assessment was performed to understand the role of key dominating mechanisms and to gain directional insight. Field data and analytical assessment suggest that higher logging speeds introduce greater error in measured temperature data and these errors are greater at elevated steamchest temperatures. Temperature tools with longer sensor response times need to be run at lower logging speeds to get accurate measurements. Ensuring an adequate level of thermally equilibrated liquid (typically water) in the observation well is essential both, for gathering accurate data and to mitigate possible safety concerns for the logging operator. Several field examples are presented to illustrate the effects of logging speed, steamchest temperature, sensor type, and wellbore fluid on recorded temperature data. Guidance on evaluating and interpreting different temperature signatures such as interpretation of liquid level in an observation well, understanding temperature signatures in air, wellbore reflux phenomenon, and examples of logs from malfunctioning logging tools, are also provided. The main purpose of this work is to aid both the operators and the service companies to gather accurate temperature data for improved steamflood management and for all investigators using thermal operation temperature data to understand how and where that data might be compromised.