Abstract
Downhole temperature is a parameter of great importance when designing and testing cement slurries and other temperature dependent fluids. A set of recommendations has been published to determine downhole temperature. However, in the strictest sense, these recommendations are only applicable within a narrow set of well conditions. Recently, the industry practice has been to use mathematical simulation to estimate downhole temperature when well conditions fall outside the parameters given in this set of recommendations.
Accurate temperature estimates provide the best test parameters to be used during the qualification of mixtures under simulated downhole conditions. A lack of accurate data could result in premature or delayed cement setting. Both of these phenomena are unwelcome consequences that can result from failing to accurately estimate downhole temperature. It is therefore important to use a tool that best simulates downhole conditions. It is ideal if the results from mathematical simulation are validated using physical measurements. This paper documents how downhole temperature during fluid circulation was physically measured using temperature sensors and was then compared to mathematical simulations.
Multiple case histories are discussed, wherein both simulated and measured temperature were validated to provide improved accuracy of downhole temperature. This led to improved design, laboratory testing, and field implementation. Historical data are presented, demonstrating the importance of accurate temperature predictions. An overview is provided to include a historical review of methods used to estimate downhole temperature gradients and the benefits and potential drawbacks of available gradient tables. A review is presented comparing computational output with data obtained from measurement sensors, resulting in improved accuracy of predictive output. Improved gradient prediction methods are presented to help enable improved laboratory testing to be performed on temperature activated slurries.
The use of downhole temperature gages has been limited in deepwater applications. This paper introduces equipment designed specifically for deepwater applications, data collected, and comparative analysis with conventional mathematical models. The authors believe the material presented will be of interest to society membership.
