The SAGD process has been utilized for the past 15 years and an efficient steam utilization process provides the best solution to reducing the variable production costs and to increasing the recovery rate. The use of real time downhole monitoring is an effective approach to achieve this optimization. The main objective of steam injection is to decrease the oil viscosity, so it can flow through the horizontal and the vertical sections.
The emergence of downhole distributed sensing (DTS) and array temperature sensing with fiber optics technology has led to instrumented wells allowing operators to access data on a real time basis leading to a better control of the operations and the ability to optimize the steam process. Additionally, fiber optics technology allows for the measurement of pressure and temperature on same fiber and in close proximity along the wellbore. In the ultra-high temperature environment the amount of pressure monitoring points are limited and many SAGD operators are asking for at least 3 pressure in-conjunction with the distributed temperature points.
The SAGD process has a number of different variables that are dynamic and complex and changing with time. The most important variables of the process include the steam injection rates, subcool and downhole pressure and temperature. One of the key objectives when using the SAGD process is to reduce the SOR to lower the high cost of steam generation. The optimization of the SOR is a process of reducing the steam injection rate and/or increasing the oil production. Since SAGD is a dynamic process this can only be achieved through the use of Real Time Optimization.
Once the steam reduces the viscosity and mobility of the oil is achieved, the SAGD well production can be optimize using the nodal analysis technique meaning that an Inflow (very dependent with temperature & viscosity) will be calculated and optimized but it is also necessary at same time to calculate the outflow which is dependent on the type and optimization of artificial lift system that is used. The integration of different measured points of pressure and temperature (40 points of temperature and 2 pressure points) using fiber optic technology along the horizontal section of the producer well with other parameters like wellhead pressures, temperatures and mainly production rates will allow for the optimization of the SAGD Process and better management of the well.
This paper will describe in detail the processes that are required to be controlled and the main variables that are needed to be measured and calculate to optimize the oil production on a SAGD well.