PDVSA has being operating a Steam Assisted Gravity Drainage (SAGD) process[I1] since 1997, as part of a pilot test carried out in the T a Juana Field, Western Venezuela.
This paper focuses on issues concerning the first step to obtain controllability and observability of the SAGD process taking into account heat distribution, heat management and evolution of steam chamber, at each time, for an efficient reservoir drainage.
Main issues concerning observability are pursued with the installation of subsurface sensors such as discrete pressure and temperature, as well as a fiber optic distributed temperature system. Experiences in PDVSA show that a little portion of the steam chamber can be observed and extrapolated to emerging analytical or numerical related models. In the other hand, issues concerning controllability can be inferred from observing patterns derived from process behavior, coming from direct measurements at bottomhole or from well testing analysis at surface.
General discussion on controllability and observability will be addressed giving particular ideas over experiences in PDVSA, exploring other ways to attack these two issues as for example using microseismic downhole sensors for steam chamber development and incorporating artificial intelligence in control algorithms to manage the process.