In reservoirs with a gas drive production mechanism, as the down hole pressure drops below the bubble point, gas breaks out of solution, and depending on the gas to oil ratio (GOR), the performance of oil wells with different artificial lift pumping systems installed are directly affected by the presence of free gas in the fluid. As a result, pump volumetric efficiency decreases reducing production, affecting the life cycle of the pump, and increasing costs due to the need of rig intervention for installing gas separators, or different assemblies for gas handling devices such as charge, tapered or two stage pumps in order to improve this volumetric efficiency.
Two newer systems for handling gas at the surface have been applied in high GOR wells in the heavy and extra heavy oil wells of Eastern Venezuela. The first system consists of implementing a closed loop device for controlling the pressure of the annular of a well to an optimal pressure value. The control algorithm based on techniques from expert systems has been applied successfully in several wells. Basically, when the pressure of casing is being controlled by an automated pressure control valve set at an optimum value, it causes a variation of the dynamic fluids reducing the amount of free gas in the annular space and pump.
The second system consists of a PCP (progressive cavity pump) device that measures fluid load through a load cell installed at the drive head of the surface equipment and detect variation in dynamic fluid, torque and motor load and surface pressure of the flow line are also recorded, and adjust the velocity of the pump with the variable frequency drive controlled by an expert system, which runs in a programmable logic controller developed for optimizing PCP. All these two systems have improved production and run life in more than 20% in different wells in which have been evaluated.