Sucker-rod artificial lift is one of the methods to lift hydrocarbons from a well to the surface, when the natural pressure from the reservoir cannot guarantee free flow. Presently, on the Oil and Gas market there is no downhole safety valve capable of closing and sealing on a reciprocating sucker rod string. This paper shows the design of an innovative Insert Sucker Rod Surface Controlled Sub Surface Safety Valve (ISRSCSSV) [2] capable of closing and sealing on a 1" sucker rod body, protecting the environment from spills due to uncontrolled blow out that may occur during the phases of oil production.
The ISRSCSSV [2] is composed of the following main sections: external housing, piston flow tube, sealing pads. The fail-safe design criteria implies that the ISRSCSSV [2] is normally closed, the pressure from the control line drives the piston flow tube connected to the sealing pads to the safety valve open position. The innovation resides in a variable geometry sealing mechanism, able to shut in the annular area between the 1" sucker rod and the valve external housing. The sealing path is composed of a segmented tapered pads system located at the end of the elastic fingers, travelling along a cone housing.
The ISRSCSSV [2] is interchangeable with a WRSCSSV, but, its installation and retrieving procedures collides with the insert rod pump anchor installation/retrieving procedure, so, an innovative insert rod pump was designed (Hybrid Pump) so that after installation through the sucker rod string, it acts as a tubing pump.
The uniqueness of this fail-safe safety valve is in the fact that it can be run downhole with the same sucker rod pumping string.
The ISRSCSSV [2] combined with the Hybrid Pump determines a new approach for retrofitting existing wells completed for spontaneous flow without costly workover interventions, representing a first fundamental step towards the application of the dual barrier policy on production wells.
Economic advantages: the innovation described, allows to recover a quantity of oil from marginal wells no longer having the energy to produce in free flowing, bringing more oil on the market at a sustainable production cost.
The first safety valve prototypes have been made and tested on a custom-built test bench and using a pilot well equipped to simulate real working conditions, initial results are very promising: tests of the sealing mechanism on the 1" rod have shown 0 leakage both with water and with nitrogen.
