Depressurization system of annuli between casings in producing wells

Abstract

A depressurization system for the annular spaces ( 3 ) between casings in the drilling activity for wells producing oil or other fluids, so as to guarantee effective hydraulic communication between the pressurized annular space ( 3 ) and the base of the exposed rock zone ( 4 ) to be broken during depressurization, which has the solid deposit with the consequent hydraulic isolation. The system is made up of a flow control device ( 11 ); a conveyance pipe ( 12 ) between two points of the annular space ( 3 ); and an isolation device ( 13 ) linked to a centralizer in the shallow casing string ( 1 ), allowing the pressurized fluid outlet and the well wall to be close together, whereby the system used will not become clogged with solid deposits over time during the sinking of these well casings.

1 . Depressurization system of annuli between casings in producing wells, characterized by being an effective communication system between the pressurized annular space ( 3 ) and the exposed rock zone ( 4 ) to be broken during depressurization. 
   
   
       2 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by being a passive system driven by the natural increase in pressure promoted by the increase in temperature of the confined liquid and carried out at the end of any pumping operation. 
   
   
       3 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by the installation of this system being performed simultaneously with the drilling and completion activities, in which the deepest casing string ( 5 ) is put in place. 
   
   
       4 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by maintaining the internal pressure of the annular space ( 3 ), comprised between the deepest casing string ( 5 ) to be protected from failure due to collapse and the shallow casing string ( 1 ) (previously installed) below the pressure limit determined to cause collapse of the casing. 
   
   
       5 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by promoting a depressurization of the annular space ( 3 ) by hydraulic communication between the pressurized zone ( 9 ) and the exposed rock zone ( 4 ), and of draining of this pressure by absorbing different volumes of fluids (liquids and/or gaseous) by a rock of any type of formation which high pressure of fluid will promote the injection of said fluid restrained on that annular space ( 3 ). 
   
   
       6 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by having a flow control device ( 11  ); a conveyance pipe ( 12 ) between two points of the annular space ( 3 ); and an isolation device ( 13 ) linked to a centralizer in the shallow casing string ( 1 ), allowing the pressurized fluid outlet and the well wall to be close together. 
   
   
       7 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by using a flow control device ( 11 ) installed on the most shallow end of the hydraulic conveyance system to impede the entrance of fluid into the interior of the conveyance pipe ( 12 ). 
   
   
       8 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by the linked isolation device ( 13 ) having a retention value or shear valve, similar to that used on the flow control device ( 11 ), located at a lower end of the system positioned close to the well wall. 
   
   
       9 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by the density of the fluid inside the system being lower than that of the external fluid, resulting in the internal pressure being greater than the external pressure and the inside of the pipe being filled with a special fluid that does not allow solids to precipitate. 
   
   
       10 . Depressurization system of annuli between casings in producing wells, in accordance with  claim 1 , characterized by this system being installed laterally and externally to the deepest casing string ( 5 ) and being fastened to it by metal straps, by brackets made for this purpose or by any other fastening system.