High flow, tubing insensitive, deep set wireline retrievable safety valve

A valve system for use downhole in a wellbore, comprising:

• a tubing retrievable safety valve (TRSV) disposed downhole in the wellbore, the TRSV
• including at least a TRSV balance line and a TRSV control line;
• and a secondary safety valve to be positioned within the TRSV, the secondary safety valve comprising:
• a valve body having a valve seat at a downhole end;
• a piston;
• a rod coupled with a downhole end of the piston and with a closure mechanism configured to engage the valve seat when the secondary safety valve is in a closed position;
• a control line;
• a balance line;
• a first pressure communication port, to communicatively couple the balance line of the secondary safety valve with the TRSV balance line;
• and
• a second pressure communication port, to communicatively couple the control line of the secondary safety valve with the TRSV control line, wherein, the control line of the secondary safety valve is directly coupled to the TRSV control line by a first seal and the balance line of the secondary safety valve is directly coupled with the TRSV balance line by a second seal, and the control line of the secondary safety valve is configured to actuate the secondary safety valve between an open position and the closed position in response to an intentional pressure change in the TRSV control line, and the balance line of the secondary safety valve is configured to use hydrostatic pressure through the balance line to compensate for hydrostatic pressure acting on the TRSV control line, with the first seal and the second seal enabling equal pressure throughout the secondary safety valve so there is no pressure differential across the secondary safety valve.

A method for controlling fluid flow downhole in a wellbore, comprising:

• positioning a tubing retrievable safety valve (TRSV) disposed downhole in the wellbore, the TRSV including at least:
• an open bore therethrough;
• a balance line of the TRSV;
• and a control line of the TRSV;
• installing a control communication port to the control line of the TRSV into the TRSV;
• installing a balance communication port to the balance line of the TRSV into the TRSV;
• positioning a secondary safety valve into the open bore within the TRSV and positioning the secondary safety valve into a locating profile in an inner diameter of the TRSV, the secondary safety valve comprising:
• a valve body having a valve seat at a downhole end;
• a piston;
• a rod coupled with a downhole end of the piston and with a closure mechanism configured to engage the valve seat when the safety valve is in a closed position;
• a control line of the secondary safety valve;
• a balance line of the secondary safety valve;
• a first pressure communication port, to communicatively couple the balance line of the secondary safety valve to the balance line of the TRSV;
• and
• a second pressure communication port, to communicatively couple the control line of the secondary safety valve to the control line of the TRSV, wherein, the control line of the secondary safety valve is directly coupled to the TRSV control line by a first seal and the balance line of the secondary safety valve is directly coupled with the TRSV balance line by a second seal, and the control line of the secondary safety valve is configured to actuate the secondary safety valve between an open position and the closed position in response to an intentional pressure change in the TRSV control line, and the balance line of the secondary safety valve is configured to use hydrostatic pressure through the balance line to compensate for hydrostatic pressure acting on the TRSV control line, with the first seal and the second seal enabling equal pressure throughout the secondary safety valve so there is no pressure differential across the secondary safety valve.