Downhole valve tool and method of use

A tubular isolation valve comprising:

• an outer tubular body adapted to attach to a work string, the outer tubular body having an axial through bore, said through bore having a reduced diameter portion defining a valve seat and a ledge;
• and
• an inner sleeve, located within the bore of the outer tubular body, and having a closed end configured to seal within the valve seat, and a shoulder spaced from that closed end, and having a radial outlet in the sleeve positioned between the shoulder and the closed end;
• wherein in use the inner sleeve is selectively moveable within the bore relative to the outer tubular body between a closed position, in which said closed end is in sealing abutment with the valve seat, and the shoulder is spaced from the ledge, and there is no flowpath through the bore of the outer tubular body, and an open position, in which the shoulder is in abutment with the ledge, and the closed end is positioned beyond the valve seat to expose the radial outlet to the throughbore beyond the valve seat, whereby the tubular isolation valve provides a flowpath through the bore of the outer tubular body, and wherein said inner sleeve is moveable at a predetermined pressure.

A method of testing the integrity of a seal between a liner top and a casing string of a wellbore, comprising the steps of:

• providing a tubular string including a tubular isolation valve and a settable liner test tool including a packer;
• running the tubular string into the wellbore with the tubular isolation valve in a closed position in which there is no flowpath through the bore of the tubular isolation valve;
• closing the annulus of the wellbore between the tubular string and the casing or liner to allow the seal to be tested;
• and
• pressurising annulus above the seal to be tested using a fluid, and using pressure developed in the annulus to open the isolation valve and establish a flowpath through the tubular into the annulus below the seal to be tested.