Abstract: An internal blowout preventer assembly having a central through-bore and flapper valve. The flapper valve permits fluid flow in a downward direction, but not the opposite (upward) direction. A retrievable tubular lockout sleeve can be conveyed via wireline, coiled tubing or other similar means and installed within the through-bore of the internal blowout preventer assembly. Once installed, the lockout sleeve prevents the flapper valve from closing, thereby permitting wireline or other concentric operations to be performed (as well as upward fluid flow) though the internal blowout preventer.