Abstract: Disclosed is a method of inserting and removing tubular valves into and from the secondary bore of a mandral having a main bore and a laterally offset secondary bore. The method includes the steps of positioning a whipstock plug having a sloping upper surface in the main bore and orienting the whipstock plug such that the upper surface slopes toward the secondary bore. The valves are removed by deflecting a retrieving tool off the upper surface of the whipstock plug to engage and remove the tubular valve from the secondary bore. The valves are inserted by deflecting the valve off the upper surface and into the secondary bore. After removal or insertion of a valve, the whipstock plug is removed from the main bore.

Abstract: Disclosed are a subsurface safety system and a method of inserting into or removing from an offset bore of a mandrel a tubular valve. The system includes an entry mandrel having a full bore outlet, a full bore primary inlet and a laterally offset full bore secondary inlet. A full bore primary tubing extends downwardly from the primary inlet to a formation. A full bore secondary vent tubing is connected to the secondary inlet and extends down the hole generally parallel to the primary tubing and includes an open lower end positioned in the annulus above the formation. A dual packer is provided in the system between the entry mandrel and the lower end of the secondary tubing. The secondary tubing includes a vent above the packer and the upper end of the secondary tubing is normally closed by a removable plug. Subsurface safety valves are provided in both the primary and secondary tubings. The subsurface safety valve in the secondary tubing is positioned between the open lower end and the vent.