the disclosure provides a valve for an annulus defined between a tubular work string or other conduit and a surrounding annular portion of an operative element disposed on production string , such as a safety valve . the annulus valve comprises an annular valve body , which may comprise an elastomeric mass , which is urged by resilient means into sealing engagement with the exterior of the tubular work string and is shiftable out of such sealing engagement , such as by an annular piston which is responsive to control fluid pressure . the same control fluid pressure may be utilized to operate the safety valve to its open position .