Annular Frac Point (19-Jan-2010)
For oilfield completions where it is desirable to hydraulically fracture multiple zones, existing completions technologies have required the use of multiple trips into the well or else leave an ID restriction. The severity of ID restrictions typically are proportional to the number of zones the system requires separate treatment for. The disclosed apparatus allows for the frac treatment of multiple zones in a single trip without introducing any further restrictions. Procedurally, the operator will run one completion string for all zones. The first step would be to set a packer above and frac the bottom zone as is well known to those familiar in the art. For the second and subsequent zones, a sliding sleeve will be actuated by applying a first annulus pressure between the tubing string and the casing or open hole. Without dropping below the first actuation pressure, a second annular actuation pressure will be achieved to hydraulically set a packer above the zone. Once the packer is set, pressure will bleed off below an opening pressure at which point a biasing member on the sliding sleeve would be able to overcome the piston force acting from the annular pressure in order to open the sleeve. The frac can then be initiated by pumping through the tubing string. For each subsequent zone the first and second annular actuation pressure must be higher than the previous actuation pressures to avoid premature setting. Alternatively the sleeves and/or packers could be timed for opening after a given number of pressure cycles.
49022
For oilfield completions where it is desirable to hydraulically fracture multiple zones, existing completions technologies have required the use of multiple trips into the well or else leave an ID restriction. The severity of ID restrictions typically are proportional to the number of zones the system requires separate treatment for. The disclosed apparatus allows for the frac treatment of multiple zones in a single trip without introducing any further restrictions. Procedurally, the operator will run one completion string for all zones. The first step would be to set a packer above and frac the bottom zone as is well known to those familiar in the art. For the second and subsequent zones, a sliding sleeve will be actuated by applying a first annulus pressure between the tubing string and the casing or open hole. Without dropping below the first actuation pressure, a second annular actuation pressure will be achieved to hydraulically set a packer above the zone. Once the packer is set, pressure will bleed off below an opening pressure at which point a biasing member on the sliding sleeve would be able to overcome the piston force acting from the annular pressure in order to open the sleeve. The frac can then be initiated by pumping through the tubing string. For each subsequent zone the first and second annular actuation pressure must be higher than the previous actuation pressures to avoid prematu...
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