Abstract: A prepack well screen assembly for separating particulate material from formation fluid has inner and outer screens concentrically mounted in radially spaced relation around a perforated mandrel, thereby defining a prepack annulus in which a plurality of spherical plastic members are disposed. The concentric inner screen includes longitudinally extending rib wires spaced circumferentially around the mandrel, and a screen wire wrapped externally about the rib wires in a longitudinally spaced pattern to define spaced screen apertures for conducting formation fluids through the inner screen. The outer screen is a cylindrical fluid-porous, particulate-restricting member which is radially spaced from the inner screen to form the prepack annulus. The particulate-restricting member includes rib wires which are spaced circumferentially around the inner screen within the prepack annulus, and an outer screen wire wrapped externally about the rib wires to define the annulus.

Abstract: A prepack well screen assembly has a resistance welded outer screen concentrically mounted in radially spaced relation on a perforated mandrel, thereby defining an annulus in which a sintered metal prepack sleeve is loaded. The longitudinal spacing distance between adjacent turns of the outer screen selectively exclude sand fines of a predetermined minimum size. The porosity of the sintered metal prepack sleeve is selected to pass sand fines in the size range of from about 10 microns to about 150 microns. The effective inlet flow area through the sintered metal prepack sleeve is substantially greater than the effective inlet flow area through the outer screen. The sintered metal prepack screen excludes sand fines from inflowing formation fluid during the initial production phase following a gravel pack operation, without limiting production of formation fluid.

Abstract: An inflatable stimulation tool designed to be deployed by coil tubing having a shuttle valve which reciprocates within the bore of a tubular mandrel. The shuttle valve, in cooperation with a reciprocally movable outer mandrel which is disposed about an inner mandrel, opens and closes various ports in the device to alternately seal and unseal the inflatable packer element. The shuttle valve also operates to open and close a flow passage through the inner mandrel to permit the passage of various stimulation fluids through the tool and into the well bore.Upon deflation of the inflatable packing means, which leaves the packing means in a somewhat distended state, the element is urged to its original close relationship with the mandrel by a return spring which cooperates with the lower tool structure to which one end of the rubber packing element is clamped to longitudinally stretch the element.