Abstract: An apparatus and method for controlling the pressure at which a fluid is introduced into a well penetrating a subterranean formation. The apparatus comprises a blow out sub having a sealed chamber between two plugs. The chamber is filled with a fluid at a known pressure. Thus, the pressure required to release the first plug is independent of the pressure in the well below the sub. The sub is attached to a tubular and positioned within the well. The first plug is then released upon application of a predetermined pressure fluid pressure, and the second plug is released upon application of a lesser pressure. The blow out sub may additionally comprise a tube forming a channel through the first plug, the chamber, and the second plug, with a means for controlling fluid flow through the channel. A first fluid may be introduced into the well via the channel prior to releasing the first plug.

Abstract: A wellbore operation in which a downhole tool is given rotary motion without rotating the tubing string to which it is attached. A "Yankee screwdriver" type of connecting element is used to connect a downhole tool to a tubing string so that compressive forces acting on the connector as a result of relative linear movement between the connector and the tool cause the tool to rotate. A number of various types of downhole operations are possible, such as rotating a tool away from an obstruction and retrieving the upper section of a lost tubing string.

Abstract: An inflatable packer assembly for use in a subterranean well bore to isolate an interval of the well bore and/or adjacent subterranean formation for treatment. The assembly comprises a hanger assembly, a fluid piston assembly and at least one inflatable packer. As constructed and positioned in the well bore, the hanger assembly and fluid piston assembly are sufficiently distant from the interval to be treated to inhibit being stuck in the well bore. By lowering and raising the tubing or drill string from which the inflatable packer assembly is suspended, the fluid piston assembly pumps well bore fluid into and from the packer to respectively inflate and deflate the packer. In this manner, the packer can be repeatedly inflated, deflated and repositioned within a well bore to treat successive intervals of the well bore.

Abstract: Method and apparatus for introducing treatment fluid into a subterranean formation by use of a reverse jet pump located in a bypass of a tubing string. A plug in the tubing between the inlet and outlet of the bypass forces production fluid to flow through the bypass. When operation of the jet pump is terminated treatment fluid introduced into the tubing string causes a sleeve to slide down over the inlet and outlet, isolating the bypass. The plug is then forced out the tubing, leaving a clear path for the treatment fluid down the tubing and out the casing perforations into the formation. This arrangement enables rapid changeover from pumping formation fluid to introducing treatment fluid.

Abstract: Means for lifting formation fluid to the surface in a drill stem test. The drill string has first openings allowing entry of formation fluid and upwardly spaced second openings which are normally closed by a sleeve slidably mounted on the drill string. Fluid pressure from within the drill string impinges on a transverse surface of the sleeve and forces it down, allowing treatment fluid to enter the drill string from the annulus between the drill string and the well bore. A jet pump comprised of a flow constriction creating a venturi effect causes treatment fluid to accelerate upwardly in the drill string, the circulation of the treatment fluid drawing the formation fluid to the surface. The second openings covered by the sleeve include the fluid crossover of the jet pump. A standing valve in the drill string between the first and second openings allows down hole shut-in and pressure build-up tests.