A fluidic oscillator is disclosed for providing oscillating flow to outlet ports (172, 173). The fluid oscillator (100) in one embodiment has no fluid communication between a pair of diverging diffuser legs (163, 164) downstream of the upstream edge (169) of a splitter (165) and no fluid communication between a chamber (162) and either of the diverging diffuser legs downstream of the splitter edge. In other embodiments, a turbulent flows generator is formed by use of bump step (202), pins (220, 230), surface discontinuities (250) or a combination thereof.

A fluid accelerating and pulsation generating apparatus for minimizing loss in fluid energy through frictional pressure drop for fluid passing through the apparatus is characterized by a body having a generally cylindrical chamber formed by a cylindrical inner wall and opposed transverse end walls. One of the end walls has one or more fluid inlet ports arranged therein and defined by passages which intersect the end wall at an angle with respect to a plane normal to the central longitudinal axis of the chamber and generally tangentially with respect to the cylindrical inner wall. Plural discharge passages intersect the opposite end wall at a curved wall portion formed between the cylindrical inner wall and the opposite end wall. The discharge passages may also be arranged to have their axes extending tangentially with respect to the inner cylindrical wall and at a predetermined angle with respect to a plane normal to the central longitudinal axis of the chamber. Pulsation generating ball members may be disposed in the chamber and engageable with the curved wall portion to momentarily cover the discharge passages as the ball members are propelled by spiral fluid flow through the chamber. The apparatus minimizes fluid pressure losses for fluid flowing therethrough and is operable to generate pulsed flow. The apparatus may be used as a fluid mixing and application device, for jet blast cleaning, material removal, and in wellbore operations for wellbore cleanout, fluid flow inducement and improved well drilling.

An apparatus and method for selectively stimulating a plurality of producing zones of an openhole wellbore in oil and gas wells in one trip. The assembly includes a plurality of modules connected in a tailpipe wherein the modules can be selectively actuated to conduct a matrix acidizing job and near wellbore erosion job on producing zones of interest in the wellbore. Each module includes a sleeve shiftable between a closed position and a treating position where a plurality of jet passageways are exposed to the central passageway of the assembly.

A tool for discharging pressurized fluids into a wellbore at high velocity to clean foreign matter from the wellbore. The tool includes an elongated, cylindrical body having an upper end that is threaded for attachment to a fluid supply conduit and a lower end that is circumferentially tapered to a narrowed, planar surface. A fluid entry channel is located in the upper end of the cylindrical body. In communication with the fluid entry channel are a pair of fluid discharge channels which terminate in a pair of fluid discharge ports. Each of the fluid discharge ports is positioned adjacent the narrowed, planar surface at the lower, circumferentially-tapered end of the cylindrical body.

A method and apparatus for improving reservoir communication includes, in one arrangement, use of one or more chambers to create an underbalance condition and/or a fluid surge in the wellbore. In another arrangement, a tool string comprises a packer, a circulating valve, and an atmospheric chamber, in which the circulating valve, when open, is adapted to vent a lower wellbore region below the packer when the packer is set, and the atmospheric chamber is capable of being operated to create an underbalance condition below the packer. In yet another arrangement, an apparatus comprises a subsea wellhead equipment including a blow-out preventer, choke line filled with a low density fluid, and a kill line filled with a heavy fluid. The choke line is adapted to be opened to create an underbalance condition in the wellbore. In yet another arrangement, a method of creating an underbalance condition comprises controlling wellbore pressure at least in a perforating interval to achieve a target level, configuring a perforating gun to achieve a target detonation pressure in the perforating gun upon detonation, and creating an underbalance condition in the perforating interval of the wellbore when the perforating gun is shot. In yet another arrangement, a tool string for use in a wellbore extending from a well surface comprises a closure member adapted to be positioned below the well surface, and a chamber defined at least in part by the closure member. The tool string further comprises at least a port selectively openable to enable communication between the chamber and a wellbore region. The port when open creates a fluid surging to the chamber to provide a low pressure condition in the wellbore region. A tool in the tool string is adapted to perform an operation in the low pressure condition.