Abstract: Apparatuses and methods for generating fluid pressure pulses are disclosed. An example apparatus may include a chamber that can collect fluid and an upstream ported disc coupled to a downstream end of the chamber. The upstream ported disc may rotate about a central axis. The upstream ported disc includes an upstream eccentric port that rotates about the central axis as the upstream ported disc rotates. The example apparatus may include a downstream ported disc coupled to a downstream end of the upstream ported disc such that the downstream ported disc remains substantially rotationally fixed relative to the upstream ported disc. The downstream ported disc includes a downstream eccentric port that may align with the upstream eccentric port to form a passageway for fluid to exit from the chamber to outside of the apparatus, at some time in a rotation cycle of the upstream ported disc.

Abstract: The present invention is directed to an apparatus and method for reverse circulation cementing a casing in an open-hole wellbore. The apparatus includes a surface pack-off device, which has a housing defined by an upper section and lower section. A load bearing plate is secured to the housing between the upper and lower sections. The load plate and lower section of the housing cooperate to prevent sloughing of the earth at the surface of the wellbore via a section of casing string. The surface pack-off device also includes a casing hanger, which couples to the casing in the wellbore. Fluid inlets allow the cement to be pumped into the wellbore in the annulus formed between the casing and wellbore sidewall. The method includes the steps of installing the surface pack-off device and operation on reverse circulation of the cement down the annulus.

Abstract: A system for cementing a casing in an open wellbore having no surface casing, wherein an annulus is defined between the casing and the wellbore, the system having: an annular plug around the casing at the mouth of the wellbore; a cement composition pump fluidly connected to the annulus through the seal; and a coupling connected to the exposed end of the casing for taking circulation fluid returns from the inner diameter of the casing.

Abstract: A back pressure valve assembly for use in a well casing string. The valve assembly comprises a housing with a stationary and a floating plate therein. The floating plate is moveable between an open position spaced from the stationary plate and a closed position engaging the stationary plate. Fluid flow downwardly through the valve assembly tends to move the floating plate toward the open position, and fluid flow upwardly through the valve assembly tends to move the floating plate toward the closed position. A finger or key may be used to prevent rotation of the floating plate with respect to the housing.

Abstract: The present invention is directed to a removable surface pack-off device adapted for use in reverse cementing applications. The device includes a housing adapted to be mounted between the ends of an inner casing and an outer casing at or near the surface of a well and at least one fluid passage disposed within the housing, which is adapted to pass fluid, such as cement, from a location outside of the well into an annulus formed between the inner and outer casings. It also includes a first pressure-activated seal disposed between the inner casing and the housing and a second pressure-activated seal disposed between the outer casing and the housing. The device further includes an attachment assembly, which enables the device to be easily removed from the well.

Abstract: The present invention is directed to plugs, plug systems and methods for using the plugs and systems in subterranean wells. The plugs comprise an inner mandrel and an outer sleeve formed of a compressible foam. The plug systems include an assembly comprising a top plug and a bottom plug having foam outer sleeves. The plug systems further comprise a float valve into which the assembly fits. In the method, the bottom plug is deployed ahead of the top plug to separate a second fluid from a first fluid and wipe the inside of the pipe string clean of the first fluid. The top plug is used to wipe the inside of the pipe string clean of the second fluid and stop the displacement of the second fluid into the annulus between the casing string and the well bore.