Andergauge Limited

Ronnie Hardie

Alan Martyn Eddison

Downhole flow pulsing apparatus comprises a housing ( ) for location in a drillstring, the housing ( ) defining a throughbore to permit passage of fluid through the housing. A valve ( ) is located in the bore and defines a flow passage ( ). The valve includes a valve member ( ) which is movable to vary the area of the passage ( ) to provide a varying fluid flow therethrough. A fluid actuated positive displacement motor ( ) is associated with the valve member ( ). In a preferred embodiment, the apparatus is provided in combination with a drill bit ( ) and a pressure responsive device, such as a shock-sub ( ), which expands or retracts in response to the varying drilling fluid pressure created by the varying flow passage area. The expansion or retraction of the shock-sub ( ) provides a percussive effect at the drill bit.

Downhole apparatus and method of use

A percussion drill has a tubular fluid transmitting body with a drill bit mounted on a drill bit support itself mounted in body via a spring and salines A mass is spring mounted in the body and is movable to impact on a face of the support Mounted to the mass is a rotating valve comprising two valve plates Each plate defines a slot such that rotation of one of the valve plates relative to the other moves the slots into and out of alignment; the change in alignment of the slots alters the flow of drilling fluid through the valve so altering the drilling fluid pressure force acting on the mass so causing mass to push against the spring and impact on the drill bit support providing a percussive act ion at the drill bit

Percussive tool

Downhole flow pulsing apparatus comprises a housing (,) for location in a drillstring, the housing (,) defining a throughbore to permit passage of fluid through the housing. A valve (,) is located in the bore and defines a flow passage (,). The valve includes a valve member (,) which is movable to vary the area of the passage (,) to provide a varying fluid flow therethrough. A fluid actuated positive displacement motor (,) is associated with the valve member (,). In a preferred embodiment, the apparatus is provided in combination with a drill bit (,) and a pressure responsive device, such as a shock-sub (,), which expands or retracts in response to the varying drilling fluid pressure created by the varying flow passage area. The expansion or retraction of the shock-sub (,) provides a percussive effect at the drill bit.

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Portlethen, United Kingdom

Ronnie Hardie