DOWNHOLE DRAG REDUCTION APPARATUS

A downhole drag reducing apparatus (18) comprises a mandrel (20) and a bearing sleeve (24) mounted on the mandrel (20), such that the mandrel (20) and bearing sleeve (24) are rotatable relative to each other. The bearing sleeve (24) defines a bore wall engaging surface. The apparatus (18) comprises...

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Bibliographische Detailangaben
1. Verfasser:	MOYES, Peter Barnes
Format:	Patent
Sprache:	eng
Schlagworte:	EARTH DRILLING EARTH DRILLING, e.g. DEEP DRILLING FIXED CONSTRUCTIONS MINING OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS
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Beschreibung
Zusammenfassung:	A downhole drag reducing apparatus (18) comprises a mandrel (20) and a bearing sleeve (24) mounted on the mandrel (20), such that the mandrel (20) and bearing sleeve (24) are rotatable relative to each other. The bearing sleeve (24) defines a bore wall engaging surface. The apparatus (18) comprises a reciprocating piston (23) mounted within a piston housing (25) to define a piston chamber (27). The apparatus (18) further comprises a rotary valve assembly (29) operated by relative rotation between the mandrel (20) and the bearing sleeve (24) to cyclically pressurise and depressurise the piston chamber (27) to provide reciprocating movement of the reciprocating piston 23 and the generation of vibration within the apparatus (18).