Importance

Loading Importance Indicators...

Abstract

A method and apparatus for use in the oil well industry for running in drilling/production liners and sub-sea casings down a borehole through drilling fluid on a drill pipe using a running tool with the benefits of surge pressure reduction are disclosed. In accordance with the present invention, a surge pressure reduction tool includes a diverter device having a housing with a set of flow holes formed therein and a sliding sleeve residing within the housing having a set of flow ports formed therein. By aligning the set of flow holes of the housing with the set of flow ports of the sleeve, the tool is set in a 'surge pressure reduction' mode. By shifting, or axially indexing, the sleeve downward, the set of flow holes is blocked by the sleeve thus setting the tool in a 'cementing' or 'circulation' mode. This shifting or indexing is accomplished using an indexing mechanism. The indexing mechanism of the present invention includes a spring ring which is initially compressed and set in a circumferential groove formed around the top of the sleeve. As the sleeve is shifted downward from surge reduction mode to cementing/circulation mode, the spring ring decompresses radially outward to engage a circumferential groove formed in the housing. This effectively locks the sliding sleeve in the cementing/circulation mode. In accordance with the present invention, a surge pressure reduction tool further includes a volume compensation device which enables the diverter device to be shifted axially downward into the cementing/circulation mode even where the drilling/production liner or sub-sea casing is plugged with drill cuttings or downhole debris. In the cementing/circulation mode, a flow path is established for cement or drilling fluid to flow downward from the drill pipe, through the diverter device, volume compensation device, and running tool, and out into the borehole via the drilling/production liner or sub-sea casing. In the surge pressure reduction mode, an alternative flow path is established for drilling fluid to flow upward from the borehole into the drilling/production liner or sub-sea casing, through the running tool and volume compensation device, and into an annular space between the drill pipe and the borehole via the set of flow holes of the diverter device.

Loading the Abstract Image...

First Claim