Pressure actuated ported sub for subterranean cement completions

摘要

A shifting sleeve has differential piston areas so that applied pressure displaces the sleeve against spring bias, which preferably is a series of Belleville washer stacks associated with modular mandrel components, to obtain the desired opposing force to the movement initiated with pressure applied to differential piston areas. An indexing feature is located between the sleeve and the mandrel passage wall and on a predetermined number of cycles disables the Belleville washer stacks from biasing the sleeve in an opposed direction as when pressure is applied. At this time the pressure in the mandrel acting on the differential piston area simply shifts the sleeve to open a lateral port so that fracturing through the cement that was earlier placed with the port closed can take place.

主权项

1. A method of cementing and subsequent fracturing comprising:
cementing through an open sleeve assembly defining a passage therethrough in a ported sub with at least one lateral port closed by said sleeve assembly; using predetermined number of cycles of applied and removed pressure in said passage through said sleeve to shift said sleeve assembly away from said lateral port with said applied cyclic pressure being lower than a first predetermined pressure previously applied in said sleeve assembly after said cementing; fracturing through said now open lateral port.