Unlimited Downhole Fracture Zone System

Abstract

Apparatus and method are provided for diverting treatment fluids in wells. Sliding sleeves or valves are sequentially opened by dropping balls that may be of uniform size. Opening of one valve moves a collet into position such that the same size ball can be used to open a second valve. Any selected number of valves can be opened with the same size balls. Systems using the valves are also disclosed, along with methods for operating.

Description

BACKGROUND OF INVENTION[0001]1. Field of the Invention[0002]This invention pertains to a system for injecting treatment fluids into a selected isolated interval in an oil and gas well. More particularly, valves disposed along a tubular are opened sequentially by pumping balls of one size down the tubular, causing one valve to open and another valve mechanism to be moved into position to be opened by a following ball.[0003]2. Description of Related Art[0004]Treatment fluids, such as hydraulic fracturing or acidizing fluids, are often used to treat multiple zones or segments of the earth penetrated by a wellbore. It is usually preferable to treat each zone or segment individually and to divert the treating fluid to another zone or segment when a designed amount of treating fluid has been injected into a zone or segment. In vertical wells, different zones of a producing formation are normally treated individually. In the horizontal wellbore portion of “horizontal wells,” different segm...

AI Technical Summary

Benefits of technology

[0009]The invention overcomes many of the above noted deficiencies with the prior art. A single size ball is employed which allows for a larger diameter production tube to be employed. This increases production compared to the prior art which requires sequentially smaller diameter balls and tubing. Since all the balls are of the same size, the possibility of mis-ordering the balls is eliminated and consequently accidental isolation of fracturing zones is eliminated, as is the requirement for post-fracturing drilling operations to remove the ball seats. Also, since the balls are of a uniform size and there is no need to reduce the diameter of the ball seats, an unlimited number of fracturing zones or intervals can be isolated and treated for a given well.

Problems solved by technology

The use of sequentially smaller ball seats on sleeves within the well results in a limited number of unique seats for a given tubing size and in a limited number of unique zones for a fracture project.

This results in reduced production from the lower zones and frequently requires post-fracturing drilling operations to remove the seats.

This requires a complicated ball launching system for balls of varying diameter and opens up the possibility of mis-ordering the balls, which would then unintentionally block off a given zone.

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