Pumpable seat assembly and use for well completion

Abstract

An assembly and process for fracturing, stimulating and producing a wellbore having a plurality of oil or gas producing zones is provided comprising introducing into the well the pumpable seat assembly comprising a generally cylindrical tube having an outer diameter and an inner diameter with an upper end forming a ball seat; setting the pumpable seat assembly below an oil or gas producing zone to be produced; introducing a dissolvable ball into the well, said dissolvable ball having a sufficiently large enough outer circumference so that it can sit on the ball seat and temporarily restrict a flow of fluids to the portion of the wellbore located below the pumpable seat assembly; and fracturing the oil and gas producing zone to stimulate oil or gas production; whereby the biodegradable ball is configured to dissolve within a predetermined period of time so that when it dissolves any oil or gas produced from zones below the pumpable seat assembly can flow through the cylindrical tube.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to the field of vertical and horizontal well completion, and, more particularly, to a process for fracturing, stimulating and producing a wellbore without having to mill out and remove fracturing / bridge plugs and to a pumpable seat assembly for use with said process.BACKGROUND OF THE INVENTION[0002]Oil and gas well are drilled to a depth in order to intersect a series of formations or zones which produce hydrocarbons. Often the drilled wells are cased with steel casing pipe and cemented to secure the casing in place. Hence, it is necessary to create a flow path from these cased producing zones to the surface of the wellbore. This is generally accomplished by stimulation processes such as fracturing using water, various chemicals and / or proppants. However, the steel and cement barrier needs to be first perforated with shaped explosive charges prior to fracturing the surrounding oil or gas reservoir.[0003]Depending on...

AI Technical Summary

Benefits of technology

[0021]a dissolvable ball having a sufficiently large enough outer circumference so that it can sit on the ball seat and temporarily restrict a flow of fluids to the portion of the wellbore located below the pumpable seat assembly.

Problems solved by technology

Unfortunately, once all of the zones have been stimulated, these temporary plugs may prevent the flow of oil or gas to the surface.

However, there are operational risks associated with this process and, further, this is a time consuming and costly procedure.

Furthermore, it has been found that frac plugs having even a minimal amount of steel are difficult to drill during removal and can damage the drill bit.

Coil tubing or jointed pipe intervention to mill out and remove the plugs on extended reach wells, e.g. lateral length exceeding 2500 m, is extremely costly, unpredictable and sometimes impossible due to metal to metal friction encountered sliding in the casing, creating what is known as coil tubing lock-up.

In some cases operations are exposed to such risks as sticking the coil tubing or bottom-hole assembly (BHA) in the well, resulting in fishing operations for pipe recovery.

Fishing operations can cost an operating company millions of dollars depending on difficulty and risk, in extreme cases wellbore have been lost due to fishing operations and associated costs.

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