Degradable Fluid Sealing Compositions Having an Adjustable Degradation Rate and Methods for Use Thereof

Abstract

When performing subterranean treatment operations, it can be desirable to temporarily divert or block fluid flow by forming a degradable fluid seal. Methods for forming a degradable fluid seal can comprise: providing a sealing composition comprising: a degradable polymer, and a water-soluble material comprising a first portion and a second portion of rigid particulates, each portion having a sealing time and a particulate size distribution associated therewith, the particulate size distributions of the first portion and the second portion differing from one another; determining an amount of the first portion relative to the second portion needed to produce a degradable fluid seal having a desired sealing time that is different than that of the sealing time of either the first portion or the second portion; introducing the sealing composition into a subterranean formation; and allowing the sealing composition to form a degradable fluid seal in the subterranean formation.

Description

BACKGROUND[0001]The present disclosure relates to methods and compositions for fluid blocking and diversion in subterranean formations, and, more specifically, to treatment operations that form a temporary fluid seal in a subterranean formation.[0002]Treatment fluids can be used in a variety of subterranean operations. Such subterranean operations can include, without limitation, drilling operations, stimulation operations, production operations, remediation operations, sand control treatments and the like. As used herein, the terms “treat,”“treatment,” and “treating” refer to any subterranean operation that uses a fluid in conjunction with achieving a desired function and / or for a desired purpose. Use of these terms does not imply any particular action by the treatment fluid. Illustrative treatment operations can include, for example, fracturing operations, gravel packing operations, acidizing treatments, scale dissolution and removal, consolidation treatments, and the like.[0003]W...

AI Technical Summary

Benefits of technology

This patent provides a method for creating a degradable fluid seal in a subterranean formation. The method involves using a sealing composition made of particulate matter and a water-soluble material. The water-soluble material is made of rigid particles that have a specific size distribution. The size distribution of these particles is different from that of similar particles that are not sized. By controlling the size distribution of the rigid particles, the sealing composition can be designed to have a desired sealing time. The sealing composition is then introduced into the subterranean formation where it forms a degradable fluid seal. This seal can then be used to perform various treatment operations on the formation while it is still intact. Finally, the seal can be allowed to degrade naturally. Overall, this method allows for a more effective and efficient way of creating a degradable seal in subterranean formations.

Problems solved by technology

Fluid loss can be problematic in a number of subterranean operations including, for example, drilling operations, fracturing operations, acidizing operations, gravel-packing operations, workover operations, chemical treatment operations, wellbore clean-out operations, and the like.

In fracturing operations, for example, fluid loss into the formation matrix can sometimes result in incomplete fracture propagation.

Use of an external degradant in a separate cleanup operation can add to the time and expense needed to produce a fluid from the subterranean formation.

In other cases, a fluid seal may comprise a substance that is natively unstable, such that the fluid seal degrades and / or dissolves over time to allow fluid flow to resume.

When relying on the native degradation rate of a fluid seal, undesirably slow degradation can again add to the time and expense of production operations.

Polymer gels formed using such crosslinking agents have proven unsuitable at higher temperatures (e.g., above about 80° C.) due to uncontrolled crosslinking rates (e.g., short gel-times), crosslinking agent precipitation, polymer degradation, and the like.

In addition, chromium and certain other transition metal ions can have an undesirable environmental impact.

As the formation permeability increases, gelled acrylamide-containing polymers can become less effective due to their reduced ability to block larger pore throats that can be characteristic of higher permeability formations.

For example, above about 0.1 D, and particularly above about 0.5 D, gelled acrylamide-containing polymers may be less effective for blocking or diverting fluid flow at normal formation operating temperatures and pressures.

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