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Application of a Silica Gel as a Chemical Packer for Isolation in Horizontal Refracs

IP.com Disclosure Number: IPCOM000248664D
Publication Date: 2016-Dec-22
Document File: 5 page(s) / 219K

Publishing Venue

The IP.com Prior Art Database

Abstract

Refracturing is becoming more prevalent in the oil and gas industry. It is believed that many existing vertical and horizontal wells that have been hydraulically fractured over the years may have been under stimulated during their initial completions. Technologies and processes have evolved overtime. As a result, there is a potential to gain access to bypassed reserves that were missed during initial completions. There are essentially two general isolation methods utilized for stimulation: mechanical isolation and diversion. Mechanical isolation can involve the use of packers, sleeves and/or liners to separate existing perforations from new perforations and direct the stimulation treatment to the new perforation clusters. Diversion typically employs the use biodegradable or dissolvable materials to transfer fluid, pressure and energy from one fracture to another during hydraulic fracturing. This process is designed to be utilized in refracturing situations where mechanical isolation would be the preferable isolation method. It utilizes a silica based gel as a chemical packer in conjunction with mechanical isolation, typically a liner or casing string placed inside the existing refrac well.

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Application of a Silica Gel as a Chemical Packer for Isolation in Horizontal Refracs

Abstract

Refracturing is becoming more prevalent in the oil and gas industry. It is believed that many existing vertical and horizontal wells that have been hydraulically fractured over the years may have been under stimulated during their initial completions. Technologies and processes have evolved overtime. As a result, there is a potential to gain access to bypassed reserves that were missed during initial completions. There are essentially two general isolation methods utilized for stimulation: mechanical isolation and diversion. Mechanical isolation can involve the use of packers, sleeves and/or liners to separate existing perforations from new perforations and direct the stimulation treatment to the new perforation clusters. Diversion typically employs the use biodegradable or dissolvable materials to transfer fluid, pressure and energy from one fracture to another during hydraulic fracturing. This process is designed to be utilized in refracturing situations where mechanical isolation would be the preferable isolation method. It utilizes a silica based gel as a chemical packer in conjunction with mechanical isolation, typically a liner or casing string placed inside the existing refrac well.

Summary

The combination of a liner or casing string placed in a previously stimulated wellbore and a silica based gel chemical packer is meant to accomplish several objectives during refracturing. Restimulation operations often times involve the re-perforating of refrac candidate wells. In order for these new perforations to be effectively stimulated, there needs to be effective isolation between those new perforations and the older perforations from the original completion. With this process, the re-perforating will be done through both the inside liner/casing and the outside casing (figure 1). Liner placement in the existing wellbore will provide isolation in the form of a frictional pressure drop across the annular space between the liner and the outside casing. With this pressure restriction, the proppant laden fluid will have a higher tendency the flow through the new perforations in the inner liner/casing and outside casing. It should be noted that perforating of the inner liner/casing and outside casing will typically be done simultaneously after liner/casing and chemical packer placement (perforate through the inner liner/casing and outer casing with the same charge). In theory, the perforating can be done in two phases as well. The outer casing can be perforated before inner liner/casing and chemical packer placement and then the inner liner/casing can be perforated after the placement of liner/casing and chemical packer.

Because the annular frictional pressure drop may not be enough to provide complete isolation between the old and new perforations, a chemical packer will be placed in the annulus of the outer wellbore and the inner liner/casing string. Pl...