The Use of Inflatable Packers

Gain an understanding of the versatile tools that can aid in a variety of tasks.

By Thom Hanna, PG, and Nick Hemenway

Inflatable packers are critical tools in the water well industry, providing essential functionality for tasks like well testing, zonal isolation, well completion, and hydrofracturing (hydrofracking). Their versatility and effectiveness in varying geologic conditions make them indispensable for professionals in this field.

I asked a good friend of mine, Nick Hemenway with Baski Inc., to coauthor this column with me as he has more experience with inflatable packers than anyone I know. This column explores the various applications, benefits, and operational principles of inflatable packers with a special focus on their role in contaminant hydrogeologic investigations and hydrofracturing.

Introduction

Figure 1. Components of an inflatable packer.

Inflatable packers are devices used to isolate sections of a borehole or well casing. They consist of a cylindrical body with an expandable rubber element that can be inflated to seal the annular space between the packer and the borehole wall or the well casing.

Packers are available in a wide variety of diameters, lengths, expansion ratios, materials, and pressure ratings. The inflation mechanism typically involves the use of fluids or gases that expand the packer’s rubber element, creating a seal. This sealing capability is essential for various operations in well construction and maintenance—including testing, isolation, and remediation tasks.

For packers used in high-pressure or high-expansion applications, a sliding-end style of packer is typically used in which the bottom end of the packer slides up and down the center mandrel as it is inflated and deflated (Figure 1). These packers are typically deployed on a short-term basis for tasks such as hydrofracturing, sampling, or grouting.

In other applications such as zone isolation that have lower pressure requirements and may be permanently installed in the well, a fixed-end style of packer is typically selected, which eliminates the need for sliding seals, allows for more corrosion-resistant materials, and can include multiple pass-throughs for water level measurements or pump leads.

Operational Principles of Inflatable Packers

The installation of inflatable packers involves lowering them into the well to the desired depth using a drill string, drop pipe, or wireline. Once in position, the packer is inflated using water, propylene glycol, or gas, which expands the rubber element to create a tight seal.

Figure 2. Nominal 16-inch inflatable packer being installed into a well for hydrofracturing.

The required inflation pressure of the packer is a function of many variables specific to the application and is carefully controlled to ensure a secure seal without damaging the packer, borehole, or well.

Inflatable packers can be deployed in a single zone or straddling a zone, with the two packers creating an isolated section between two seals, allowing for more precise testing and interventions.

After the operation is complete, the packer is deflated by reversing the inflation process or venting the inflation medium. Deflation allows the packer to return to its original shape, making it easier to retrieve. The packer is then removed from the well for reuse or disposal, depending on its condition and the specific requirements of the operation.

Usage of Inflatable Packers
Zonal Isolation

In zonal isolation, packers are used to prevent fluid movement between different geological formations. This application is crucial for accurate testing and sampling of individual aquifer layers, as it ensures that the samples are representative of the specific zone being studied without contamination from adjacent
layers.

Zonal isolation is also essential in managing water production and controlling unwanted water inflows from certain strata while allowing production from higher quality zones. Zonal isolation is also used in geothermal applications where water is pumped from one zone in a well, is run through a heat exchanger, and injected above or below the pumping zone.

Well Testing

During well development, packers enable the testing of discrete sections of a borehole. This targeted testing helps in determining the productivity and characteristics of different aquifer zones, providing valuable data on the hydraulic properties such as transmissivity and storativity.

Accurate well testing is essential for designing effective water extraction systems and ensuring sustainable groundwater management. Pumps are often deployed along with packers to collect samples for water quality testing or to test for water production rates.

Grouting and Sealing

Packers are used to inject grout into specific sections of a borehole or well to seal off undesirable water flows or to stabilize the well structure. This application is particularly important in preventing cross-contamination between aquifers and sealing off sections of the borehole that may be prone to collapse or water ingress.

Grouting and sealing operations help maintain the structural integrity of the well and enhance its longevity. Packers are commonly used in tunneling applications to pressure grout ahead of the tunnel-boring machine to create a low permeability zone to prevent water intrusion into the tunnel. Pressure grouting with packers is also common in foundation and soil stabilization projects, including dams.

Contaminant Hydrogeologic Investigations and Remediation

Inflatable packers are instrumental in isolating contaminated zones for detailed sampling and testing. They help in assessing the extent of contamination, groundwater flow, and contaminant transport mechanisms. By isolating specific sections of the borehole, packers allow for precise determination of contaminant concentrations at various depths, aiding in the development of effective remediation strategies.

In site characterization, packers isolate sections of a borehole to sample groundwater from specific depths, allowing for precise determination of contaminant concentrations at various stratigraphic levels. This helps in understanding the vertical distribution of contaminants, which is crucial for developing an accurate conceptual model of the site.

In tracer tests, packers can be used to study groundwater flow paths and contaminant transport mechanisms. By injecting tracers into isolated sections of the aquifer, researchers can track the movement of contaminants and identify preferential flow paths and potential barriers to flow.

Packers optimize pump-and-treat remediation systems by isolating and extracting contaminated groundwater from specific zones, enhancing the efficiency of contaminant removal, and reducing the volume of water that needs to be treated. They facilitate in-situ remediation techniques by isolating sections of the aquifer where treatment agents can be injected, sometimes at high pressures, ensuring targeted delivery and improving the effectiveness of remediation efforts by reducing the quantities of remediation solutions that are injected.

Additionally, packers allow for the monitoring of groundwater conditions over time by isolating sections of the aquifer for repeated sampling, which is critical for assessing the progress of remediation efforts and making necessary adjustments to treatment strategies.

Hydrofracturing (Hydrofracking)

In hydrofracturing operations (Figure 2), packers are used to isolate specific sections of the wellbore, allowing for the precise application of high-pressure fluids into the fractured hard rock formations in the well. This may be done with a single packer or two packers in a straddle configuration. By isolating the fracture zones, packers help to direct the high-pressure fluids to the desired locations, enhancing the effectiveness process.

The primary goal of hydrofracturing is to break up and remove clay and sediment buildup within the existing fractures in the well, allowing for increased groundwater flow and well productivity. When the injection pumps are turned off, the injected water carries the loosened particles up and out of the well.

This can be enhanced using dispersants to increase well production (Gleeson et al. 2005). The process may be repeated multiple times. Packers play a crucial role in this process by allowing the buildup of pressure within the borehole and ensuring that the fracturing fluids are concentrated in the zones that require enhancement.

A detailed summary of packers used in hydrofracturing can be found in Groundwater & Wells, Third Edition (Sterrett 2007).

Conclusion

Figure 3. Preparing to install a fracking packer in a well. Note the inflation lines above the packer.

Inflatable packers (Figure 3) play a vital role in the water well industry, offering a versatile and effective solution for zonal isolation, well testing, well completion, contaminant hydrogeologic investigations, and hydrofracturing. Their ability to adapt to various geologic conditions and operational requirements makes them an essential tool for well professionals.

By understanding their applications, operational principles, and benefits—water well professionals can enhance the efficiency and safety of their well operations. With proper use and maintenance, packers can have a service life of many years. It is vital to understand the operation of your packers and carefully follow all the instructions of the manufacturer.

Inflatable packers are versatile and applicable in a wide range of borehole diameters, pressure requirements, and geologic conditions. They are cost effective, as reusable packers reduce the overall cost of well operations and efficient isolation reduces the need for multiple well interventions.

They provide precision, allowing for accurate testing and sampling of specific zones and enhancing the ability to manage and control fluid movements within the well. Additionally, inflatable packers enhance safety by minimizing the risk of uncontrolled fluid release during well operations and providing a reliable method for sealing and stabilizing boreholes, thereby improving overall well integrity.

Maybe you have had applications where you could have used an inflatable packer or might in the future. Hopefully this brief overview will help you understand how inflatable packers can help with a future project.

References

Gleeson, T.T., T.M. Hanna, and G. Wendling. 2005. “Squeezing a few more drops from bedrock using dispersants to increase the yield of hydrofractured wells.” Water Well Journal 59, 8: pages 16-17.

Sterrett, R.J., 2007. Groundwater & Wells, Third Edition. Johnson Screens: New Brighton, Minnesota.

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Thomas M. Hanna, PG, is a technical director of water well products/hydrogeologist for Johnson Screens where he works in areas of well design, development, and well rehabilitation. He is a registered professional geologist in Arizona, Kentucky, and Wyoming and has worked for several groundwater consulting firms. Hanna can be reached at thom.hanna@johnsonscreens.com.

Nick Hemenway is a mechanical engineer and the general manager of Baski Inc. in Denver, Colorado, a manufacturer of inflatable packers, downhole flow control valves, and pitless units. Over his 17 years with Baski, Hemenway has been involved with a wide variety of packer applications in the groundwater and geotechnical industries. He can be reached at nick@baski.com.