Design Methodology for Swellable Elastomer Packers in Fracturing Operations

Abstract

During the past 7 years, swellable elastomer technology has been so well accepted in the oilfield that its scope of application has shown an unusually rapid expansion. Its success has been due to its capability to form a permanent seal through its elastomeric expansion in hydrocarbon or water. With the increasing acceptance of this concept for the oilfield, new field applications are being explored; this paper will discuss the application of swellable elastomer packers (SEPs) in stimulation operations. These applications include acid stimulations and/or hydraulic fracturing operations. This paper will explore the technical challenges, and the resulting design concepts were developed. The design process included modeling of downhole parameters and anchoring forces as well as laboratory testing that included thermal contraction measurements that were developed to resolve the technical challenges for stimulation operations. The resulting design methodology is not limited to stimulation applications but is applicable to any scenario with dynamic loads on SEP applications such as in water injection wells, etc.Finally, case histories are provided to illustrate the successes that have been achieved using the SEP methodology developed for stimulation scenarios.

Effect of the friction coefficient for contact pressure of packer rubber

“…2,9 Available research on the mechanical properties of swelling rubber is limited. 10,11 With the development of the finite element method (FEM) and computer technology, the mechanical properties of rubber materials have been widely researched. Currently, the strain energy density function is commonly used in FEM to indicate the mechanical properties of rubber materials, as shown in the hyperelastic constitutive models of Neo-Hookean, 12 Yeoh, 13 and Mooney-Rivlin.…”

Valhall – Pushing the Limits for Openhole Zonal Isolation — Qualification and Field Trial of 10,000-psi Oil-Swelling Packers

“…(Evers, et al, 2008) Compared to mechanical packers that will be ready for fracing as soon as they have been set, SEPs require time to swell and build up internal swelling pressure, before they are ready for the fracturing to commence. Zonal isolation was achieved initially by using mechanical openhole packers or inflatable packers, but the use of SEPs is gaining in popularity.…”

“…Additional details of this test can be found in SPE paper 116256 (Evers, et al, 2008) • Full cool-down of the packer and reservoir -Temperature dropping from 95° C to 20° C where 20° C is the estimated surface temperature of the fracturing fluid. This is based on constant heating from the reservoir and cooling from the frac fluid from inside the tubing.…”

Valhall – Pushing the Limits for Openhole Zonal Isolation ─ Qualification and Field Trial of 10,000-psi Oil-Swelling Packers

“…When designing SEPs for use in dynamic downhole conditions, it is critical that the SEP be designed with capability to hold the expected differential pressure, considering the cool down experienced during the stimulation or injection. (Evers, et al, 2008) Compared to mechanical packers that will be ready for fracing after they have been set, SEPs require time to swell and build up internal swelling pressure before they are ready for the fracturing to commence. Depending to the design and required delta P this can be from under a day up to weeks.…”

“…This is based on constant heating from the reservoir and cooling from the frac fluid from inside the tubing. Additional details of this test can be found in SPE paper 116256 (Evers, et al, 2008) • Full cool down of the packer and reservoir -Temperature dropping from 95° C to 20° C where 20° C is the estimated surface temperature of the fracturing fluid. The methods are described in more detailed below along with the obtained results from the test.…”