Deployment of Swelling Elastomer Packers in Shell E&P

Abstract

In Shell Exploration & Production, swelling elastomers have been deployed in a variety of applications: as a means to establish zonal isolation in liner completions, as a production separation packer, and as an integral part of an expandable open hole clad. In these applications, the elastomers have been run in various open hole, casing, and tubing sizes. A total of around 60 deployments in Shell have been recorded, all of which were technically successful. Case examples of each of the three mentioned applications will be presented from Shell operations in the North Sea, the Middle East, and the Far East. Introduction In most areas where Shell operates, especially in the more mature oil field environments, there is a high focus on well cost reduction. Various technology applications have been identified to meet this business need and allow the operator to drill wells cheaper and smarter, making the most of existing infrastructure. One technology that is experiencing a rapid uptake is the application of swelling elastomer packers. These packers, which swell naturally when exposed to the appropriate swelling agent, have successfully been used as a replacement for traditional mechanical packers and cement. The business case for using swelling elastomer packers is different per application and can include time savings as well as direct tool cost savings. Shell implemented swelling elastomers in combination with the deployment of a Solid Expandable Tubular (SET) system called Open Hole Clad (OHC) in July 2002. First application of swelling packers for zonal isolation was in the South Furious field in Malaysia in June 2003. Since then, over 60 deployments have taken place in operations in Malaysia, Brunei, Nigeria, Gabon, Oman and the UK. Theory and Definitions A swelling elastomer packer, or swelling packer, is a rubber element vulcanised onto pipe. The main property of the rubber is that it swells significantly when exposed to either aromatic hydrocarbons or saline water through a process of absorption. An oil swellable packer is a swelling elastomer packer, which swells primarily through the absorption of hydrocarbons. This is a diffusion process. Typical operating temperatures for oil swellables are 80–130°C. A water swellable packer is a swelling elastomer packer, which swells through the absorption of (saline) water. This is an osmosis process. Typical operating temperatures for water swellables are 50–90°C. The three main design parameters of swelling packers are life-span, pressure rating, and swelling time. Because of the relatively recent development of swelling packers, our understanding of these parameters is still growing and a full theoretical treatment of the subject is beyond the scope of this paper. The main factors to consider in determining the three design parameters are temperature and the geometry of the pipe, packer and borehole. Pressure ratings have been tested up to 3500 psi, although higher ratings have been recorded in the industry. Swelling times in our operations range widely from 5 to 50 days. The case examples provided in this paper show three distinctly different uses of the swelling elastomer packer: the liner completion, the production isolation packer, and the expandable open hole clad. A liner completion is defined as a liner system with slots or perforations to allow access to the producing formation. The swelling packers are used in combination with blank liner joints to isolate oil bearing zones from water zones, where conventionally a cement column would be used. The production isolation packer is defined as a seal between a production tubing and a production liner in order to isolate the various perforated sections. Swelling packers are used to replace conventional hydraulically or mechanically set packers. An expandable open hole clad is defined as an expandable tubular used to seal off water bearing formations or water producing fractures in a barefoot well section. Swelling elastomers are used to provide the seal between formation and tubular.

Inhomogeneous swelling of a gel in equilibrium with a solvent and mechanical load

“…The unusual combination of the attributes makes gels the materials of choice for diverse applications, such as medical devices (Wichterle and Lim, 1960;Peppas et al, 2006), tissue engineering (Lee and Mooney, 2001;Wong et al, 2008), actuators responsive to physiological cues (Beebe et al, 2000;Dong et al, 2006;Cho et al, 2008), and packers in oil wells (Kleverlaan et al, 2005). Mixtures of macromolecular networks and solvents also constitute tissues in plants and animals, where the networks retain structural forms, while the solvents enable the transport of nutrients and wastes.…”

A finite element implementation of a coupled diffusion-deformation theory for elastomeric gels

“…Gels can be designed to swell by several hundred percent in volume, and the amount of swelling can be controlled by varying various stimuli-humidity, temperature, and pH. Gels are ubiquitous-they are found in foods and medicines, and they find use in several important and diverse applications including carriers for drug delivery (Peppas et al, 2006), actuators and sensors in microfluidic devices (Beebe et al, 2000), tissue engineering matrices (Chan and Mooney, 2008), as well as packers for sealing in oil wells (Kleverlaan et al, 2005;Bhavsar et al, 2008).…”

Hybrid Hydrogels with Extremely High Stiffness and Toughness

“…4 Many other applications require hydrogels of exceptional mechanical properties. Examples include biomedical applications such as materials for cartilage replacement, 5 engineering applications such as swellable packers for oil and gas recovery, 6 and artificial muscles and artificial nerves in the nascent field of soft machines. 7-9 These load-bearing applications of hydrogels are often limited by low stiffness and toughness.…”