Lab Investigation of Oil Swelling Elastomers for Smart Well Completions

Abstract

Achieving successful zonal isolation is critical to install smart completion tools. Currently, cementing and mechanical packers are the only conventional methods used in Saudi fields to provide zonal isolation. However, these techniques are difficult to operate and result in reduced inner casing string diameter. Another method to provide zonal isolation for smart completion tools and to complete them in single stage is to use a rubber elastomer bonded onto a base pipe. The rubber swells in oil and provides a seal between the base pipe and the open hole. This paper will outline the step-by-step qualification testing that was carried out by Saudi Aramco facilities in an attempt to improve zonal isolation for smart completions.In this study, we present lab evaluation of elastomers at 190°F using six different oil samples. The evaluation involved studying the effect of oil viscosity and API gravity. Also, the study investigated the effect of acids on the swelled elastomers. To the best of the authors' knowledge no previous work was done to investigate the impact of these factors on the swelling mechanisms.The elastomer bonded in pipes was tested in autoclaves. The pressure drop across the pipes was measured as a function of time. The effects of other factors were investigated using elastomer samples and fluid characterization. The oil swelling elastomers withstood pressure up to 5,000 psi at 190°F after placing the elastomers in some crude oils. In addition, the elastomers swelled rapidly in some oils and slowly in others.

Introductory Chapter: Swelling Elastomers in Petroleum Drilling and Development

“…Swelling results in change in volume, thickness, density, hardness, and other material properties [10][11][12][13][14][15]. Water-swelling elastomers swell through absorption of saline water through the mechanism of osmosis [16].…”

Novel Expandable Cement System for Prevention of Sustained Casing Pressure and Minimization of Lost Circulation

“…It can be pumped into tiny cracks and fissures to provide sealing. Swelling elastomers have been used in the oil and gas industry in many applications including casing–casing annulus (CCA) and water shutoff . Swelling elastomers swell upon contacting with the formation fluid.…”

“…They also fail if they cannot seal the mother bore liner. Chemical means have less than 50% success rate due to not spotting them at the exact location of water flow, hydrodynamic connectivity, and wrong chemicals . There is a strong need to develop high-performance solutions to counter the SCP.…”

Analytical Model for Seal Contact Pressure

“…Elastomers can withstand very large strains without any permanent deformation [3]. Flexibility, extensibility, resilience, and durability are the special additional features that elastomers offer [4,5]. Without some sort of performance analysis, one cannot proceed with appropriate selection of a swell packer for a given set of field conditions, improvement of sealing design, assessment of seal integrity, etc.…”