Studying the Effect of Chemical Aging on the Properties of a Shaped Memory Material
Authors: Ren Jason , Gerrard David Peter , Goodson Jim 
Published: May 2011

Traditional materials used in downhole sand management applications have been studied in various downhole fluid environments and are well understood. Shape memory materials are relatively new and their environmental performance characteristics under downhole conditions have not previously been studied.

The long-term response of shape memory materials at reservoir temperature and pressure depends on the thermal and chemical resistance properties of the material. To fully understand the properties of the shape memory material and its potential application window in the downhole environment, the material has been aged in various inorganic and organic fluids for extended time periods, and at different temperatures up to 120° C. The mechanical, thermal, and chemical properties of the material as a function of aging time, aging temperature, and aging chemical environment have been studied by dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FT-IR) methods. Based on the test results, the service life of the material has been estimated using the Arrhenius Equation.

In addition, the material has been studied after aging in other wellbore fluids, such as completion fluid, drilling muds, acids, and Norsok M710 standard hydrocarbon and sour gas mixtures. The thermal, mechanical, and chemical properties of the aged material can assist in determining potential service life of the shape memory material in different operating environments.

This paper describes the work involved in conducting this research, results, and conclusions for future achievements.

Introduction

Shape memory polymers (SMP) have been developed and applied in many industries, such as medical industry, space applications, structure applications, etc.1, 2 There are, however, few publications regarding shape memory polymers used in the oil and gas industry. To be used in the oil and gas industry, the polymer materials must be resistant to the hot and wet downhole environment. In addition, they should be resistant to harsh sour gas conditions. Recently, polyurethane-based shape memory nanocomposites have been developed.3, 4 Some nanofillers, such as nanoclay and carbon nanofiber, have been shown to improve shape memory properties. However, the thermal activation temperature of these materials is too low to be used in the downhole environment.

A shape memory polymer foam material has been developed at Baker Hughes. The material displays excellent shape memory, filtration, and environmental resistance properties in the temperature range of 65 to 85° C. The material has the potential to be used as a totally conformable screen material for sand control applications. To evaluate the potential of the material for use in a downhole environment, the material was aged in various inorganic and organic chemicals and Norsok sour gas environment at elevated temperatures for various periods of time. The mechanical, thermal, and chemical properties of the material were studied as a function of aging temperature and time and the service life of the material was estimated by using the Arrhenius Equation. It was found that the material could be used in brines, drill-in-fluids, heavy crude oils, and sour gas mixtures in long-term exposure within certain operating windows as well as in drilling fluids, acids, and completion fluids for short-term exposure. Based on the study, the shape memory material developed is acceptable to be used as a totally conformable screen material in a downhole environment. Compared to traditional sand control technology, it is very cost-effective to use the shape memory material for sand control applications.