Evaluation of sealing performance of a compression packer at high temperature

Abstract

Rubber is the key component of a compression packer, which directly affects the success or failure of seals. Presently, the contact stress between the rubber and borehole walls is used as the main evaluation criterion for the sealing ability of the rubber of the compression packer. However, this evaluation criterion is imperfect. This study establishes the sealing performance and reliability evaluation system of a compression packer at 120°C. Considering the influence of time and temperature on the mechanical characteristics of rubber materials, the international advanced test technology was used to complete the uniaxial, planar and biaxial tensile tests and stress relaxation test for hydrogenated nitrile butadiene rubber (HNBR) of a compression packer under high temperature. Next, the hyperelastic and viscoelastic constitutive models of rubber materials based on high-temperature test data were established. Comprehensive sealing performance and reliability evaluation system for the compression packer rubber with compression rate, linear pressure, surface pressure and sealing performance coefficient were proposed. The evaluation system tested the rubber's stress relaxation effect on the rubber's sealing performance. The establishment of the evaluation system improved the shortcomings of the current packer-sealing performance evaluation system and provided a theoretical basis for the design and optimisation of the key structure of the packer-sealing system. Besides, based on the evaluation system, a platform for automatic structure simulation analysis and optimisation design of packer sealing system was developed and successfully applied to the actual design and optimisation process of packer. The system can effectively predict the sealing ability of the packer and guide field applications of the packer.

New methodology to predict operational limit of hydrogenated acrylonitrile butadiene rubber packer element for downhole application in energy industry

“…The new findings extended our previous works 14,15 to more complex geometry and compression of HNBR downhole packer using fundamental material behavior such as viscoelasticity, hyperelasticity, chemical degradation based on laboratory tests, and FEA for long-term sealing application. The current study has additional consideration of fluid aging for a long-term operation to conventional FEA analysis of packer rubber studied by Zheng et al 16,17 and Chen et al 18 The proposed FEA methodology by chemical aging is not limited to the size of the elastomer shape and can be readily extended to develop a successful operation limit for various elastomer applications in the energy industry.…”

“…FEA analysis for HNBR for packer rubber was conducted on compression rate, liner pressure, surface pressure, and sealing performance coefficient. 16 Stress relaxation effect on sealing performance of packer rubber was studied. 17 The results indicated that the temperature and stress relaxation had an appreciable impact on the sealing performance of a packer rubber seal system.…”

“…Hyperelastic and viscoelastic constitutive models were established based on high‐temperature test data. FEA analysis for HNBR for packer rubber was conducted on compression rate, liner pressure, surface pressure, and sealing performance coefficient 16 . Stress relaxation effect on sealing performance of packer rubber was studied 17 .…”

Adaptability of hydraulic fracturing packers and optimization of their sealing performance for three common clastic rock reservoirs based on finite element analysis

“…Hydraulic fracturing is one of the methods for measuring in-situ stress specified by the International Professional Committee of Rock Mechanics Testing Technology, and it is also the most effective method for measuring deep in-situ stresses. At present, the differential pressure of some newly developed bridging packers in the world is around 35 MPa, which cannot fully meet the temperature and pressure conditions required for deep hole geostress testing (Wakuda et al, 2002;Zhao et al, 2021a;Zhao et al, 2021b;Liu et al, 2022;Zhao et al, 2022;Zheng et al, 2022). Packers are important tools for downhole stress measurements.…”

“…In order to improve the performance of the rubber cartridge, some scholars have carried out related research on the selection and design of the packer (Lan et al, 2019;Liu et al, 2020;Zheng et al, 2022). However, in the research on the improvement of the rubber tube structures of the packer and the selection of rubber materials, there is no systematic analysis of the influence of different lithologies on the adaptability of the packer.…”