High-Temperature Mechanical Properties and Microstructure of High Belite Cement

Wu Zhiqiang,Xie Renjun,Yang Jin,Cheng Xiaowei,Ni Xiucheng

doi:10.3389/fmats.2022.831889

Abstract

The use of the class G oil well cement for cementing in high-temperature deep-seated oil and gas wells declines its mechanical properties, which limit its application under high-temperature conditions. The high belite cement (HBC), a new class of energy-saving and environmentally friendly cement, has been widely used in recent years. In this study, the mechanical properties, phase composition and microstructure of HBC and quartz sand have been analyzed at high temperature, so as to optimize the amount of sand and provide guidelines for further exploring the application of HBC in the high-temperature oil and gas well cementing. The experimental results show that the high-temperature mechanical properties of the cement stone mixed with 40% quartz sand are the highest, thus, delaying the decline in the strength to the greatest extent. The microscopic analysis reveals that HBC produces dicalcium silicate hydrate and hydroxyl silicon calcium stone at high temperature. On mixing the quartz sand, xonotlite is observed to appear in the cement hydrate phase. These products are observed to be small in size and dense in structure, thus, leading to a delay in the decline of the high-temperature mechanical properties of the cement stone.

Highlights

The petroleum exploration and exploitation technologies are becoming more mature, and the exploitation is gradually advancing to the deep and ultra-deep wells (Vidal et al, 2018; Guo et al, 2019; Kuzielová et al, 2019)
This study uses quartz sand to delay the decline in the strength of the high belite cement at high temperatures
The high-temperature mechanical properties have been explored, and the corresponding mechanism has been analyzed through the microscopic characterization methods

Summary

Introduction

The petroleum exploration and exploitation technologies are becoming more mature, and the exploitation is gradually advancing to the deep and ultra-deep wells (Vidal et al, 2018; Guo et al, 2019; Kuzielová et al, 2019). The temperature of the deep wells can reach up to 110–150°C (Wang et al, 2019), whereas the temperature of the ultra-deep wells can reach above 200°C (Bu et al, 2016; Vidal et al, 2018; Guo et al, 2020) Under such working conditions, the mechanical properties of the conventional class G cement systems are significantly deteriorated and cannot meet the cementing quality requirements (Wei et al, 2021). The clinker system of HBC can be grinded and possesses a low firing temperature (Koumpouri et al, 2021) It exhibits significant advantages such as low heat of hydration and high later strength (Sui et al, 2015; Cuesta et al, 2021).

Methods

Results

Conclusion