Impact of wet supercritical CO2 injection on fly ash geopolymer cement under elevated temperatures for well cement applications

Syahrir Ridha,Muslim Abdurrahman,Astra Agus Pramana,Riau Andriana Setiawan

doi:10.1007/s13202-019-0693-y

Abstract

An alternative cement system created through geopolymerization of fly ash offers favorable properties such as able to resist acidic fluids and possess high compressive strength. However, the application of fly ash geopolymer as wellbore cement under carbon dioxide (CO2) environment at elevated temperature is not well recorded in the literature. This paper characterizes the fly ash-based geopolymer cement and experimentally investigates its mechanical and microstructure changes after exposed to CO2 under elevated temperature. Microstructure identification on the altered cement paste was conducted by the analysis of XRD and SEM. In this study, fly ash-based alkali-activated cement was made using 8 molal sodium hydroxide and sodium silicate as alkali activators. The results found that crystal-like shape identified as calcium carbonate was formed at the surface of spherical fly ash particle after carbonation formation. The strength of geopolymer cement was found not to be decreased although carbonation process was occurred. Microstructure analysis revealed that zeolite was formed during CO2 acid exposure for geopolymer cement which contributes to the strength development.

Highlights

Enhance oil recovery (EOR) is aimed to increase the percentage of oil production from unrecovered reservoirs
The high calcium content of fly ash leads to higher reactivity as compared to the low calcium fly ash, and this can be seen from the short thickening time in geopolymer paste measured using consistometer or Vicat needle apparatus (Ridha et al 2017)
X-ray diffraction (XRD) analysis of cement samples exposed to wet supercritical CO2 shows geopolymer network of Si–O–Al–Si–O and calcium carbonate phase with prominent peaks at 2θ 26.5° and 29.5°

Summary

Introduction

Enhance oil recovery (EOR) is aimed to increase the percentage of oil production from unrecovered reservoirs This is a well-established method which offers economic benefit in term of oil production and reduces the cost of CO2 storage (Dai et al 2016). Good cement system is one of key element for well integrity to sustain CO2 in the formation and prevent uncontrolled fluids seep to the surface (Ridha et al 2018a, b). This was early indicated by Benson et al (2003) that incompatible well construction materials have major role causing failure of injection wells. Good cement materials and slurry design are important factor of having good wellbore integrity (Velayati et al 2015)

Methods

Results

Conclusion