Study and Use of Geopolymer Mixtures for Oil and Gas Well Cementing Applications

TLDR

The study presents laboratory testing of Class F fly ash geopolymer for oil well cementing applications. The authors used API Class H Portland cement with a controller and performed UCS, shear bond, thickening time, shrinkage, free water, cyclic, and durability tests. The geopolymer mix achieved over 5 h thickening time, with temperature strongly influencing this, and demonstrated increasing compressive strength over 1–14 days, higher shear bond strength, greater ductility and fracture toughness, and zero free water, indicating suitability for deviated wells.

Abstract

The study here presents laboratory testing results of Class F fly ash geopolymer for oil well cementing applications. The challenge reported in literature for the short thickening time of geopolymer ash has been overcome in this study, where more than 5 h of the thickening time is achievable. API Class H Portland cement used a controller on all the tests conducted in this work. Tests conducted in this research include unconfined compressive strength (UCS), shear bond strength, thickening time, shrinkage, free water, and cyclic and durability tests. Results indicate temperature as a crucial factor affecting the thickening time of geopolymer mix slurry. UCS testing indicates considerably higher compressive strength after one and fourteen days of curing for geopolymer mixtures. This indicates gaining strength with time for geopolymer mixture, where time retrogression effects are observed for Portland cements. Results also indicate higher shear bond strength for geopolymer mix that can better tolerate debonding issues. Additionally, more ductile material behavior and higher fracture toughness were observed for optimum geopolymer mixes. Tests also show applicability of these materials for deviated wells as a zero free water test was observed.