Abstract:In this paper, the impact of temperature and admixture-based salts on the mechanical and rheological properties, and composition of geopolymers was studied. Neat geopolymer and Class-G cement, manufactured by Dyckerhoff, were used as reference samples at elevated temperatures. To enhance the additive properties of the geopolymer slurry, a combination of K and Zn was examined with a variety of K:Zn ratio ranging from ∼0.15 to ∼0.25. The workability of samples was tested by using an atmospheric consistometer, wh… Show more
“…The mix design of the neat sample (Geo-Neat) and retarded sample (Geo-Zn/K) is presented in Table 2. The used ratio was experimentally concluded after running several tests and past experiences using the combination of both Zn 2+ and K + species [27].…”
Geopolymer material has a potential to function alongside Portland Cement as an efficient cementitious material for well cementing and plug & abandonment applications. Geopolymer material requires retarding agents to be displaced into the well while considering the properties required to maintain efficient zonal isolation through superior mechanical properties. Chemical admixtures affect the material structure and can, in some cases, jeopardize material integrity if not engineered properly to suite downhole conditions. The present article shows the effect of Zn2+ and K+ species have as retarding agents on slurry, mechanical, and microstructural properties. The approach has been carried out to obtain a preliminary overview of how retarding agents can behave in mix design slurries where eventually sealing performance was examined. Samples were cured and examined for periods of 1, 3, 7, 14, and 28 days at downhole conditions. The results obtained confirm a retardation effect by the addition of Zn2+ and K+ species and some shortcomings in early strength development due to a poisoning mechanism by Zn2+ species. This phenomenon indicates the formation of Ca-Zn phase that can hinder the nucleation of the geopolymeric gel structure. No significant effects were observed on the microstructural development throughout the curing period. The effect of Zn2+ species was also observed in increasing threshold for hydraulic sealability. It may be concluded that the tested retarding agents require furthermore development to minimize shortcomings in mechanical properties specifically early strength development.
“…The mix design of the neat sample (Geo-Neat) and retarded sample (Geo-Zn/K) is presented in Table 2. The used ratio was experimentally concluded after running several tests and past experiences using the combination of both Zn 2+ and K + species [27].…”
Geopolymer material has a potential to function alongside Portland Cement as an efficient cementitious material for well cementing and plug & abandonment applications. Geopolymer material requires retarding agents to be displaced into the well while considering the properties required to maintain efficient zonal isolation through superior mechanical properties. Chemical admixtures affect the material structure and can, in some cases, jeopardize material integrity if not engineered properly to suite downhole conditions. The present article shows the effect of Zn2+ and K+ species have as retarding agents on slurry, mechanical, and microstructural properties. The approach has been carried out to obtain a preliminary overview of how retarding agents can behave in mix design slurries where eventually sealing performance was examined. Samples were cured and examined for periods of 1, 3, 7, 14, and 28 days at downhole conditions. The results obtained confirm a retardation effect by the addition of Zn2+ and K+ species and some shortcomings in early strength development due to a poisoning mechanism by Zn2+ species. This phenomenon indicates the formation of Ca-Zn phase that can hinder the nucleation of the geopolymeric gel structure. No significant effects were observed on the microstructural development throughout the curing period. The effect of Zn2+ species was also observed in increasing threshold for hydraulic sealability. It may be concluded that the tested retarding agents require furthermore development to minimize shortcomings in mechanical properties specifically early strength development.
“… Fig. 1 Consistency data of the slurries, for a variety of geopolymer mixtures, at ambient pressure and two different bottomhole circulation temperatures [ 7 , 27 , 31 ]. …”
Section: Experimental Datamentioning
confidence: 99%
“…All the tests have been conducted three times to minimize errors and uncertainties originating from experimental work. The chemistry and mix designs of these slurries have been thoroughly discussed in previous publications [ 10 , [27] , [28] , [29] , [30] ].…”
“…Similar to other cementitious materials, the pumpability of geopolymers is reduced as the temperature increased (Salehi et al, 2019). Introducing the chemical admixtures to retard the geopolymerization affects the early strength development of geopolymers (Chamssine et al, 2021). A decent understanding of geopolymerization reaction is the key to success for controlling fluid-state and mechanical properties after solidification.…”
Primary cementing operation is the process of pumping and placing a cementitious slurry in a well. After setting, the so-called barrier material has to provide zonal isolation in the annular gap behind casing string. After a hundred years of using hydraulic Portland cement as prime material for cementing operation, although the chemistry of the material is well-developed, still shortcomings are reported in short- and long-term properties. Safe and cost-efficient operations have been the motivation for improving the performance of barrier material. Additionally, annual increase of the carbon tax is a driving force for switching to green alternatives to Portland cement. The present study includes scientific examination of candidate barrier materials for cementing operation. These materials are an industrial class of expansive cement, a non-cement-based pozzolanic material, an inorganic polymer known as geopolymer, and organic thermosetting resin. The materials were assessed aiming to evaluate their performance at equal conditions. The thesis is divided into two main sections comprising a core that describe the research project and appended papers discussing scientific achievements. The outcome of this study includes strengths and weaknesses of each material, which are published in seven scientific papers: three journals, two peer-reviewed conferences, and two SPE conferences. The papers are included as Appendix and labeled using Roman numerals. In the present review, same numerals are used when referring to the papers. Paper I includes fluid-state properties of the candidate barrier material. Density, viscosity profile, static fluid-loss, and the pumpability of the materials are tested at bottom-hole circulating temperature. Paper II presents short-term mechanical properties of Portland cement-based systems and highlights the effect of chemical additives on the mix design. In this study, the mechanical properties of expansive cement and API neat class G cement are included. The samples were cured from one day to fourteen days at bottom-hole static temperature and under elevated pressure. Paper III includes the mechanical properties of candidate barrier materials. The short-term mechanical properties were tested up to seven days. Paper IV shows mechanical properties of the materials up to one month. In this paper, uniaxial compressive strength, tensile strength, and Young’s modulus are measured and possible correlations between these parameters are investigated. Moreover, sonic strength development rate of the materials is tested by using ultrasonic cement analyzer. Paper V includes shear bond and hydraulic sealability of cement-based systems and geopolymer. Shear bond strength of these materials is examined at two circumferential surfaces by placing the cementitious material between a pipe and bar. For both shear bond and hydraulic sealability, both clean and rusty steel are considered as casing string representatives. Paper VI has bond strength and hydraulic sealability of the setting materials. The interface of materials with steel is studied by scanning electron microspore. Morphology and mineralogy of materials at their interface satisfy the behavior of materials in shear bond and hydraulic sealability tests. Paper VII includes mechanical properties of the materials up to nine months of curing at bottom-hole static temperature and elevated pressure. Additionally, morphology and mineralogy of the materials are tested to support the mechanical behavior of materials.
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