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Since the beginning of this century, assessment of the environmental impacts and the global warming potential of industrial practices and technologies are on the top agenda. Therefore, many construction materials such as cement systems are being designed for reducing the environmental impacts and greenhouse gas emissions. For that purpose, the petroleum industry is also striving for developing environmentally friendly cementing systems for oil well application; for example, a better alternative to the class-G cement, which is consumed in a tremendous amount worldwide. In finding the greener alternative to class-G cement, geopolymer binders are being researched for possible applications for oil-well cementing jobs. This paper presents the experimental investigation of the effects of temperature on the morphological characteristics of geopolymer binders. For that purpose, sodium silicate and sodium hydroxide were used as the alkaline activator with fly ash as the precursor. Fifteen samples were prepared with a density of 10, 11, 13, 15 and 17 ppg (3 samples for each value of density). The samples were subjected to a temperature of 30, 60, and 90 °C and cured in a water bath for 24 h. Morphological and microstructural characteristics were analyzed using XRD and FESEM. In an overview, increases in temperature significantly impact the geopolymerization process where the microstructure in geopolymer cement produces more reacted particles, which results in excellent mechanical strength. Generally, the strength of geopolymers is associated with the fly ash dissolution FESEM image for 17 ppg mixture cured at 90 °C clearly shows that it underwent extensive geopolymerization with the formation of continuous alumino-silicate gel and almost entirely reacted fly ash particles, resulting in relatively dense geopolymer matrix.

The oil-based mud is preferred to drill highly technical and challenging formations due to its superior performance. However, the inadequate chemical and thermal stability of conventional additives have greatly influenced the performance of oil-based mud at high-temperature conditions. Therefore, it is critical to design an oil-based mud with additives that withstand and improve its performance at high-temperature conditions. The nanoparticles have emerged as an alternative to the conventional additives that can significantly enhance the rheological and filtration characteristics of oil-based mud at high-temperature conditions. In this research study, a novel formulation of OBM enhanced with GNP is formulated, and its performance at high-temperature conditions is investigated. An extensive experimental study has been performed to study the effect of graphene nanoplatelets on the rheological and filtration properties along with flow behaviour, viscoelastic properties, electrical stability and barite sagging of oil-based mud at high temperatures. The graphene nanoplatelets are characterised to ascertain their purity and morphology. The result shows that the graphene nanoplatelets exhibited efficient performance and improved the rheological and filtration properties of oil-based mud. The plastic viscosity and yield point are improved by 11% and 42%, with a concentration of 0.3 ppb. Similarly, the gel strength and barite sagging tendency are enhanced by 14% and 2%, respectively. The filtration loss is also significantly decreased by up to 62% and 46%, with 0.5 ppb concentration at 100 and 120 °C. The addition of GNP results in the formation of a thin mud cake compared to the base mud sample. The rheological modelling recommends the shear-thinning behaviour of oil-based mud (n Graphical abstract

Ensuring oil-well-integrity is one of the challenging tasks when cementing is designed. It has been well established that cement tends to degrade when exposed to a corrosive environment and at elevated temperatures. This paper presents the results of the uniaxial compressive strength of the qualified mixes of geopolymer cement containing fly ash as the precursor. Geopolymer cement samples were cured in the potable water heated at 60 °C and 90 °C for 24 h before testing for uniaxial compressive strength. Uniaxial confined compressive strength test was performed for samples cured at a 60 °C, and results of the samples bearing density of 13, 15, and 17 ppg were obtained as 4.12, 9.21 and 17.68 kPa, respectively. For 90 °C, the compressive strengths were 4.43, 15.34 and 78.14 kPa, respectively, for the samples bearing the same density. Samples cured at 90 °C showed the higher value of UCS as compared to the samples cured at 60 °C, and it was because heat is required to stimulate the polymeric reaction.

For many years, Ordinary Portland Cement (OPC) is used in oil well cementing operation. But the OPC gets degraded in the acidic environment because of having poor mechanical characteristics. A new technology called geopolymeric cement system is developed from the secondary byproducts of the industry to replace the conventional cement slurry in oil well cementing operation. This study focus on the preparation of cement slurry with new formulation using fly ash and alkali binders at two sodium hydroxide treatment methods with various concentrations of NaOH solution and analyzing the prepared cement slurry for compressive strength, defiance to acid and fluid loss amount. Different cement slurry compositions made of 70:30 fly ash to alkaline activator ratios with 10, 12, 14 Molar NaOH solution with two sodium hydroxide treatment methods of direct addition and mixing after one day soaking of NaOH were prepared and cured for 24 hours at a temperature of 80°C and pressure 3000 psi. The obtained cement specimens were tested for compressive strength, resistance towards acid and density. Then based on the results, geopolymer can be considered as alternative for Class G cement in oil well cementing operation due to its high compressive strength and high acid resistance.

In this paper, we report the results of the investigations on the effects of sodium hydroxide (NaOH) concentration and different ratio of silicate to hydroxide on the density, rheology and compressive strength of geopolymer cement system used in oil well. Different ratios of Class F fly ash is mixed with different ratios of sodium silicate to sodium hydroxide ratio (2.5, 1, 0.5 and 0.25) to produce different geopolymer slurry densities and dispersant is added to control the rheological properties of the system. The NaOH solution was prepared by diluting NaOH pellets with distilled water according to the specified molarity (8, 10, 12 and 14 M). The solution was then mixed with sodium silicate to form the alkaline solution. Class F fly ash were added to the reactive to form homogeneous mixture, which was tested for its density and rheological properties at surface temperature. The mixture was placed in a 50 mm mould and cured at 930C and 3000 psia for 24 hours and the cubes were tested for destructive compressive strength. The results showed that as the concentration of sodium hydroxide increases, the density of the geopolymer cement increases. There was no significant variation on the density of the geopolymer cement. Also, as the ratio of silicate/hydroxide increases, the viscosity of the slurry increases and the workability of the geopolymer cement become poorer. Furthermore, the compressive strength increases as the NaOH molarity increases however when it reaches 14M, the adverse effect to the strength development was observed.

Increasing concern of greenhouse gas emission had been a chief highlight in inducing global warming. Application of Ordinary Portland Cement (OPC) for oil well cementing contributes a large portion for these gases, and therefore, geopolymeric technology is proposed to help curb down CO2 emission by replacing OPC. However, enough justification has to be shown to ensure the new technology is reliable enough to replace OPC for oil well cementing. This study aims to study the effect of silica fume addition to low calcium fly ash geopolymer cement by focusing on compressive strength and other properties such as thickening time, fluid loss and acid resistance test. Low calcium fly ash pose geopolymeric properties besides having a very low utilization rate which justify fly ash as our base material. Further analysis on structure of cement was done via FTIR, EDX and FESEM studies. Five different composition of varying silica fume (SF) content (0, 5, 10, 15 and 20%) was prepared and cured under wellbore condition (3000 psi and 200 F) slurry was 21minutes (static) and 36minutes (dynamic) and fluid loss rate 32 ml. Geopolymer cement has good resistance up to 10% HCl enough to withstand acidizing operations in wellbore. Compared to Class G cement (without addictive), geopolymer cement pose higher compressive strength and lower thickening time with high fluid loss rate. Thus, it's proven that geopolymer cement can be applicable as a replacement material for Class G cement from a shallow to medium depth cementing process. It helps to reduce greenhouse gas emissions, reduces landfill dumping issues and saves cost.

Polymer electrolyte membranes with different degrees of grafting were prepared by radiation-induced graft copolymerization of styrene monomer onto poly(vinylidene fluoride) (PVDF) films and subsequent chemical activation with liquid electrolyte consisting of lithium hexafluorophosphate (LiPF 6 ) in a mixture of ethylene carbonate/diethylene carbonate (EC/DEC). The chemical changes in the PVDF films after styrene grafting and subsequent chemical activation were monitored by FTIR spectroscopic analysis and the crystallinity was evaluated using differential scanning calorimetric (DSC) analysis. The swelling in electrolyte solution (electrolyte uptake) and the ionic conductivity of the membranes were determined at various degrees of grafting. The conductivity of the membranes was found to increase with the increase in the degree of grafting and reached a magnitude of 10 −3 S/cm at a degree of grafting of 50%. The results of this work suggest that radiation-induced graft polymerization provides an alternative method to substitute blending in preparation of polymer electrolyte membranes for application in lithium batteries.