In this paper, the effect of natural trass rock as a pozzolanic mineral additive on the rheological, physicochemical and mechanical properties of class G Portland cement, widely used in oil well drilling and workover operations, was studied. Trass, obtained from the Koroglu deposit in the Lesser Caucasus region of Azerbaijan, was incorporated into the cement system at 5, 10 and 15 wt.% replacement levels. Its chemical and mineralogical properties were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses. Experimental results show that the addition of trass significantly improves the performance of the mixture by increasing slurry fluidity and reducing the plastic viscosity, while simultaneously increasing stability under dynamic conditions. The rheological stability of the cement slurry was improved by approximately 7-9 % compared to pure cement systems. In addition, the compressive strength increased significantly, indicating improved structural integrity. These effects are mainly attributed to pozzolanic reactions between reactive amorphous silica (SiO₂) and alumina (Al₂O₃) in the trawl and calcium hydroxide formed during cement hydration, and the interaction promotes the formation of additional calcium silicate hydrate (C–S–H), resulting in a denser and finer microstructure. In addition, the modified cement systems demonstrated increased durability, including higher resistance to thermal cycling and aggressive formation fluids such as saline waters and CO₂-rich environments. İn this study use of natural trass can help reduce the carbon footprint associated with traditional cement systems by partially replacing the clinker content. Keywords: oil well cementing; class G Portland cement; natural trass; rheology; pozzolanic reaction; zonal isolation.
The presented article reviews and evaluates contemporary engineering solutions aimed at optimizing the operating modes of gas-lift wells in modern oil field operations. Within this study, the estimation of the current performance and energy efficiency of gas-lift systems using real-time field data is considered of particular importance for sustainable production. To achieve this, efficiency factor (η) of the lifting system was meticulously calculated for selected wells where a reliable database of operational parameters was available. For the analytical part of this research, the specialized methodology developed by A. S. Alasgarov was utilized as the primary evaluative framework. To investigate operational efficiency based on actual surface parameters, and to identify candidates for production enhancement - specifically those where targeted technological interventions could yield positive results – a detailed joint analysis of the aforementioned well parameters was conducted. Based on extensive field data, the individual operating modes of several gas-lift wells were investigated under various conditions. The results revealed that in five specific wells characterized by exceptionally high water cut levels, the overall lifting efficiency decreased drastically, ranging from 44.5 to 82 %. To mitigate these losses and restore productivity, it is recommended that the effectiveness of bottomhole and reservoir stimulation methods against water cut be further evaluated for the respective wells. Finally, to enhance operational efficiency, the optimization of wells with similar fluid and pressure parameters was addressed by categorizing them into distinct diagnostic groups based on multi-variable criteria. Keywords: gas lift operation method; optimization of operation mode; gas injection rate; well efficiency; similarity criterion.
A new experimental finding regarding the violation of Darcy's law during the flow of liquids in a microcrack with an opening less than its critical value h
The investigation of the rheological properties and demulsification behavior of oil–water emulsions formed in oil gathering systems is of considerable importance for addressing technological challenges associated with crude oil treatment, dehydration, and transportation. In this study, the rheological behavior of oil–water emulsions containing 0–90 % formation water and the performance of a newly developed demulsifier composition were experimentally evaluated under laboratory conditions. The results demonstrated that the effective viscosity and shear stress of the emulsions are strongly dependent on water content. An increase in the volumetric fraction of water enhanced droplet–droplet interactions, promoted structural strengthening of the system, and increased resistance to flow. Rheological measurements confirmed the non-Newtonian behavior of the investigated emulsions and revealed a significant increase in viscosity with increasing dispersed phase concentration. To intensify the demulsification process, a novel formulation based on polypropylene glycol, polyethylene polyamine, sodium naphthenate, and methanol was developed. Laboratory experiments showed that the proposed composition provided a water separation efficiency of 77–81 % in emulsions containing 60% water. This effect is attributed to the reduction in the stability of the interfacial layer and the acceleration of water droplet coalescence. It was also found that freshly prepared emulsions were demulsified more readily than emulsions stored for five days, while increasing the demulsifier dosage improved separation efficiency only up to an optimum level. The obtained results indicate a clear relationship between the structural-rheological characteristics of emulsions and their demulsification efficiency, providing a scientific basis for improving the technological efficiency and operational reliability of crude oil dehydration processes. Keywords: oil–water emulsion; rheological properties; gathering system; demulsifier composition; emulsion breakdown; flowability.
The effect of metal nanoparticles on the interfacial activity of demulsifiers at the kerosene–distilled water interface was investigated using aluminum (50–70 nm), iron (40–60 nm), and copper (40–60 nm) nanoparticles. The study aimed to evaluate the influence of metallic nanoparticles on the performance of demulsifiers used in crude oil dehydration and desalting processes and to identify the optimum nanoparticle concentration for the development of highly efficient demulsifier formulations. Four commercially available water-soluble demulsifiers—Alkan DE-202B, Alkan DE-318A, ND-12, and Disolvan 4411—commonly applied in the treatment of water-in-oil emulsions containing salts and suspended solids were examined. Demulsifier solutions were prepared at concentrations of 0.01–0.05 wt.%, while nanoparticle concentrations ranged from 0.0005 to 0.01 wt.%. The results demonstrated that the incorporation of nanoparticles at concentrations of 0.001–0.005 wt.% reduced the interfacial tension of the demulsifier solutions by up to 60%, indicating a significant enhancement in interfacial activity. However, a slight increase in interfacial tension was observed at higher nanoparticle concentrations (0.005–0.01 wt.%), suggesting the existence of an optimum dosage. FTIR analysis confirmed that the incorporation of aluminum nanoparticles into the polyether matrix (Laprol-4202) did not alter its molecular structure. In addition, the viscosity of the commercial demulsifier Alkan DE-318A increased slightly from 69.0 to 74.0 mPa·s after the addition of 0.005 wt.% Al nanoparticles. The efficiency of the nanoparticle-modified demulsifiers was further evaluated using crude oil emulsions from the Buzovna and Gala oil fields. The modified formulations exhibited superior demulsification performance, achieving deeper dehydration of highly stable crude oil emulsions than the corresponding unmodified commercial demulsifiers. Keywords: demulsifier; Alkan DE-202B; Alkan DE-318A; Disolvan 4411; ND-12; aluminum nanoparticles; copper nanoparticles; iron nanoparticles; interfacial tension; demulsification; crude oil emulsion.
