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Growing demand to drill high-pressure, high-temperature (HPHT) wells requires improved technology to overcome the HPHT challenges. Designing and testing for cost-effective cementing at simulated downhole conditions for HPHT gas and oil wells poses a challenge necessitating special consideration in the choice of cement slurry. A successful cementing job is dependent on how quickly and efficiently cement achieves its strength. Another critical aspect is to efficiently displace the mud out of the annulus by designing the cement slurry with desired rheology. Achieving desired mechanical and rheological properties of cement becomes harder and more complex at HPHT conditions. A wide variety of admixtures are commonly mixed with the oilwell cement slurries to accommodate the extensive range of pressure and temperature and achieve enhanced mechanical and rheological properties. Carbon nanotubes are one of the most recent admixture options. This paper describes a study carried out to examine compressive strength and rheological properties (plastic viscosity, yield stress and gel strength) of oilwell cement slurries integrating chemical additives and multi-walled carbon nanotubes (MWCNT) at HPHT conditions. The study determined that integrating MWCNT in oilwell cement led to substantial increase in the compressive strength values. The rheological properties of oilwell cement slurries are greatly reliant on temperature, water/cement ratio and the admixture used. The study indicated that using MWCNT in cement slurries improved the rheological properties of cement slurries and therefore their displacement efficiency in challenging conditions.

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According to standard cosmology, the universe is homogeneous and isotropic at large scales. However, some anisotropies can be observed at the local scale in the universe through various ways. Here, we have studied the Bianchi Type I model by customizing the scale factors to understand the anisotropic nature of the universe. We have considered two cases with slight modifications of scale factors in different directions in the generalized Bianchi Type I metric equation, and compared the results with the [Formula: see text]CDM model and also with available cosmological observational data. Through this study, we also want to predict the possible degree of anisotropy present in the early universe and its evolution to current time by calculating the value of density parameter for anisotropy [Formula: see text] for both low and high redshift [Formula: see text] along with the possible relative anisotropy that exist among different directions. It is found that there was a relatively higher amount of anisotropy in the early universe and the anisotropic nature of the universe vanishes at the near past and the present epochs. Thus, at near past and present stages of the universe there is no effective distinction between this anisotropic model and the standard [Formula: see text]CDM model.

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