Influence of Graphene Oxide on Rheological Parameters of Cement Slurries

Modern Methods of Strengthening and Sealing Salt Mines

In order to ensure safe working conditions for miners underground, many works are carried out in mines to strengthen and seal mining excavations. This article presents the successfully applied technology for removing water inflow from the unique Salt Mine. Failure to take such action may ultimately lead to the flooding of the “Wieliczka” Salt Mine (KSW). On the basis of the authors’ research studies, some of the implemented works at the “Wieliczka” Salt Mine are presented, the purpose of which is to better protect the mine against the risk of flooding with water. Thanks to this, the mine can safely survive for many more years. This article presents two innovative technologies in salt mines: (1) sealing of the rock mass surrounding the Kościuszko shaft casing in the “Wieliczka” Salt Mine, where jet injection was used as the basic method of making an anti-filter screen outside the shaft casing and classic injection as a supplementary method for sealing the anthropogenic embankment; (2) reconstruction of the internal pillar of safety by implementing a patented technology called “pipeline injection” on the example of the Mina cross-section, in which a catastrophic water inflow was previously created that threatened the existence of the “Wieliczka” Salt Mine. The first method consists of making an anti-filter screen, which is located outside the shaft housing. Unfortunately, it is not possible to perform injection works from inside the shaft housing, because the Kosciuszko shaft, as a ventilation shaft, must be open constantly. To solve this problem, it is designed as the main technology known as jet grouting, which is supplemented by pressure injection at a depth of up to several meters with continuous monitoring of the condition of the casing during injection works. The second example concerns the reconstruction of the internal pillar of mine safety in the area of the northern border of the salt deposit. In this case, the catastrophic hazard is documented, as evidenced by the inflow to the Mina transverse, which is located on the fourth level of the mine. This task was successfully completed by the implementation of a patented technological solution called pipeline injection, the details of which are discussed in this article.

Improving the Efficiency of Oil Recovery in Research and Development

By creating a special edition entitled Fundamentals of Enhanced Oil Recovery, the editors focus on the problem of the global increase in energy demand [...]

Influence of Hblock Fine-Grained Material on Selected Parameters of Cement Slurry

Fine-grained materials are used to seal the microstructure and improve the mechanical parameters of the formed cement sheath. They are used in cement slurries designed to seal casing columns at great depths and in geothermal boreholes to improve thermal conductivity. Such additions shorten the setting time and the transition time from the value of the initial time of the setting to the final of the setting. This allows the shortening of the time needed to bind the slurry and move on to further work. Additionally, it helps to eliminate the possibility of gaseous medium intrusion into the structure of the setting cement slurry. The goal of the work is to determine the influence of the Hblock fine-grained material on selected parameters of the cement slurry. Hblock is used in the research ranging from 1% to 20% (bwoc (bwoc—by weight of cement)), and the two types of cement most commonly used in the petroleum sector. Then the technological parameters of fresh and hardened cement slurries were tested. Research on rheological parameters, determined rheological models and flow curves are performed. On the basis of the obtained test results, the influence of the additive on the technological parameters of the cement slurry is discussed. The research results allow for further work and then the application of the fine-grained material in the petroleum sector.

Effect of core-shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes

SiO₂ nanoparticles (50 nm in diameter) coated with poly(ethylene glycol) methyl ether methacrylate (PEGMA) were synthesized by radical polymerization. The SiO₂/PEGMA nanocomposites were characterised using FITR, ¹HNMR and TGA methods. The load of PEGMA in SiO₂/PEGMA nanocomposites was 72.9 wt%. The hydration products, microstructure, pore structure, density, compressive strengths and rheological properties of cement were investigated. The SiO₂/PEGMA nanocomposite could not only significantly improve the cement hydration and densify the microstructure by reducing the content of calcium hydroxide and promoting the production of calcium silicate hydrate, but also efficiently enhance the fluidity of the cement slurry. The compressive strength of cement with 2 wt% SiO₂/PEGMA nanocomposites was increased by 40.1% curing for 28 days, which was much better than cement with the physical blending of SiO₂ nanoparticles and superplasticizers. The SiO₂/PEGMA nanocomposites with core-shell structure novelly combine the advantages of SiO₂ nanoparticles and superplasticizers to significantly improve the performance of cement pastes. The results obtained provide a new understanding of the effect of the core-shell nanocomposites on cement pastes and demonstrate the potential of the nanocomposites for well cementing applications.

Increasing the Efficiency of Sealing the Borehole in Terms of Spacer Pumping Time

The tightness of a borehole is essential for its long-term durability. For this purpose, the column of the pipe is sealed with cement slurry. After contacting the slurry, mud in the borehole is removed. However, the slurry does not effectively remove the remaining drilling mud. Therefore, the annular space is cleaned with a wash. Effectively cleaning the borehole presents quite a problem, as many variables that affect the stability of the borehole need to be considered. The time of contact between the borehole and the wash is very important. On the one hand, insufficient contact time does not guarantee proper removal of the mud. On the other hand, a long contact time may destroy the wall of the borehole. To address these problems, studies were carried out to assess the effect of the wash contact time on annular space cleaning. When determining the time of washing, a compromise between effective cleaning and the stability of the borehole wall is required. In the research presented in this publication, the simplest wash was used, i.e., water. This choice was based on the objective of observing the influence of the wash time on cleaning, i.e., the preparation of the borehole for cementing. By using water, the physicochemical action of surfactants can be ignored. In order to capture changes in cleaning due to differences in contact time, a control test was performed using a pure sandstone core without mud. The effect of the wash contact time on the cleaning of the annular space was investigated by determining the adhesion of the cement sheath to the rock core. First, mud was formed on the core, and then it was removed. By comparing the obtained adhesion to the reference sample, the effectiveness of the deposit removal was determined. On the basis of this research, the optimal wash contact time was determined.

Effect of Cleaning the Annular Space on the Adhesion of the Cement Sheath to the Rock

Drilling boreholes in gas zones and in zones with the possibility of migration or gas exhalation requires a high index of well tightness. An important parameter determining the effectiveness of sealing the annular space is the adhesion of the cement sheath to the rock formation. Low values of adhesion of the cement sheath to the rock formation and to the casing surface result in the formation of uncontrolled gas flows. The lack of adhesion also reduces the stabilization of the pipe column. To obtain the required adhesion, the annular space should be properly cleaned. Thorough removal of filter cake from the drilling fluid increases adhesion and reduces gas migration from the annular space. Therefore, in this work, the authors focus on determining the effect of cleaning the annular space on the adhesion of the cement sheath to the rock formation. The results of the research work allow for further research on the modification of spacers and cement slurries in order to obtain the required increase in adhesion. The article presents the issues related to the preparation of the borehole for cementing by appropriate cleaning of the rock formation from the residue of the mud cake. During the implementation of the works, tests of cleaning the rock surface are performed. The obtained results are correlated with the results of adhesion on the rock–cement sheath cleaned of the wash mud cake contact. When analyzing the obtained test results, a relationship is found between the cleaning of the rock surface and the adhesion of the cement sheath to it.

An Outlook of Drilling Technologies and Innovations: Present Status and Future Trends

The present article analyzes the technological advancement and innovations related to drilling operations. It covers the review of currently proven and emerging technologies that could mitigate the drilling operational deficiencies and instabilities that could hinder operational performance activities and the economic part of drilling development with great effort to minimize their environmental footprint. Drilling system design and operations are among the major aspects and cost-effective endeavors of the oil and gas industries, which are therefore technology dependent. They are also considered to be among the most expensive operations in the world, as they require huge expenses daily. Drilling success, depending on prevalent conditions, is a function of several general factors. These include the selection of the best technologies and tools, procedural optimization, concrete problem-solving, accurate prediction, and rapid decision-making. Consequently, any sorts of tools or advanced technologies that can improve the time-efficient operational and economic performance of drilling activities are essential and demanded. The paper provides a review of available technologies and developmental innovations based on both company-based and academic research-enabled drilling solutions over the past 5 years in the field of drilling systems and technological design. The paper further highlighted potential technologies that could be tapped in from other industries and could possibly be adopted by pushing the conventional boundaries of drilling operations.

Possibilities of Limiting Migration of Natural Gas in Boreholes in the Context of Laboratory Studies

Gas migration through fresh and hardened cement slurry is an ongoing problem in the oil industry. In order to eliminate this unfavourable phenomenon, research is being conducted on new compositions of slurries for gas wells. The article presents the results of research for slurries with low and high resistance to gas migration. The proper selection of the quantity and quality of components makes it possible to design slurry with the required static structural strength values. In addition, the cement sheath of such anti-migration slurry has low porosity and a very low proportion of large pore spaces. Additionally, the mechanical parameters do not decrease during long-term deposition in borehole-like conditions. By obtaining these results, it was possible to design slurry whose cement sheath has high corrosion resistance. The new slurry has a lower water-cement ratio. Additionally, GS anti-migration copolymer, anti-filter additive and latex are used. The presence of n-SiO2 aqueous solution and microcement allows for sealing the microstructure of the hardened cement slurry. Such modifications significantly improve the technological parameters of the cement slurry and the cement coat formed from it.