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

Synergistic Effects of Magnesium Oxide and SBR Latex Additives on Cement Sheath Stability in Oil Well Operations

Leaks through cement sheaths remain a complex and challenging issue in the oil industry, representing a persistent obstacle that has endured for decades. The drying shrinkage, an inherent characteristic of Portland cement, substantially exacerbates this problem, driving the formation of microcracks and heightened permeability under variable stress conditions. In this context, additives emerge as significant elements in addressing this issue, offering a pathway to mitigate the adverse effects of leaks. Among these additives, magnesium oxide (MgO) stands out for its ability to reduce drying shrinkage through structural modifications in the cement matrix. Simultaneously, SBR Latex, another important additive, acts to minimize gas migration due to its polymeric microstructure while also strengthening acid resistance and enhancing microstructural cohesion. This study aims to deepen the understanding of the interaction between MgO and SBR Latex additives in cement slurries, employing an experimental design to substantiate and expand upon the analyses conducted. The results reveal a synergistic integration of these additives, with MgO acting as an effective agent in reducing drying shrinkage and gel formation, thereby contributing to the strengthening of shear strength. Conversely, SBR Latex provides elasticity to the slurry, although with a slight compromise in compressive strength, with a relatively limited effect on shear strength. The strategic combination of these additives results in improvements in the mechanical integrity of cement slurries, a positive advancement in the context of petroleum well cementing operations. Thus, this study not only highlights the individual properties of MgO and SBR Latex but also offers valuable perspectives for the careful formulation of cements, with potential applications in challenging operational environments in the oil industry.

Research on the Performance of Cement-Based Composite Borehole Sealing Material Based on Orthogonal Test

In order to achieve better sealing of boreholes, the performance of sealing materials is modified to improve the efficiency of coalbed methane extraction. In this paper, a new type of cement-based hole sealing material was prepared by using silicate cement (PC) and cement sulfoaluminate (SAC) as raw materials, supplemented with various additives, such as fly ash, Na2SO4, Ca(OH)2, and poly(vinyl alcohol) (PVA) fiber. The effects of these additives on the fluidity, setting time, and compressive strength of the PC-SAC compounded cementitious pore sealing material were investigated by orthogonal tests, and the hydration process and hydration products were analyzed by X-ray diffraction (XRD), thermogravimetry-differential thermogravimetry (TG-DTG), and scanning electron microscopy (SEM). The results show that the water-cement ratio has the most significant influence on the various properties of the material; the two additives of Na2SO4 and Ca(OH)2 play a key role in the setting time of the material; the optimal group, i.e., water-cement ratio of 0.5, fly ash of 5%, Na2SO4 of 1%, Ca(OH)2 of 0.75%, and PVA fibers of 0.8%, is obtained by the orthogonal test method, which is the closest to the actual needs of the project. The hydration products of the optimized materials have obvious changes, and the needle-like AFt and C-S-H increase so that the performance of the materials has been significantly improved.

Preparation and Performance Investigation of Optimized Cement-Based Sealing Materials Based on the Response Surface Methodology

A new cement-based sealing material, which used Portland cement (PC) as a raw material and supplemented several gel components, such as accelerant, alkali activator, suspension agent, expansion agent, reinforcing agent, was prepared in this work. The effects of these components on the fluidity, setting time, and expansion rate of these sealing materials were investigated by an orthogonal test. The results show that the water-cement ratio and the reinforcing agent content, the accelerant content and the water-cement ratio, and the expansion agent content and the accelerant content are the most important influencing factors on fluidity, setting time, and expansion rate, respectively. In addition, the regression models and response surfaces of the factors were established using a multiple linear regression method. By this means, the influences of the two main factors on each performance of this sealing material were accurately and intuitively reflected for obtaining the optimal value in the optimization area. The results indicate that the sealing materials possess the best performances when the water-cement ratio is 1.1, the accelerant content is 50%, the expansion agent content is 0.1%, and the reinforcing agent content is 3%, which is corresponding to a fluidity of 360-380 mm, an initial (final) setting time of 60 (80)-80 (100) min, and an expansion rate of 2-12%. Furthermore, the microstructures of the optimized sealing material also reveal that the main hydration products of PC are transformed from layered Ca(OH)₂ crystals into fine needle-like AFt crystals and C-S-H gels by the promotion effect of the optimizing ratio, thus leading to a more compact structure of optimized cement-based sealing materials.

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 [...]