Analytical Modeling of Wax Plug Transportation during Pipeline Pigging Using a Foam Pig

Summary In our previous article (Gao et al. 2020), a mathematical model including elastic and yield components but not viscous component was developed to predict the wax plug transportation force. In this work, an analytical model was developed to calculate the wax plug transportation force, and the viscous component was introduced into the analytical model to capture some of the time effects. In this analytical model, the viscoelastic behavior of the wax deposit was characterized by a three-parameter model, formulated by adding an additional spring element to the Kelvin-Voight model. The Laplace transformation was used to solve the model. According to the calculated results of the analytical model, the transportation force of the wax plug was observed to slightly increase with time and then tended to level off. To obtain a parameter in the model and verify the model, the pigging experiments were conducted using foam pigs. During the pigging process of the foam pig, the wax plug transportation force in a five-phase wax removal profile was determined by taking the steady wax breaking force from the resistive force of the wax layer. Moreover, the linear increase of the wax plug transportation force per unit contact area with the shear strength of the wax layer was found, as described by the functional relationship in the analytical model. The interfacial lubrication coefficient calculated from the experimental data based on the analytical model is between the coefficient for diesel-prepared deposits and coefficient for oil-A-prepared deposits. Experimental verification results show that the average relative error of the model is 12.47%. Field implication was proposed to illustrate the application of the model and the formation condition of the wax blockage.

The anisotropic mechanical characteristics of layered rocks under numerical simulation

Layered rocks pose the challenge of wellbore stability in drilling engineering because of the anisotropic mechanical properties caused by the distinct weak planes. To understand the significant anisotropy of layered rocks in real formation condition, true triaxial compression tests are conducted by numerical simulation in this study. It is revealed that the mechanical responses of layered rocks are either controlled by the rock matrix or dominated by the weak plane and exhibit three different types associated with the orientations of the weak plane (including the dip direction α and dip angle β). When the orientations of the weak plane are α = 0°–90° and β = 0°, 60°–90°, the failure and strength properties of layered rocks depend entirely on the rock matrix, classified to the first type. Whereas the layered rocks with angle α ≤ 45° and β = 15°–45° fail by slipping failure along the weak plane, the relationship curves of rock strength versus the intermediate principal stress (σ2) are downward convex parabolas. In the last type, the mechanical behaviors of layered rocks with α > 45° and β = 15°–45°, involved in the changes of failure mode and the strength curve, are complex. Besides, the limitation of the simulation is discussed, and further studies on layered rocks are essential.

Optimization Strategies of Production Parameters to Prevent Hydrate Reformation in Marine Gas Hydrate Production System

In recent decades, the development of natural gas hydrates has become a research hotspot of scholars all over the world. However, the decomposed gas and water in marine gas hydrate production system may regenerate gas hydrates due to the low-temperature and high-pressure environment in seafloor. In this study, a transient temperature and pressure calculating model was established to predict the risk of hydrate reformation in production pipelines during offshore natural gas hydrate development. Using the proposed model, the region of hydrate reformation in gas hydrate production wells were predicted quantitatively. Meanwhile, the hydrate reformation management strategies through optimization of production design parameters in combination with hydrate inhibitor injection were proposed and discussed in detail. The results indicate that the risk of hydrate reformation is the highest in the drainage pipeline (DP); however, the flow in gas-water mixed transportation and gas production pipelines (MTP and GPP) basically does not satisfy the hydrate formation condition. In the process of production well design, adding additional the EH and ESP can fully eliminate the hydrate reformation risk in the DP without using the hydrate inhibitor.

The Formation of the Future Specialist Professional Culture in the Educational Space of the University

The article highlights the theoretical foundations on the formation of future specialist professional culture the in the field of professions "person-person". It is established that this is a purposeful, specially organized influence on the individual to improve his/her motivational sphere, value orientations, professional knowledge, skills and abilities, ability to empathy and reflection. This problem was studied by the author from the view of several scientific approaches: axiological, cultural, competence, activity. Based on the definitive analysis, the "professional culture of a specialist" concept is formulated, which is considered as a combination of professional and personal values and qualities of a specialist, his/her professional competence, which ensure highly effective fulfilment of professional duties based on reflection and self-development. Structural and semantic analysis allowed identifying components of the professional culture of future professionals i.e. value, cognitive, personal, and reflexive. The experimental research diagnostic tools of a formation condition of the future specialist professional culture in educational space of university are developed and tested: criteria, indicators, levels, techniques which reflect integrity of the investigated phenomenon structural components. The organizational and pedagogical conditions for the formation of the professional culture of the future specialist in the field of professions "person-person", which were implemented in the educational environment of the university, have been developed and theoretically grounded. An experimental study was fulfilled and the effectiveness of the proposed organizational and pedagogical conditions was proved.

RELIGION LITERACY AS A FORMATION CONDITION KAZAKHSTAN'S CIVIL DISCOURSE

The formation of a civil community takes place in the process of statehood formation and involves the development of a system of communication between communities and social groups that have different characteristics of economic, ethnic, linguistic, confessional, settlement, and demographic plans. In the light of the above, one of the most important functions of the state is to promote the formation of a civil discourse that is understandable to all social groups without exception. Depending on the characteristics of the community, the civil discourse can coincide with the national, confessional discourse or represent a supra-corporate, supra-group integral. Since the 2000s, in Kazakhstan (which also reflects the global trend), concepts that set the principles of orientation of modern man in the post – secular world-a world in which a large-scale return of religion to everyday life and the practices of individuals, social communities and institutions began to actively penetrate into civil discourse. To fully participate in the communications conditioned by the discourse of this type, individuals need religious literacy. The request for its formation is received by the education system, which acts as an instinct for the socialization of individuals. The article examines the transformation of Kazakhstan’s civil discourse from the point of view of the presence in it of concepts reflecting the principles of state-confessional relations at various stages of Kazakhstan’s development over the years of independence. The authors undertake a special analysis of what challenges the education system faces and how it solves them in the context of the formation of civil discourse.

Tree stand mortality in nationally important park-monument of landscape art Feofaniya

Tree stand mortality in urban ecosystems indicates the influence level of biotic and abiotic factors primarily on their life state. The significance of these processes lies in the knowledge of the forest stands patterns development and their use for forecasting and assessing ecosystem services. The territories of the nature reserve fund have been taken as research sites, as significant indicators of anthropogenically altered territories. The structure of biomass and forest stands species composition was found to be associated with the growth and development of living trees and the formation of dead trees. Biotic and abiotic factors, intraspecific competition and peculiarities of local formation condition and stands growth are determined to affect the life state of the main forest-forming species directly and indirectly. It was revealed that in the medieval oak plantation, the loss of trees during the research period (2016-2020) prevailed over the increase in the stand ground phytomass. It was found that the carbon deposited amount in the forest stands aboveground phytomass reflects the unusual dynamics for the overwhelming number of territory indicators. The litter formation caused the changes in the deposited carbon structure of the research stands phytomass by tree species. It also led to an increase in the deadwood carbon pool and the onset of carbon emissions from the detritus decomposition.

Eoarchean to Neoproterozoic Detrital Zircons from the South of Meiganga Gold-Bearing Sediments (Adamawa, Cameroon): Their Closeness with Rocks of the Pan-African Cameroon Mobile Belt and Congo Craton

The core of detrital zircons from the southern Meiganga gold-bearing placers were analyzed by Laser Ablation Split Stream analytical techniques to determine their trace element abundances and U-Pb ages. The obtained data were used to characterize each grain, determine its formation condition, and try to trace the provenance. The Hf (5980 to 12,010 ppm), Y (27–1650 ppm), U (25–954 ppm), Th (8–674 ppm), Ti (2–256 ppm), Ta, Nb, and Sr (mainly <5 ppm), Th/U (0.06–2.35), Ti zircon temperature (617–1180 °C), ∑REE (total rare earth element) (98–1030 ppm), and Eu/Eu* (0.03 to <1.35) are predominant values for igneous crustal-derived zircons, with very few from mantle sources and of metamorphic origin. Crustal igneous zircons are mainly inherited grains crystallized in granitic magmas (with some charnockitic and tonalitic affinities) and a few from syenitic melts. Mantle zircons were crystallized in trace element depleted mantle source magmatic intrusion during crustal opening. Metamorphic zircons grown in sub-solidus solution in equilibrium with garnet “syn-metamorphic zircons” and in equilibrium with anatectic melts “anatectic zircons” during crustal tectono-metamorphic events. The U-Pb (3671 ± 23–612 ± 11 Ma) ages distinguish: Eoarchean to Neoproterozoic igneous zircons; Neoarchean to Mid Paleoproterozoic anatectic zircons; and Late Neoproterozoic syn-metamorphic grains. The Mesoarchean to Middle Paleoproterozoic igneous zircons are probably inherited from pyroxene-amphibole-bearing gneiss (TTGs composition) and amphibole-biotite gneiss, whose features are similar to those of the granites, granodiorites, TTG, and charnockites found in the Congo Craton, south Cameroon. The youngest igneous zircons could be grains eroded from Pan-African intrusion(s) found locally. Anatectic and syn-metamorphic zircons could have originated from amphibole-biotite gneiss underlying the zircon-gold bearing placers and from locally found migmatized rocks that are from the Cameroon mobile belt, which could be used as proxies for tracking gold.

Modelling the Formation of Gas Hydrate in the Pipelines

Water and hydrocarbon are generally found beside each other in nature i.e., hydrocarbons are formed in aqueous environment. Natural gas and crude oil of storage reservoirs and transferring pipes from petroleum wells to industrial processes of oil and gas are in contact with water and they are in equilibrium with each other. Generally, water is considered as an intruder in oil and gas industry from primary production to ultimate consumption. It causes corrosion in pipelines and reduces the heating value of the fuel. High pressure and low temperature could also cause water condensation and liquid water considerably reduces pipelines efficiency. Low temperatures in winter or an adiabatic pressure drop could ultimately lead to hydrate formation in pipelines. Therefore, hydrate formation causes various problems and costs. In order to prevent hydrate formation, there should be comprehensive information about hydrate formation conditions. The available data on hydrate are outdated and might not have enough accuracy. The data are also specified for a single gas component while mixtures of gases are generally observed in pipelines. The current work tries to increase modeling accuracy of hydrate formation condition in pipelines with different compositions. In this research, a program was coded in MATLAB which specifies hydrate formation condition. In this program, the most accurate equations were used to predict the most efficient condition. Results of the program were compared with real data as well as results of PVTsim simulator. The comparisons indicated that this program could predict hydrate formation condition more accurately.