Thief-zone plugging mechanism and application of calcite particles in fractured formations

Lost circulation in fractured strata during drilling incurs additional costs and leads to difficulties in promoting drilling safety and efficiency. Plugging-while-drilling is a feasible means to address lost circulation in fractured formations. The particle size distribution (PSD) of plugging particles is determined empirically; therefore, it is often not matched with the fracture sealing requirement. This study investigates the lost circulation mechanism of fractured strata and identifies a calcite particle-based material as the preferred plugging agent. The plugging mechanism and the design of PSD and particle concentration are demonstrated. Based on the concentration, a plugging-while-drilling technique was developed for fractured strata. The results show that calcite particles tend to form the filling layer at the fracture inlet, which cuts off the leakage of the drilling fluid into the fracture, eliminating the drilling fluid pressure applied on the fracture surface. Thus, a stable sealing for the fractured formation is achieved, and the pressure-bearing capacity of the borehole wall is increased. The result also reveals the optimal mixing and concentration models for calcite particles with various diameters. The plugging technique based on calcite particles for fractured formations is applied in a field experiment. The results confirm that the technique can improve the chance of lost circulation prevention and thief-zone plugging in fractured strata and remarkably reduce both the event quantity of lost circulation and the volume of circulation loss. The findings of this research lay a theoretical basis to address lost circulation in fractured formations and, thus, have important practical significance.

Problems of Production and Circulation of Criminological Information

Modern criminology and criminal law are in the prolonged crisis provoked by inadequate and ineffective mechanism of informational circulation between these two spheres of social science and practice. The failure in the production of criminological information and its perception by criminal law serves as a symptom and as a cause of this crisis simultaneously. The way out of the crisis is seen as the analysis of the main components of the criminological information circulation mechanism and finding the way of its perfection. On the basis of critical analysis of the achievements of modern science the article investigates the main directions of perspective development of criminological science in order to produce modern and claimed by criminal law information. The research discusses the scientific problems of the production and circulation of scientific criminal information and the results of criminal law activities; proposes the mechanisms of calculation and use of criminological information in law making and law enforcing activities.

RESEARCH INTO THE ROLE OF BIVALVE MOLLUSKS IN THE PREVALENCE OF TRICHINELLA IN MARINE BIOCENOSES

Trichinosis is a dangerous anthropozoonotic disease caused by a nematode of the genus Trichinella. Being polyhostal, Trichinella is recorded in more than 150 species of animals, including marine mammals. While the circulation mechanism in terrestrial animal species is well-studied and has a logical explanation, the ways of infection of marine mammals remain unexplored in many respects up to the present. Among marine mammals, trichinosis is most common in walruses with the prevalence of 1.5% (Bukina L.A., 2015). The main sources of trichinosis infection for benthophagous walruses are probably their most important prey items, amphipods and bivalve mollusks. The purpose of the present paper was to study the role of bivalves in the transmission of infective material to a potential host. In the experimental infection, decapsulated trichinella larvae isolated from the muscle tissue of cage-kept arctic foxes were used. Trichinella larvae were isolated by the method of trichinelloscopy and digestion of muscle tissue in artificial gastric juice. It was found that the filter feeding structure of mussels does not let trichinella pass into the intestine. However, larvae trapped in the mantle cavity are filtered out and removed as pseudofaeces through the excurrent siphon to the environment. At the same time, they remain viable for 113 hours. The most invasive and viable were trichinella isolated from pseudofaeces and wash off from the mantle cavity (mantle complex) within 30 to 70 hours. The bio-assays performed on white outbred mice were positive. Therefore, mussels can be direct or indirect sources of the invasion. Taking into account that walruses can eat more than 3,000 mollusks in one feeding, the probability of infection increases significantly.

The Role of Slope Runoff in Flooding of Settlements in the Foothills of the Krasnodar Region When Local Rainstorms Fall (on the Example of Bagovskaya Village on May 20, 2019)

In the articles the authors have assessed the role of slope runoff formed during local storm precipitation in flooding of settlements in the foothill part of the region using the example of flooding of a part of the territory of the Bagovskaya village in the Krasnodar region on May 20, 2019. Hydrometeorological conditions that contribute to the formation of intensive slope runoff have been considered. It was identified that in the case of the development of the elementary circulation mechanism, the probability of local rainfall increases in the territory of the region, the intensity of which in the foothill zone can reach more than 100 mm/day. Precipitation is, as a rule, are of an areal character, but the field distribution of precipitation is uneven. In the case of major precipitation in the high-altitude zone of 300-700 m, rivers cope with the passage of rainwater and flooding of settlements occurs because of the slope runoff coming from the surrounding slopes. In the case of precipitation intensity of 10 mm/10 min the flow modulus is 16.7 m3/skm2. When intense precipitation shifts to a high-altitude zone of more than 1000 m, a flood occurs on rivers and watercourses. In this case, flooding of localities will occur first as a result of runoff of slope drains, and then, as a result of rising water levels in the river, above dangerous levels.

Effect of Forestland Property Rights and Village Off-Farm Environment on Off-Farm Employment in Southern China

Reasonably promoting the off-farm employment of rural surplus labor in China’s collective forest areas is an important way to increase forest resources and increase farmers’ income. China’s new round of collective forest tenure reform (CFTR) aims to optimize forest area labor allocation by strengthening forestland property rights. Therefore, in different village off-farm environments, it is necessary to explore how forestland property rights affect off-farm employment in forest areas. Based on survey data from 742 households in Zhejiang and Jiangxi provinces, this paper examines this effect using the double-hurdle model. The results indicate that forestland transfer rights promote decision-making about, and the supply of, off-farm labor, while forest harvesting rights significantly increase the supply of off-farm labor. The villages’ off-farm income ratio also affected the supply of off-farm labor. Moreover, under the regulation of the village off-farm income ratio, the positive incentives of forestland transfer rights on decision-making about, and the supply of, off-farm labor gradually weakened, but the incentive effect of forest harvesting rights on the supply of off-farm labor gradually increased. It is proposed that the CFTR should be further promoted, the forestland circulation mechanism and regulating forest harvest quota system should be improved, and implementation of forestry property mortgages should be strengthened.

EXPERIENCE OF FINANCING HOUSING CONSTRUCTION IN BELARUS USING MECHANISM OF HOUSING BONDS

The article studies the current trends in the use of housing bonds on the real estate market of Belarus, their legal mechanism. The problems and investment risks for owners of housing bonds, directions for improving the issue and circulation mechanism are disclosed.

Method for evaluating the heat-island mitigation effect of porous/water-retentive blocks using a climatic chamber

This paper presents a method and mock-up design for evaluating the heat-island mitigation effect of porous/water-retentive blocks in a climatic environmental chamber using ambient temperature measurements. To create the proposed method, the heat circulation mechanism of blocks was considered. From this, we specified the climatic chamber design requirements, determined the required components and equipment for the mock-up, and developed the proposed method for evaluating heat-island mitigation performance based on ambient temperature. Using the proposed mock-up design and method, we confirmed that both surface and air temperatures were lower when porous/water-retentive blocks were installed compared to conventional blocks. This method can be used to analyze the difference between surface and ambient temperatures under various conditions to quantify the heat-island mitigation performance of different materials according to ambient temperature.