PLANKTONIC COMMUNITY IN WATERBODIES OF THE KHARANORSKAYA SDPP: CURRENT STATE AND DINAMICS

This paper presents the results of studies of phyto- and zoop-lankton communities in reser-voirs of the Kharanorskaya SDPP cooling system (cooling pond, water supply and drai-nage channels), conducted in April, July and October of 2019. Long-term changes in the diversity and structure of planktonic associations during 1995–2019 are analyzed. A total of 141 taxa of algae ranked below the genus level and 52 taxa of invertebrates are identified in plankton. The phytoplankton total abundance and total biomass changed from 20 to 742×103 cells/l and from 65 to 711 mg/m3; zooplankton, from 7 to 212×103 ind./m3 and from 0.01 to 2.7 g/m3. The greatest abundance of algae was observed in summer and autumn, invertabrates – in spring and summer. Long-term observations of planktonic biocenoses show an increase in the species richness of diatoms and rotifers and a decrease in green algal and chrysophyts. Also there is a tendency towards a decrease in the phyto- and zooplankton total abundance as the abundance of cyanophytes, green algal, rotifers and cladocerans increases.

ANALYSIS OF SPECIES COMPOSITION, PROBLEMS OF IDENTIFICATION AND DISPERSAL PATHWAYS OF INVASIVE SPECIES OF FISH IN VOLGA RIVER BASIN

The article describes the intensive economic activity in the second half of the 20th century, which, along with apparent global climatic changes in recent decades, led to an increase in the number of alien fish species in the water bodies of the Volga basin. There has been presented the data on the occurrence of invasive species in scientific catches in the Volga River reser-voirs, as well as in its unregulated areas and delta. The invaders’ share in the fish species composition varied from 8 to 32%, depending on the geography of sampling. Special attention is paid to the reasons and pathways of invasive species’ dispersal, as well as to changes in the genetic structure of their populations taking place during acclimatization to the new conditions. It has been proposed to utilize a combined genetic-morphological approach in order to enhance the species identification of found invaders. Collected material can be used in the development of control methods, as well as for suppressing the abundance of dangerous or undesirable invasive species

Approbation of the technology for displacing residual gas with nitrogen for the conditions of a depleted gas reservoir in the VS-9 horizon of the Lyubeshivske gas field

Most natural gas reservoirs of Ukraine are depleted to some extent; still they contain significant tail gas reserves. A promising direction for increasing gas recovery from depleted gas reservoirs is the displacement of tail gas from the porous medium with nitrogen which is easily accessible and does not cause corrosion of the down-hole equipment. This article characterizes the technologies for increasing gas recovery from depleted gas reser-voirs by injecting nitrogen into them. The technology of replacing tail gas with nitrogen is tested on the example of the depleted reservoir of ND-9 horizon of Lyubeshivskyy gas field, the productive deposits of which are composed mainly of sandstones with interlayers of limestone and clay. The authors consider fifteen options of injecting ni-trogen into the reservoir, including options of treating the bottom-hole of low-production wells at the beginning of the process of further reservoir development and at the beginning of the injection of nitrogen into the reservoir. In all cases, the reservoir is first redeveloped in the depletion mode until the reservoir pressure decreases to 0,1 from the initial value. After that, nitrogen is injected into one of the producing wells which is transferred to the injection well. The injection of nitrogen into the reservoir continues until the nitrogen content in the last produc-ing well is less than 5 % vol. All options are characterized by high values of the gas recovery coefficient and close values of the dura-tion of the reservoir further development. The positions of the front of the displacement of natural gas by nitrogen at various time points are given. According to the research results, the gas recovery coefficient for tail gas for var-ious options varies from 14,12 to 34,58 %. With the introduction of the technology of injecting nitrogen into the reservoir, the overall gas recovery coefficient increases from 72,25 % (at present development system) to 80,28 % when the residual gas is displaced by nitrogen.

Pore types in the Blue Nile shale from the Blue Nile Basin using FE-SEM Method: Contribution to understanding gas storage

Successful exploration and development of shale gas reservoirs have enabled the United States to ensure a predominantly domestic supply of gas for many years. Pore structures can significantly impact the mechanical and physical properties of the rock such as permeability, strength and durability. Understanding the microstructures of the rocks accurately and quantitatively is essential to petroleum engineering for evaluating and development of oil and gas, especially for the unconventional reserves with abundant interior nanoscale pores such as shale. The pore structure and morphology of twelve shale samples from the Blue Nile Formation in the Blue Nile Basin were carried out by apply-ing Field emission scanning electron microscopy (FESEM). FESEM is a widely used technique to examine pore structures in shale reser-voirs. The results of FESEM show that the Blue Nile shale samples have nanoscale pores which can be classified into four types: inter-particle pores, organic pores, intra-particle pores and micro-fractures. The common types are inter-particle pores between the clay particles and organic nano-pores. These pores are all large enough to store gas molecules.

It's not how new you make it, but how you make it new

Before the “;mathematics revolution” of some fifteen years ago, the emphasis of instruction in school mathematics was almost entirely on the “how” of manipulation. Little or no attention was paid to the “what” and “why” of understanding. Since then the efforts of committees and of individual teachers have effected changes both in curriculum content and in teaching techniques. These cha nges were designed to make basic understanding, as well as significant manipula tion, a fundamental responsibility of all levels of instruction. No longer is the teaching of mathematics designed to result merely in a catalog of rules for mechanical application. Ra ther, it is designed to develop, a long with a facility in use, a comprehe nsion of and an appreciation for bas ic concepts. Further, it is designed to develop an understanding of the purpose and function of opera tional procedures that they may serve as resource reser voirs for intelligent attack on problem situations whenever and however they may occur. Thus the underlying philosophy of this new emphasis in instruction is to present mathematics as an important, logically structured segment of our cultural heritage rather than as a tool kit of rules, formulas, and assorted mnemonics.