Petrography of bottom rock material

The Quaternary sediments of the Barents Sea contain a large amount of coarse clastic bottom rock material (BRM), with varying degrees of grain roundedness. Its study is important in determining the type and composition of the earth's crust, with paleogeographic constructions and revealing data on the dynamics of the ice cover. Studies of the Barents Sea BRM began in the 20s of the last century. During this period, were formed basically two hypotheses about the relationship between the distribution of BRM with elements of the sea topography and bedrock exposure. One of them considers BRM a marker suitable for identifying petrographic provinces at the bottom of the Barents Sea [Klenova, 1960]. In this chapter, on the basis of new up-to-date data obtained in 67 and 68 cruises of the RV Akademik Mstislav Keldysh in 2016–2017, the grain size, petrochemical and mineral compositions of BRM are estimated, their distribution patterns are given, transportation methods are analyzed and its feasibility is evaluated use in geological mapping. 4,193 samples were processed in Quaternary sediments, among which 86 reference types were identified. It was shown that the diversity of the composition of the Barents Sea BRM depends on glacial and ice-ice spacing. Therefore, the use of BRM for geological mapping of the bottom of the Barents Sea is unsuitable. The petrographic composition of the BRM in different regions of the Barents Sea is subject to significant fluctuations, but in general it is complementary to the set of rocks in the areas of demolition of adjacent land and depends on the extent of exaration and the removal of exaration material by the glacier to sedimentation areas.

DEVELOPMENT OF A MODIFIED SELF-EXTENDING MIXTURE FOR INCREASING STABILITY OF ROCKS

Purpose. Search and analysis of rational forms of bottom rock strengthening at their block-discrete structure in the conditions of intensive raising in underground mine roadways. Method. The research methods used are a comprehensive approach, which includes: laboratory research on structural models, computer processing, analysis and interpretation of the results. Results. The urgency of the direction of increasing the stability of the rocks in bottom of the mine roadways by their local directional strengthening is indicated. The method of structural modelling conducted a series of studies on the installation, which was designed and assembled for the research. The influence of different schemes of strengthening block rocks in bottom of the mine roadways on the rock raising, vertical and horizontal convergence is determined. By comparing the areas of displaced rocks, calculated using a graphical editor, a conclusion was made about the effectiveness of each of the comparative hardening schemes. As a result, the scheme of hardening is determined, which allows restraining as much as possible the displacement of rocks into the roadway cavity. Scientific novelty. As a result of research it was found that when creating a bottom of the mine roadways, which is maintained in the conditions of repeated violation of its equilibrium state, a fortified zone in the form of a straight prism with the triangle of its base facing the bottom of the roadways, the volume of rocks extruded less than for the no-action model. The given form of the strengthened zone is the most effective. Practical meaning. A new method of local strengthening of bottom rocks, which can be represented by a block inhomogeneous medium, has been developed.

Study on temperature field of thermal cracking drilling flow field under the condition of bottom hole submerged jet

In the deep well bottom hole environment, there are several different substances in the process of pyrolysis drilling, such as high temperature supercritical jet medium, cooling water and cuttings, which can be considered as submerged non free jet of supercritical fluid in low temperature environment. From the energy point of view, there are heat transfer between supercritical fluid and cooling water, heat transfer between supercritical fluid and bottom rock surface, and heat transfer between up flow and well wall. Due to the complexity of the components, the transfer process of these energies is very complex, which has an important impact on the efficiency of thermal cracking drilling. Therefore, it is of great significance to study the heat transfer law under the condition of bottom hole submergence.

Analysis on the Influence Factors of Well Deviation in Gas Drilling

Well deviation control has become a bottleneck restraining the development of gas drilling. Without lubrication of drilling fluid and the existence of negative pressure differential, the reasons of well deviation in gas drilling are different from in mud drilling. The effects of stress distribution difference, rock-breaking mechanism, well bore enlargement and water export on well deviation during both gas drilling and mud drilling are compared and studied on the basis of the previous studies in this paper. The conclusion demonstrates that the new stress state of the bottom rock, the uneven crater which is formed by rock breaking and the borehole enlargement are the main causes of well deviation during gas drilling.

The Rock Failure Mechanism of Air-Decked Blasting in Hole Bottom

The application of air-decked blasting technology has enabled the efficient use of explosion energy, which proves that the air-decked blasting technology can overcome many disadvantages caused by column charge effectively, getting ideal explosion effect. Based on the JHC model of concrete damage evolution, the dynamic stress characteristics and failure mechanism of blast-hole near-field about bottom-air-decked charge structure is studied by numerical simulation. Result shows that the failure mechanism of typical elements changes from compression-shear failure into shear-tensile failure gradually with the increase of their position, for the effecting factors of the freedom and the loading from the hole. Comparing the dynamic stress characteristics of different detonating manners, indirect initiation can improve the static function intensity and delay the time of detonation gas, so it is easier to destroy the bottom rock of hole.

Intensité et stabilité d'aimantation des basaltes de l'Oregon et Washington et leurs applications à l'expansion du fond de l'Océan et à d'autres problèmes géophysiques

It is shown that the intensity and stability of magnetization of reversed and normal Upper Tertiary lava flows from the United States of America can be summarized by average decay curves of very simple form. When first measured the intensity of normally magnetized specimens is one third greater than that of reversely magnetized specimens, and this is interpreted as being due to secondary viscous components (mean intensity 0.77 × 10−3 gauss) imposed by the recent field on a stable primary component (mean intensity 3.02 × 10−3 gauss). The differences between normal and reversed samples in low demagnetizing fields (<100 Oe) can be used to discover polarity in unoriented rock, and this could be useful in the study of dredge samples from the deep oceans, where, in order to test the hypothesis of ocean floor spreading it is desirable to relate the bottom rock polarity to the sign of the field anomaly observed at the surface. After demagnetization in alternating magnetic fields of 100 Oe (peak), the secondary magnetization disappears and the stable magnetization in normal and reversed samples is indistinguishable whether in its magnitude or its decay characteristics. This suggests that the mean intensity of the field at the time of extrusion was the same irrespective of polarity, and that the mineralogical variations (notably oxidation) affecting remanent intensity are the same in both normal and reversed rocks. The coherent decay of both secondary and primary components suggests a new method of determining intensity of the field in the geological past.

THE MOLLUSCAN FAUNA OF MEACH LAKE, QUEBEC

The shallow water zone (0–10 ft.) of Meach Lake provides three types of bottom:— rock, sand and mud. Certain species of mollusca live in all three habitats, some in two and some in one. Seventeen species were found, two of which were confined to the drainage. Nine of the seventeen are recorded for Meach Lake for the first time. The number of species and the size of individuals are both smaller in the inlet and in the streams flowing into the lake than in the lake itself. A dwarfed fauna occurs at the outlet. One species has apparently disappeared from the lake in a period of two years.