In 1988 more than 25.5 million meters of wells were drilled for solid minerals in our country. Obviously, this was the maximum for all the years of existence of the geological industry, and it is unlikely that such a volume of drilling will be achieved in the future. However, during the period 1968-1990 the volume of geological exploration drilling decreased by almost 3 million meters. What are the main reasons for the decline in drilling?
The fruitful activity of Academician D. V. Nalivkin is inextricably linked with such a milestone event in the history of the Soviet geological service as the creation of the geological map of the USSR. Although this did not exhaust the tasks of geological mapping, still the problem of erasing "blank spots" began to lose its acuteness. In the foreground came the tasks of improving the efficiency of geological exploration, in the solution of which the geological map has acquired the role of a kind of compass, helping to determine the direction of prospecting and exploration work.
For engineering geology it is very important to take samples of soil with undisturbed structure. Especially difficult in this respect is the sampling of monoliths from frozen soils in the process of borehole sinking. In order to work out the technology of drilling wells in frozen soils, experiments were set up, in the course of which the main difficulty was the choice of the method of control over the state of structure preservation in the process of drilling ...
Drilling operations at placer deposits are difficult due to the specific structure of placers. Incohesion, friability of sandy-pebble deposits, their water content, disorderliness, presence of boulders of different sizes complicate drilling in alluvial strata ...
Перспективные запасы месторождений ракушечниковых фосфоритов Эстонии и Ленинградской области оцениваются в 2—3 млрд. г. Генетически они связаны с толщей кварцево-оболовых песчаных отложений пакерортского горизонта раннего ордовика, распространенной почти на всей территории Эстонии и протягивающейся на 320 км восточнее ее (Ленинградская область). Мощность продуктивной толщи колеблется в пределах 1—6 м, средняя мощность 4 м. Фосфоритосодержащие песчаные отложения с размывом залегают на песчаниках, алевролитах или глинах кембрия ...
