Vol 57 Iss. 2

The beginning of scientific, pedagogical and industrial activity of Doctor of Technical Sciences, Professor F. A. Shamshev coincided with a remarkable historical period in the life of our country - its transformation into a powerful industrial power Geological service, which before the October Revolution was only in its infancy, began to develop rapidly.

Until recently, the main way to combat the loss of flushing fluid, well wall collapses in rocky rocks broken by tectonic fractures, was casing. But, as it is known, the use of casing pipes is associated with loss of diameters, so under difficult geological conditions, multi-column well designs are obtained and initial diameters are increased. This leads to additional complications, as the basic rule of drilling is violated: the smaller the diameter of wells, the less wall collapses and the more productive the work is, all other things being equal. Currently, this provision is generally accepted, in connection with which in all countries are moving in the exploration of solid minerals to drilling with drill bits d 46-59 mm in one-stage design of wells, ie, fix the upper unstable rocks pipes, and then drilling is carried out without casing.

Until recently, quick-setting mixtures were virtually non-existent. (BSS) for perennially frozen rocks. In this connection in the Leningrad Mining Institute were conducted experiments on the development of such mixtures on one- and two-salt basis.

In recent years, when drilling wells for water as a production string is increasingly used pipes are not steel, but from other, cheaper materials. At opening of mineralized waters refusal from application of steel pipes is a necessary condition for normal operation of wells. In this case asbestos-cement, plywood glued and plastic pipes are used for fixing well walls. At present the electrochemical method of well wall fixing is being mastered.

The problem of the rate of penetration in rotary drilling of hard rocks with a sharpened cutter is reduced to the establishment of the general dependence of penetration H on time t at given parameters of the drilling mode: axial load c₀ and the number of revolutions n and to determine the initial rate of penetration v₀ ...

Permafrost is spread on the area of about 49.7% of the USSR territory. Drilling of boreholes in frozen rocks is connected with a number of specific difficulties. Weakly bound loose Quaternary sediments, as well as destroyed bedrock cemented in the frozen state by ice, are very sensitive to violation of their temperature state. When ice thaws, such rocks lose cohesion and stability and may become fluid. Any frozen rocks, including monolithic and stable rocks, are accumulators of huge reserves of cold, which also significantly complicates the processes of conducting wells.

Constant improvement of exploratory well drilling technology, caused by increasing depths of exploratory wells, as well as the ever-increasing complexity and diversity of geological and technical conditions, has led to the creation of a large number of different flushing agents. Currently used flushing agents - from air and natural gas to weighted clay solutions - have very different physical properties that have a significant impact on the drilling process and the main indicators of drilling.

The intensity of rock destruction in rotary-impact drilling depends, as is known, on a number of factors, the most important of which are the energy and frequency of impacts, the magnitude of axial load and the speed of rotation of the tool. The joint action of these factors causes a very complex nature of the drilling process, which makes the study of its regularities very difficult. Insufficient study of the mechanism of rock destruction and the process of interaction of the tool with the rock during rotary impact drilling restrains the development of this effective method of drilling.

The purpose of simultaneous with the drilling process of freezing of passed melted rocks is to ensure their monolithicity and strength, which makes it possible to avoid complications associated with the instability of loose wet rocks, and to obtain a high core yield.

Due to increasing depths and intensification of drilling processes there is a practical necessity to take into account thermal phenomena in drilling wells. The temperature of the flushing medium becomes one of the main factors determining the success of drilling operations.

“The area of the Deputatskoye field, where drilling was carried out, is composed of lithologically monotonous sediment strata dislocated in large gentle folds of sublatitudinal and northeastern strike. In terms of physical and mechanical properties that determine the choice of diamond tools, the rocks composing the deposit can be divided into three main groups: 1) heavily crushed, often crushed medium- and fine-grained sandstones and sandy-clay shales cemented with calcareous material and ice, VІІІІ-ІХ categories of drillability; 2) sandy-clay shales of VІІІІ category of drillability; 3) dense occluded, in some places keratinized fine-grained low-abrasive sandstones of X-XІ categories of drillability.

The most important task of exploratory core drilling is to ensure high yield and quality of core - source material for geological and engineering-geological sampling. Analysis of production data of a number of organizations engaged in drilling in permafrost rocks shows that when drilling with flushing the core yield is 60-70% for bedrock with moisture content of 2 - 5% and 20-30% in rocks with moisture content of 15% and more. In production conditions very often in order to increase the core yield one switches to “dry” drilling. However, the core quality deteriorates sharply. Partial or complete thawing of the core takes place with violation of its structural characteristicsю

Due to the special sensitivity of diamonds to the temperature factor, compliance with the normal thermal regime of diamond bits during drilling is one of the main conditions for their efficient operation. The normal thermal regime should be considered to be such a thermal regime at which the diamond heating temperature does not reach the value causing their oxidation, graphitization or deformation due to temperature stresses.

At electrochemical consolidation of unstable rocks in boreholes, tubular and sliding electrode designs are usually used. Tubular electrodes are the most widely used.

Creation of cement pipes directly in the wellbore is an actual problem. Cement casing can act as a production string when drilling for water, as well as cover certain complicated zones associated with collapse of well walls or absorption of flushing fluid.

Nowadays in prospecting and exploration drilling the methods of sinking loose rocks based on their compaction are becoming more and more widespread. Such methods include squeezing and vibratory drilling. These methods are applied at penetration of rocks of I-III categories on drillability for classification of rotary drilling and have high mechanical speed.

Successful testing of technical means and technology of drilling wells with bottom-hole cleaning by cooled compressed air, developed by the department of TTBS of LGI under the contract with the Dalstroyproekt Institute (Magadan), allowed drilling by this method in production conditions and give a preliminary assessment of its economic efficiency in comparison with the method of drilling wells in frozen rocks “dry”, i.e. without bottom-hole cleaning by any circulating agent.