Wells are used in the mining industry, in geological exploration, construction, and water supply. Therefore, depending on the purpose, the design of the wells has its own characteristics in each of the fields of application.
A well is a cylindrical mine, the diameter of which is much less than the depth, drilled using special equipment without human access to it from the surface of the earth to the bottom.
By the spatial location and purpose of the well, there are
- horizontal
- inclined and vertical,
- gas
- oil
- water intake
- artesian,
- overflow,
- supporting
- exploratory.
The design of the well is a diagram of its structure with an indication of the initial, intermediate and final diameter of the rock cutting tool, the depth, diameter and length of the casing strings, places and methods of plugging.
The successful construction of wells depends on the correct choice of its design. This is a very crucial moment. The reliability of the entire structure depends on the correctly taken into account working conditions, wear of the columns (casing pipes, fastening shafts) during the period of operation, the nature of loading.
The well design is being designed based on technical, economic and geological factors and depends on the goals, equipment, drilling techniques, depth and other factors. In this case, the geological structure of the rock section is invariably taken into account.
The most sophisticated borehole device . It consists of a mouth (beginning) and a bottom (bottom), a wall, an axis and a trunk, casing for various purposes (production and intermediate casing, conductor and direction).
The direction (the first, widest pipe in the well structure) serves to prevent collapse of the rocks around the wellhead when installing the conductor and erosion. The space behind the direction is filled with concrete or grouting mortar.
The conductor covers the upper part of the geological section and all those intervals that complicate the drilling process. It must necessarily block all layers saturated with fresh water.
Intermediate columns are needed to achieve the required depth. The production string (the last pipe string reaching the bottom of the borehole) is designed to take the fossil.
The design of the well is determined by the depth and diameter of drilling, the number, diameter and length of the casing strings, their wall thickness, the diameter of the trunk sections, and the angle of deviation from the vertical.
The most popular is the water well. Its design affects throughput and lifetime, it must be convenient to operate and minimally simple.
There are two types of wells for water intake: filter (up to 35 m) and deep (up to 100 m and more), they are also called "artesian".
A single-column well design is called if it consists only of a production string (bottom, in contact with the aquifer), two-column - if there is one intermediate and production string, etc.
According to the use of filters, wells are filter and open-hole.
The design of the well depends on its depth. The greater the depth, the more it looks like a telescopic antenna, descending with ledges of smaller diameter.
Filter wells are several times cheaper and easier to drill, but at the same time they lose in durability.
Requirements for well designs are specific and are in a rather complicated relationship. Therefore, their justification and choice is based on a thorough assessment of all factors.
The selected design determines the consumption of materials, the amount of work and significantly affects the cost of construction and operation.
Knowledge of the actual well designs made it possible to develop rational standard designs that allow the introduction of advanced drilling methods, use forced modes, and reduce accident rates.