Product Description
Centralizers are devices that perform a support-centering function. Most often they are used where wells are drilled to take oil and gas. These devices are installed on the drill string or in the bottomhole motor, directing them in the right direction, which allows you to straighten the axis of the borehole, and if necessary, even change the direction of the well.
Centralizers Depending on the specific application, centralizers are divided into two types: columned and mobile. The former are respectively mounted on the column, and the latter on the engine. At the same time, columnar centralizers are used when drilling deep, even wells, and mobile ones - when creating deviated wells.
In addition to the centering and supporting functions, column centralizers also perform well calibration. They should be used when drilling the deepest wells, when the bit falls under a serious load. Columnar centralizers are made of chromium-nickel steel in the calculation of the most difficult geological conditions.
A special difference between the columnar centralizers is the execution: they have a monolithic design. At the same time, they are equipped with three special blades that have undergone reinforcement and pressing procedures. They diverge to the sides, touching the walls of the well. To increase the stability of the centralizer, the blades are framed with additional weapons at the ends. This feature also ensures long-term preservation of the centering capabilities of the device. In a complex, reinforcement and armament can increase the strength and durability of the product.
If columnar centralizers must be installed on the connection between the hardened drill pipes (UBT), then they are produced with two types of locks - external and internal thread. To mount the centralizer above the bit, both locks are made from the inside. The latter type of columnar centralizer may be provided with a cutting element for calibrating the surface of the well.
If necessary, change the direction of the well using mobile centralizers. They are made on the basis of the analysis of the assigned technological task. This takes into account the necessary level of stabilization of the wellbore and the angle of change of its inclination. Such centralizers consist of a main clutch, blades and collets. Six reinforced blades are located on the surface of the coupling. And the collet, having the usual tapered thread, is screwed into the coupling. This is usually necessary to secure the movable centralizer to the engine. When the coupling rotates, the collet begins to compress, reliably securing the motor housing. For the same purpose, longitudinal strips are made on the inner surface of the collet from an alloy of tungsten and cobalt.
The collet thread has a stepped type, due to which seizing occurs when reaching maximum screwing. As a rule, the degree of effort for this should reach 100-500 kN, and is different due to the moment of make-up, which is usually equal to 23 to 56 kN.m.
As you can see, mobile centralizers have a fairly simple structure, while performing a very responsible task. It is the simplicity of the device that guarantees the convenience of work and the necessary level of reliability.
It is certainly worth noting the marking affixed to the centralizers. It depends on the type of rocks through which the device is able to pass. For example, the MS marking indicates the possibility of a centralizer passing through soft rock formations having interlayers of medium hardness. Marking C indicates centralizers working with rocks of medium hardness, and the letter T marks centralizers for extremely hard rocks.
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