RU2029862C1 - Implement to check well shaft condition for casing string - Google Patents

Abstract

FIELD: well drilling. SUBSTANCE: device has a body and three sectors, installed one beneath others, which comprise three longitudinal plates evenly distributed over body circumference. The plates are displaced along circumference as to plates in adjacent sectors to generate the same clear cross-section along device. External surface of the plates in each sector is reinforced with pins of hard alloy. Total length of the sectors is determined by expression presented in claim. EFFECT: high speed drilling. 2 dwg

Description

 The invention relates to techniques for drilling a well, and in particular to devices for checking the condition of a wellbore of a drilled well.

 A well-known template for checking the borehole before lowering the casing using the following layout of the bottom of the drill string: three-cone drill bit, heavy drill pipe (UBT) 10-12 m long, three-cone drill reamer of the same size as the bit, UBT 10-12 m long, three-cone expander, the rest of the drill collars, drill pipes [1].

 The disadvantage of this design template is its complexity and low technology. In the case of the presence of ledges and protrusions in the wellbore, the indicated structure is not able to detect them, therefore, in practice there are cases of inadmissibility of casing strings after the well has been patterned with the indicated template design.

 There is also a known template for checking the condition of the well before lowering the casing using the following layout of the bottom of the drill string: three-cone bit, reamer, drill collar 10-12 m long, reamer, drill collar and drill pipes [2].

The disadvantages of this template are the design complexity, low technology and low reliability. It should be noted that the length of the working part of the expanders is in the range of 16-18 cm and they are located on the circumference of one relative to another at an angle of 120 ^about in three places. During the descent of such a design of the template into the well with ledges and protrusions, the passage of the template is possible without an obstacle, which makes it unreliable.

 Also known is a template for checking the condition of production casing containing a housing, sub, ring and plates [3].

 The disadvantages of this template are the design complexity, low technology and low reliability. The existing ring on the template when it is lowered into the drilled well will be the place of rock collection, thereby contributing to the deterioration of the smoothing of the walls of the wellbore and increase the low-tech design in operation. The absence of plates and elements on the working surfaces that increase the wear resistance of the template in operation does not make it possible to use it to smooth the walls of the drilled well bore when lowering it into the well, rotating the drill string, thereby reducing the reliability of the template in operation.

 The aim of the invention is to improve the quality of work due to the full coverage of the test surface with the study of the walls of the well.

l_ок, где I_ок - момент инерции обсадной трубы;
l_ок - средняя длина обсадной трубы;
I_с - момент инерции секции снаряда, определяемый по формуле
I_c = 0,025 d_н ⁴ + 0,032(D⁴ - d⁴), где d_н - наружный диаметр сектора снаряда, равный диаметру долота, используемого при бурении проверяемой скважины;
D - наружный диаметр корпуса снаряда;
d - внутренний диаметр корпуса снаряда.The goal is achieved in that the projectile is equipped with an additional sector, and the plates of adjacent sectors are displaced in the circumferential direction relative to each other with the formation of the same bore in the light between the plates, the outer surface of the plate of each sector is reinforced with carbide pins, and the total length of each sector l _c is determined in accordance with addiction
l _c =

l _ok , where I _ok - the moment of inertia of the casing;
l _ok - the average length of the casing;
I _c - the moment of inertia of the projectile section, determined by the formula
I _c = 0,025 d _n ⁴ + 0,032 (D ⁴ - d ⁴ ), where d _n is the outer diameter of the projectile sector, equal to the diameter of the bit used when drilling the tested well;
D is the outer diameter of the shell;
d is the inner diameter of the shell of the shell.

 In FIG. 1 shows a projectile for checking the condition of a wellbore in a section; in FIG. 2 is a section AA in FIG. 1.

The projectile consists of a sub 1, housing 2 and has three working sectors, each of which consists of three plates 3, 4 and 5, welded to the housing 2. The plates of adjacent sectors are displaced relative to each other in the circumferential direction with the formation of the same passage between the plates sections. As a result of such placement segment is formed with an angle 40 between the plates ^of the adjacent sectors. The outer surface of the plates 3, 4 and 5 is reinforced with carbide pins. The total length of the sectors is determined in accordance with the dependence given above.

 The projectile is lowered into the well using drill pipes. Due to the total length of three sections, taken in accordance with the dependence, it is possible to create a projectile of the necessary rigidity, providing high reliability of the process of checking the state of the wellbore of a drilled well before lowering the casing string into it.

 The implementation of the working part of the projectile with nine plates, on the working surfaces of which the outer diameter is equal to the diameter of the bit used when drilling the wellbore, eliminates the possibility of hydraulic fracturing of rocks and absorption of the drilling fluid when the tool is lowered into the well.

 Ensuring the reliability of control in the presence of carbide pins on the outer surface of the plates, the walls of the well are smoothed during the rotation of the projectile during its descent into the well.

Claims (1)

EQUIPMENT FOR CHECKING THE STATE OF THE BOREHOLE BORE UNDER THE COATING COLUMN, including the housing, the sub and two sectors mounted on the housing one under the other, containing three longitudinal plates equally distributed in each of them along the housing circumference, characterized in that, in order to improve the quality of work due to full coverage of the test surface with the study of the walls of the well, it is equipped with an additional sector, and the plates of adjacent sectors are displaced in the circumferential direction one relative to the other with the formation Clearance between the plates of the same flow section, the outer surface of each sector plates carbide reinforced with pins, and the total sector length l _c is determined according to the relation

where J _{about to} - the moment of inertia of the casing;
l _{about to} - the average length of the casing;
J _with - moment of inertia of the projectile section, determined by the formula
J _c = 0,025d $\genfrac{}{}{0ex}{}{\text{4}}{\text{n}}$ +0.032 (D ⁴ -d ⁴ ),
where d _n - the outer diameter of the sector of the projectile, equal to the diameter of the bit used when drilling the tested wells;
D is the outer diameter of the shell;
d is the inner diameter of the shell of the shell.

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