RU2291267C1 - Assembly of lower section of drilling column - Google Patents

Abstract

FIELD: drilling, namely, devices for driving inclined wells by turbine method.

SUBSTANCE: assembly of lower section of drilling column contains bit 1 with diameter DD, calibrator 2, with diameter DK, mounted on the shaft 3 of face engine, and localizer 4, having diameter DC, mounted on the body of face engine 5. Diameter of calibrator is determined from formula DK≤DC+L₂(DD-DC)/(L₁+L₂), where L₁ - distance from the end of bit to most remote point of working surface of calibrator, while L₂ - distance between most remote point of working surface of calibrator and closest point of working surface of localizer.

EFFECT: improved technical and economic characteristics of drilling due to provision of stable operation of bit, increased durability of bits and face engines.

2 dwg

Description

The invention relates to drilling, and in particular to devices for drilling directional wells in a turbine manner.

Known layout of the lower part of the drill string (BHA), including a bit with a diameter of DD, a calibrator with a diameter of DK mounted on the shaft of the downhole motor, and a centralizer having a diameter of DC mounted on the body of the downhole motor [1, 2, 3].

The calibrator is designed to calibrate the borehole wall, and the centralizer is used to create a deflecting force on the bit that is necessary to stabilize the zenith angle (angle of inclination of the well) or, if necessary, change it with the required intensity. In practice, calibrators are widely used whose diameter DK is equal to or close to the diameter of the bit DD. The inevitable result of using a calibrator with the indicated dimensions is that the calibrator becomes a supporting element, and the centralizer ceases to interact with the well wall; a gap is formed between it and the borehole wall. This gap is further increased while milling with the chisel of the upper wall of the well and the development of the lower wall by the calibrator, leading to the formation of an oval section of the well.

The proximity of the calibrator, which performs the function of a centralizer, leads to unstable operation of the layout: growth, stabilization (unreliable) and a decrease in the zenith angle of the well with an intensity that varies during drilling can be obtained. This is confirmed by numerous fishing data. The instability of the layout during the operation of the calibrator as a reference element is noted in [2, pp. 82-83], which indicates that the calibrator should not perform the function of the reference element. Nevertheless, these same authors recommend installing a calibrator with a diameter of 215.9 mm in the layout with a 215.9 mm bit ([3], Table 10 on page 80), and with this diameter it cannot but be a supporting element layouts.

Theoretical calculations give an unstable solution with unrealistically high values of the deflecting force when the calibrator is located close to it. In practice, this means that there is a rapid development of the upper wall of the well, and the bit together with the calibrator go into the development mode of its lower wall. Depending on the combination of numerous factors, the ratio of the phases of development of the upper and lower walls may be different, and as a result, the layout becomes unstable.

The problem to which the invention is directed, is to develop a layout of the bottom of the drill string, ensuring the normal operation of the centralizer and excluding the possibility of the calibrator working as a support element.

When carrying out the invention, the task is solved by achieving a technical result, which consists in improving the technical and economic performance of drilling by ensuring the stable operation of the bit, in increasing the durability of the bits and downhole motors.

The specified technical result is achieved by the fact that the layout of the bottom of the drill string contains a bit, a calibrator mounted on the shaft of the downhole motor, and a centralizer mounted on the body of the downhole motor, while the diameter of the specified calibrator is determined by the formula:

DK, DB, DD - the diameters of the calibrator, centralizer, bit, respectively; L ₁ is the distance from the end of the bit to the farthest point on the working surface of the calibrator, L ₂ is the distance between the farthest point on the working surface of the calibrator and the nearest point on the working surface of the centralizer.

The invention is illustrated by drawings, where in figure 1 presents BHA, figure 2 is a graph of stabilization of the zenith angle for various diameters of the calibrator.

The bottom hole assembly (BHA) contains a bit 1 with a diameter of DD, a calibrator 2 with a diameter of DK mounted on the shaft 3 of the downhole motor, and a centralizer 4 having a diameter DC installed on the body of the downhole motor 5.

To ensure normal operation of the centralizer, the dimensions of the calibrator should not protrude beyond the bounding cone of the BCH (Fig. 1). Cone generator (WEIGHT or FGOH) - a line connecting the point "B" of the calibrating part of the bit 1 (on the calibrating crown of the cone in the case of a cone bit) and the nearest point "C" of the working surface of the centralizer 4. Point E - the most distant from the bit 1 point of the working calibrator surface 2.

Satisfying this condition, the diameter of the calibrator 2 should not exceed the value determined by the formula following from the diagram (see figure 1):

L ₁ is the distance from the end of the bit to the most distant point on the working surface of the calibrator (point E);

L ₂ is the distance between the farthest point on the working surface of the calibrator (E) and the nearest point on the working surface of the centralizer (C).

Figure 2 shows the field data for the use of the layout, including the calibrator, the diameter of which is determined based on the claimed conditions (1):

DD = 215.9 mm; DK = 213 mm; DC = 212 mm; L ₁ = L ₂ = 0.6 m

From figure 2 it is seen that due to the use of a calibrator with a diameter that meets the proposed condition (1), a good stabilization of the zenith angle and high technical and economic performance of drilling are obtained.

The layout of the bottom of the drill string is as follows.

The centralizer 4, mounted on the body of the downhole motor 3, contributes to the creation of a deflecting force on the bit 1, providing the required low-intensity growth of the zenith angle or its stabilization, which is determined by the actual profile of the well. Calibrator 2, the diameter of which satisfies condition (1), while not being a supporting element, ensures that the centralizer 4 performs the functions described above.

The application of the proposed layout of the bottom of the drill string, taking into account the determination of the diameter of the calibrator, will allow you to: reduce costs associated with the deviation of real well profiles from design; improve technical and economic performance of drilling by improving the working conditions of the bit, increase the stability of bits and downhole motors, use worn calibrators and reduce the need for them by reducing the wear rate and the permissible degree of wear.

Information sources

1. Drilling of deviated and horizontal wells / A.G. Kalinin, B.A. Nikitin, K.M. Solodky, B.Z. Sultanov. M .: Nedra, 1997 .-- 648 p.

2. Sushon L.Ya., Emelyanov P.E., Mullagaliev R.T. Management of deviation of deviated wells in Western Siberia. - M .: Nedra, 1988 .-- 124 p.

3. Instructions for drilling deviated wells from well pads at oil fields in Western Siberia. RD 39-0148070-6.027-86. - Tyumen: SibNIINP, 1986. - 138 p.

Claims (1)

The layout of the bottom of the drill string containing a bit, a calibrator mounted on the shaft of the downhole motor, and a centralizer mounted on the body of the downhole motor, characterized in that the diameter of the specified calibrator is determined by the formula:

where DK, DC, DD are the diameters of the calibrator, centralizer, bit, respectively; L ₁ is the distance from the end of the bit to the most distant point on the working surface of the calibrator; L ₂ is the distance between the farthest point on the working surface of the calibrator and the nearest point on the working surface of the centralizer.

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