JP2005256885A - Oil well pipe screw joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil well pipe screw joint that reduces flow resistance of fluid in an oil well pipe. <P>SOLUTION: This oil well pipe joint 10 connects oil well pipes 21 and 22 of different inner diameter to each other. An inner circumferential surface 12 at a seal shoulder part 11 abutted with an end part of the oil well pipe is formed in such a surface to fit to inner circumferential surfaces of the oil well pipes 21 and 22 at parts in contact with the oil well pipes 21 and 22, with middle parts smoothly changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil well pipe threaded joint for connecting oil well pipes to each other.

  Recently, the depth of oil drilling has been increasing, and the length of the oil well pipe tends to be longer. The oil well pipe is suspended while being connected by a joint. With long oil well pipes, the suspension load becomes large, and impact loads due to various causes cannot be avoided. Therefore, it is necessary to use a thick pipe for the upper pipe of the oil well pipe. Yes.

On the other hand, a threaded joint is generally used as a joint for an oil well pipe. In an oil well pipe that places importance on the sealing performance of the joint, a seal shoulder may be provided at the center of the joint. Conventionally, the seal shoulder provided at the center of the threaded joint has the same inner diameter because there is no difference in the inner diameters of the upper and lower oil well pipes (see, for example, Patent Document 1).
In such a conventional threaded joint, when the inner diameter of the connected oil well pipe is different, a step is formed between the inner diameter of the oil well pipe and the inner diameter of the seal shoulder portion of the threaded joint in a portion adjacent to the wall having a small wall thickness. . Such a level | step difference has a problem that it becomes a big flow resistance with respect to the fluid which passes the inside of an oil well pipe.
Japanese Patent Laying-Open No. 2003-74763 (page 7, FIG. 3)

  An object of the present invention is to solve the above problems and to provide an oil well pipe threaded joint in which the flow resistance of fluid inside the oil well pipe is reduced.

  The present invention has been made to solve the above problems, and is an oil well pipe threaded joint characterized by taking the following technical means. That is, according to the present invention, in an oil well pipe threaded joint for connecting oil well pipes having different inner diameters, a seal shoulder portion that abuts against an end portion of the oil well pipe to be connected is provided, and the inner peripheral surface of the seal shoulder portion is applied to the oil well pipe. The oil well pipe threaded joint is characterized in that the contacting portion is formed on a surface that smoothly matches the inner peripheral surface of the oil well pipe to be connected and the intermediate portion changes smoothly.

  The threaded joint according to the present invention has female threads that are engaged with male threads at the end of an oil well pipe to be connected at both ends, and a seal shoulder portion that is in contact with the end of the oil well pipe at an intermediate portion thereof. The inner peripheral surface of the end portion of the seal shoulder portion is made to coincide with each inner peripheral surface of the oil well pipe, and the intermediate portion is formed into a shape connected by a smooth curved surface. As a result, there is no step between the inner surface of the oil well pipe and the inner peripheral surface of the seal shoulder, and the fluid resistance passing through the oil well pipe is significantly reduced.

  Since the oil well pipe threaded joint of the present invention is configured as described above, there is no step between the inner peripheral surface of the oil well pipe and the inner peripheral surface of the seal shoulder, and the excellent effect that the fluid resistance passing through the oil well pipe is significantly reduced. Play.

  The present invention is an oil well pipe threaded joint formed so that the inner peripheral surface of a seal shoulder portion is flush with the inner peripheral surfaces of upper and lower oil well pipes having different inner diameters. Such an oil well pipe threaded joint can be manufactured by machining the inner peripheral surface of the shoulder into a smooth different diameter surface. In this oil well pipe threaded joint, the flow resistance of the fluid flowing inside the oil well pipe is prevented from increasing at the step portion between the seal shoulder and the oil well pipe inner surface, and the flow resistance is reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 shows that an upper oil well pipe 21 and a lower oil well pipe are formed by screwing a lower end male thread portion of an upper oil well pipe 21 and an upper end male thread portion of a lower oil well pipe 22 into a female screw of an oil well pipe joint 10. 22 is a cross-sectional view of a coupling portion that couples 22. Usually, the lower oil well pipe 22 and the oil well pipe threaded joint 10 are combined in advance with a predetermined torque, and the upper oil well pipe 21 is screwed on-site. The oil well pipe threaded joint 10 includes female threads that are screwed into the upper and lower oil well pipes 21 and 22, and a seal shoulder 11 at an intermediate portion. The upper and lower end surfaces of the seal shoulder 11 have recesses 15 and 16 in close contact with the roundnesses 23 and 24 of the end portions of the oil well pipes 21 and 22, and the oil well pipes 21 and 22 are coupled via the oil well pipe threaded joint 10. When this is done, the rounds 23 and 24 and the recesses 15 and 16 are formed so as to form a tight seal.

  FIG. 3 is a cross-sectional view showing an enlarged view of the conventional seal shoulder 11. The inner peripheral surface 13 of the seal shoulder 11 has a uniform diameter, and there is a step 14 with the inner diameter of the thick oil well pipe 21 on the upper side. This step 14 is a difference dimension in radius.

  FIG. 1 is a sectional view showing an oil well pipe threaded joint 10 according to an embodiment of the present invention. The inner peripheral surface 12 of the seal shoulder 11 of the oil well pipe threaded joint 10 is flush with the inner peripheral surface 25 of the upper thick oil well pipe 21, and the lower normal wall thickness oil well pipe 22 It is flush with the inner peripheral surface 26. The intermediate portion has a smooth curved surface, and the fluid flowing in the oil well pipe is a smooth flow with a low flow resistance.

It is sectional drawing which shows the oil well pipe threaded joint of an Example. It is sectional drawing which shows the part of an oil well pipe and a threaded joint. It is sectional drawing which shows the oil well pipe threaded joint of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Threaded joint 11 Seal shoulder 12 Inner peripheral surface 13 Inner peripheral surface 14 Level difference (difference of radial dimension)
15, 16 Roundness 21 Upper oil well pipe 22 Lower oil well pipe 23, 24 Recess 25, 26 Inner peripheral surface

Claims (1)

  In an oil well pipe threaded joint for connecting oil well pipes having different inner diameters, a seal shoulder portion that abuts the end portion of the oil well pipe to be connected is provided, and the inner peripheral surface of the seal shoulder portion is to be connected to a portion that contacts the oil well pipe An oil well pipe threaded joint, characterized in that it is formed on a surface that coincides with each inner peripheral surface of the pipe and in which the intermediate portion changes smoothly.

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