SU1439196A1 - Double drill string - Google Patents

Abstract

The invention relates to the drilling of exploration wells, namely, a column, and is intended to: - for drilling a well with an extension to the surface of a core mother; carry the connections of each column. from two pipe sections; contains the same length concentrically located 1SHR pipe pipe (t) 1 n ЗН1 Т-

Description

barks

L

The same T 2 and T 1 and 2 are displaced one relative to the other along the longitudinal axis and rigidly connected by centering ribs 3. Each section has stepped threaded sections at the ends: the inner U 4 on one and the outer U 5 on the other. At the same time, U 4 has a thrust end 6 on T 1 and a thrust ledge 7 on the inner surface T 2, and U 5 has a thrust ledge 8 on the outer surface T 1 and a thrust end 9 on T 2 "The number of threads of the thread engaged in the engagement T 1 and 2, is selected from the ratio Nc / Ng W, | where NH, Ng, n are the number of turns by T 1 and 2, respectively, W, Wm, is the moment of resistance of the cross section, respectively T 1 and 2. The column is expanded by connecting two-pipe sections in series. For this, a stackable section is inserted into the U 5 into the internal U 4 of the previous section. The threaded connection is tightened until the end face 9 is in contact with step 7 and end face 6 with step 8. 2 cpf-ly, 3 i.p.

one

The invention relates to the drilling of exploration wells, namely to twin drill strings designed for drilling wells with continuous removal of core material to the surface of the core material with an upstream flow of a cleaning agent.

The aim of the invention is to increase the reliability of the double drill string connections.

FIG. 1 shows a double pipe section of a double, drill string in FIG. 2 — connection of sections into a drill string | Fig, 3 - cut LA

in figure 2,

I

The double drill string includes double-pipe sections (FIG. O each of which contains identical outer 1 and inner 2 pipes concentric in length, offset from each other along the longitudinal axis and rigidly connected with centering ribs 3. Each section has at one end (upper) internal stepped threaded section 4, on the other (lower) step-like threaded section 5, threaded section 4 has a stop end 6 on the outer pipe 1 and an obtrusive ledge 7 located on the inner surface of the inner nd tube and a threaded portion 5 has upornsh shoulder 8 on the outer surface of the outer pipe and the abutment face 9 on the inner tube.

The number of threads of the thread engaged in the outer 1 and (

inner 2 tubes are selected from the ratio

NM

vc

Wbh

Wh

where N and Ngu are the number of turns

threads, respectively, on the outer and inner pipes;

W K and Wgj, is the moment of resistance of the cross section of the outer and inner pipes, respectively.

The double pipe section of the double drill string can be made as follows: 10 centering ribs 3 are welded to the inner pipe near the ends with a longitudinal seam, the pipe with ribs is inserted into the outer pipe, in which the grooves are cut at the points of contact with the ribs and through the weld 11 connected to the ribs, after which cutting is performed at one end of the outer section and at the other inner stepped threads (one thread level is located on the outer pipe, the other stage is inside pipe). Thread cutting is completed from one machine on a thread-cutting machine.

During operation, the double drill string transmits torque and axial load to the rock-destruction tool, and also ensures the delivery of a cleaning agent to

 U

the battle of the well and transportation of the destroyed rock (sludge) and core PA surface. The build-up of the drill string in the process of dredging a well or the descent of the string into the well is made by connecting two-pipe sections in series (Fig. 1). For this, the expandable section is inserted with an external (nipple) thread 5 into the internal (sleeve) thread A of the preceding section. The threaded connection (Fig. 2) is tightened until the stop end 9 contacts the stop step 7 and the stop end 6 and the stop step 8, which ensures reliable sealing of the drill string connection nodes and allows the external loads perceived by the column to be distributed between the external and internal ones. pipes.

Due to the rigid connection of the outer and inner pipes of each two-pipe section, external loads are distributed between the outer and inner pipes.

The step-by-step design of the joint assembly of two-pipe sections allows reducing the stresses arising in the thread of the column bend due to the optimal distribution of the thread windings on the outer and inner pipes in accordance with the ratio

WSH

Wh

de N, and NBM WH and WgH

the number of turns of the thread. respectively on the outer and inner tubes; moment of resistance of the cross section of the outer and inner pipes, respectively

96 Form

ula invention

Claims (3)

1, Double drill string for drilling with hydrotransport of the core, containing two-pipe sections, each of which is made of rigidly connected concentrically arranged external and internal pipes of equal length with external threaded sections at one end and with internal threaded sections RS with another, about m-l h and y shch and with to, that. in order to increase the reliability of the connection, the outer and inner tubes of each section are axially c axis one relative to the other, and the threaded sections at the ends of the sections form a single stepped threaded section. 2. The drill string according to claim 1, characterized in that the number of threads in the outer and inner tubes is selected in accordance with the ratio WH and Wg where N and Ng is the number of turns corresponding to the on and inside pipes; moment of resistance of the cross section of the outer and inner pipes, respectively 3. The drill string in n.l, which is related to the fact that the threaded sections of the tube have recess ledges, one of which is located on the outer surface of the outer pipe, and the other on the inner surface of the internal thread. -f Fiz.g