RU2071541C1 - Device for drilling boreholes in sea bottom - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: device has inserted downface motor mounted in tube string foot. Body of motor is fixed in working position against turning relative to tube string. Connected to motor shaft is leading rock crushing tool, and expander is installed on tube string foot. String is made of casing tubes, and expander is installed on foot with possibility of free rotation on radial- thrust bearing. EFFECT: high efficiency. 1 dwg ЫЫЫ1

Description

 The invention relates to the field of drilling, namely, devices for drilling wells with simultaneous descent of casing strings.

 A device for drilling wells, including a pipe string, to the shoe of which an expander is attached, a hydraulic plug-in downhole motor, the casing of which is fixed in the working position inside the pipe string, a pilot bit attached to the motor shaft (ed. St. USSR N 395557, E 21 B 4/00).

 The disadvantage of this device is the inability to load rock cutting elements with sufficiently high loads. The pipe string is excluded from the process of loading rock-cutting elements with axial load during the operation of the downhole motor.

 The invention is aimed at solving the problem of increasing the efficiency of drilling. The use of the invention allows for additional loading of rock cutting elements with an axial load and at the same time eliminates the rotation of the pipe string, which are used as casing pipes.

 To do this, in a device for drilling boreholes at the bottom of the sea, including a pipe string, to the shoe of which an expander is attached, a hydraulic plug-in downhole motor, the casing of which is fixed in the working position inside the pipe string, a pilot bit attached to the motor shaft, the pipe string consists of casing pipes and the expander is attached to the pipe string by means of an axial radial bearing.

 The connection of the expander and the pipe string by means of an axial radial bearing allows the axial load to be transmitted to the rock cutting elements (expander) from the pipe string, excluding the rotation of the pipe, which prevents its failure in case of using casing pipes.

 The drawing shows a device for drilling wells in longitudinal section.

 An expander is mounted on the lower thread 1 of the shoe 2 of the pipe string (not shown), having cantilever 4 cones 4 on the legs 5. The expander is equipped with a swivel thrust radial bearing 6, which allows the expander to rotate freely relative to the casing string. The gap formed by the inner cylindrical surface of the rotating cages of the swivel bearing 6 and the outer cylindrical surface of the stator cages of the same bearing is sealed with an oil seal 7. The traverse 3 of the expander is mounted on a sub having a conical seat 8.

 A column of pipes descends into the sea water column together with a reamer mounted on the thread 1 (which can be both cone, diamond, and combined weapons).

 In the position “above the bottom” of the sea, at a distance of 1 10 m from it, a hydraulic plug-in downhole motor is discharged into the column. Its body 9 has an overall outer diameter of 3.5 mm smaller than the inner diameter of the casing. The motor shaft 10 has at its end a sub 11 to which a pilot bit 12 is attached, the outer diameter of which is 2 3 mm less than the bore diameter of the conical seat 8.

 The sub 11 has a mating conical surface corresponding to the conical seat 8.

 The upper sub 13 of the casing 9 of the hydraulic downhole motor has a lip seal 14 vulcanized to it, made of an elastic material (for example, reinforced rubber).

 After the engine has been dumped into the column, a flushing head is screwed onto the top of the column (not shown in the drawing), the pumps are turned on and the hydraulic motor is brought to the stop of the sub 11 in the conical seat 8. With this, the elastic seal cuff 14 is self-sealing.

 The body sub 13 of the engine 9 has a head 15 fixed therein. If the engine needs to be removed from the column to change the pilot bit 12, then the head 15 is captured by a rope overshot and when the flushing head is turned off, the engine is removed from the column.

Device operation
After the pumps are turned on and the lip seal 14 is absorbed by the pressure drop triggered in the engine and pilot bit 12, a spacer force arises between them and the inner surface of the column, sufficient to keep the motor housing 9 from rotating under the action of it reactive torque. The motor shaft 10 begins to rotate by rotating the pilot bit 12 mounted on it and, through the sub 11 and the conical seat 8, the expander. The process of deepening the column into the bottom of the sea is carried out in one step at 25-30 m (without rotation of the pipe string).

 Then the pumps stop; the flushing head is turned away and the pipe string is extended.

 The flushing head is again screwed onto the pipe string and the process of deepening the column into the bottom of the sea continues.

 After the specified depth of the column into the bottom of the sea is reached, the pumps are turned off, the flushing head is turned away, the rope overshot that captures the head 15 is dropped into the column, and the engine with the pilot bit 12 is removed from the column. Further, if necessary, the column is cemented at the bottom of the sea.

 With further deepening of the well (already using clay mud), the conical seat 8 of the expander is drilled with a bit, which further deepens the well. The metal from which the saddle 8 is made is selected so that it can easily be drilled with existing types of bits.

 The best embodiment is its implementation of aluminum alloy.

Claims (1)

 A device for drilling wells, including a plug-in downhole motor installed in the shoe of the pipe string, the casing of which in the working position is fixed against rotation relative to the pipe string, a pilot rock cutting tool attached to the motor shaft and an expander mounted on the shoe, characterized in that the string is made of casing pipes, and the expander is mounted on the shoe with the possibility of free rotation on a thrust radial bearing.