RU2523096C2 - Span-7 borehole seismic probe - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in the probe case there is an electric drive, seismic vibration sensors, a pressure piston, the upper and lower slave pistons with a compensating piston placed in the upper one. Space between the pressure and upper pistons as well as between the upper and lower slave pistons is filled with incompressible liquid. The probe case is equipped with holding arms spread along its length.

EFFECT: simplification of the probe structure, increase in safety of borehole measurements.

1 dwg

Description

The invention relates to the field of knowledge of vibrational motion and can be used to record seismic vibrations in wells propagating in rocks during work using vertical seismic profiling (VSP) or non-longitudinal vertical seismic profiling (NVSP) methods. With VSP, the excitation of vibrations is performed at points close to the wellhead, and with NVSP - at remote points.

A well seismic device (A.S. 1073725, class G01V 1/52, 01/30/86), consisting of a housing in which an electric drive is located, including an electric motor and a gearbox, a screw pair and two clamping levers, is known for recording vibrations in wells. the device is rigidly fixed in the well, pressing against its wall. The presence of two clamping levers, firmly pressing the device to the wall of the well from two directions, significantly increases its stability when receiving vibrations. However, the displacement of the device from the axis of the well to the wall leads to its asymmetric position relative to the axis of the well, which generates anisotropy of sensitivity, i.e. dependence of sensitivity on the direction of wave approach. Anisotropy of sensitivity leads to a distortion of the dynamic parameters of the recorded waves (amplitude, frequency, etc.) i.e. the contact of the device with the medium, performed by such a clamp, has a circular sensitivity diagram that does not coincide with the circle. In addition, due to the unevenness of the borehole walls, the cylindrical body of the device is pressed against the borehole wall of the entire cylinder generatrix. As a result of which a situation often arises when one of the ends of the device or both ends remain free, i.e. not pressed against the wall of the well. In this case, they will be the sources of resonant interference that will occur during registration of excited oscillations.

Known patent RU No. 2305299 IPC G01V 1/52 for the invention "Downhole seismic probe" SPAN-6 ", adopted for the prototype, which contains at least two modules, one of which is power, and the other are receiving. Power and receiving modules are located in separate buildings. The housings must be interconnected by a strong flexible cable, an electric communication line and a high pressure hose. An electric drive, a screw pair and a delivery piston, as well as an electronic unit must be located in the housing of the power module.

Sensors registering the oscillations of the probe together with the surrounding rock, and a mechanism for clamping the probe to the borehole wall, ensuring hard contact of the receiving module housing with surrounding rocks, should be placed in the housing of the receiving module.

The disadvantage of this probe is the need to use a high-pressure hose connecting the power module to the receiving module instead of the standard logging cable, which complicates the design of the probe, reduces the level of work safety due to possible destruction of the hose during transportation of the probe in the well.

The aim of the invention is:

- simplifying the design of the probe by eliminating the use of high pressure hoses:

- increase the level of safe work at the well.

To achieve this goal, it is necessary to place in one housing an electric drive, a screw pair, a rod that is connected to a discharge piston, sensors, discharge and actuating pistons, to which the clamping levers are fixed, as well as seismic vibration receivers.

The applicant does not know the technical solutions that distinguish the claimed solution from the prototype, therefore, we can conclude that it meets the criteria of "Novelty" and "Inventive step.

Schematic representation of a borehole seismic probe proposed by S. Antipin and Antipin G.S. (and therefore referred to as the “Antipins Borehole Tool - SPAN-7”) for the case where the power module is located between the clamping levers, is shown in FIG.

The probe comprises a housing 1, in which a discharge piston 2, an upper 4 and a lower 10 actuating pistons are placed, which are movably connected to the pressure arms of the upper group 5 and the lower group 11, respectively, in each group there are three pressure arms pivotally connected to the probe body, an electric drive 8 with a screw pair 6 and an electronics unit 9, the space 3 between the discharge piston 2 and the upper actuating piston 4. and also the space 7 between the actuating pistons 4 and 10 is filled with an incompressible fluid at the end of the lower housing commoners auxiliary piston 12, which end communicates with the external environment, and one or more compensating pistons placed in the upper actuating piston 13.

The device operates as follows. Before the device is lowered into the well, the injection piston 2 should occupy its highest position. In this case, spaces 3 and 7 will create a vacuum and fluid pressure under the lower plane of the injection piston 2 in space 3 and, accordingly, in space 7 will be reduced. In this case, the clamping levers 5 and 11 in each group are located along the device body.

Then the device descends to a predetermined depth of the investigated well. At this depth, power is supplied to the electric drive 8 and through the screw couple 6 the pressure piston will move to the center of the probe. Under the action of the arising pressure in the space 3, the piston 4 will move to the lower end of the probe, opening the clamping levers 5 and creating pressure in the space 7, which will cause the piston 10 to move, as a result of which the clamping levers 11 will open. and the lower groups is achieved using a compensating piston 13, which operates as follows. There are two options for the process of pressing the levers to the wall of the well. In one case, the upper group of levers has already reached the wall of the well, and the lower has not yet reached. Then the movement of the actuating piston 4 will stop and it will not create pressure in the cavity 7 and the pressure created by the delivery piston will set the compensating piston in motion, which will equalize the pressure in the cavities 3 and 7. Equal pressure in the cavities 3 and 7 will ensure that the pressure forces are equal upper and lower level.

In another case, the walls of the well first reach the lower group of levers. Then, the actuating piston 10 will not move and the injection piston, creating pressure in the cavity 3, will only move the actuating piston 4 until the levers of the upper group reach the borehole walls.

After pressing the levers in the upper 7 and lower 11 groups to the wall of the well with a predetermined force, which is determined by the amount of current consumed, the electric drive is turned off, and excitation and registration of vibrations are performed by sensors located in the container 9.

At the end of the measurements, the electric drive is turned on to move the pressure piston up. As a result, a vacuum is created in the cavity 3, the actuating piston will move upward, weakening the pressure of the upper group levers to the borehole wall and creating a vacuum in the cavity 7. In this case, the actuating piston 10 will also move upward, weakening the pressure of the lower group levers on the borehole wall. An additional force to move the upper and lower actuating pistons creates an auxiliary piston 12, perceiving the pressure of the well fluid.

The movement of the actuating pistons 4 and 10 leads to the folding of the clamping levers 5 and 11 along the body of the device and they will not impede the movement of the device in the well. After that, the probe on the cable rises up to a new point of vibration reception and the cycle of work is repeated.

Claims (1)

     A downhole seismic probe comprising a housing, an electric actuator with a movable rod, and two groups of clamping levers spaced along the length of the device, characterized in that the electric actuator, a screw pair, the rod of which is connected to the discharge piston, sensors and two actuating pistons, are located in one probe housing Of these, a compensating piston is placed, the space between the discharge and one of the actuating pistons, and also between the actuating pistons, is filled with an incompressible fluid.