RU2549224C2 - Seismic logging tool "span-8" - Google Patents

Abstract

FIELD: physics; geophysics.

SUBSTANCE: invention relates to geophysics and can be used to detect wave processes in vertical and inclined wells during seismic profiling. The probe consists of modules having pistons, the space above which is linked with the medium outside the module housing. Under the pressure of the well fluid, the pistons move, thereby opening clamp levers and providing rigid contact of the device with the wall of the well.

EFFECT: high quality of recorded information and safety of operation when detecting seismic vibrations in cased and uncased wells.

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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 by methods of downhole seismic exploration.

To record fluctuations in wells, a downhole seismic probe is known (RU Pat. 2305299 C2 G01V 1/52 2006.01), divided into two or more modules: the first module is a power module, and the second and subsequent ones are receiving ones. Power and receiving modules are located in separate buildings. The cases of the power modules and all receiving modules must be interconnected by a strong flexible cable, an electric communication line and a high-pressure hose.

The power module housing houses an electric drive, a screw pair and a delivery piston, as well as an electronic unit.

In each receiving module, sensors and two executive (lower and upper) pistons are placed, to which the clamping levers are articulated. The space between the actuating pistons must be filled with incompressible fluid. The receiver module casing is fixed in the well when the clamping levers are opened and their ends are pressed firmly against the well wall at two levels. In this case, the housing of the receiving module is installed along the axis of the well.

The disadvantages of such a probe include the complexity of the design through the use of an electric motor, screw pair and high pressure hoses and, accordingly, a decrease in the reliability of the design and an increase in the cost of the probe.

The probe described in First break volume 23, October 2004 in the article “High resolution 3D seismic imaging using 3C data from large downhole seismic arrays”, authors Bjorn Paulsson, Martin Karrenbach and others.

This probe contains receiving modules connected to a receiving arrangement (similar to a seismic streamer), is lowered into the well with a tubing string. The pressing of the probe modules to the wall of the well is achieved by creating pressure in the liner located in the same column between the receiving modules and the wall of the column.

The advantage of such a probe is that it can contain a large number of receiving modules.

The main disadvantage of such a probe is the unilateral non-rigid pressing of the receiving modules to the wall of the well. Rigid contact of the receiving modules when unilaterally pressing them to the wall of the well substantially distorts the recorded seismic signals, i.e. reduces the quality of information received.

The aim of the invention is to improve the quality of information received.

To achieve this goal, it is necessary to ensure tight contact of the geophones with the borehole wall, placing them along the borehole axis by means of clamping arms.

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. A schematic representation of the proposed module of the downhole seismic probe is shown in Fig. 1.

The module comprises a housing 1, in which an upper chamber 2 is placed, connected to an environment external to the housing of the module; the upper piston 3, through which the channel 4 for extending the communication line; upper clamping levers 5 mechanically connected at one end to the upper piston and having rotating rollers 6 at the ends, provided with a brake mechanism; sensor block 7; a lower chamber 8 connected to an environment external to the module case; a lower piston 9 through which the channel 10 extends to extend the communication line; upper clamping levers 11, mechanically connected at one end to the lower piston and having rotating rollers 12 at the other ends.

The device operates as follows. Before lowering the device into the well, the clamping levers 5 and 11 must be folded along the module casing so as not to impede the descent of the probe into the well, and secured with a latch. In this case, the pistons 3 and 9 will occupy the highest position. After the probe is lowered into the well to a predetermined depth, at the signal of the operator, the latches release the clamping levers and under the pressure of the wellbore fluid entering the upper chamber 2 and lower chamber 8, the pistons 3 and 9 will move downward, opening the clamping levers 5 and 11 until they stop their ends into the wall of the well. Next, the operator includes a device (brake) that prevents the rollers from rolling along the borehole wall, while the probe module is firmly pressed against the borehole wall. Then the vibrations are excited and registered by the geophones installed in block 7. After the oscillations are recorded, the operator gives a command to release the rollers, and the probe is moved to register the vibrations at the next point and then the work cycle is repeated: the rollers are fixed at the new point, the excitation and reception are performed oscillations, then the rollers are released and the probe moves to a new point, etc.

Thus, the proposed design of the module of the seismic probe, which does not contain electric motors, screw pairs, simplifies the design, reduces the weight of the module and at the same time provides stable fixation of the probe in the center of the well, which helps to improve the quality of the information received.

Robust construction and ease of implementation ensure its effective applicability in industry.

Claims (1)

A downhole seismic probe containing receiving modules connected to a receiving arrangement, the contact of which with the borehole wall is achieved by creating external pressure in the liner located in the same column between the receiving modules and the casing wall, characterized in that the hard contact of the receiving modules with the borehole wall is made by means of clamping levers mechanically connected with the upper and lower pistons and moved due to the pressure created by the borehole fluid in the upper and lower chambers, communicating with the environment.