SU947412A1 - Cable-suspended apparatus for investigating formations in uncased wells - Google Patents

Description

The invention relates to oilfield geophysics, namely, devices for sampling formation fluid from open hole walls.

A cable arrangement is known in which the selection of formation fluids is carried out in an airtight container under a depression equal to the formation pressure l.

Such a sampling regime does not allow obtaining high-quality materials for determining the hydrodynamic properties of a reservoir (in particular, permeability) due to the dissolution of the sample caused by a major depression to the reservoir.

Devices are known in which special hydroresistance is used to reduce the depression to the formation. In such devices, the withdrawn fluid is transferred to the separation powder, the cavity under which is filled with the working fluid, while the latter is displaced into the additional container through the Kshibirovanny fitting (hydroresistance). In these devices, a set of calibrated fittings is used, since each hydroresistance can be

effectively used only in the y: eko permeability range of 2j.

When using such devices, it is necessary to know in advance the value of the emitted parameter, i.e. permeability, which complicates their use and reduces the effectiveness of research. In addition, the devices are very labor-intensive for the process of research, since they allow to investigate only one point of the reservoir in one trip operation.

It is also known a cable-based device for investigating formations in superfluous wells, comprising an electric drive, a plunger pump with suction and discharge channels and valves, a decentralizer,. metiruyuschee element and probiorem nick Z.

In this device, the formation of a depression on the formation is carried out using a hydraulic drive, which allows multiple exploration of the formations. The amount of power transmitted to the electric drive of such a device is ligated by the characteristics of the cable, and therefore the magnitude of the depression to the reservoir, at a constant pump flow rate, is also limited. With low reservoir properties, as well as with the loss of a mudcake from a well wall, at the beginning of studies of this magnitude, depression may turn out to be insufficient, which is not. allows to cause influx from reservoir. At the same time, with good reservoir properties, no major depression is required to carry out the extraction from the reservoir, therefore, the power of the electric drive is not fully utilized, which ultimately reduces the quality of research results and leads to an increase in test time with a simultaneous decrease in research efficiency.

The purpose of the invention is to increase the efficiency of investigation of reservoir properties.

This goal is achieved by the fact that the device is equipped with an automatic depression controller installed in the channel between the suction and discharge channels and made in the form of a spring-loaded spool placed in a sleeve having a series of holes arranged along its axis, each of which individually communicates the suction channel with one from the suction valves of the pump, with the spool installed with the possibility of blocking the holes in the sleeve, and the cavity under it is hydraulically communicated with the discharge channel.

Supplying the device with an automatically controlled depression controller allows an unlimited number of reservoir studies with any reservoir properties. This is achieved because, depending on the permeability of the reservoir, the pump capacity, the number of active plunger pairs, is such that the depressions created by this cause the inflow of fluid from the formation to be called at a rate equal to the pump performance. The change in the number of active plunger pairs is made by a spring-loaded spool that is controlled by the pressure differential at the pump.

The drawing schematically shows the proposed device in its original position.

The device includes an electric drive 1 connected to the plunger pump 2, which is automatically equipped with a depression controller consisting of a sleeve 3 and a spring-loaded spool 4, a decentralizer 5 for pressing the device against the borehole wall, a sealing element b, an insulating section of the borehole wall when it is taken from it sample switch valve 7 to control the sampling process from the formation into the receiving chamber 8,

equipped with a separation piston 9 and sample ejection into the well. The receiving chamber 8 is communicated through the separation valve 10 with the cavity of the spring-loaded compensator 11, which maintains the well pressure in the hydraulic system of the device. In the sleeve 3, holes 12 are made, which connect the suction cavity of the pump with suction valves 13. The threshold of the cavity 14 of the receiving chamber 8 is filled with working fluid and is connected by hydraulic suction channels 15 and discharge 16 to the cavity compensator 11.

The device works as follows.

The device is lowered into the well in the initial position. After lowering it into the study interval, the hub 5 pushes the sealing element 6 against the wall of the well. Include the actuator 1 and the plunger pump 2 pump the working fluid from the receiving chamber under the compensator 11, compressing its spring. In this case, the piston 9 moves and fluid flows from the formation into the receiving chamber 8. During the selection process, pressure in chamber 8 and the speed of movement of piston 9 are measured (measuring equipment is not specified).

When testing formations with good reservoir properties, a large depression is not required to receive the inflow, and hence the force acting on the spool 4 is not sufficient to compress its spring, so it remains in its original position when all the holes in the sleeve 3 are open and the pump 2 gives maximum performance.

In the study of reservoirs with poor reservoir properties, it is necessary to create a major depression in order to obtain inflow from the reservoir. This means that under the action of a large pressure drop at the ends of the spool, compressing the spring and moving in the sleeve 3, closes one or more openings 12 connecting the suction cavity to the pump suction valves. Plungers that have the suction channel closed are turned off, therefore the number of active plunger: pump pairs is reduced, and hence its capacity decreases. Since the power applied to the pump is constant, the depression created by it decreases as the pump performance decreases. The lower the permeability of the formation, the higher the depression is needed to test it, which means that the Longer the plunger pairs are turned off by the spool and the lower the pump performance becomes. Therefore, with the help of the depression controller, the proposed device automatically selects the optimal mode of formation fluid selection depending on the reservoir properties. The distance between the holes in the liner and the characteristic of the spring are selected so that during all modes of pump operation, the amount of work done by him (i.e. the product of pump performance by the depression created by him) remains constant.

After taking one sample from the studied point of the reservoir, the switching valve 7 informs the receiving chamber 8 with the well, and the separating valve 10 - the compensator 11 with the receiving chamber. As a result, the working fluid from the cavity of the compensator under the action of the spring flows into the receiving chamber, from which the sampled sample is displaced into the well. By setting valves 7 and 10 to their original position, you can repeat the selection from this point in the reservoir. Similarly, all well intervals of interest can be investigated without lifting the device to the surface. If necessary, the selected sample can be brought to the surface.

The proposed device allows to significantly expand the range of studies of reservoir properties of formations, reduce research time, and, consequently, increase the efficiency of research with devices on the cable.

Claims (3)

1. A cable for investigating formations in open hole wells, comprising an electric drive, a plunger pump with suction and injection channels and valves, a decentralizer, a sealing element, and a test receiver, which is equipped with an automatic a depression controller installed in the channel between the suction and discharge channels. 2. The device according to claim 1, characterized by the fact that the automatic depression controller is made in the form of a spring-loaded spool placed in a sleeve having a series of openings located along its axis, each of which individually communicates the suction channel with one from the suction valves of the pump, with the spool installed with the possibility of blocking the holes in the sleeve, and the cavity beneath it is hydraulically communicated with the discharge channel. Sources of information taken into account in the examination 1. Author's certificate of the USSR 177375, cl. Е 21 В 49/06 ,. 1963. 2. US patent 3305014, cl. 166-3, pub. 1967. 3. Author's certificate of the USSR 149370, cl. E 21 V 49/02, 1960 (prototype).