EP0143236B1 - Pump rods - Google Patents

Abstract

The sucker rod system in a deep well sucker rod pump consists of a plurality of unidirectionally reinforced composite fiber rods extending substantially parallel but not in contact with each other, the cross-sectional area of which rods is less than 1 cm2. This enables the advantageous material properties to be utilized to a high degree. The sucker rod system can be assembled on site. The individual composite fiber rods can be monitored when they are in the working position.

Description

The invention relates to a pump in which a piston hanging in a riser pipe on a pump rod is moved up and down in a pump housing at the bottom of the riser pipe by an above-ground pump drive.

With such pumps, the actual pump in the ground and the drive can be several 1000 m apart. The power transmission via the pump linkage ("sucker rods") is of great importance. The pump rod is usually screwed together from rods of standardized structural steel, for example 7.5 m in length. The pump linkage is very heavy.

Since the material to be conveyed can contain corrosive components, it is proposed in CA-A-1 087 521 and in US-A-4 360 288 to replace the steel rods with fiber composite materials. To enable the rods to be connected, steel sleeves are glued to the ends of the rods. In addition to the considerable manufacturing effort and the additional weight due to the sleeves, the connections are weak points which are still at risk of corrosion and which allow only a very limited use of the strength properties of the fiber-reinforced rods.

The object of the invention is to provide a pump rod assembly for pumps which avoids or reduces the problems which occur with known rod assemblies.

The object is achieved in that the pump linkage consists of several, essentially parallel, but not adjacent, unidirectionally reinforced fiber composite rods, each of which has a cross-sectional area of less than 1 cm ^{2 that} remains constant over the entire length. Developments of the invention are described in the subclaims.

This ensures in particular that no corrosion problems occur due to the material used; due to the elimination of the connecting sleeves, considerable weight savings occur, so that the drive power and the stability of the power transmission device do not have to be as high, and a further economic advantage can be achieved through the simplified assembly. The failure of a fiber composite rod does not immediately lead to the failure or destruction of the entire rod.

With this power transmission, only one connecting element is required at the top and one at the bottom, which are advantageously designed as clamping plate anchors.

Even if this element has to be made of expensive steel due to the corrosive environment, a very considerable price and weight reduction is achieved. With this linkage, the outstanding strength properties of the unidirectionally reinforced fiber composite can be exploited to a greater extent.

Because a linkage is constructed from several fiber composite rods, a simple adaptation to the requirements can be achieved in a simple manner by means of their number. In principle, a coiled endless strand of fiber composite rods, for example with a cross section of 0.75 cm ² , is sufficient to cover all practical tasks. The fiber composite rods run in any case from the lower clamping plate anchoring through to the upper end, since an adjustment of the cross section, as is sometimes done with steel rods, is not necessary and does not bring any cost advantages.

The composite fiber rods are made of unidirectionally-reinforced material, as described for example in EP-A-0000734 and as it is, for example, under the trade Polystal ^® commercially. All fiber composite rods with 70 to 85% by weight of continuous fibers made of glass fibers, carbon and aramid fibers are suitable. Epoxy, polyester, polyurethane and phenolic resins can be used as reaction resins. The bulk density is between 1.4 and 2.2 kg / dm ² . Areas between 20 and less than 100 mm ² , preferably 40 to 80 mm ² , are suitable as cross sections. The tensile strength is between 1000 and 2000 N / mm ² . The bending modulus is - based on the entire cross section - 40,000 to 20,000 N / mm ² . The fiber composite rods in the specified dimensions can be wound on drums. This significantly facilitates transport and feeding in the riser.

It happens that the borehole is not exactly vertical or is offset or curved in places. To compensate for such irregularities, the pump linkage according to the invention is extremely suitable. It can be useful to provide guide elements in the form of spacers on the linkage at several points in the riser pipe. They preferably consist of thermoplastic polymers which, for. B. can be attached to the pump linkage by clamping. The number and arrangement of the spacers can also influence the vibration behavior of the pump linkage.

The pump linkage in the upper region of the riser pipe can also be sealed in a similarly simple manner. The conventional “poling rod” requires the so-called “polishing rod”.

The pump linkage is insensitive to corrosion.

According to a development of the invention, each individual fiber composite rod can also be checked for its usability in the installed state. Even with particularly high quality material, it is often unavoidable under the given circumstances that individual fiber composite elements are damaged will. This had catastrophic consequences for the pump rods used up to now, because it can take several days for a pump to be recovered if the pump rod breaks. In the pump linkage according to the invention, it can at least be ascertained in a simple manner for each individual fiber composite rod whether it is broken if an indicator is embedded in the continuous production of the fiber composite; metallic or light conductors are preferred. The electrical resistance is particularly easy to measure. With light guides, you can roughly estimate how far a disturbed area is from the attenuation. Based on such measurements, the severity of a damage can be assessed and, for example, a linkage consisting of twelve fiber composite rods, in which only one fiber composite rod is destroyed, may be responsible for the continuation due to the oversizing, whereas the expansion can be considered without separate control.

The pump linkage according to the invention can also be combined from different fiber composite rods, in particular through different fiber content or through different types of fiber reinforcement. As a result, the vibration behavior of the pump linkage is influenced.

In addition, the individual fiber composite rods can also be covered with a thermoplastic, for example as additional protection against corrosion and mechanical damage.

• Fig. 1 schematische Darstellung der Pumpe;
• Fig. 2 Klemmplattenverankerung eines Gestänges aus sechs Faserverbundstäben;
• Fig. 3 perspektivische Ansicht eines Schnittes nach Fig. 2;
• Fig. 4 Abstandshalter;
• Fig. 5 Überwachungssystem der einzelnen Faserverbundstäbe mit eingelegtem Leitungsdraht.

The new pump is shown in the drawing in one embodiment and described in more detail below. Show it:

• Fig. 1 shows a schematic representation of the pump;
• Fig. 2 clamping plate anchorage of a rod made of six fiber composite rods;
• Fig. 3 perspective view of a section according to Fig. 2;
• Fig. 4 spacers;
• Fig. 5 monitoring system of the individual fiber composite rods with inserted wire.

The above-ground drive 1 moves the pump handle 3 with the so-called "horse head" 4 at the end via the crank rod 2. The pump linkage 5 is continuous without any intermediate connection and consists of a number of unidirectionally reinforced fiber composite elements. At the beginning and at the end they are gripped by the upper and lower clamping plate anchors 6 and 7; the connection to the horse's head 4 and the actual pump 9 is thus established via the wire rope 8. Spacers 10 are provided for guiding the pump rod 5. In the case of the prior art boom pumps, the upper area of the riser pipe 11 is sealed with a stuffing box 12 through which the polishing rod is guided.

In the pump according to the invention, a correspondingly long plastic cylinder 13, which serves as a "spacer" and takes over the sealing function, is provided as a polishing rod in this area. The riser pipe 11 is surrounded by a casing pipe 14 which is perforated in the lower region. The liquid is removed from the head 15 of the riser 11. The piston 16, the piston valve 17 and the foot valve 18 are indicated by the actual pump 9.

Because of the high strength of the unidirectionally reinforced fiber composite material, the formation of an appropriate clamping plate anchorage for force application is very important. Such an element for six round fiber composite rods 21 is shown in FIGS. 2 and 3. The diameter of a fiber composite rod 21 is 7.5 mm here. The anchoring consists of several superimposed clamping plates 22, 23, 24, 25, in which the fiber composite rods 21 are embedded, which enables a very good volumetric pressure. The clamping plates 22, 23, 24, 25 are clamped together by means of expansion screws 26. The expansion screws 26 also prevent the clamping plates 22, 23, 24, 25 from sliding against one another. The maximum load capacity of a fiber composite rod 21 is approximately 60 kN, the modulus of elasticity is approximately 50,000 N / mm ² ; in the case of a 2,000 m deep borehole, the weight of the unidirectionally reinforced fiber composite rods is approximately 1,200 kg; Clamping plates, polishing bar and spacers make up another 200 kg. So far, similarly powerful pump rods are unknown.

Fig. 4 shows a spacer 10 which is constructed essentially like a clamping plate anchor; the outer diameter is only matched to the inner diameter of the riser pipe 11, and plastic is usually used instead of steel. This prevents the rod from rubbing against the pipe wall in the event of damage or curved drill holes and improves guidance. The polishing rod is similar, but longer than a plastic spacer 10.

The monitoring of the individual fiber composite rods is shown schematically in FIG. 5. An electrical conductor 31 can be inserted into each rod 30 already during the production of fiber composite rods. For the sake of simplicity, only three fiber composite rods and the upper and lower clamping plate anchors 32 and 33 are shown schematically. The conductors 31 are each led out of the fiber composite rods 30 at the end. In the area of the lower clamping plate anchor 33, the conductors 31 are all connected to one another. The conductors 31 led out on the upper clamping plate 32 are connected to measuring devices 34.

The assembly of a pump rod is possible on site. The "continuous fiber composite rods" wound on winding drums are moved to the borehole. There, the ends of the fiber composite rods and the electrical control device with the pump-side clamping plate anchoring are first installed and connected to the pump. The pump is then drained into the borehole; the release speed is controlled by a braking device on the winding drum. If necessary, spacers are screwed on at certain intervals. When the pump has reached its position, the drive-side clamping plate anchoring is installed and connected to the wire rope mounting head of the pump horse head. Shortly before the pump end position is reached, the guide element, which acts as a polishing rod, is mounted on the fiber composite rods.

Claims (9)

1. Pump in which a piston (16) suspended to sucker rods (5) in an ascending pipe (11) is moved up and down in a pump housing (9) at the bottom of the ascending pipe (11) by a pump drive (1) situated above ground, characterised in that the sucker rods (5) consist of a plurality of unidirectionally reinforced composite fibre rods (21) which extend substantially parallel to one another but are not in contact with one another, each of which rods has a uniform cross-sectional area of less than 1 cm² over its whole length.

2. Pump according to Claim 1, characterised in that the sucker rods (5) are connected to the piston (16) and the drive (4) only by way of a lower and an upper clamping plate (7 and 6, respectively) serving as anchoring means.

3. Pump according to Claim 1 or 2, characterised in that spacers (10), preferably of a plastics material, are clamped to the composite fibre rod (21) to guide the sucker rods (5) in the ascending pipe (11).

4. Pump according to one of the Claims 1 to 3, characterised in that a plastics cylinder (13) is clamped to the composite fibre rods (21) to seal off the sucker rods (5) at the top end of the ascending pipe (11).

5. Pump according to one of the Claims 1 to 4, characterised in that each composite fibre rod (30) contains an electric conductor (31), the conductors (31) are connected together in the region of the lower anchoring clamping plate (33), and the conductors extend outwards in the region of the upper anchoring clamping plate (32) to such an extent that connections can be established to a conductivity measuring apparatus.

6. Pump according to one of the Claims 1 to 4, characterised in that each composite fibre rod contains a metallic conductor and the conductors extend outwards in the region of the upper anchoring clamping plate to such an extent that connections can be established to a measuring instrument for ultrasound measurement.

7. Pump according to one of the Claims 1 to 4, characterised in that each composite fibre rod contains an optical fibre cable and the optical fibre cables extend outwards in the region of the upper anchoring clamping plate to such an extent that a connection can be established to a measuring instrument for the damping of light.

8. Pump according to one of the claims 1 to 7, characterised in that the suction rods (15) consist of differing composite fibre rods, in particular rods differing in their fibres or fibre contents.

9. Pump according to one of the claims 1 to 8, characterised in that the composite fibre rods are covered with thermoplastic polymers.

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