JP2001329578A - Finishing method for well by circulative washing and partial surging device used for this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a screen section might be possibly collapsed when the water level in a well is abruptly lowered or swabbing is applied before a mud wall is fully removed in the finishing work of the well provided with a stable filter layer of sand and gravel having high water permeability and preventing the flow of sand in a stratum. SOLUTION: A submerged pump 2 is inverted upside down and stored in a case 1 provided with a case intake port 12 and packers 3 at the lower section. The case 1 is suspended in a well screen 4, and a large quantity of water is discharged from a discharge port 21 into filled gravel G and an aquifer W through the well screen to circulatively wash the filled gravel and aquifer. The circulated water and the underground water are sucked by the submerged pump through the well screen, the case intake port, and a pump strainer 22. Circulative washing is performed with a large quantity of water. A sand separator 23 and a jet nozzle 24 may be provided on the discharge side of the submerged pump. A partial surging device is used for implementing this method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for finishing a well by circulating cleaning and a partial surging apparatus used in the method.

[0002]

2. Description of the Related Art Conventionally, there are two typical well drilling methods. One is a rotary method in which muddy water is ejected from a bit tip by a pump through a rotating drill pipe, and crushed by the bit, cuttings are put on the muddy water stream and carried out to the ground. Another one is to suspend a heavy steel bit with a wire rope in a hole filled with muddy water,
A percussion method is used in which a vertical motion is given to the bit, the stratum is crushed by the impact, and the cuttings are carried out to the ground by a baler (a cylindrical tool with a valve at the bottom).

[0003] In any of the methods, the formation is analyzed based on data of a formation sample, an electric logging and the like collected during excavation. When the installation position of the screen and the selection of the gravel to be filled are completed, the casing and the screen are correctly installed at the center of the open hole, the gravel is uniformly filled around the casing, and the shape of the well is completed.

However, since the mud used during excavation adheres to the wall of the excavation hole to form a mud wall, the mud wall is completely washed and removed, and fine particles in the formation to be sampled are drawn into the well. The development of wells is required to integrate the gravel around the screen and the gravel in the stratum in a vigorous manner, and to form a stable filter layer of gravel that has high permeability and prevents the flow of sand in the stratum. Done. The finishing work of the well is very important, and it is not an exaggeration to say that the value of the well is determined by this method.
is generally performed as the simplest method.

In the well finishing procedure, first, water in the well is moved by a gentle operation, and mud walls are gradually disassembled and removed. If the water level in the well is rapidly lowered or rough work such as swabbing is performed while the mud wall is not sufficiently removed, the screen portion may be crushed, which is not possible.

Although a percussion excavator has a sand line for operating a baler for collecting cuttings in a hole, a baling operation can be performed. However, most rotary excavators do not have a sand line function. Therefore, since mechanical finishing work such as baling is omitted, and only the finishing by pumping is performed, a well dug by the rotary method generally does not completely remove the mud and sand around the outside of the screen. For this reason, the water level tends to be large and the wells tend to be inefficient, with poor drainage.

There are various finishing methods such as baling, pumping, swabbing, and other mechanical surging. However, even a method with a good finishing effect requires a large-scale apparatus, a long working time, and is not cost-effective. And the like.

[0008]

The present invention is more effective than the conventional finishing method, and can be used not only by a rotary type or a percussion type excavating machine but also by a winch using a three-pronged method. There is a need for a method that is short.

[0009]

According to the method of finishing a well by circulating cleaning according to the present invention, a submersible pump is turned upside down and housed in a case provided with a suction port and a packer at a lower portion, and this is placed in a well screen. Hang it down. A large amount of water is discharged from the outlet of the submersible pump through the well screen into the gravel and aquifer to wash the gravel and the aquifer. Water that has been washed and groundwater is sucked into the pump strainer from the aquifer through the well screen and the case inlet.

[0010] Even if the submersible pump is used upside down,
There is no mechanical problem. The reason for turning over is that if the discharge port of the partial surging device is above the suction port, sand from the aquifer may flow into the well from near the discharge port, damaging the submersible pump, and Is to prevent the possibility of accumulating on the packer and deterring the entire apparatus.

The case containing the submersible pump is hung in a well screen. The number of the discharge ports is preferably two or more, and is preferably arranged at an equal central angle, and the area of the discharge ports is large enough not to cause water erosion (erosion) on the well screen.

The well screen is preferably a conventional V-slot wire screen. This type of screen is constructed by arranging a plurality of rods on the same circumference at intervals and in parallel with each other, and welding wires outside of these rods in a spiral shape and maintaining a water collecting gap with each other. Have been. A pair of upper and lower packers is used to form a space for limiting the range of groundwater suction, elastic packing is attached to the outer periphery of the packer and the discharge port, and it comes into contact with the rod of the well screen, but it is connected to the wire. It does not touch and does not hinder the sliding of the device within the well screen.

[0013] Since the case suction opening is opened to an independent space by both packers, the washing efficiency of the aquifer is improved. In addition, there is no problem even if some sand is mixed in the submersible pump.

When the submersible pump is operated, a large amount of water is continuously circulated in the gravel and aquifer around the discharge port and the case suction port to clean the gravel,
Fine-grained sediment such as silt and fine sand flows toward the case inlet, and most of the particles smaller than the wire gap width of the well screen are sucked into the well to be efficiently finished.

In the case of the structure corresponding to claim 2, the sand separator and the jet nozzle are provided on the discharge side of the submersible pump having the structure described in claim 1. When the submersible pump is operated, a large amount of water is jetted from the jet nozzles to remove clogging materials on the well screen and to wash and recirculate while disturbing the gravel in the filled gravel and the aquifer. In this way, efficient high-speed jetting finish is performed, but if sand is mixed in the jet stream, the well screen will be eroded in the state of sandblasting,
It is necessary to provide a sand separator so that sand is not mixed in the jet stream.

In parallel with the finishing by jetting,
A large amount of groundwater is continuously sucked from the aquifer around the outside of the case inlet, and the water is used to wash the gravel, while fine sediment such as clay, silt, and fine sand flows toward the well, Most of the particles smaller than the wire gap width of the well screen are sucked into the well, and are finished by a large amount of continuous water absorption.

If the material is clogged on the well screen, it must be removed by high-speed jetting, and the finishing method using this configuration is suitable.

The method according to claims 1 and 2 can obtain excellent effects in a short time, and these methods can be applied from the lower part to the upper part of the well screen installation location, little by little in each local section. Move to finish.

When these methods, that is, partial surging and / or jetting, are performed, fine-grained sediment flows into the well from the filled gravel and the aquifer on the outer periphery of the well screen. The higher the height of the circular column of the gravel, the greater the pressing force exerted on the aquifer, and the finer the sediment becomes easier to flow, so that the finishing effect is greater. When the finishing is performed, as the fine particles in the packed gravel are removed, the toroidal column sinks and is replenished as needed from the ground. However, if finishing is done from the top first, the filled gravel circular column is divided at that position, and the pressing force of the filled gravel column above causes the aquifer to proceed with finishing after that. Less effective, reducing the overall well finishing effect. This is the reason for finishing from the bottom to the top.

According to a third aspect of the present invention, a partial surging device according to the present invention includes a case, a submersible pump, and a packer. The case is cylindrical and has a connecting portion at one end and a suction port at the other end. The submersible pump is housed in the case, the discharge port is below the case suction port, and the pump strainer is in the case and communicates with the case suction port. The packer is a pair of upper and lower parts, the outer diameter of which is adapted to the inner diameter of the well screen, each of which is disposed on the outer periphery of each end of the suction part, and the finishing area is limited to a local area.

The case inlet may have the same structure as the well screen, but may have another structure as long as it can support a pair of packers and secure a required flow rate.

The packer has a well-known structure in which the outer peripheral portion is made of an elastic material. When the packer is in the well screen, the outer peripheral portion contacts the inner wall surface of the well screen, and the inside of the well screen where the case inlet is located is moved. Partition into an independent space.
Therefore, the space is kept at a low pressure during operation of the submersible pump, and water and groundwater engaged in finishing work outside the well screen are effectively sucked.

The space partitioned by the packer and the flow area of the discharge port are large enough to sufficiently reduce the flow velocity of the water flow in the well screen.

According to a fourth aspect of the present invention, in addition to the third aspect, a sand separator and a jet nozzle for separating and removing sand from water are interposed on the discharge side of the submersible pump. In this case, when the clogging substance of the well screen is removed, the sand contained in the water sucked by the submersible pump is removed by the separator, so that even if the water is circulated and injected from the discharge port, the sand is removed. Can prevent damage to the well screen.

According to a fifth aspect of the present invention, in addition to the third aspect, an opening end of the discharge port is surrounded by an elastic cushioning material. In this case, since the discharge port is closely or close to the inner surface of the well screen, the washing water effectively flows into the gravel and the aquifer, and the washing effect is improved.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus according to the present invention will be described with reference to the drawings showing an embodiment of the apparatus. 1 is a case, 2 is a submersible pump, 3 is a packer.

The case 1 is cylindrical and has a connecting portion 11 at one end and a case inlet 12 at the other end.

The submersible pump 2 is housed in the case 1, and its discharge port 21 is close to the well screen 4, and the pump strainer 22 is in the case 1 and communicates with the screen type case suction port 12.

The number of the discharge ports 21 is four, arranged at a central angle of 90 °, and the shape is a nozzle shape. The outlet 21 is oriented at right angles to the well screen 4, that is, horizontally. The outer diameter of the packer 3 is a pair of upper and lower parts, and the outer diameter of the packer 3 is adapted to the inner diameter of the well screen 4. The outer diameter in this case is
It is approximately equal to the dimension between a pair of rods 41 diametrically opposed.

The case inlet 12 of the case 1 has the same structure as the well screen 4. The case 1 is connected to the suspension rod 5 at a connection portion 11 at one end, and is suspended from the case suction port 12 side into the well screen 4. In the well screen 4, the submersible pump 2 is vertical, with the outlet 21 down and the pump strainer 22 up. Discharge port 21 is case 1
From below and point the well screen 4.

The packer 3 has a well-known configuration in which the outer peripheral portion is made of an elastic material. When the case 1 is inserted into the well screen 4, the outer peripheral portion of each packer 3 approaches the inner wall surface of the well screen 4. The inside of the well screen 4 where the inlet 12 is located is partitioned into an independent space S. Therefore, during operation of the submersible pump 2, the space S is kept at a low pressure by suction from the case suction port 21, and groundwater including water engaged in finishing work of the aquifer W surrounding the outside of the well screen 4 is effectively removed. Inhale and concentrate the finish range.

The well screen 4 is a usual V-slot wire type, and as shown in FIG. 3, a plurality of rods 41 are arranged on the same circumference at intervals and in parallel with each other. The wire 42 is wound spirally and with a water gap 43 therebetween, and the joint between the wire 42 and the rod 41 is welded. The outer periphery of the packer 3 contacts these rods 41 but does not contact the wires 42, so that there is no problem in sliding the packer 3 in the well screen 4.

When the submersible pump 2 is operated, a large amount of water is sent from the discharge port 21 to the aquifer W through the water gap 43 of the well screen 4 on the one hand, and the case suction port 12 on the other hand.
A low-pressure region is generated around the discharge port 21 and the water that has washed the aquifer W has been washed once by the pump.
It circulates in the sand and gravel between the case and the case inlet 12 and performs washing again to enhance the finishing effect.

The water sucked from the pump strainer 22 is separated from the sand and discharged from the discharge port 21. By doing so, the clogging substance of the well screen 4 can be removed, and even if the water jetted from the discharge port 21 hits the well screen 4, the sand 42 is removed, so that the wire 42 is less likely to be damaged. .

According to the partial surging apparatus according to the present invention, the case 1 is provided with the submersible pump 2 for normal use.
The well screen 4 in which the case suction port 12 communicating with the pump strainer 22 of the submersible pump 2 is located by the pair of upper and lower packers 3 is partitioned into an independent space S. Therefore, the space S can be maintained at a low pressure during operation of the submersible pump 2, and groundwater including water engaged in finishing work outside the well screen can be effectively sucked.

In the case of another partial surging device according to the present invention shown in FIG. 2, a sand separator 23 and a jet nozzle 24 for separating and removing sand from water are interposed on the discharge side of the submersible pump 2. In this way, when the clogging substance of the well screen is removed, the sand contained in the water sucked by the submersible pump 2 is removed by the separator 23, so that the water is circulated and jetted from the jet nozzle 24. However, the well screen 4 can be prevented from being damaged by sand.

According to a fifth aspect of the present invention, in addition to the third aspect, the opening end of the discharge port is surrounded by an elastic cushioning material. In this case, since the discharge port is closely or close to the inner surface of the well screen, the washing water effectively flows into the gravel and the aquifer, and the washing effect is improved.

In the drawing, 51 is a clay layer, G is a filled gravel, 53 is a mud wall formed during excavation, 54 is a centralizer, 55 is a separator for generating a swirling flow of water in the separator 23. Spiral wings, 56 is the outlet for the separated sand,
57 is an outflow pipe of water from which sand has been removed.

[0039]

According to the present invention, by operating a submersible pump upside down in a well screen, a large amount of groundwater is sucked from the surrounding aquifer, and the gravel and aquifer are filled by the water flow. Wash the layer of gravel and finish,
On the other hand, a large amount of water is flowed from the discharge port of the pump toward the aquifer, and the gravel is washed while circulating between the suction part and the finishing effect is doubled. In this way, a better finishing effect can be obtained than with any of the previous methods.

According to the second aspect of the present invention, the injected pressure water removes clogging material of the well screen, and sand is removed from the pressure water. Less risk of damage.

According to the third aspect of the present invention, when the packer is in the well screen, its outer peripheral portion is close to the inner surface of the well screen, and partitions the inside of the well screen where the case inlet is located into an independent space. During operation of the submersible pump, the space is kept at a low pressure, and groundwater including water used for finishing work outside the well screen can be concentrated and inhaled effectively.

According to the present invention, since a separator for separating sand from water is interposed on the discharge side of the submersible pump, sand contained in water is removed by this separator, Prevents water sprayed from the nozzle from damaging the well screen.

According to the fifth aspect of the present invention, since the discharge port is closely or close to the inner surface of the well screen, the cleaning water effectively flows into the gravel and the aquifer, and the cleaning effect is improved.

[Brief description of the drawings]

FIG. 1 is a partially cut-away side view showing a specific example of a method of finishing a well by circulating cleaning according to the present invention, together with an example of a partial surging apparatus used in the method.

FIG. 2 is a partially cut-away side view when another example of a partial surging device is used.

FIG. 3 is a detailed view of a discharge port.

FIG. 4 is a partially cut-away side view showing a specific example of a separator.

FIG. 5 is a plan view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Submersible pump 3 Packer 4 Well screen 11 Connection part 12 Case suction part S Space W Aquifer 21 Discharge port 22 Pump strainer 23 Separator

Claims (5)

[Claims] 1. A submersible pump (2) is turned upside down and housed in a case (1) provided with a suction port (12) and a packer (3) at a lower part, and this is suspended in a well screen (4). A large amount of water is discharged from the discharge port (21) into the gravel (G) and the aquifer (W) through the well screen (4), and discharged.
(G) and the aquifer (W) are circulated, and the circulated water and groundwater are passed through the well screen (4), the case suction port (12) and the pump strainer (22), and the submersible pump (2) is used. A method of finishing a well by circulating washing, characterized by circulating and washing with a large amount of water. 2. A submersible pump (2) is turned upside down and housed in a case (1) provided with a suction port (12) and a packer (3) in a lower part, and a sand pump is provided on the discharge side of the submersible pump (2). Separator (2
3) and a jet nozzle (24), which are hung in a well screen (4), and pressurized water from which sand has been separated and removed by the sand separator (23).
4) from the well screen (4), and jet the jet flow while removing the clogging material even if there is clogging material in the well screen, the surrounding gravel (G) and aquifer ( W), and the water and groundwater circulated through the case suction port (12) and the pump strainer (22) are sucked into the submersible pump (2). The method of finishing the well by circulating cleaning. 3. Case (1), submersible pump (2), packer
(3), the case (1) is cylindrical and has a connection part (11) at one end, a case suction port (12) at the other end, and the submersible pump (2) is attached to the case (1). Housed and its outlet
(21) is at the bottom of the case inlet (12), and the pump strainer (22) is inside the case (1) and the case inlet (12)
The packer (3) is a pair of upper and lower parts, the outer diameter of which is adapted to the inner diameter of the well screen (4), each of which is disposed on the outer periphery of each end of the case inlet (12), and the finishing range is locally A partial surging device used in a method of finishing a well by circulating cleaning characterized by being concentrated in a limited manner. 4. Case (1), submersible pump (2), packer
(3), sand separator (23) and jet nozzle (24)
The submersible pump (2) is housed upside down in the case (1), the sand separator (23) and the jet nozzle (2).
4) is the discharge side of the submersible pump (2) and the case suction port
(12) At the bottom, the outer diameter of the jet nozzle (24) matches the inner diameter of the well screen (4) and the pump strainer (22)
Is in the case (1) and communicates with the case inlet (12), the packer (3) is a pair of upper and lower parts, and the outer diameter is the well screen (4).
Partials used for the method of finishing wells by circulating washing, characterized in that each is arranged on the outer periphery of each end of the case suction port (12), and the finishing range is limited to a local area. Surging equipment. 5. An opening end of the discharge port (21) is formed of an elastic cushioning material (25).
4. A partial surging apparatus used in the method of finishing a well by circulating cleaning according to claim 3, which is surrounded by a circle.