JPS58109582A - Water leakage inhibitor - Google Patents

Abstract

PURPOSE:To provide a water leakage inhibitor excellent in rapidity, effectiveness, easiness and economy, by molding a mixture composed mainly of bentonite, a fibrous material, petroleum, a surfactant and a binder. CONSTITUTION:A mixture composed mainly of bentonite, a fibrous material, petroleum, a surfactant and a binder is molded into powder greater than granule. When bentonite is contacted with water, it is swollen to clog cracks. Said fibrous material can impart strength to the moldings and inhibits the flowing-out of the swollen bentonite, whereby the shape retention of the swollen material and mutual physical binding are promoted and cracks are clogged. Said petroleum has a function of preventing bentonite from being swollen in contact with water until the moldings reach cracks causing a water leakage. Said surfactant has a function of causing water in the neighborhood of the moldings to penetrate into the moldings to control the swelling rate of bentonite. Said binder has a function of binding the above four components to form the moldings.

Description

[Detailed description of the invention] The present invention relates to a water loss prevention agent.

More specifically, the present invention relates to an agent for preventing water loss, which is a particularly serious obstacle among the obstacles encountered in drilling wells. To describe the present invention in detail from the perspective of the operating mechanism, a molded body having a size north of the granules is sent into a crack where water loss occurs using a mud water pump, or after a drill string is pulled up, it is inserted into a hole from the ground. Before the molded product swells after being dropped into the well, it penetrates into the cracks that caused water loss.
This invention relates to a water loss prevention agent that has the function of completely sealing cracks by the molded body starting to swell after the end of penetration, and is excellent in speed, effectiveness, easy dusting, and economy for water leakage prevention.

Lost water refers to the escape of mud, water, cement slurry, etc. into the geological formations when drilling wells for oil, natural gas, geothermal, etc., and is also called lost mud or lost excretion.

Drainage is broadly divided into those caused by naturally existing cracks and those caused by artificial cracks.

Water loss countermeasures can be divided into two areas. One is a technology to prevent water loss, which involves adding muddy water conditioners such as clays, dehydration control agents, and dispersion deflocculants to muddy water to provide a function of reducing dehydration, as well as adjusting the specific gravity of the muddy water appropriately. It is to maintain. Toring is a natural mud control technique, but it is especially effective when there are cracks in the strata. Another field of water loss countermeasures is technology that stops the water loss that occurs and closes the water loss layer.

For water loss (1) Light water loss (less than 2Kf/Hr of water loss)
, (2) Partial water loss (water loss amount 2-10'OKl/I(r
) (3) Total water loss (water loss: 100Kj!/I (r or more)) and (4) Severe total water loss (water loss: 200Kf/Hr or more)
Severe total water loss includes crossflow that occurs when groundwater flows across the well.

When water leakage occurs, drilling fluid flows out from the cracks into the surrounding strata of the wellbore, so drilling cannot be continued unless more drilling fluid than the flow out is replenished from the ground. Continuing to excavate from the ground by adding a large amount of fresh water and a small amount of bentonite as necessary is called Itsui-digori or Blind-digging.
This method is only applicable to a limited range of depths, as it carries the risk of strata collapse and entrapment. Further, it is extremely uneconomical and impracticable to excavate with regular mud water mixed with various mud conditioners.

If measures are taken incorrectly to prevent water loss, water loss becomes the initial trigger and various secondary problems occur. These include detention, collapse, and eruption, which lead to serious accidents. In addition, if water loss countermeasures are not perfect, it may take several months to reach the same depth.
This is an extremely large factor that increases drilling costs.

For the above reasons, there is a strong desire in the field of excavation technology to quickly establish a technology for preventing water loss that is quick, effective, easy, and economically superior.

Known water loss countermeasure techniques are shown in Table 1.

Table 1 Known water loss prevention techniques [A] Water loss prevention techniques that do not use water loss prevention agents (a-1)
Adjustment of excavation work aimed at lowering the pressure inside the well (a-2) Lift pipe waiting method [B] Water loss countermeasure technology using walnut shells, etc. (b-1) Water loss prevention agent mixed mud (LCM) muddy water) (b-2
) Highly dehydrated slurry squeeze (b-3) Surface mixing soft plug [C'3 Water loss countermeasure technology using gelatinized slurry (c-
1) Light oil-based water loss countermeasure technology (C-1-1) Light oil bentonite mixed slur IJ-(DO
B) Method (c-1-2) Light oil bentonite cement mixed slurry (DOBC) method (c-1, -3) Bengum method (c-2) Other methods (c-2-1) Water glass/calcium chloride method (D) Water loss countermeasure technology using cement slurry (d-1) Neat cement method (d-2) Bentonite cement method ((1-3) f Thinite cement method [B] Used for water loss countermeasure technology such as walnut shells Table 2 shows the water loss prevention agents.

Hereinafter, the various inhibitors shown in Table 2 will be collectively referred to as walnut shells, etc.

Table 2: Water loss prevention agent for walnut shells, etc. [A] Powdered and granular materials: walnut shells, wheat bran, grains (broad beans, peas, rice, etc.), cork, plastic grains, bentonite, limestone, giltstone, perlite, Rock stone, peat, coke, rock waste, bricks, concrete blocks, 5- glass waste, rubber chips, etc. [mouth] Fibrous materials rock wool, asbestos, processed pulp products, cotton, cottonseed residue, tree fibers, bark plowing, fiber, hay, corncob, sugar cane fiber, sugar beet pulp, hemp fiber,
flax peel, cellulose waste, cancer waste, glass fiber,
Fabric fibers, pig hair, leather, chicken feathers, etc. [c] Flake-like substances mica, cellophane, films, fish scales, etc. The known water loss countermeasure techniques listed in Table 1 have many drawbacks.

Below, various water loss countermeasure technologies are indicated by the symbols in Table 1.

(A) is often applied only to mild or partial water loss, but is not effective for medium-sized or larger water loss.

[8], CCD, CD) attempt to close the cracks with various water loss prevention agents, but these have a number of drawbacks as described below.

The drawbacks of the technique [B] are as follows. In order for water loss prevention agents such as walnut shells to work effectively, powdery granular substances,
It is necessary to contain at least three or more types selected from fibrous substances and flaky substances in appropriate proportions. However, it is difficult to formulate a water loss prevention agent that is suitable for the cracks that are the cause of water loss, and there are only a few cases in which water loss can be prevented simply by injecting walnut shells, etc. Multiple injections are required, and if countermeasures are delayed, secondary problems such as detention, collapse, and eruption may occur. Furthermore, even if water loss has temporarily stopped, when excavation is restarted, the bit may peel off the walnut shells, etc. that are blocking the surface of the crack, causing water loss to occur again. This is thought to be because the composition of the water loss prevention agent made of walnut shells, etc. is not compatible with the cracks, and even if it is adapted, the ability of the water loss prevention agent made of walnut shells, etc. to penetrate into the cracks is small. . In the technique [B), it is necessary to uniformly disperse walnut shells etc. in muddy water before injection. If it is not dispersed uniformly, it may block the feed pump, and even if it does not cause blockage, muddy water containing a water loss preventive agent that does not uniformly disperse black husk, etc. has an extremely small ability to close cracks, and may cause problems in places. I am unable to reach my goals for the term. Furthermore, even after successful treatment with walnut shells, etc., drilling mud with residual water loss prevention agent will have a negative effect on the propulsion rate, so it is necessary to remove the water loss prevention agent before resuming propulsion. However, it is difficult to remove it during one cycle of mud water using a shell shaker, etc., and it takes several hours to obtain a normal excavation rate. That is, [B]
This technique has drawbacks in terms of speed, effectiveness, ease of use, and economy.

[CD technology also has a number of drawbacks.

The biggest drawback of the method belonging to (c-1) relates to the operating principle of this method, in which bentonite suspended in light oil rapidly gels when it comes into contact with muddy water or water. For this reason, when making light oil slurry on the ground in advance, there must be no muddy water or water in the tank where the light oil slurry is made, so use a tank that is used after completely cleaning the muddy water tank, or use light oil separately. It is necessary to prepare a tank for slurry adjustment. Before feeding the light oil slurry, it is necessary to clean the area between the feed pump and the pit in order to prevent the slurry from gelling. Furthermore, if the amount of preceding clean water and trailing clean water is incorrect, the desired effect may not be obtained. Additionally, this method is not effective in cases of medium-sized or larger water loss. Otherwise, the gel-like material obtained by this method is not strong enough.

The consumption of large amounts of diesel oil also poses problems from an economical and environmental point of view.

In the technique (C-2), it is necessary to prepare a water glass tank and a calcium chloride dissolution tank, respectively. Shimizu,
Calcium chloride solution, fresh water, water glass, and fresh water are introduced in this order, but this operation is extremely complicated and requires a considerable amount of time for preparation. Handling water glass is difficult when the temperature is low. Similar to the technology (c-1),
The gel-like body formed by this technique is not very strong.This technique alone is often unable to solve water loss, and this technique is also not effective for medium-sized or larger water loss.

CD) technology, [N], [13], [C
Although a stronger sealing ability is obtained than with technique D, it has a number of drawbacks. Cement slurry can be made by emptying the muddy water tank, but since cement slurry comes into contact with muddy water inside the mine, there is a problem of cement contamination of the muddy water after the slurry removal measures have been completed. Wait for curing (WOC) is required. The cement slurry method is also not effective in cases of medium-sized or larger water loss. Additionally, this method can cause the drill string to lag if not performed quickly.

In particular, for geothermal wells, it is necessary to consider very carefully whether technology [D] is used or not. In geothermal development,
The wells advance into the subsurface crevices, but the crevices that serve for the production of steam and hot water, or for the return of the hot water underground, are numerous and closed. However, these cracks usually result in large amounts of water leaking, posing a big dilemma.

Furthermore, in reality, areas where half of the steam or hot water used for geothermal power generation and areas where hot water is returned underground are located in high-temperature strata, and cracks of medium or larger size may be used underground as production or return wells. We need to consider the possibility of a connection. Furthermore, if the leakage water is stopped immediately, the underground layer will cool down, leading to a decrease in the amount of power generation, resulting in a huge economic loss. Therefore, when cement slurry is introduced without considering underground interference, it goes without saying that the problem of water leakage cannot be solved, and even the wells that are actually useful will be blocked.

Therefore, although the CDI technology is more effective than other technologies, it has the disadvantage of being difficult to adopt.

The inventors of the present invention have conducted extensive research in the laboratory and in the field of geothermal wells in order to establish a technology that overcomes many of the drawbacks of conventional technology. Moreover, the present invention is simple and economically superior.

Due to the superiority of the present invention over the known technology, the excavation period has been significantly shortened and significant savings in excavation costs have been made possible.

In the following, the invention will be described in detail.

The present invention provides a water loss prevention agent that is suitable for water loss problems of all sizes, from light water loss to severe total water loss such as crossflow.

The water loss prevention agent of the present invention is a water loss prevention agent made by molding bentonite, a fibrous substance, petroleum, a surfactant, and a binder into a size larger than granules.

Definitions of terms for these substances and the functions of these substances are as follows.

Bentonite is a clay mainly composed of the mineral montmorillonite, and when bentonite comes into contact with water, it swells and closes cracks.

Fibrous substances refer to the substances listed in Table 2, which not only give strength to the molded body, but also suppress the outflow of the swollen bentonite, promote the retention of the shape of the swollen body and mutual physical bonding, and prevent cracks. Close up.

Petroleum refers to light oil, heavy oil, kerosene, lubricating oil, waste oil from various types of slags, etc.The molded body caused water leakage problems, but it swells when it comes into contact with bentonite and anaerobic water until it reaches the cracks. It has the function of suppressing

The surfactant has the function of allowing water existing near the molded body to penetrate into the molded body when the molded body reaches the crack that caused the water leakage problem, and to adjust the swelling rate of bentonite over time. be.

Binders refer to binders that have the ability to mold bentonite, fibrous substances, petroleum, and surfactants, and may be either inorganic or organic, and may be used in muddy water, fresh water, etc. It is preferable to avoid materials that dissolve into the concrete and cause problems when re-excavation or when cementing the casing pipe. Typical examples of binders include asphalt 1. Examples include pituminous materials such as tar and pitch, carboxymethylcellulose, and hollyvinyl alcohol.

The ratio of bentonite to fibrous material and the type of fibrous material can be arbitrarily selected within a range that does not deteriorate the strength of the molded product.

The size of the molded body can also be changed arbitrarily depending on the scale of lost water. That is, in the case of relatively small-scale water loss, a pellet-like molded body of granules or more and soybean grains or less is sent into the well with muddy water, fresh water, etc. by a muddy water pump. In the case of large-scale water loss, it is necessary to send in a large molded body, so all drill strings are pulled up and the briquette-shaped molded body is dropped from the ground 5. In this case, the size of the brigette-shaped molded body should be greater than or equal to the diameter of a soybean and less than or equal to the diameter of an open hole, and should have a diameter that does not cause bridging in the mine during dropping. The length of the briquette-like molded body in the longitudinal direction can be increased as necessary to close large-scale water leakage cracks with depth. No special equipment is required for molding the molded body. Pellets of granules or more and less than soybeans that are sent by a mud water pump are molded using a granulator, pan/pelletizer, etc., and briquette-like molded products that are dropped directly into a well from the ground are molded using a briquette machine or a brick. Mold using a molding machine, etc. The strength of the molded body can be adjusted by the type and amount of binder, the operating conditions of various molding machines, etc.

As the petroleum, heavy oil with high viscosity is preferred because it facilitates molding. The petroleum contained in the molded body that enters the wellbore is effective in improving the properties of muddy water when drilling is restarted as an oil-in-water emulsion after the water loss problem has been resolved. The amount of petroleum compounded is determined by taking into account the bentonite/fibrous material ratio, the type of fibrous material, molding pressure, the type and amount of surfactant, the time at which swelling of the molded product starts, etc.

The surfactant is selected between anionic surfactants and nonionic surfactants. Anionic surfactants are preferred because nonionic surfactants form micelles at high temperatures.

The molded body may contain a powdery substance or a flaky substance if necessary. Further, there is no problem even if a weighting agent such as pallite is contained. Adding a weighting agent to molded bodies used for petroleum valves that require increased specific gravity of muddy water will prevent the briquette-like molded body from falling into the wellbore if it is directly injected into the well from the ground in the event of large-scale water loss. This is advantageous in that it is quick.

Swelling adjustment of the molded product near the cracks depends on the type and amount of surfactant, as well as the type of bentonite, type of fibrous material, bentonite and rim, ratio of male material, frame type and amount of petroleum, etc. Type and amount of binders, molding pressure, shape and size of the molded body, time since the molded body came into contact with fresh water for mud 7X, edge flj near the crack, pressure, p I-
It is also related to I, etc. In particular, if the bentonite is expected to be affected by salts, gypsum, cement, etc., it is preferable to use activated bentonite, which has a large swelling capacity.

Specifically, consideration should be given to the case where the mud used in offshore oil well drilling is seawater mud, and the combined use of attapulgite is also effective.

The advantages obtained by the present invention are as follows.

(1) The molded body is easy to use, and by adjusting the size of the molded body, water loss problems of all sizes can be quickly solved.

(2) It is effective against large-scale water loss such as crossflow, which is difficult to solve with conventional techniques.

(3) Effective against water loss problems in geothermal wells where it is difficult to adopt water loss measures using cement slurry.

(4) Because the swelling of the molded body can be adjusted, this molded body has excellent ability to penetrate into cracks. It often happens again.

(5) When implementing this technology, special equipment is required at the excavation site.

(6) Mud water is often contaminated by implementing this technology, and excavation can be resumed promptly after treatment.

Next, examples of the present invention will be described.

Example 1 The composition of the water loss prevention agent was as shown in Table 3, and the water was heated to 200 K.
30mm x 30mm molded in y/cm2. After placing the briquettes at the yoke height in a beaker, add fresh water at 20C or 80C, and observe the progress of swelling of the briquettes in an environment of 20C or 80C, and obtain the results shown in Figure 1. .

Table 3 Composition of briquette molded body Unit: parts by weight are clear. Moreover, the final swelling height is slightly larger for those containing a larger amount of bentonite. It is assumed that the swelling is rapid when the temperature is high, and the swelling of the Brikent molded body is rapid when the temperature of the formation is high, such as in a geothermal well.

After 200 minutes, the fresh water was stirred at a rotational speed of 250 RJ'M with a stirring blade of 20mm height x 100mm width, but no change was observed in the shape of the swollen briquette molded body.

From the above, it is clear that this briquette molded body has a high swelling ability and a strong sealing ability.

Example 2 Test piece No. 3 having the compounding composition of Example 1 No. 4
00+o+$X 30+++m height, molding pressure 2Q Q
+ (200 bags of briquette molded bodies of y/cm2 packed in 2 packs were prepared and placed in the geothermal well KN-3 of Japan Heavy and Chemical Industry, Kitakakkonda, Nagayama, Oaza, Shizukuishi-cho, Iwate-gun, Iwate Prefecture). (See Figure 2). 79 of 12 Finch Pit
2.3 Kj! /min
While excavating in muddy water, we encountered a complete loss of water. When the bonder was stopped, the water head drop in the annular part reached 225 m in 5 minutes, and it was discovered that the water loss was approximately 220 to 1/I (r scale), so the pipe was immediately lifted and the prepared briquette molded body was added little by little, and 75 bags (1500Kp) were used.The time required to add the briquette molded bodies was 35 minutes.

After adding the briquette molded body, the water head decreased by 7 in 10 minutes.
．． 4m, and the amount of lost water decreased to about 4Ω/I (r), so it was sieved and suppressed with a 12-ton drill collar.
Issui stopped completely. Even after resuming the 4th bend, no loss of water was observed. The time required from the occurrence of total loss of water to the complete stoppage of water loss was only 4 hours and 10 minutes.

[Brief explanation of the drawing]

FIG. 1 shows the progress of swelling of a molded briquette according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of well No. KA-3. 1... Bit, 2... Drill collar, 3... Drill pipe, 4... Open pit, 5... Crack) 6 1 10 Fu Ribut Messe, 4! 【Running】
Towed by -2Eti4. Audience 2 procedure correction! I (Method) % Formula % 1. Display of the case 1982 Patent Application No. 208206 3. Person making the amendment Relationship with the case Patent Applicant Address 8-4-5 Nihonbashi Koami-cho, Chuo-ku, Tokyo Amendment Target "Drawings" 6. Contents of amendment As per the attached sheet $+@'j13t@ Procedural amendment (voluntary) May 2, 1980 Commissioner of Japan Patent Office 1 Indication of case 1988 Patent Application No. 208206 3 Relationship with the case of the person making the amendment Patent applicant address 8-4-4 Nihonbashi Koami-cho, Chuo-ku, Tokyo Supplementary [E]
Column 5 of ``Detailed Description of the Invention'' and ``Brief Description of Drawings'' in the subject specification of , preferably bentonite 50-90
% by weight, 5 to 50 parts by weight of fibrous substances, 4 to 30 parts by weight of petroleum, 0.01 to 0.5 parts by weight of surfactants, and 1 to 10 parts by weight of binders. 2) Delete "KA-3 well" on page 19, line 10 of Dossou. 3) On page 20 of the circular, lines 8-9, ``Figure 2 is a schematic diagram of the KA-3 well'' is corrected to ``Figure 2 is a schematic diagram of the geothermal well.''that's all

Claims (1)

[Claims] Bentonite, fibrous substances, petroleum, surfactants A water loss prevention agent made mainly of agents and binders.