JPH0657244A - Drilling fluid additive - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an additive for a drilling fluid, which has excellent dispersion characteristics of the drilling fluid, excellent flow characteristics of the drilling fluid even in a high temperature and high pressure environment, and an excellent dehydration suppressing function. [Structure] 100 parts by weight of a lignin-based material, 1 to 50 parts by weight of a tannin-based material, 1 to 200 parts by weight of a lignite-based material, and 5 to 5 parts of an ethylenically unsaturated fatty acid vinyl monomer.
150 parts by weight are mixed, and the total solid content concentration is 10 to 50% by weight.
The pH of the drilling fluid additive obtained by adjusting the pH of the solution to 5.0 to 10.0, adding 1 to 10 parts by weight of a polymerization initiator, and performing a polymerization reaction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water-clay drilling fluid additive for drilling oil, gas, geothermal steam wells and other wells encountered at high temperatures. Specifically, various organic salt substances such as lignin sulfonic acid, tannin, and lignite, and monomers obtained by copolymerizing functional group-polymerizable monomers in an aqueous solution in the presence of a polymerization initiator are used as a drilling fluid. The present invention relates to an additive for a drilling fluid, which has excellent dispersion properties, improves the flow characteristics of the drilling fluid even in a high temperature and high pressure environment, and has an excellent dehydration suppressing function.

[0002]

2. Description of the Related Art As a method of excavating a well, there have been basically rotary type, percussion type, spindle type, etc. since ancient times due to the operating principle of an excavating machine. , Its function is recognized in all aspects, and it has become a major part of excavating machines. This rotary drilling technology crushes rocks in the formation with a bit by rotating a pipe with a "bit" attached to the lower end of a hollow pipe (drill string), and uses a drilling fluid (hereinafter referred to as drilling mud). A method of transporting crushed rock excavation from the mine to the surface.

The drilling mud used in it has several functions in addition to continuously removing the debris crushed by the bit from the downhole. It controls the pressure of the formation so that fluids such as oil, gas and geothermal steam from the formation do not eject, reduces the frictional resistance with the pit wall, creates a thin and strong mud wall on the pit wall, It is intended to prevent the well from collapsing and minimize production obstacles to the oil layer, gas layer, steam layer, etc. If the mud wall is formed due to the dewatering effect due to the difference between the formation pressure and the mud pressure on the pit wall surface, and the amount of dewatering increases, the wall becomes thicker, which affects the drilling rate of the well and prevents pressure differential detention. In some cases, shale collapse, sticking, caliber enlargement, etc. may occur. Therefore, it is extremely important to use an additive in order to make mud water having a dispersion property and a dewatering property suitable for well conditions. Generally, drilling mud requires a great number of functions, and it is necessary to function properly and stabilize the well to contribute to the rate of drilling. In recent years, it has become difficult to drill many wells, and in order to obtain stable drilling mud even under high temperature and high pressure conditions, a drilling mud additive having excellent properties is desired.

The composition of conventional drilling mud is determined according to the condition of the stratum, and the basic composition of mud is as follows. (1) Muddy water composition mainly composed of natural clay minerals such as bentonite, CMC, or synthetic polymers such as acrylic acid (2) The muddy water composition of (1) is supplemented with a lignin sulfonic acid derivative, a lignite derivative, or a complex salt thereof. Muddy water composition to be added (3) Inorganic synthetic polymer, organic synthetic polymer, or mixed type muddy water composition. As other drilling mud additives used in these basic muds, phosphates, tannins, and their derivatives are used, and due to the technological progress, the ferrochrome lignosulphone, which is a lignin sulfonic acid derivative, is used. At present, phonate and chromium lignite sodium, which is a lignite derivative, are used and occupy the majority of drilling mud.

Since these drilling mud additives contain heavy metals, they are limited in terms of use due to environmental pollution, pollution, etc., and can only be used within a certain range. Therefore, drilling mud mainly composed of polymers, which does not cause these problems, has been improved so that a wide range of well temperature from low temperature to high temperature can be used. However, it is difficult to obtain the stability of the rheological properties of drilling mud easily with these polymers, and the well temperature 12 in the drilling environment, such as high specific gravity, high solids, and high temperature.
It loses stability above 0 ° C. Moreover, alkaline earth metal ions such as Ca ⁺⁺ and Mg ⁺⁺ and other divalent or higher cations inactivate the drilling mud additive, which causes considerable problems in terms of use such as loss of drilling mud function. is the current situation.

Recently, in oil and gas drilling wells, the depth has become deeper and the maximum bottom hole temperature often exceeds 200.degree. In geothermal drilling wells, the maximum bottom hole temperature may exceed 300 ° C even if the depth is shallow. It is difficult to maintain the environment of drilling mud stably for a long period of time because the well conditions change momentarily with the progress rate. That is, the compositional components of drilling mud are altered, and rheological properties such as increase in viscosity of drilling mud, gelation, and increase of dehydration amount are changed. A drilling mud additive that maintains stable rheological properties of drilling mud even under high-temperature drilling conditions, improves dewatering adjustment properties on the mine wall, and improves resistance to the contamination of drilling mud by various salts in the formation. Development is coveted.

[0007]

The present invention is a heavy metal free drilling mud additive. Further, the drilling mud added with the drilling mud additive of the present invention maintains stable and good dispersion characteristics, reduces the dehydration amount of the drilling mud, and enhances the mud wall forming effect on the pit wall surface. Further, excellent rheological properties can be maintained for a long period of time even under a high temperature and high pressure environment.

[0008] The gist is to add 1 to 50 parts by weight of a tannin type substance, 1 to 200 parts by weight of a lignite type substance, and 5 to 150 parts by weight of an ethylenically unsaturated fatty acid vinyl monomer to 100 parts by weight of a lignin type substance, and to add all of them. Solid content concentration 1
As an aqueous solution of 0 to 50% by weight, this is adjusted to pH 5.0 to 1
A drilling mud additive to be added to a water-clay drilling fluid consisting of a copolymerization reaction product obtained by keeping the value at 0.0 and adding 1 to 10 parts by weight of a polymerization initiator to cause a polymerization reaction, and drying and powdering this. It is in.

The drilling mud additive of the present invention keeps the flow characteristics of drilling mud stable in drilling mud, prevents collapse of the mine wall, and drills against contamination by cations eluted from the formation. Prevents deterioration of muddy water, suppresses swelling of cuttings (cuttings), facilitates transportation to the surface, and contributes to improving the excavation rate.

The polymerization reaction for obtaining the drilling mud additive of the present invention is carried out by adding 1 to 50 parts by weight of a tannin-based material, 1 to 200 parts by weight of a lignite-based material, 100 parts by weight of a lignin-based material, and ethylenically unsaturated fatty acid vinyl. Monomer 5-15
Add 0 parts by weight, and add these to a total solid concentration of 10 to 50% by weight.
And preferably an aqueous solution containing 20 to 40% by weight. Then, using sodium hydroxide, potassium hydroxide, ammonium hydroxide or the like, pH 5.0 to 1
After adjusting to 0.0, 1 to 10 parts by weight of a polymerization initiator is added and the reaction initiation temperature is set to 30 to 100 ° C. to carry out a polymerization reaction. The reaction temperature of this polymerization reaction can be appropriately selected depending on the type of the polymerization initiator. When carrying out aqueous solution polymerization using these reaction compositions, the free radical type of vinyl monomer polymerization technology can be applied, and the reaction of the present invention is preferably carried out in an aqueous medium.

The lignin-based substance according to the present invention is one of the main components in a woody plant composition such as wood, bamboo and straw, and is composed of a C ₆ -C ₃ -bonded phenyl propane monomer skeleton, each of which is condensed. It is a reticulated polymer compound produced by Although the chemical structure has not been clarified yet, it has an aromatic structure as a structural unit. It is a substance which is extracted from waste liquor of pulp production, shows brown to light brown color, is soluble in an alkaline solution of water, sodium hydroxide, potassium hydroxide and the like, but is insoluble in ether, benzene and the like.

The tannin-based substance means a plant tannin widely distributed in the plant kingdom, and has a molecular weight of 600 to 20.
It is defined as a substance having a complicated structure of about 00, which has a basic skeleton of polyoxyphenyl and can be decomposed with alkali to obtain phenols, phenolcarboxylic acids and the like. The typical one is the cabracho tannin,
There are wattle tannins and chestnut tannins.
These tannins are classified into hydrolyzable pyrogallol substances and condensed catechol substances. The pyrogallol type is one in which gallic acid, polyoxydiphenic acid, and the like and a saccharide form a depside bond. The catechol type has a structure in which catechin, leuco and cyan, etc. are condensed into a plurality. Further, not only vegetable tannins but also substances generally called synthetic tannins can be used. Of these, condensed vegetable tannins are particularly preferable. The tannin-based substance is used in an amount of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, more preferably 8 to 35 parts by weight, based on 100 parts by weight of the lignin-based substance.

The lignite-based substance is an alkali-soluble, acid-insoluble amorphous polymer organic acid obtained from young coals such as grass charcoal, lignite, lignite, or those obtained by oxidative decomposition of these with an oxidizing agent such as nitric acid, or , An alkali metal salt or an ammonium salt. This is a substance generally called humic acid, regenerated humic acid or nitrohumic acid or salts thereof (hereinafter referred to as "humic acid"). Humic acid having a low ash content is particularly preferable. This humic acid is an organic acid whose chemical molecular structure has not yet been clarified, and is a substance that is defined as "an alkali-soluble, acid-insoluble amorphous polymeric organic acid" (scientific dictionary). This is used in an amount of 1 to 200 parts by weight, preferably 10 to 120 parts by weight, more preferably 15 to 80 parts by weight, based on 100 parts by weight of the lignin-based substance.

As the ethylenic unsaturated fatty acid vinyl monomer, one kind or two or more kinds of monomers selected from monomers such as acrylic acid, methacrylic acid, acrylic acid alkyl ester, acrylic acid hydroxyalkyl ester, acrylamide and acrylonitrile can be used. Can be used. Further, as acid type ethylenically unsaturated fatty acid vinyl monomers such as acrylic acid and methacrylic acid,
It is also effective to use an alkali metal salt such as sodium potassium or an ammonium salt. They are,
The lignin-based substance is used in an amount of 5 to 150 parts by weight, preferably 10 to 130 parts by weight,
It is more preferably 15 to 90 parts by weight.

The polymerization initiator is redox when used in combination with an inorganic salt such as ammonium persulfate or potassium persulfate, an organic peroxide, an azo compound, a free radical type polymerization initiator such as hydrogen peroxide, or an oxidizing agent or a reducing agent. System initiators can also be used. The copolymer-containing solution thus obtained is made into powder by spray drying or the like to be used as a drilling additive.

The reaction temperature in the copolymerization reaction is appropriately selected within a wide range of 30 to 100 ° C. corresponding to the polymerization initiator used. The proper concentration of the copolymerization reaction is preferably 10 to 50% by weight after the completion of the copolymerization reaction from the viewpoint of the ease of handling and the productivity of the obtained aqueous solution copolymer,
A preferred concentration range is 20-40% by weight. The reaction pH of the copolymerization reaction is not particularly limited as long as it is within the range where aqueous solution polymerization is possible, but the range is pH 5.0 to 10.0.
And preferably pH 6.0 to 9.0. In this polymerization reaction, when a polymerization initiator is added, heat generation and reaction viscosity increase with the reaction. The polymerization reaction is terminated when the reaction viscosity reaches the maximum. The maximum reaction viscosity is controlled by various conditions such as the starting material of the reaction system, concentration, temperature control, and the like.

The water-soluble copolymerization reaction product thus obtained exerts a great effect in improving the heat resistance and salt resistance of drilling mud. The drilling mud additive of the present invention, according to factors such as temperature and pressure of well conditions encountered during drilling,
Moreover, it is necessary to change the addition to the drilling mud depending on the contamination status of the drilling mud. Usually, it is preferable to use the added amount of about 0.5 to 10.0% per drilling mud. The amount added is determined by the results of routine muddy water tests.

The drilling mud additive of the present invention thus obtained has a composition as base mud of 100 parts by weight of a clay suspension prepared by adding 1 to 20 parts by weight of clay mineral to 100 parts by weight of water. By adding 0.5 to 10.0 parts by weight, the fluidity characteristics of the drilling mud and the drilling mud can be stably maintained even in a high temperature and high pressure environment.

The clays used for the muddy water include carion (kaolinite, halloysite, etc.) bentonite (montmorillonite, etc.) illite, attabalgite, sepiolite, etc., and asbestos can be used for the same purpose. Further, when excavating a high-pressure formation, the specific gravity of the drilling mud must be increased. To increase this specific gravity, barium sulfate, barium carbonate, or iron oxide, or a mixture thereof may be used as a weighting agent. , It does not impair the flow characteristics of the drilling mud. Furthermore, in addition to the drilling mud additive of the present invention, these drilling muds include commonly used dispersants, dehydration reducing agents, surfactants, and known additives (thickeners, lubricants, mud sludges). Inhibitors, oils, etc.) can be appropriately used because they are inert to the drilling mud additive of the present invention.

[0020]

【Example】

[Example-1] Mechanical stirring device, thermometer, reflux condenser,
In a 2 L separable flask equipped with an inert gas inlet, etc., add 33.5% sodium acrylate monomer to
73.2g, water 161g, natural humic acid 7
8 g is added, 11.2 g of sodium hydroxide is added, and a neutralization reaction is performed at a temperature of 85 ° C. to 90 ° C. for 30 minutes. The neutralization reaction solution was adjusted to have a concentration of 30%. The pH of this aqueous solution is 9.5.
Met. Next, 972 g of a 49.40% by weight concentration of a ligning aqueous solution and 42 g of tannin in an anhydrous conversion were added, and the reaction was carried out at a temperature of 75 to 80 ° C. for 30 minutes. Then 2
18 g of 5% by weight sulfuric acid was injected. The pH of this reaction solution was 6.47 and the concentration was 40.9% by weight. Then, the inside of the separable flask was replaced with nitrogen gas, the temperature was adjusted to 80 ° C., and then 15% hydrogen peroxide solution 8 was added as a polymerization initiator.
Polymerization reaction is carried out for 45 minutes by adding 0 g at a flow rate of 1.26 ml per minute. In this reaction, the viscosity of the reaction liquid increased with the polymerization, and heat was generated to raise the temperature. After completion of the polymerization reaction, the mixture was stirred for 30 minutes and allowed to cool. The viscosity of this liquid dispersion rose from 38 CPS before the reaction to 250 CPS. This was spray-dried to obtain the product of the present invention-1.

[Example-2] To the separable flask used in Example-1, 473.2 g of 33.5% sodium methacrylate monomer, 243 g of water, and 270 g of nitrohumic acid were added in an amount of 25% by weight. 194.4 g of sodium hydroxide solution is added, and a neutralization reaction is carried out at a temperature of 85 to 90 ° C. for 30 minutes. This neutralization reaction was adjusted to a concentration of 34% by weight. The pH of this aqueous solution was 9.6. Then 4
631.6 g of a 9.4 wt% concentration lignin aqueous solution and 20.4 g of tannin in terms of anhydrous water were added, and the temperature was 75 to 80 ° C.
And reacted for 30 minutes. Then, 60 g of 25 wt% sulfuric acid was injected to neutralize. The pH of this reaction is 6.35 and the concentration is 3.
It was 8.0% by weight. Then, the inside of the separable flask was replaced with nitrogen gas and the temperature was adjusted to 80 ° C., and 80 g of 15% hydrogen hydrogen peroxide solution as a polymerization initiator was added at 1.26 ml / min.
Was added at a flow rate of and the polymerization reaction was carried out for 45 minutes. This reaction is a violent reaction in which the viscosity increases with progress and exotherm occurs. After completion of the polymerization reaction, the mixture was stirred for 30 minutes and allowed to cool. The viscosity of this liquid dispersant is from 64 CPS before reaction to 320 CP
It rose to S. This was spray-dried to obtain product-2 of the invention.

Example 3 Bentonite (sodium montmorillonite: trade name Telgel) was added to fresh water to obtain 7
A suspension having a concentration of 100% was prepared and used as a base mud. To 100 ml of this base muddy water, 3.0 parts by weight of the products of the present invention-1, -2 and comparative products, and 80 parts by weight of a weighting agent were added and stirred (specific gravity of muddy water of 1.60), and Kattingusu (swelling shale) 2
Add 0 parts by weight and stir. P with sodium hydroxide
Put mud water adjusted to H10.0 and stirred into a closed container,
Curing was carried out at a curing temperature of 80 ° C. for 16 hours (rolling 60 rotations / min) and the muddy water properties were examined. It should be noted that a test in which the pH of the product of the present invention is not adjusted with sodium hydroxide is also performed.
The results are shown in Table-1.

[Table 1]

Example 4 Bentonite (sodium montmorillonite) was added to fresh water to prepare a suspension having a concentration of 6%, which was used as a base mud. This base muddy water 100
5.0 parts by weight of the present invention products -1, -2 and the comparative product,
Add 100 parts by weight of a weighting agent and stir. (Muddy water specific gravity 1.7
0) and 15 parts by weight of Kattingus (swelling shale) are added and stirred. Further, adjust the pH to 10.0 with sodium hydroxide and stir the muddy water into a closed container.
It was aged for 16 hours (rolling 60 revolutions / minute) and the property of mud was examined. It should be noted that a test in which the pH of the product of the present invention is not adjusted with sodium hydroxide is also performed. The results are shown in Table-2.

[Table 2]

[Example-5] Bentonite (sodium montmorillonite) was added to fresh water to prepare a suspension having a concentration of 4%, which was used as a base mud. This base muddy water 100
The present invention products -1, -2 and comparative products (3.0 parts by weight of sodium chromic humate, 1.0 part of sodium chrome tannate) per ml.
Parts by weight, sulfonated-styrene / maleic acid copolymer 0.5 parts by weight) 4.5 parts by weight, thickening / dehydration reducing agent (trade name HOSTA-DRILL) 1.0 parts by weight, weighting agent 10
0 part by weight is added and stirred (specific gravity of muddy water is 1.70), and 10 parts by weight of Kattens (swelling shale) is added and stirred. Further, the pH of the mixture was adjusted to 10.0 with sodium hydroxide, and the muddy water was stirred and placed in a closed container, and was cured at a curing temperature of 200 ° C. for 16 hours (rolling 60 rotations / min) to examine the properties of the muddy water. It should be noted that a test in which the pH of the product of the present invention is not adjusted with sodium hydroxide is also performed. The results are shown in Table-3.

[Table 3]

Example 6 Bentonite (sodium montmorillonite) was added to fresh water to prepare a suspension having an 8% concentration, which was used as a base mud. This base muddy water 100
The present invention products -1, -2 and comparative products (composite salt of chromic lignin sulfonate and sodium humate) in ml.
2.0 parts by weight and 0.5 parts by weight of sodium chloride as a pollutant were added and stirred to examine the properties of the muddy water by the API muddy water test method. The results are shown in Table-4.

[Table 4]

[Example 7] Bentonite (sodium montmorillonite) was added to fresh water to prepare a suspension having a concentration of 8%, which was used as a base mud. This base muddy water 100
The present invention products -1, -2 and comparative products (composite salt of chromic lignin sulfonate and sodium humate) in ml.
2.0 parts by weight and 1.0 part by weight of cement as a pollutant were added and the properties of the muddy water were examined by the API muddy water test method for the muddy water. The results are shown in Table-4.

[0027]

EFFECTS OF THE INVENTION The products of the present invention obtained from the above Examples-3, 4, 5, 6, 7 show excellent dispersion characteristics and show fluidity of muddy water as compared with other existing muddy water additives. It is clear that the effect is excellent as an additive for drilling mud, because the amount of dehydration is stable and the amount of dehydration that is judged to be the effect of forming mud walls is small, and there is little change in heat even under high temperature and high pressure environments.

Claims (1)

[Claims] 1. 100 parts by weight of a lignin-based substance, 1 to 50 parts by weight of a tannin-based substance, and 1 to 200 of a lignin-based substance.
After mixing 5 parts by weight and 5 to 150 parts by weight of an ethylenically unsaturated fatty acid vinyl monomer to prepare an aqueous solution having a total solid content concentration of 10 to 50% by weight, the pH is adjusted to 5.0 to 10.0, and a polymerization initiator is added. A drilling fluid additive obtained by adding 1 to 10 parts by weight and conducting a polymerization reaction.