Fluid loss reducer, white oil, humic acid, barite, etc. are some treatment agents, some of which are used to adjust mud properties. Baryonite is used to increase the specific gravity. Each treatment agent They all have different functions. If you want to write a graduation project, you must read some related books yourself. I recommend several books, such as drilling fluid and geotechnical engineering slurry, geotechnical drilling engineering, etc.
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1. Colloidal rate
The colloidal rate of the pore-forming liquid is the degree of hydration and dispersion of the liquid material and the suspension stability. Simple and effective metrics. 8.5 Determination of colloid ratio: 8.5 Put 100 ml of mud into a measuring cylinder, plug the bottle tightly, and after 24 hours of rest, observe the volume (ml) of the clear liquid at the top of the measuring cylinder. 8?5 The colloid rate is expressed as a percentage:
2. Specific gravity
The specific gravity of the pore-forming liquid refers to the ratio of the weight of the pore-forming liquid to the weight of the same volume of water.
3. Solid content
The solid content of the pore-forming liquid refers to the weight or volume percentage of solid particles in the pore-forming liquid.
The solid phase in the pore-forming fluid includes useful solid phase and useless solid phase. The former is such as pulping clay, barite, etc., and the latter is drill cuttings.
The solid phase in the pore-forming liquid can be divided according to the solid phase gravity and can be divided into heavy solid phases (barite has a specific gravity of 4.5, hematite has a specific gravity of 6.0, galena has a specific gravity of 6.9, etc.) and Light solid phase (the specific gravity of clay is generally between 2.3 and 2.6, and the specific gravity of rock fragments is generally between 2.2 and 2.8). 8?3 Solid phase content determination method
"Distillation separation principle":
A. Take a certain amount (20ml) of pore-forming liquid and place it in the distillation tube;
B. Use electric heating at high temperature to evaporate it to dryness;
C. The water vapor enters the condenser, and uses a graduated cylinder to collect the condensed liquid phase;
D. Then weigh out the dried The weight of the solid phase in the still;
E. Read the volume of the liquid phase in the graduated cylinder;
F. Calculate the solid phase content;
G .The unit is weight or volume percentage.
4. Sand content
The sand content of drilling fluid refers to the percentage of sand particles in the drilling fluid that cannot pass through the 200 mesh screen, that is, the sand particles with a particle size greater than 74 μm account for the total volume of the drilling fluid. . In field applications, the smaller the value, the better, and it is generally required to be controlled below 0.5. This is because excessive sand content will cause the following hazards to drilling:
(1) Increase the density of drilling fluid, which is detrimental to increasing drilling speed.
(2) The formed mud cake will be soft, resulting in increased filter loss, which is not conducive to the stability of the well wall and affects the quality of cementing.
(3) Excessive coarse sand content in the mud cake will increase the friction coefficient of the mud cake and easily cause differential pressure drill sticking.
(4) Increase the wear on drill bits and drilling tools and shorten their service life.
The most effective way to reduce the sand content in drilling fluid is to make full use of vibrating screens, desanders, desilters and other equipment to effectively control the solid sand content of drilling fluid.
The sand content of drilling fluid is usually measured using a specially designed sand content meter. The instrument consists of a graduated glass container similar to a centrifuge test tube and a sieve cylinder with a funnel. The sieve used is 200 mesh. When measuring, inject a certain volume of drilling fluid into the glass container, and then inject clean water up to the mark. After shaking vigorously, pour the fluid in the container into the screen cylinder and sift. After sifting, turn the funnel over the screen cylinder and insert the funnel mouth into the glass container. Pour the sand that cannot pass through the sieve into the glass container with clean water. After all the sand particles have settled, read the volume scale. Finally, the sand content N in the drilling fluid is calculated from the following formula
N=(V sand grains/V drilling fluid)×100
5. Rheology
The rheology of pore fluid refers to the flow and deformation properties of drilling fluid, which takes the viscosity of pore-forming fluid as its main research object. The index reflecting the viscosity of liquid has different expression methods according to different liquid flow patterns, and its basis is based on the rheological constitutive relationship.
The viscosity of the hole-forming fluid is crucial to the impact of trenchless drill hole expansion. 8?3 Rheological performance testing instruments: funnel viscometer, rotational viscometer 8?3 Six-speed rotational viscometer
Notes:
To load and unload the outer cylinder, hold the outer cylinder with one hand Hold the outer cylinder with the other hand and turn it clockwise until the bayonet of the outer cylinder is aligned with the pin in the outer cylinder and then remove the outer cylinder. When installing the outer cylinder, align the notch of the outer cylinder with the pin in the outer cylinder, then rotate the outer cylinder counterclockwise, and avoid collision with the inner cylinder.
When loading and unloading the inner cylinder, hold the inner cylinder shaft firmly with one hand and rotate the inner cylinder internally with the other hand. Do not bend the inner cylinder shaft.
When transporting over long distances, be sure to remove the inner cylinder and install the outer cylinder to prevent the inner cylinder shaft from being bent.
The adjustment of the torsion spring stiffness is not allowed at will.
6. Water loss and wall-building property
Under the action of the difference between the liquid pressure in the pore and the formation pore fluid pressure, the free water in the pore-forming fluid flows through the pores or cracks in the pore wall to Penetration in the formation is called water loss of pore-forming fluid. While losing water, the solid particles in the pore-forming fluid adhere to the well wall to form mud skin (mud cake), which is called wall building. 8.3 The impact of water loss on drilling: 8.5 The beneficial impact of water loss in the pore-forming fluid on drilling is: the initial water loss can wet the rock and soil, reducing its strength, which is conducive to the drill bit crushing it, improving the Drilling speed; 8.5 In mud shale, loess, and clay formations, excessive water loss will cause the hole wall to absorb water and expand, shrink, peel off, and collapse; 8.5 For formations with fracture zones and cracks, the freedom of penetration Water washes the bond between the contact surfaces of the broken objects, reducing the frictional resistance. The broken objects can easily slide into the holes, causing accidents such as hole wall collapse and drill sticking; 8.5 The more water is lost in soluble formations, , the higher the degree of dissolution of the hole wall formation; 8.5 Thick mud skin will increase the adsorption of drilling tools and increase the rotation resistance of the drill pipe; 8.5 Thick mud skin will reduce the annulus flow area, causing circulation Resistance and pressure increase.
7. Inhibitory property
The inhibitory property of the pore-forming fluid refers to the ability of the pore-forming fluid to inhibit the hydration, expansion, and dispersion of the rock and soil on the hole wall. 8.5 Evaluation methods: 8.5 Soaking test method; 8.5 Expansion tester; 8.5 Roller furnace rolling recovery method; 8.5 Capillary absorption time method; 8.5 Shale stability index experimental method, etc. .
8. Lubricity
The lubricity of the pore-forming fluid is closely related to drilling tool wear, circulation flow resistance, equipment power consumption, etc.
Improve the lubricity of the pore-forming liquid - add oil, polymers, lubricants, and graphite powder;
The lubricity of the pore-forming liquid is measured with a lubrication coefficient measuring instrument.
9. pH value
The pH value of the drilling fluid filtrate is usually used to indicate the acidity and alkalinity of the drilling fluid. Since the strength of acidity and alkalinity is directly related to the degree of dispersion of clay particles in the drilling fluid, it will greatly affect the viscosity, shear force and other performance parameters of the drilling fluid.
When the pH value is greater than 9, the apparent viscosity increases sharply as the pH value increases. The reason is that when the pH value increases, more OH- will be adsorbed on the surface of the clay crystal layer, further enhancing the negative charge on the surface, making the clay more easily hydrated and dispersed under shear.
In practical applications, the pH value of most drilling fluids is required to be controlled between 8 and 11, that is, to maintain a weak alkaline environment. This is mainly due to the following reasons: (1) It can reduce the corrosion of drilling tools; (2) It can prevent damage to drilling tools and casing caused by hydrogen embrittlement; (3) It can inhibit calcium, Dissolution of magnesium salts; (4) There are quite a few antiseptic treatment agents that require alkaline media to fully exert their effectiveness, such as tannins, lignite and lignosulfonate treatment agents.
For different types of drilling fluids, the required pH ranges are also different. For example, the pH value of dispersed drilling fluids is generally required to be above 10, and the pH value of calcium-treated drilling fluids containing lime is more controlled. In 11~12, the pH value of calcium-treated drilling fluid containing gypsum is mostly controlled at 9.5~10.5, while in many cases the pH value of polymer drilling fluid is only required to be controlled at 7.5~8.5.
Chapter 4 Commonly used pore-forming fluid treatment agents
Section 1: Main types of pore-forming fluids
With the continuous development of drilling technology, drilling fluids There are more and more types. At present, there are various classification methods for drilling fluids at home and abroad. Among them, the simpler classification methods are as follows: 8.3 According to its density, it can be divided into non-weighted drilling fluid and weighted drilling fluid. 8?3 According to the strength of hydration with clay, it can be divided into non-inhibitory drilling fluid and inhibitory drilling fluid. 8?3 According to the difference in solid content, drilling fluids with lower solid content are called low-solid drilling fluids, and drilling fluids with basically no solids are called solid-free drilling fluids.
However, the generally referred classification method is based on the composition characteristics of the fluid medium and system in the drilling fluid. According to the different fluid media, it is generally divided into three types: permanent drilling fluid, oil-based drilling fluid and gas-based drilling fluid. Recently, a type of synthetic-based drilling fluid has appeared. To be more specific, it is divided into 7 types as shown in Figure 1-1.
Since water-based drilling fluids have always occupied a dominant position in practical applications, they are divided into several types according to the composition of the system. The following are various drilling fluid types recognized in China based on reference to foreign drilling fluid classification standards.
The main types of pore-forming fluids are shown in Table 4-1-1
Table 4-1-1
Type Name Material Composition
Clear water, clear water
Mud bentonite, water, treatment agent
Compound solution compound, water
Emulsion water, oil, emulsifier
Foam slurry air, foaming agent, foam stabilizer
Saline slurry NaCl, bentonite, water, treatment agent
Cement slurry cement, water, additives
Section 2 Commonly used inorganic treatment agents
1. Soda ash
The scientific name is sodium carbonate, also known as soda ash, and its molecular formula is Na2CO3. White powder, density is 2.5g/cm3, easily soluble in water. It is easy to absorb moisture and agglomerate, so be careful to prevent moisture. The aqueous solution is alkaline (pH value is 11.5), and it is easy to ionize and hydrolyze in water. Among them, ionization and primary hydrolysis are strong, so Na, C032-, HCO3- and OH- ions mainly exist in the soda ash aqueous solution. The reaction formula is:
Na2CO3=2Na CO32-
CO32- H2O=HCO3- OH-
Soda ash can turn calcium clay into sodium clay through ion exchange and precipitation, that is,
Ca-clay Na2CO3→Na-clay CaCO3
Function:
A. Improve the hydration and dispersion properties of clay, so adding an appropriate amount of soda ash can reduce the filter loss of the new slurry and increase the viscosity and shear force.
B. Excessive soda ash will cause the clay particles to agglomerate, destroying the performance of the drilling fluid.
C. When the drilling cement plug or drilling fluid is invaded by calcium, add an appropriate amount of soda ash to precipitate Ca2 into CaCO3, thereby improving the performance of the drilling fluid, that is, an organic compound containing sodium carboxylic functional group (—COONa). When the solubility of the treatment agent is reduced due to calcium intrusion (or excessive Ca2 concentration), the effectiveness can generally be restored by adding an appropriate amount of soda ash.
2． Caustic soda
Caustic soda is sodium hydroxide, and its molecular formula is NaOH.
Characteristics: Milky white crystal in appearance, density 2.0~2.2g/cm3, easily soluble in water, and releases a lot of heat when dissolved.
The aqueous solution is strongly alkaline. Caustic soda easily absorbs moisture and carbon dioxide in the air, and reacts with carbon dioxide to form sodium carbonate. It should be stored in a moisture-proof cover.
Function:
a. Mainly used to adjust the pH value of drilling fluid;
b. Used together with tannin, lignite and other acid treatment agents, Convert them into active ingredients such as sodium tannin and sodium humate respectively;
c. It can also be used to control the concentration of Ca2 in calcium-treated drilling fluids.
3. Lime
Quicklime is calcium oxide, and its molecular formula is CaO. After absorbing water, it turns into slaked lime, namely calcium hydroxide Ca(OH)2.
Characteristics: The solubility in water is low, 0.16% at room temperature, and its aqueous solution is alkaline. And the solubility decreases as the temperature increases.
Function:
a. In calcium-treated drilling fluid, lime is used to provide Ca2 to control the hydration and dispersion ability of clay and maintain it in a moderate flocculation state;
b. In water-in-oil emulsion drilling fluid, CaO is used to convert emulsifiers such as sodium alkylbenzene sulfonate into calcium alkylbenzene sulfonate and adjust the pH value.
Note: Lime drilling fluid may undergo a solidification reaction under high temperature conditions, causing the performance to fail to meet requirements. Therefore, it should be used with caution in high temperature deep wells. In addition, lime can also be formulated into lime milk sealing agent to seal the leakage layer.
4. Gypsum
The chemical name of gypsum is calcium sulfate, and its molecular formula is CaSO4. There are two types of plaster of paris (CaSO4?6?12H2O) and anhydrous gypsum (CaSO4).
Characteristics: Gypsum is white powder with a density of 2.31~2.32g/cm3. The solubility at room temperature is low (about 0.2%), but slightly greater than that of lime. Before 40℃, the solubility increases with the increase of temperature; after 40℃, the solubility decreases with the increase of temperature. It will form hard lumps after absorbing moisture. Care should be taken to prevent moisture when storing.
Function: In calcium-treated drilling fluid, gypsum and lime have roughly the same function, both are used to provide an appropriate amount of Ca2. The difference is that gypsum provides a higher calcium ion concentration than lime. In addition, treatment with gypsum can prevent the pH value of the drilling fluid from being too high.
5. Calcium chloride
Characteristics: Anhydrous calcium chloride is extremely water-absorbent and usually contains six crystal waters. Its appearance is colorless orthorhombic crystals with a density of 1.68 g/cm3. It is easily deliquescent and soluble in water (about 75% at room temperature). Extremely soluble.
Function: Its solubility increases with temperature. In drilling fluids, CaCl2 is mainly used to prepare high-calcium drilling fluids with better anti-collapse properties. Treating drilling fluids with CaCl2 often causes a decrease in pH.
Section 3 Commonly used organic treatment agents
1. Humic acids
Humic acid (Hunfic Acid) is mainly derived from lignite. Lignite is an immature coal with a relatively low combustion value. Its active ingredient is humic acid. The humic acid content of good lignite can reach 70-80%. The structure of humic acid is very complex and the relative molecular mass is not uniform.
Main functional groups: phenolic hydroxyl group, carboxylic acid group, alcoholic hydroxyl group, quinone group, methoxy group and carbonyl group, etc. Due to their large molecular weight, they are generally difficult to dissolve in water, but are easily soluble in alkali solutions, forming Sodium humate is an active ingredient as a fluid loss reducer in drilling fluids.
The hydrating groups such as sodium carboxylate group with strong hydration effect make sodium humate not only have good filter loss reduction effect, but also have certain viscosity reduction effect.
2． Cellulose
Cellulose is a long-chain polymer compound composed of many cyclic glucose units. A series of drilling fluid fluid loss additives can be produced from cellulose, among which the most commonly used ones are Sodium carboxymethyl cellulose is referred to as CMC and hydroxyethyl cellulose is referred to as HEC.
(1) Physical properties of sodium carboxymethylcellulose
Pure sodium carboxymethylcellulose is a white fibrous powder, which is hygroscopic and forms a gel when dissolved in water. liquid. It is a widely used fluid loss reducer with good performance.
(2) Structural characteristics and properties
In the process of making sodium carboxymethyl cellulose from cellulose, in addition to the obvious reduction in the degree of polymerization, another change is that -CH2COONa (sodium carboxymethyl) is linked to the glucose units of cellulose through ether bonds. Usually, among the three hydroxyl groups on each glucose unit of the cellulose molecule, the number of hydrogens on the hydroxyl groups that are substituted to form ethers is called the degree of substitution or the degree of etherification. Research shows that there are two main factors that determine the properties and uses of sodium carboxymethylcellulose: one is the degree of polymerization n, and the other is the degree of substitution d.
(3) The fluid loss reduction mechanism of sodium carboxymethylcellulose
CMC ionizes in drilling fluid to generate long-chain multivalent anions. The hydroxyl and ether oxygen groups on its molecular chain are adsorption groups, while the sodium carboxylate group is a hydration group. The hydroxyl and ether oxygen groups form hydrogen bonds with the oxygen on the surface of the clay particles or form coordination bonds with Al3 on the bond-breaking edges of the clay particles so that CMC can be adsorbed on the clay; while multiple sodium carboxylate groups make it adsorbable on the clay through hydration. The hydration film on the surface of the clay particles becomes thicker, the absolute value of the electric potential on the surface of the clay particles increases, and the negative charge increases, thereby preventing the clay particles from agglomerating into large particles due to collision (gel protection effect), and multiple fine clay particles It will be adsorbed on a molecular chain of CMC at the same time, forming a mixed network structure that covers the entire system, thereby improving the coalescence stability of clay particles, helping to maintain the content of fine particles in the drilling fluid, and forming a dense filter cake. Reduce filtration loss.
3. Acrylic polymers
Acrylic polymers are one of the main types of treatment agents for low solid polymer drilling fluids. The main raw materials for preparing this type of polymer include acrylonitrile, acrylamide, acrylic acid and propylene sulfonic acid.
A series of drilling fluid treatment agents can be synthesized based on the introduced functional groups, relative molecular weight, degree of hydrolysis and generated salts.
Section 4: The principle of action of commonly used organic treatment agents
1. Reduce water loss: By forming low permeability, flexible, thin and dense filter ice on the well wall, it can reduce water loss as much as possible. It may reduce the filter loss of drilling fluid;
2. Dilution: dismantle the end-face structure between clay particles, destroy the network structure inside the mud system, release free water, and keep the clay dispersed, thereby reducing Viscosity and shear force;
3. Flocculation: The adsorption base on the macromolecules adsorbs or captures the cuttings particles, causing the cuttings to flocculate and then remove them through the solid control system;
4 . Thickening: long-chain cyclic polymer compounds with strong hydrophilic groups, soluble in water, and have high viscosity. The molecular chains can form a network structure due to hydrogen bonds or cross-linking agents, thereby increasing the viscosity;
6. Flow pattern adjustment: Linear polymer compounds with long molecular chains have great flexibility, bind more water molecules, and have small internal friction between molecules, which can improve the shear dilution of mud. Function and improve the ability of mud to carry cuttings.
Chapter 5: Design and preparation of pore-forming fluid
Section 1: Basic design process of pore-forming fluid
According to the actual engineering conditions, in order: 8?4 Design the main technical indicators and important performance parameters of the pore-forming liquid 8.4 Select the type of pore-forming liquid 8.4 Select the basic materials and treatment agents for pulping 8.4 Design the formula of the pore-forming liquid treatment agent 8.4 Materials of the pore-forming liquid Dosage calculation 8.4 Determine the preparation method of pore-forming fluid 8.4 Develop a pore-forming fluid circulation, purification, and management plan 8.4 Other matters that need attention
Section 2: Design principles of commonly used pore-forming fluids
1. Determine the rheology of the pore-forming fluid by considering the requirements for suspended drilling ballast and wall sealing.
The apparent viscosity is generally between 10mPa?6?1s and 100mPa?6?1s, and the shear force is between 0 and 20Pa.
2. Calculate the specific gravity of the pore-forming fluid according to the requirements of balancing formation pressure. Generally, the specific gravity of pore-forming fluid is between 0.60 and 1.30.
3. The reference range of other design indicators of the pore-forming fluid is: the water loss should not be greater than 15ml/30min, the sand content should not be greater than 8, the colloid rate should not be less than 90, and the pH value should be within 6 depending on the situation. Adjust between ~11, and the lubrication coefficient should be controlled between 0.02 and 0.50.
Section 3 Types of pore-forming fluids classified by formation
According to applicable conditions, pore-forming fluids can be divided into: 8 to 4 for sand layers, pebble layers, crushed Mud for mechanically dispersed strata such as loose layer mud; 8.4 Mud for water-sensitive strata such as soil, mudstone, shale, etc.—water-sensitive inhibitory mud; 8.4 Used for rock salt, potassium salt, Mud for water-soluble formations such as trona - water-soluble inhibitory mud; 8.4 Mud used for relatively stable hard rock drilling with small leakage - hard rock drilling mud; 8.4 Used for abnormally low pressure or abnormally high pressure formations Low specific gravity mud or weighted mud;
Section 4 Preparation of Pore-forming Fluid
The basic process of a more comprehensive mud design is: design the weight, rheology, and loss reduction of the mud Main technical indicators such as water properties; determine the colloid rate, allowable sand content, solid content, pH value, lubricity, permeability, mud skin quality and other important parameters of the mud; select mud making clay and treatment agents; carry out mud treatment agents Formula design; calculation of mud material dosage; determination of mud preparation methods; formulation of mud circulation, purification, and management measures.
(1)． Calculate the mud weight ν according to the requirements of equilibrium formation pressure. That is νh=PC or νh=P0. PC and P0 are the formation side pressure or formation pore fluid pressure at well depth H respectively. See Section 3 for their determination methods. So, whether to calculate based on PC or P0 depends on which pressure balance is more important in the actual situation. If both need to be balanced, the two results should be calculated separately and a value between the two should be weighed. Generally, the gravity of drilling mud is between 1.02 and 1.40.
(2). Determine the rheology of the mud by considering the requirements for suspended drilling ballast and wall sealing. The main indicators of rheology are viscosity η and shear force τ. The adjustment ranges of eta and τ are very wide. Generally, the range of eta is between 10cP and 100cP, and the range of τ is between ~ , which should be determined according to different drilling conditions. For details, see Chapter 2 and the introduction in Sections 6 to 10 of this chapter. In addition, in some cases, the shear thinning effect and thixotropy of the mud must also be considered.
(3)． The reference range of other design indicators of mud is: water loss should generally not be greater than 15ml/30min, sand content should not be greater than 8, colloid ratio should not be less than 90, pH value varies between 6 and 11 depending on different muds, lubricity if necessary should be controlled.
The drilling purposes, formation characteristics, drilling process methods, etc. under various drilling conditions are very different, so there are obviously different requirements for drilling mud performance, etc., and the design focus is also different. For example, in formations with thick drilling ballast and loose well walls, rheological indicators such as mud viscosity and shear force become the focus of design; when drilling in stable hard rock, the focus of mud design is on the cooling of the drill bit and the stability of the drilling tool. Lubrication, while the wall protection and powder discharge are in a secondary position at this time. Another example is when drilling in a formation that expands when exposed to water and collapses. The focus of mud design should be on reducing water loss and protecting the wall. In pressure-sensitive formations, the heavy design of mud is particularly important. In this way, for specific drilling conditions, finding the corresponding design points in the comprehensive design is the key to good mud design.
Some contradictory situations may be encountered in mud performance design. When some design indicators are met, other indicators are not met. In this regard, we should grasp the main issues, take into account the secondary issues, and take comprehensive care of the overall performance.
In some situations where the requirements are not high, the design of mud performance can be streamlined as appropriate, and the requirements for some relatively minor indicators can be appropriately relaxed to achieve the ultimate low cost and high efficiency.
Section 5 Calculation of Material Amount
1. Calculation of the total volume of mud
The total amount of mud required V is the amount of mud in the borehole V1, the amount of mud on the surface The sum of the mud volume V2, leakage and other losses V3 in the circulating purification system: V=V1 V2 V3
Among them, the mud volume in the borehole is:
The mud volume in the surface circulation purification system is The sum of the volumes of the mud tank, sedimentation tank, circulation tank and surface manifold. Leakage and other losses should be determined based on actual conditions.
2. Calculation of the amount of clay powder
The weight q of clay required to prepare 1m3 volume of mud is deduced and calculated according to the following process:
In the formula: ―― of clay Specific gravity, 2.6 ~ 2.8;
——Proportion of mud;
——Proportion of water
3. Calculation of water consumption for slurry preparation
The amount of water Vw required to prepare 1m3 volume of mud is
4 Calculation of the amount of soil (or barite) added to increase the specific gravity
When preparing weighted mud, the amount of water required to add 1 m3 of mud The weight W (Kg) of the weighting agent required is:
In the formula: ——The specific gravity of the weighting agent; ——The specific gravity of the weighted mud; ——The specific gravity of the original pulp
5 reduction Amount of water required for mud specific gravity proportion.
6 Calculation of the dosage of mud treatment agent
Generally speaking, the amount of treatment agent added to the mud is small, and it generally only accounts for 0.1~ of the total volume of the mud in terms of volume content. 1. The specific value is determined by different formulas. It is worth noting that the dosage unit of the treatment agent must be clarified. Powders are generally calculated based on the weight added per unit volume of mud, while liquid agents are calculated based on the volume added per unit volume of mud. In some special cases, it is also calculated based on how much treatment agent is added per unit weight of clay powder.