Functional liquid

The present invention relates to drilling mud containing an aqueous surfactant.

The term "drilling slurry" is used here in relation to the liquids used for drilling holes in the rock to lubricate and cool the drill bit, and to remove rock wells from the wellbore. The term also includes "fracturing fluids that are used to clean the sides of wells prior to cementing. Drilling sludges are used to make deep wells and wells, as well as special wells in oil and gas mining. In the present application, the term "drilling mud" also includes "construction sludge, which is used in civil engineering and in the construction industry to stabilize wells and excavations by preventing shale collapse under water.

Here, the term "electrolyte" means ionic compounds that dissociate at least partially in aqueous solution to form ions and which, at current concentrations, tend to decrease the total solubility (including nicelar concentration) of the surfactants in such solutions through the phenomenon of "salting out." The term electrolyte content or concentration as used herein refers to the total amount of dissolved electrolyte, but without suspended solids.

The designation "micelle" means a particle in the shape of either a ball or rod formed by the aggregation of surfactant molecules and having a radius smaller than a second multiple of the average length of the surfactant molecules. The particles in the micelle are typically located such that their hydrophilic ("front") groups lie on the surface of the micelles and the lipophilic ("rear") groups are located inside the micelles.

The term "double layer" means a surfactant layer with a thickness of approximately two particles, which is formed of two adjacent parallel layers, each containing surfactant molecules that are arranged such that the lipophilic portions of the molecules are located within the double layer , and the hydrophilic parts are located on its external surfaces. The term "double layer" also includes layers with a comb structure that have a thickness less than two particles. A layer with a comb structure can be considered a double layer in which both layers have penetrated each other enabling at least some overlap between the rear groups of the particles of both layers.

The term "spherulite" means a spherical or spheroidal body with dimensions of 0.1 pm to 50 pm. Spherolytes can sometimes be distorted into an elongated, flattened, pear or dumbbell shape. The term "bubble" means a spherolite containing a liquid phase bounded by a double layer. The term "multiple bubble" means a bubble that contains one or more smaller bubbles. Spherolites found in structured surfactant systems are typically concentric multiple bubbles.

The term "plate phase" means a hydrated solid or liquid crystal phase in which a plurality of double layers are arranged substantially in a parallel system of indefinite span, separated by layers of water or an aqueous solution and having a sufficient regular grid spacing from 25 nm to about 150 nm to allow easy detection by neutron scattering or X-ray diffraction when present as a significant proportion of the composition. As used herein, this term does not include multiple concentric bubbles.

The term "G phase" means a liquid crystalline plate phase of the type also known in the literature as the "ordered ** phase or the" plate ** phase. The G phase for each surfactant or surfactant mixture normally exists in a narrow concentration range. Pure G phases can normally be identified when testing the sample under a polarizing microscope between crossed polarizers. Characteristic structures are observed according to the classical study of Rosevear, JAOCS Vol. 31 P628 (1954) or J. Colloid and Interfacial Science, Vol. 20 No. 4, P. 500 (1969). G phases normally have a repeatable spacing of 50-70 nm when examined by X-ray diffraction or neutron scattering. "Stretched G phase" means a G phase with a repetition spacing of 110-150 nm.

The term "spherical G phase" means multiple bubbles formed from substantially concentric coatings of a double layer of surfactant alternating with a water phase with a G phase spacing or an extended G phase. Typically, conventional G phases may contain a small amount of spherical G phase.

The term "lye" means an aqueous liquid phase containing an electrolyte, which phase is separated from a second liquid phase containing a more active ingredient and less electrolyte than the lye phase.

The term "platelet composition" means a composition in which most of the surfactant is in the platelet phase or in which the platelet phase is the main factor in inhibiting sedimentation. The term "spherulitic composition" means a composition in which most of the surfactant is in the form of a spherical G phase or which is substantially stabilized against sedimentation by the spherical G phase.

The term "structured surfactant" means a liquid composition which has a shear viscosity and a property for receiving solids into a suspension, and which contains an intermediate surfactant phase which can optionally be dispersed in or with the aqueous phase, wherein the water phase is typically the lye phase. For example, the intermediate phase may contain a G phase, spherolites, especially a spherical G phase, or a plaque hydrated solid.

The term "loading agent **" means a water-insoluble, particulate mineral with a specific density greater than 3.5, preferably greater than 4, for example barite or hematite. The term "drilling mud" means coolant for drilling that contains mineral particles in suspension, such as rock drillings or a loading agent.

The main problem with coolant lubricants for drilling is that they most often contain mineral oil, which is potentially an environmental pollutant and a fire hazard. The present invention relates to solving this problem by using aqueous structured surfactants

166 Active substances that are better accepted by the environment than mineral oils do not create a fire hazard, but may have the same or better physical properties and chemical stability.

Drilling sludges used in oil mining are normally pumped continuously downwards through the drill rod, through the holes in the drill bit, and then are pushed to the surface through the annular space between the drill rod and the borehole wall and lift rock drills in suspension. On the surface, the drill bits are separated from drilling mud, which is recycled. Before cementing the well, the slurry is replaced by a distance liquid that drains loose particles from the well and leaves a clean, wet surface to ensure good cementation.

Some rocks pose particular problems when drilling or excavating due to their tendency to disintegrate in the coolant and lubricant forming a fine-grained material that is very difficult to separate from the liquid and which quickly accumulates in the recycle stream causing an increase in viscosity. The main rock among these problematic rocks is shale, which usually decays in the presence of water.

An acceptable drilling coolant must have a viscosity that is low enough under shear to ensure easy flow, but it must also have suspended solids. To meet these conflicting requirements, a thixotropic liquid is usually needed. In addition, this liquid must not cause excessive disintegration of rocks, such as slate. If it is to be suitable for deep drilling, the liquid must be thermally stable and it is important to avoid excessive liquid loss in the formation.

Until now, these requirements have almost always been met by using as a coolant for drilling either oil or an oil-water emulsion. The oil covers the slate particles and protects them from contact with water, thus inhibiting their breakdown. However, this in turn creates environmental problems, especially when drilling in the seabed, where rock drillings are thrown away. To avoid serious environmental contamination, oil must be separated from the drillings before they can be discarded. Reducing oil contamination to an acceptable level is very difficult and expensive, but even such small residual amounts of oil are ecologically undesirable, and there is a desire to replace all oil-based cooling lubricants.

The alternative of using aqueous solutions containing polymeric dispersants or suspending agents and / or bentonite to form a suspension containing rock drilling is less harmful to the environment and may be slightly cheaper than using oil-based sludges, but only with shallow drilling and where rock formation does not create special problems. For deep drilling or drilling or digging in difficult rock formations, such as slate, which is very often encountered in oil drilling and excavations, such cheap water liquids are not suitable. They have insufficient thermal stability to withstand high temperatures in deep rock formations and cause shale disintegration. Their lubricating ability is also usually worse than with oil-based sludges.

Attempts have been made to improve the properties of aqueous cooling lubricants for drilling through various special additives such as polymer coating agents and high electrolyte concentrations to help stabilize shale. This significantly increased the cost of sludge, but failed to create an aqueous liquid with properties that would enable it to replace oil-based sludge in the event of deep drilling. However, the emphasis on environmental protection is increasing and forcing oil mining companies to use relatively expensive and technically inferior water-based liquids instead of conventional oil-based sludges.

The field of formulation of laundry detergents and similar cleaning preparations is remote from the field of formulation of lubricating liquids and hydraulic fluids. The problems to be overcome in these two areas are not similar. However, we have noticed that liquid cleaning preparations often require the use of solids in suspension. For example, scouring creams for hard surfaces require the presence of abrasive materials, and effective washing detergents require costly, effective fillers

166 502 active, which may be slightly soluble or insoluble in water. These problems were solved by exploiting the interaction between electrolytes and surfactants to form solid dispersion structures based on thixotropic suspensions or mutual suspensions of intermediate surfactant phases with aqueous electrolyte solutions.

United Kingdom Patent No. 2123846 describes the use of a platelet surfactant dispersed with a solution of electrolyte in a liquid laundry detergent. Another structure, also referred to in UK Patent No. 2,123,846 and which occurs, although not specifically identified, in the formulations exemplified in a number of other publications, contains a system of spherolytes, each of which has many concentric surfactant coatings arranged alternating with layers of electrolyte solution. The patents that provide formulations that are likely to have a spherulitic or platelet structure are as follows:

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166 502

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although in most cases the structures that would be present in the formulations described would be insufficiently stable to keep particulates in suspension. United Kingdom Patent No. 2,153,380 describes a spherulite structure and methods for making a tightly packed, space-filling structure strong enough to withstand various forms of shear and temperature stress, but mobile enough to be easily poured. This method requires optimization of electrolyte concentrations within strict limits.

In our current UK Patent Application No. 8906234.3 we described the use of structured surfactants as a carrier for pesticides.

Our currently pending United Kingdom Patent Application No. 891925 describes methods for obtaining a surfactant structure suitable for suspending solid particles in substantially electrolyte-free systems.

Previously known functional fluids, including oil-based drilling muds and lubricating liquids, contained small amounts of surfactants as oil emulsifiers or as a sludge dispersant. Surfactants typically exist essentially as single layers surrounding oil or solid droplets or particles in a colloidal size suspension. The protection of shale in drilling slurries was essentially carried out by the fact that the shale was oil-coated. The slurry properties and the thioxotropic nature of oil-based drilling mud were ensured by the interaction of dispersed oil droplets. For oil-free sludge, shale protection was provided by the presence of polymers that surrounded the rock particles in an irreversible manner, and therefore were used quantitatively in rock separation. The suspension properties of solids are provided by polymeric thickeners such as sodium carboxymethyl cellulose or methacrylates. They aim to stabilize the suspension at the expense of liquid mobility.

Electrolytes were used in both oil-based drilling sludge and water-based drilling sludge to control water activity. If the electrolyte concentration is high enough to reduce the water activity in the sludge to the same level as the water activity in the shale, then hydration of the shale will not occur. However, if the water activity in the sludge is too low, the slate will tend to dehydrate and become brittle, whereas if this water activity is too high, the slate will tend to hydrate and break down, unless there is a protective barrier between the slate and water factor. Unfortunately, it is not possible to consistently maintain an optimal electrolyte level due to the fact that the mineral layers contain soluble salts that tend to dissolve in the sludge, changing the electrolyte content as the sludge passes through the hole.

We have now discovered that aqueous, structured surfactants have amazingly good lubrication properties for both rock and metal, even at very high pressures and in the absence of additives for very high pressures. In addition, such structured surfactants exhibit the rheological properties required for a drilling coolant or hydraulic fluid, as well as the ability to receive solid rock chippings into slurries or filings, and, surprisingly, they protect slate from decay even in the absence of oil or protective polymer. We believe that slate is protected by coating it with a surfactant. The liquid can easily be separated from rock drillings, and any residual surfactant can be easily flushed out of the drillings with water. Clean drill bills pose no ecological danger and can be disposed of safely. water

166 502

Ί the surfactant is a structured surfactant such as those which have been formed by the interaction of the surfactant with the dissolved electrolyte, preferably in a spherulitic system. Typically, this is the aqueous intermediate surfactant phase dispersed with the aqueous continuous phase or the aqueous electrolytic continuous phase.

An important and particularly remarkable property of spherulitic compositions when used as cooling lubricants for drilling is the low formation fluid loss that is significantly less than that of conventional cooling lubricants for drilling, even without the additives that are normally needed. Structured surfactants can easily be formulated in a thermally stable form for high temperature applications such as deep drilling.

In our invention, both slurry and slate protection properties are essentially provided by the surfactant, preferably in combination with some dissolved electrolyte. Although we do not want this to be a limitation, we believe that a surfactant can coat reversible slate particles. It can also help maintain optimal water activity. The surfactant is preferably present in our composition as a spherical G phase, dispersed platelet phase or micelles.

The invention provides the possibility of drilling wells, consisting in the use as a cooling lubricant for drilling or cutting of aqueous, structured surfactants, which is preferably a solution containing surfactant micelles or mutually dispersed surfactant solid platelet, sufficiently spherulitic or G-phase to prevent shale disintegration or to provide metal surface protection against abrasion and to keep rock drills in suspension under normal drilling conditions.

Drilling mud containing the aqueous surfactant according to the invention contains a structured surfactant as the surfactant.

The sludge according to the invention contains suspended solid particles of slate and / or a loading agent.

The sludge according to the invention suspended barite and / or hematite particles.

The sludge according to the invention as a structured surfactant comprises (A) an aqueous phase and (B) a plate-like solid, a spherolytic phase or a G phase dispersed or dispersed with said aqueous phase, the electrolyte solution being the aqueous phase.

According to the invention, part of the electrolyte solution may be brine, with sea water as the brine.

The sludge according to the invention contains graphite particles in suspension.

The sludges according to the invention preferably contain 5-45% by weight of surfactant. Surfactants may constitute up to about 35% by weight of sludge, although for both economic and rheological reasons it is preferred to use lower concentrations, e.g. below 30%, usually below 25%, preferably less than 20%, e.g. 10-15% by weight .

The surfactant may, for example, consist essentially of at least a sparingly water-soluble salt of sulfonic acid or monoester sulfuric acid, e.g. alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate, olefin sulfonate, alkane sulfonate, alkylphenol sulfate, alkylphenol ether sulfate, alkylethanolamide sulfate, amide ether sulfate-alkyl ethanol or alpha-sulfo fatty acid or its esters, each with at least one alkyl or alkenyl group of 8-22, typically 10-20 aliphatic carbon atoms. Said alkyl or alkenyl groups are preferably straight chain primary groups, but may optionally be secondary or branched chain groups. The term "ether" refers herein to homogeneous and mixed polyoxyalkylene groups, such as polyoxyethylene, polyoxypropylene, glycerol, and polyoxyethylene oxy 8 mixed polyoxyethylene groups.

166 502 propylene or mixed glycerol-oxyethylene, glycerol-oxypropylene, or glycerol-oxyethylene-oxypropylene groups, typically containing from 1 to 20 oxyalkylene groups. For example, the sulfonated or sulfated surfactant may be sodium dodecylbenzene sulfonate, sulfonate sulfonate, potassium sulfonate sodium dodecyl dimethylbenzene, sodium lauryl sulfate, sodium tallow sulfate, potassium oleyl sulfate, monoethoxy ammonium volauryl sulfate or monoethanolamine-ethyl-10 mol-ethoxylate sulfate.

Other anionic surfactants useful in the present invention include fatty alkyl sulfosuccinates, fatty alkyl ether sulfosuccinates, derivatives of fatty alkyl sulfosuccinates, derivatives of fatty alkyl ether sulfosuccinates, acyl sarcosinates, acyl taurates, icencinates, oleates, linnates, such as stearates rosin soaps and alkyl ether carboxylates and saponates. Anionic phosphate esters, including surfactants found in nature, such as lecithin, may also be used. In any case, the anionic surfactant contains at least one aliphatic hydrocarbon chain with 8-22, preferably 10-20, usually an average of 12-18 carbon atoms, an ionizable acid group such as a sulfo group, a sulfuric acid group, a carboxy group, a phosphonium group or phosphoric acid group and, in the case of ethers, one or more glycerol groups and / or 1-20 ethyleneoxy and / or propyleneoxy groups.

The preferred anionic surfactants are sodium salts. Other salts of industrial interest are those of potassium, lithium, calcium, magnesium, ammonium, monoethanolamine, diethanolamine, triethanolamine and alkyl amines containing up to seven aliphatic carbon atoms, for example isopropylamine.

The surfactant preferably contains or consists of nonionic surfactants. The nonionic surfactant may be, for example, a C10-22 alkanolamide from a lower order mono or dicalkanolamine, such as monoethanolamide or coke or tallow diethanolamide. Other nonionic surfactants that may optionally be used include ethoxylated alcohols, ethoxylated carboxylic acids, ethoxylated amines, ethoxylated alkylamides, ethoxylated alkylphenols, ethoxylated glycerol esters, ethoxylated sorbic acid esters, ethoxylated phosphate and propoxylated esters, butoxylated and mixed ethoxy analogues propoxy and / or butoxy of all the aforesaid ethoxylated nonionic agents, all having Ce-22 alkyl or alkenyl group and up to 20 ethyleneoxy and / or propyleneoxy and / or butyleneoxy groups, or any other nonionic surfactant that has hitherto been used in powdered or liquid detergent compositions, e.g. amine oxides. The latter typically have at least one Ce-22 alkyl or alkenyl group, preferably C10-20, and up to two lower-order alkyl groups (e.g. C1-4, preferably C1-2).

Preferred nonionic agents for the purposes of the invention are, for example, those having an HLB range of 2-18, e.g. 8-18.

The sludges of the invention may contain cationic surfactants which include fourth order amines having at least one long chain (e.g., C12-22, typically C16-20) alkyl or alkenyl group, optionally one benzyl group, and as the other four substituents short chain alkyl groups (on example C1 -4). They also include imidazolines and quaternary imidazolines having at least one long chain alkyl or alkenyl group and amidoamines, and quaternary amidoamines having at least one long chain alkyl or alkenyl group. All quaternary surfactants are usually salts of anions that confer some degree of water solubility such as formate, acetate, lactate, tartrate, chloride, metasulfate, ethosulfate, sulfate or nitrate. Particularly effective as lubricants are cationic surfactants having two long chain aliphatic alkyl groups, for example tallow groups such as bis-tallyl quaternary ammonium and imidazole salts.

The sludges of the invention may also contain one or more amphoteric surfactants, which include betaines, sulfobetaines and phosphobetaines formed by the reaction of a suitable tertiary nitrogen compound having a long chain

166 502 alkyl or alkenyl with a suitable reagent such as chloroacetic acid or propane sulfone. Examples of suitable nitrogen-containing tertiary compounds include: tertiary amines having one or two long chain alkyl or alkenyl groups and optionally a benzyl group with the other substituent being a short chain alkyl group; imidazolines having one or two long chain alkyl or alkenyl groups, and amidoamines having one or two long chain alkyl or alkenyl groups. Usually, amphoteric surfactants are less preferred than nonionic or anionic surfactants.

The types of surfactants described above are only examples of more general surfactants suitable for use in the present invention. Any surfactant can be used. For a more complete description of the main types of surfactants that are commercially available, see "Surface Active Agents and Detergents", Schwartz, Perry and Berch.

In general, the surfactants for use according to the invention should preferably be substantially non-toxic, especially for marine life and should be substantially stable at temperatures above 100 ° C, preferably above 120 ° C, especially above 150 ° C, for example for deep drilling applications - above 180 ° C.

Dissolved electrolytic compounds are very preferred components of the composition. Although it is possible to prepare structured surfactants without electrolyte if the surfactant concentration is high enough, the mobility of such systems is often insufficient, unless the surfactant is chosen with great care. The addition of electrolyte enables the preparation of mobile structured surfactants with a relatively low concentration of surfactant.

Suitable electrolytes include water soluble alkali, ammonium and alkaline earth metal salts derived from strong inorganic acids. Sodium and potassium salts, especially chlorides, are particularly preferred. However, lithium, calcium and magnesium salts may also be used. Salts that are useful may include phosphates, nitrates, bromides, fluorides, concentrated phosphates, phosphonates, acetates, formates and citrates. It is often particularly advantageous for coolant to be drilled to form a composition by diluting the surfactant concentrate in place with locally occurring natural brine (e.g. sea water for bottom drilling). The brine may be all or part of the electrolyte contained in the cutting fluid for drilling.

The electrolyte may be present in concentrations up to saturation. Usually, the lower the surfactant content, the more electrolyte will be needed to form a structure capable of carrying solid materials. It is beneficial to use higher electrolyte concentrations and lower surfactant concentrations, and to select the cheapest electrolytes for economic reasons. The electrolyte should normally be present at a concentration of at least 0.1% by weight based on the total weight of the composition, usually at least 0.5% by weight, for example more than 0.75%, preferably more than 1%. Usually the concentration is less than 30%, more often less than 10%, for example less than 8% by weight. Typically the concentration is in the range of 1-5%.

The maximum electrolyte concentration depends, among others, on the type of structure and the required viscosity, as well as on cost issues. It is preferred to form spherulitic compositions such as those described in the United Kingdom patent application GB-A-2, 153,380, to obtain a satisfactory balance between mobility and a large amount of solids in suspension. Optimal electrolyte concentration for each specific type and amount of surfactant can be ensured, as described in the aforementioned patent application, by measuring-changing the electrical conductivity with increasing electrolyte concentration until the first minimum conductivity is observed. Samples can be prepared and tested by centrifugation for 90 minutes at 20,000 g, adjusting the electrolyte concentration to obtain a suspending agent that does not separate into two phases during centrifugation.

Preferably, the electrolyte concentration is adjusted so as to obtain a composition that does not sediment when left for 3 months at ambient temperature or at 0 ° C or 40 ° C. Compositions that show no signs of sedimentation or separation are preferred

166 502 into two or more layers after holding for 72 h at 100 ° C in an autoclave. Preferably, the electrolyte concentration is also controlled to obtain a shear stable composition and one that is desirable that does not increase its viscosity significantly when left under normal shear.

Alternatively, a sufficient amount of electrolyte can be added to form a lamellar system, such as described in British Patent No. 2123846, for example by adding enough electrolyte to ensure that the liquid suspending agent is separated by centrifugation at 800 g after 17 hours, forming the lye phase containing little or no surfactant. The amount of water in the formulation can then be adjusted to obtain an optimal balance between mobility and stability.

For drilling slurries and distance fluids, it is usually desirable to provide a borehole with a liquid that contains the necessary concentration of surfactant and electrolyte to form a structure to form a suspension of solid particles. However, salts found in rock in which drilling is carried out may sometimes have the ability to form such a structure in situ as soon as an aqueous surfactant is provided. It is often advantageous to provide an aqueous system containing less than the optimal amount of electrolyte to allow the minerals present in the well to dissolve.

The amount of electrolyte needed also depends on the nature and solubility of the surfactant. Typically, high cloud point surfactants require less electrolyte than low cloud point surfactants. For some surfactants, no electrolyte is needed at all.

Surfactants or mixtures of surfactants that can be used in the non-electrolyte compositions of the present invention are typically those that form the G phase at ambient temperature, but preferably do not form the M1 phase. Generally speaking, the aqueous surfactant has a cloud point greater than 30 ° C, usually greater than 40 ° C, and preferably greater than 50 ° C. Aqueous surfactants with a cloud point above 60 ° C are particularly useful. Alternatively or additionally, the surfactant may have a reverse cloud point below 30 ° C, more often below 20 ° C, especially below 10 ° C, preferably below 0 ° C. Surfactants whose back-cloud point is below -10 ° C are particularly preferred. Back-clouding temperatures are typical for some non-ionic surfactants in which increasing temperatures tend to break the hydrogen bonds responsible for hydrating the hydrophilic part of the molecules, making it less soluble. Normal cloud point temperatures are more typical for anionic or cationic surfactants. Mixtures of anionic and non-anionic surfactants may have a cloud point and / or a reverse cloud point.

It is usually preferred that the surfactant is present at a concentration of at least 1%, for example at least 3% by weight of the composition, more often above 5%, especially above 8% and preferably 10-15%. The typical concentration range of surfactants is from 6 to 15%, more often 7-12%. Another concentration of surfactants that can be used is 1-30%, for example 2-15% by weight. The surfactant concentration should preferably be sufficient in the presence of any electrolyte in the formulation to form compositions with a plastic viscosity as measured by a Fann viscosity meter 5-35 cP, i.e. 0.0050.035 Pa · s, preferably 0.015-0.03, for example 0, 02-0.025 Pa · s. Preferably the composition should have a yield point greater than 7.25 Pa, more preferably 14-25 Pa, especially 17-22 Pa, for example 20 Pa. It is particularly preferred that the composition has a yield strength to plastic viscosity ratio of 50 to 120, especially 70-95, e.g. 85.

Surfactant concentrations above 60% are possible, but very unlikely for industrial use in at least most of the anticipated uses of the invention.

Particularly preferred in electrolyte-free systems are nonionic and mixed nonionic surfactants, especially mixtures of aliphatic alcohol ethoxylates, and mixtures of aliphatic alcohol ethoxylates with fatty acid ethoxylates

166 502 or mixed ethoxylate / propoxylated alcohols, and fatty acid ethoxylates. For example, mixtures containing one or more C10-C20 aliphatic alcohols and / or alkoxylated fatty acids with 5-10 ethyleneoxy and / or propyleneoxy groups are particularly useful. Other nonionic surfactants that may be used include alkoxylated alkylphenols, alkoxylated amines, alkoxylated sorbic or glycerol fatty acid esters and alkanolamides, such as coconut mono or diethanolamide, and mixtures thereof.

Drilling sludges contain suspended solids, which may be rock debris such as shale and / or may contain a loading agent such as barite or hematite. The total amount of solid in suspension may typically vary from about 5% by weight to about 60% by weight, or more preferably 10-50%, for example 35-45%.

Preferably, a sufficient amount of loading agent is used to obtain a specific weight of 1-1.8.

Drilling mud may optionally contain a suspending agent such as carboxymethyl cellulose or polyvinyl pyrrolidone, usually in amounts up to 5%, for example 0.5-2% by weight. For reasons of cost and rheology, however, it is preferable to avoid the use of such suspending agents.

Drilling sludges according to the invention are preferably substantially free of oil or organic solvents or also water-miscible solvents, such as lower-order mono or polyhydroxy alcohols, ketones and polyethers or water-insoluble solvents such as aromatic hydrocarbons, and are also free of any hydrotropic agents. such as urea, benzene sulfonate or lower-order alkyl benzene sulfonates. Solvents and hydrotropes tend to interfere with the structuring of the surfactant, and require the use of much larger amounts of surfactant and / or electrolyte. They also increase the cost of formulation without significantly improving properties. Oil and solvents are also very undesirable for environmental reasons. If they are used at all, it is preferred that the oils, solvents and hydrotropes are present in an amount less than 10%, more preferably less than 5%, most preferably less than 1%, for example less than 0.5%, usually less than 0.1 % and most often less than 0.05% by weight of the composition.

It is preferred that there are no polymer thickeners, such as resins, or that they are present in concentrations less than 5%, preferably less than 0.5%, since they are not usually needed to stabilize the composition and increase the costs and the viscosity of the suspension.

Drilling sludges or other functional fluids according to the invention may optionally contain auxiliary structuring agents such as bentonite, but such additives are not normally necessary to prevent fluid loss and may be detrimental to rheological properties. If used, bentonite should preferably not constitute more than 5% of the total weight of the composition. However, the coolant drilling fluids of the invention typically abolish the presence of bentonite accidentally derived from minerals in the well.

Drilling sludges may optionally contain graphite in suspension to increase lubricity.

The composition may optionally contain a biocide such as glutaraldehyde or preferably a tertiary phosphonium hydroxymethyl salt such as THP sulfate or a mixture thereof with glutaraldehyde to inhibit the growth of sulfate-reducing bacteria that can cause pipe corrosion, liquid delamination and / or infection of the formation.

Lubricants may contain additives for high pressures, and all functional fluids of the invention preferably contain corrosion inhibitors such as phosphite esters, phosphonates, polyphosphonates, chromates and zinc salts. Corrosion inhibitors are preferably organic chelating agents or other corrosion inhibitors caused on the metal surface by aqueous solutions.

The invention will be further illustrated in the examples where all percentages are given by weight of the total weight of the composition, unless otherwise stated.

166 502

<td>Example</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td>

<td>AES</td><td> 3,2</td><td> 3</td><td> 2,65</td><td> -</td><td> -</td>

<td>IPABS</td><td> 6,4</td><td> 7</td><td> 4,02</td><td> -</td><td> -</td>

<td>LABS</td><td> -</td><td></td><td> -</td><td> 10,7</td><td> 10,7</td>

<td>AO</td><td> -</td><td> -</td><td></td><td> 2,1</td><td> 2,1</td>

<td>DEABS</td><td> -</td><td></td><td> -</td><td> 2,1</td><td> 2,1</td>

<td>KC</td><td> 1</td><td> -</td><td> 1</td><td> 1,2</td><td> 1,0</td>

<td>KA</td><td></td><td> 0,4</td><td> -</td><td> -</td><td> -</td>

<td>Yield point N m '²</td><td> 35,43</td><td> 24,42</td><td> 18,19</td><td> 6,22</td><td> 4,79</td>

<td>Plastic viscosity Pa · s</td><td> 0,015</td><td> 0,043</td><td> 0,021</td><td> 0,025</td><td> 0,02</td>

<td>GP / LP X10 '³</td><td> 23,62</td><td> 5,58</td><td> 6,66</td><td> 2,49</td><td> 2,4</td>

<td>Loupe Recovery</td><td></td><td></td><td></td><td></td><td></td>

<td>at room temperature</td><td> 94,8</td><td> 96,2</td><td> 97,8</td><td> 95,8</td><td> 91,2</td>

<td>Slate recovery at 60 ° C</td><td> -</td><td> 92,0</td><td> 93,2</td><td> 91,8</td><td> 87,0</td>

AES - sodium sulfate Ci2-ie-aikyl-3 mol-ethoxy,

IPABS - C10-14-limicyl benzene isopropyioamine sulfonate,

LABS - sodium Cio-14-linear alkylbenzene sulfonate,

AO - Ci-2 alkyl dimethyl amine oxide,

DEABS - diethanolamine-Cio-1-4-alkyl hbenzene sulfonate,

KCl - potassium chloride,

KA - potassium acetate.

Examples 1, 2 and 3 were transparent micelles solutions. Examples 4 and 5 were opaque spherolite compositions.

All five examples were able to be suspended from 50 g of barite in 350 ml at 80 ° C for 18 hours.

Example 6. Drilling slurry was prepared by suspending 1118.7 g barite in 1500.0 g of 10% aqueous IPABS. The latter was an opaque spherolite composition, and the formed sludge was a stable suspension.

Example 7. Drilling slurry was prepared by suspending 1028.8g of barite and 3 g of silicone antifoaming agent in 1500 g of an aqueous spherolite composition containing 2.25% diethanolamine, 10.5% LABS and 2.25% amine oxide.

Example 8. Drilling slurry was prepared by suspending from 1094.6 g barite, 37.5 g bentonite and 3g silicone antifoam in 10% aqueous IPABS.

Example 9. Drilling mud suitable for use in seabed drilling using seawater contains 8% LABS, 8% coconut diethanolamide and 4% sodium chloride.

Example 10. The products of examples 6.7 and 8 were compared with commercial oil-based sludge in terms of sedimentation using an inclined pipe test. A drilling pipe 1 meter long and 40 mm in diameter containing the tested slurry and set at an angle of 45 ° to the vertical was left for 120 hours, and at the end of this period the separation of the less opaque phase was visible in the upper zone of 35 cm of oil-based slurry, while the desired separation was not seen in the samples of the invention.

Example 11. Commercially available oil-based sludge was compared with the products of Examples 6 and 7 in terms of static filtration at low pressure. This indicates the sludge tends to lose formation fluid. The results are given in Table 1.

Table 1

<td></td><td>Oil based sludge (comparative)</td><td>Example 6</td><td>Example 7</td>

<td>Filter cake thickness</td><td>1 mm</td><td>&lt;1 mm</td><td>&lt;1 mm</td>

<td>Obtained filtrate</td><td>3.5 ml</td><td>3.6 ml</td><td>1.7 ml</td>

Example 12. The lubricity of the composition described in example 9 was tested using the FALEX method described in the test method IP 241 69 of the Institute of Petroleum.

The clean metal roller was rotated between two V-shaped fittings with a gradually increasing load, the roller being immersed in the lubricant under test without circulation.

166 502

The sludges according to the invention were compared with three comparative lubricants, namely water, mineral oil and bentonite suspension. All three comparisons failed (at 2.2 kN, 4.5 kN and 6.7 kN, respectively). In contrast, the composition according to the invention showed excellent spreadability at all loads including a maximum load of 17.8 kN. Only this lubricant of all four withstood the test without any damage.

Example 13. Various structured surfactants were compared with water, mineral oils and solutions of unstructured surfactants in the test according to example 12. The results are summarized in Table 2, where all percentages are by weight of the total weight of the mixture. Lubricants are listed in order of increasingly better properties. Only the last three lubricants withstood the entire test without galling.

Table 2

<td>Lubricant</td><td>Coefficient of friction 1</td><td>Damage</td>

<td> 1 2</td><td> 3</td><td> 4</td>

<td>x i.Water</td><td> 0,107</td><td>7 s at 3.3 kN</td>

<td>x ii. Mineral oil containing additives</td><td></td><td></td>

<td>for high pressures ("Tellus R10)</td><td> 0,065</td><td>44 s at 3.3 kN</td>

<td>x iii. Mineral oil</td><td></td><td></td>

<td>without additions ("Turbo T68)</td><td> 0,048</td><td>6s at 5.6 kN</td>

<td>x iv.30% LABS (without structuring)</td><td> 0,050</td><td>45 s at 6.7 kN</td>

<td>v. Example 1 of UK Patent 2123846</td><td></td><td></td>

<td>(plate structure)</td><td> 0,048</td><td>54 s at 6.7 kN</td>

<td>vi. 14% LABS 6% OB (spherulitic)</td><td> 0,042</td><td>13 s at 0.9 kN</td>

<td>vii.10% IPABS (spherulitic)</td><td> 0,038</td><td>45 s at 11.2 kN</td>

<td>viii.3% IPABS, 12% AES, 4% NaCl</td><td></td><td></td>

<td>(Sferolitowy)</td><td> 0,063</td><td>41 s at 12.2 kN</td>

<td>ix. 12% LABS, 8% AE, 3% NaCl (spherolytic)</td><td> 0,031</td><td>41 s at 15.5 kN</td>

<td>x.50% IPABS (phase G)</td><td> 0,024</td><td>57 s at 17.8 kN</td>

<td>xi.8% LABS, 8% coconut diethanolamide,</td><td></td><td></td>

<td>4% NaCl (spherulolite)</td><td> 0,024</td><td>51 s at 19 kN</td>

<td>xii.8% LABS, 8% coconut diethanolamide,</td><td></td><td></td>

<td>4% NaCl 2% graphite (spherulitic)</td><td> 0,027</td><td>51 s at 19 kN</td>

<td>xiii.20% LABS, 10% coconut diethanolamide</td><td></td><td></td>

<td>(Sferolitowy)</td><td> 0,028</td><td>no damage at 20 kN</td>

<td>xiv.3% LABS, 12% IPABS, 2% NaCl</td><td></td><td></td>

<td>(Sferolitowy)</td><td> 0,026</td><td>no damage at 20 kN</td>

<td>xv.25% imidazolines² (Sferolitowy)</td><td> 0,020</td><td>^M AT</td>

x Comparative example,

1. Friction coefficients measured just before damage / end of test,

2. 1-Methyl, 1-tallowamidoethyl, 2-tall-azoline imino sulfate.

UP Department of Publications. Circulation of 90 copies

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