MXPA01007216A - Electrically conductive non-aqueous wellbore fluids - Google Patents

Abstract

A wellbore fluid having a non-aqueous continuous liquid phase that exhibits an electrical conductivity increased by a factor in order of 104 to 107 compared to conventional invert emulsion comprises from about 0.2%to about 10%by volume of carbon black particles, and one or more emulsifying surfactant(s) selected from the class including:nonionic emulsifiers of Hydrophilic-Lipophilic Balance (HLB) less than about 12, and anionic surfactants wherein the counter-ion (cation) is any of alkali metal, ammonium, or hydrogen ions. This wellbore fluid can be used for drilling or completing a well and can be used for providing enhanced information from electrical logging tools, measurement while drilling, logging while drilling, geosteering and the like.

Description

NON-AQUEOUS, ELECTRICALLY CONDUCTIVE POLLUTION FLUIDS This invention relates to non-aqueous probing fluids and in particular concerns probing fluids which are electrically conductive. The invention also relates to the use of said subterranean fluids such as wells In the drilling process - rotating a well, a sediment or drilling fluid is circulated down the rotary drilling pipe, through the trephine, and up to the annular space between the pipe and the formation of zero cladding pipe , to the surface. The drilling fluid carries out different functions. Removes cuts from the bottom of the hole to the surface, suspends cuts and weighting material when circulation is interrupted, controls surface pressure, isolates fluids from formation by providing enough hydrostatic pressure to prevent entry or formation of fluids in the borehole, cools and lubricates the trephine and drill string, maximizes the speed of penetration, etc. An important objective to drill a well is also to ensure the maximum amount of information about the type of formations that penetrate and the type of fluids or gases in the formation. This information is obtained by analyzing the cut and by electrical digraph technology and by the use of various digraph techniques at the bottom of the hole, including electrical measurements. The required functions can be achieved by a wide range tA-L_ - ...________- _, ____? _ l ___ «i of fluids composed of various combinations of solids, liquids and gases and classified as aerated to the constitution of the continuous phase mainly in two groups: aqueous drilling fluids (based on water) and non-aqueous drilling fluids (synthetic base or mineral oil), commonly called "oil-based fluids". Water-based fluids are the most commonly used type of drilling fluid. The aqueous phase is made of fresh water or, more frequently, of a brine. As discontinuous phases, they may contain gases, hydro-immiscible fluids such as diesel oil to form an oil-in-water emulsion, and solids including clays and weighting material such as barite. The properties are typically controlled by the addition of clay minerals, polymers and surfactants. Perforating water sensitive areas such as reactive shales, production formations or where lower hole temperature conditions are severe or where corrosion is a major problem, drilling fluids based on oil are preferred. The continuous phase is a synthetic or mineral oil and commonly contains water or brine as a discontinuous phase to form a water-in-oil emulsion or invert the emulsion. The solid phase is essentially similar to that of fluids based on water and these fluids contain too many additives for the control of density, rheology and fluid loss. The inverted emulsion is formed and stabilized with the help of one or more specially selected emulsifiers. Although oil-based drilling fluids are more expensive than water-based sediments, they are based on the added operations advantage and superior technical performance of oil-based fluids that are often used for water-based operations. drilling. An area where oil-based sediments have been at a technical disadvantage, due to their very low electrical conductivity, is found in the digraph of the well. Several imaging and digraph operations are carried out during the drilling operation, for example, while drilling in the receiving region of an oil / gas well in order to determine the type of formation and the materials therein. Such information can be used to optimally locate the payment area, ie, wherein the container is drilled in order to allow the influx of hydrocarbons into the borehole. Some digraph tools work on the basis of a resistivity contrast between the fluid in the borehole (drilling fluid) and that already in the formation. These are known as resistivity digraph tools. Briefly, the alternating current flows through the formation between two electrodes. In this way, the fluids in the path of the electric current are found in the formation fluids and the fluid that has penetrated the formation by means of filtration. The filtrate and the mud coast result from the filtration of the sediment on a permeable medium (such as a formation rock) under differential pressure. Another example where the conductivity of the fluid plays an important part in the drilling operation is found in the _d ^, __, A "i__ directional drilling where the signals produced in the drilling assembly have to be transmitted through an electrically conductive medium to the control unit and / or sediment telemetry unit further back in the drill string . At present, the use of resistivity digraph tools is mainly limited to chaos where the water-based drilling fluid is used for the drilling operation (the very low conductivity of the oil base in case of sediments from synthetic base / oil prevents the use of resistivity tools in such fluids). Although the brine dispersed in the oil phase is electrically conductive, the discontinuous nature of the droplets prevents the flow of electricity. However, the inability of these emulsions to conduct electricity (until a very high potential difference is applied) is used as a standard emulsion stability test. For that extension it is best to keep in mind that the electrical conductivity of the oil base is typically in the range of 10"6 to 5 x 10" 2 μSm "1 at a frequency of 1 kHz while an electrical conductivity of less than 10 μS.m'1 and preferably not less than 103μS.m "1, is desirable for electric digraph operations. Thus there is a need to increase the electrical conductivity of the fluid by a factor in the order of 104 to 107. A few attempts to make electrically conductive oil-based drilling fluids for the purpose of electrical design have been reported, although none of them have been reported. they have been a commercial success. The U.S. Patent No. 2,542,020, the U.S. Patent. Do not. 2,552,775, the U.S. Patent. No. 2,573,961, the U.S. Patent. No. 2,696,468 and the U.S. Patent. No. 2,739, all to Fischer, describe stabilized oil-based soap fluids comprising an alkaline earth metal base dissolved in up to 100% by weight water. Fischer claims to reduce the electrical resistivity to below 500 ohm-m, which corresponds to an increase in conductivity to? > 2000 μS mA However, those fluids that appear to be very sensitive to contaminants and higher amounts of water lead to an unacceptable increase in fluid loss. In essence, these fluids depend on the content of added or residual water to dissolve the salts / surfactants. In addition, the continuous oil phase fails to show any increase in its electrical conductivity and there is no reference to it occurring to the filtrate, which under optimal conditions is essentially made of continuous oil phase. Twenty-five years later, the US Patent. No. 4,012,329 discloses an external oil micro-emulsion made with sodium petroleum sulfonate and with reported resistivity of < 1 ohm-1 (?> 1 S m "1) In such a micro-emulsion, sodium petroleum sulfonate forms micelles containing water and clay so that the clay has to be added as a dispersion in water, and can not be added as dry powder It should also be emphasized that a micro-emulsion is distinctly different from a standard emulsion, being thermodynamically stable, smaller in size, higher in surface to volume ratio and forming both muddy and fluid filtrate of a different nature, obtaining the necessary combination of -§-. ?? -.__ nt? J * "-" "iB" a? i »* _4___ i ..

Bulky properties and rock interactions without damage is more difficult than for a standard inverted or direct emulsion fluid, and such fluids are not generally favored for drilling oil wells. Although the prior art contains formulations for ma the drilling fluid based on conductive oil, the methods thus described adversely affect other properties of the sediment, another reason why none has been commercialized successfully. When mixed in an article in sufficient concentrations, the natural gas carbon black is known to impart electrical conductivity to otherwise insulate materials such as plastics or elastomers. Extremely small natural gas carbon black particles (<; < 1 micron) is known to form an interconnection network that allows the conduction of electricity. Such articles can in this way, for example, prevent the formation of static electricity or shield against magnetic interference. However, when natural gas carbon black is added to a conventional inverted oil emulsion oil sediment or drilling fluid (hereinafter referred to as OBM), little or no increase in conductivity was observed. More specifically, it has been found that calcium soaps of acid grades such as liquid resin fatty acid will interact with the network of carbon particles, reducing the attractive particle-particle forces by absorbing them in the particles. Similarly, inverted emulsifiers or wetting agents having primary, secondary and tertiary amine groups or ammonium group Quaternary have been found to similarly absorb and disrupt the conductive network of natural gas carbon black particles. Examples of such amine-containing products include fatty alkyl amidoamines, fatty alkyl imidazolines, alkylamidoamines, fats reacted in addition or degraded with acids. di- or tp-basic such as maieic acid. Such calcium fatty acid soaps and functional amine products are in common use in all inverted emulsion drilling fluids known to applicants. This invention has discovered that when blending natural gas carbon black into an OBM containing certain types of emulsifiers or oil wetting agents, high levels of electrical conductivity can be obtained in advantageously low concentrations of natural gas carbon black. Surprisingly, it has been found that despite the very high surface area and absorption capacity of natural gas carbon black, certain inverted emulsions or types of oil wetting agent do not disrupt the electrically conductive natural gas carbon black network. According to the invention, an electrically conductive inverted emulsion probing fluid comprises from about 0.2% to about 10% by volume of natural gas carbon black particles and one or more surfactant (s) emulsifiers selected from the class that includes: Non-ionic emulsifiers of Hydrophilic-Lipophilic Balance (HLB) less than about 12, and l__A_ -__-___ l____ - .taUmÍIUt it it *? < aa * > M? ~. , _.._______ - anionic surfactants wherein the counterion (cation) is any of alkali metal, ammonium or hydrogen ions. All nonionic non-ionic agents found at the date of a suitable Hydrophilic-Lipophilic Balance (HLB) to promote inverted emulsification do not destroy conductivity. These include dietnaolamides based on higher fatty acids of more than 12 carbon atoms such as oleic acid or liquid resin fatty acid (TOFA9, higher a-oxylated fatty alcohols, alkoxylated alkylphenols, and ethylene oxide / oxide block polymers. of propylene Generally, the most suitable HLB values are less than 10, but occasionally in combination with other emulsifiers, the highest HLB values up to a maximum of 12 may be useful.The other suitable classes of surfactants are non-surface active agents. Ionics of a sufficiently lipophilic character where the surfactant is in the form of an alkali metal soap, ammonium soap, or as the free acid Polyethylene metal ion soaps (eg, calcium) of these agents surfactants are excluded because they have been found to disrupt the conductive network of the natural gas carbon black particles, esumably by absorption through the ion bridge by the polyvalent cation. The most preferred anionic surfactants are sulfonates such as alkylene sulfonates, alpha-olefin sulfonates, alkylenyl sulfonates, polyolefin sulfonates, and acryl taurates, all characterized by the number of carbons of the hydrophobic part being at least about 12.

Other anionic emulsifiers or wetting agents include the alkali metal or ammonium salts, or the free acid of fatty acids of 12 or more carbon atoms, phosphate esters of alcohols of 12 or more carbon atoms, ethoxylated alkylphenol phosphate esters of 14 or more carbon atoms, and alkylaminomethylene phosphonic acids wherein the alkylamine precursor contains 12 or more carbon atoms. The total dose of emulsifiers is preferably in the range of 0.5% to 10%, based on the total weight of the sounding fluid. A natural gas carbon black in this invention has a significantly higher specific surface area (i.e., at least 500 m2 / g) compared to 100-300 m2 / g of natural gas carbon black. This provides natural gas carbon black particles with a higher ability to form a network of interconnected particles that lead to a thixotropic rheological effect and a significant increase in electricity conduction. The most important attribute of the invention, is that the electrical conductivity of the fluid is increased by a factor of the order of 104 to 107. This allows the successful application of many electrical digigraphy techniques and the transmission of electrical telemetry signals when the fluids of Organic liquid-based probes fill the borehole. Another object of the present invention is therefore a method for providing increased information of electrical digraph tools, measurement while drilling (MWD), digraphics while drilling (LWD), geodirection and the like where efficiency is increased by the sounding fluids of con t? improved electrical efficiency of the invention. In this invention it has been found that oil-based, electrically conductive drilling fluids can be provided which maintain the expected performance advantages of oil-based drilling fluids (or based on synthetic organic liquid). Therefore, the fluids of this invention minimize adverse interactions with perforated formation, such as dispersion or swelling of clay formation, hole collapse, or undesirable dissolution of salt formations underground. They also provide the expected performance advantages of oil-based fluids with respect to increased lubricity, reduced differential adhesion of the drill pipe, and good stability at elevated temperatures. According to a preferred embodiment of the present invention, the sounding fluid also comprises material capable of precipitating or comparing polyvalent metal cations such as calcium, magnesium and iron ions which can contaminate the sounding fluid. This is to avoid the metal cation of forming a soap with emulsifiers which are then absorbed on the surface of natural gas carbon black particles and interferes with the conductive network. Examples of precipitation materials are dissolved anions such as phosphate, carbonate or silicate. Examples of suitable complexing agents are the ammonium or alkali metal salts, or the free acids, of citric acid, gluconic acid, glucoheptanoic acid, , - ^ - 1 1 - ascorbic acid, erythorbic acid, nitroloacetic acid, tetraacetic acid of diamine ethylene, pentaacetic acid of diethylenetriamine, diphosphonic acid of hydroxyethylidene, nitrolotrismethylene-phosphonic acid, phosphonates of aminomethylene based on ethylene diamine or diethylenetriamine or higher ethyleneamines, and polyphosphates such as tetrasodium pyrophosphate. The continuous non-aqueous phase can be selected from any synthetic or refined fluid known to be suitable as a base fluid of sounding fluid such as crude oil, refined hydrocarbon fractions of crude oil such as diesel fuel or mineral oil, synthetic hydrocarbons such as n-paraffins, alpha-olefins, internal olefins and poly-alpha-olefins; synthetic liquids such as dialkyl ethers, alkyl alkanoate esters, acetals; and natural oils such as tpghcéridos including rape seed oil, sunflower oil 15 and mixtures thereof. Highly biodegradable and low toxicity oils will generally be preferred especially for subsea oil drilling. The discontinuous liquid phase is water or a brine and is present from about 0.5% to about 70% 20 by volume of the emulsion. In order to provide other required properties of sounding fluids, the sounding fluids of this invention may contain any known sounding fluid additive such as clay, organoclay, or polymeric viscosifiers, filtration reducing agents such as as lignitite derivatives or asphalt filtration reducers from Utah in dust, asphalts, asphaltites or polymers swollen by oil. These additives help to provide a drilling sediment that has the following characteristics: • it must be fluid and produce a pressure drop that can be provided in surface pipes and drill string • have an adequate production tension to support / transport sediment solids and cuts drilling • be chemical, thermal and mechanically stable • provide hole stability • provide good lubricity • prevent excessive fluid loss to the formation. The invention will now be illustrated by the following examples. Example 1 This example demonstrates the effectiveness of natural gas carbon black to increase electrical conductivity of a non-conductive mineral oil (Surdyne B 140). The oil conductivity is below 1 μS / m. 1.5% by weight of a natural gas carbon black dispersion in the mineral oil was prepared. The natural gas carbon black particles form irregularly shaped aggregates of extremely fine carbon particles fused together. The size of the aggregates is in the range of 10-250 nm but the larger aggregates can be reduced in size by mechanical cutting. The conductivity of the carbon black dispersion of Natural oil gas was approximately 20,000 μS / m at 500 Hz and at room temperature. EXAMPLE 2 This example shows the effect of addition of natural gas carbon black in the conductivity of an oil-based pellet using a tallow oil fatty acid soap of tallow oil as the emulsifier: Table 1: Formulation for a heavy sediment with inverted fatty acid emulsifier; 80/20 oil / water ratio. Components Amount in 350 ml of sediment Mineral oil (Surdyne B140) 183.3 g Fatty oil oil acid 9.0 g Liquid loss additive (TRUFLO 100 ™) 4.5 g Lima 5.0 g Natural gas smoke black 6.0 g Sodium chloride 22.67 g Water 63.2 g Barite 131.2 g The conductivity of the complete sediment formulation is reduced to approximately 15 μS / m at 500 Hz. The results suggest that a conventional tallow fatty acid emulsifier soap (as used in almost all conventional oil-based sediment formulations) it does not allow the conductive network of natural gas carbon black particles to form. This is attributed to the strong absorption of the neutralized calcium emulsifier in the natural gas carbon black particles, inhibiting the particle-particle interactions that form the network. , ____ »Example 3 The effect of natural gas carbon black on the electrical conductivity of an oil-based sediment using fatty acid diethanolamines (WITCAMIDE 51 1, a product of WITCO) as the emulsifier. Table 2. Formulation for a heavy conductive OBM; Oil / water ratio, 80/20 Component Quantity sn 350 ml sediment Mineral oil (Surdyne B140) 183.3 g Nonionic emulsifier 8.0 g Alpha-olefin sulfonate emulsifier 1.0 Fluid loss additive (TRUFLO 100 ™) 4.5 g Natural gas smoke black 6.0 g NaCl 21 .43 g Water 59.75 g Barite 131.1 g The conductivity of the previous formulation was 10,000 μS / m at 500 Hz in the complete sediment formulation. It can be seen that this type of emulsifier allows the conductive network of natural gas carbon black (and therefore conductivity) to be maintained, while imparting good emulsion stability, even in a weighting fluid where the baritine has an effect of Dilution in the conductive network and reduces the conductivity to some degree. The function of the alpha-olefin sulfonate in the formulation is to improve the wetting of baritine oil. - íi (t-A - * • £ ___ -. < 1¿__ ______ _

Claims (10)

1. CLAIMS 1. An electrically conductive inverted emulsion sounding fluid comprising: i) from about 0.2% to about 10% by volume of natural gas carbon black particles; and ii) one or more emulsifying surfactants selected from the class including: nonionic emulsifiers of Hydrophilic-Lipophilic Balance (HLB) of less than about 12, and anionic surfactants wherein the counterion (cation) is any of the ion alkali metal, ammonium or hydrogen.
2. 2. A probing fluid according to claim 1, characterized in that the natural gas carbon black shows a surface area of at least 50 m2 / g, and preferably at least 1500 m2 / g.
3. 3. A probing fluid according to any of the preceding claims, characterized in that the non-ionic emulsifier (s) is (are) selected from the class that includes: diethanolamides based on fatty acids of more than of 12 carbon atoms, alkoxylated fatty alcohols, alkoxylated alkylphenols, and propylene oxide block polymers of ethylene oxide.
4. 4. A sounding fluid according to any of the preceding claims, characterized in that the anionic surfactant (s) is (are) selected from the class that includes: alkane sulphonates, alpha-olefin sulfonates, alkyl sand silphanates, polyolefin sulphonates and acryl taurates, all characterized by the carbon number of the hydrophobic portion being at least about 12, and by the counter ion (cation) being of any of alkali metal, ammonium and hydrogen ions.
5. 5. A sounding fluid according to any of claims 1 to 4, characterized in that the anionic surfactant (s) is (are) selected from the class that includes: fatty acids of 12 or more carbon atoms, phosphate esters of ethoxylated alcohols of 12 or more carbon atoms, phosphate esters of ethoxylated alkyl phenols of 14 or more carbon atoms, and alkyl aminomethylene phosphonates wherein the alkylamine precursor contains 12 or more carbon atoms, all characterized by the counter-ion (cation) being any of alkali metal ion, ammonium or hydrogen ions.
6. 6. A sounding fluid according to any of the preceding claims, characterized in that the total dose of emulsifier (s) is in the range of 0.5% to 10% by weight.
7. 7. A sounding fluid according to any of the preceding claims, characterized in that it contains material capable of precipitating or complexing polyvalent metal cations such as calcium, magnesium and iron ions.
8. 8. A sounding fluid according to claim 8, characterized in that the emulsified salt phase contains dissolved anions such as phosphate, carbonate, silicate which will form insoluble precipitates with any ion of the calcium, magnesium or iron cations.
9. 9. A sounding fluid according to claim 8, characterized in that the complexing agent is selected from the class that includes the alkali metal or ammonium salts, or the free acids, of citric acid, gluconic acid, glucoheptanoic acid, ascorbic acid, erythorbic acid, nitroloacetic acid, ethylene diamine tetraacetic acid, diethylenetriamine pentaacetic acid, hydroxyethylidene diphosphonic acid, nitrolotrismethylene phosphonic acid, aminomethylene phosphonates based on higher ethylene diamine or diethylenetriamine or ethyleneamines, and polyphosphates such as tetrasodium pyrophosphate.
10. 10. A method for drilling or completing a well, wherein the sounding fluid is used as in any preceding claim. 1 1. A method to provide increased information of electric digraph tools, measurement while drilling (MWD), digraphics while drilling (LWD), geodirection and the like where efficiency is increased by the electrical conductivity of any of the fluids according to claims 1 to 9. ** JS ^ P? _T? 1 } - | ta "J" 'M "- ^ ^ tí ^ -áiMáJl? ^? ¿í, ^ idl¡L ^? á ^? - ^ * ^' '^' si