WO2005097937A1 - Systemes colloidaux ou de type colloidaux stabilises - Google Patents

Systemes colloidaux ou de type colloidaux stabilises Download PDF

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Publication number
WO2005097937A1
WO2005097937A1 PCT/US2005/011477 US2005011477W WO2005097937A1 WO 2005097937 A1 WO2005097937 A1 WO 2005097937A1 US 2005011477 W US2005011477 W US 2005011477W WO 2005097937 A1 WO2005097937 A1 WO 2005097937A1
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Prior art keywords
aphrons
aphron
composition according
drilling
fluid
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PCT/US2005/011477
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English (en)
Inventor
Frederick B. Growcock
Gerard A. Simon
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Masi Technologies, L.L.C.
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Publication of WO2005097937A1 publication Critical patent/WO2005097937A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
    • C09K8/516—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls characterised by their form or by the form of their components, e.g. encapsulated material
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/02—Well-drilling compositions
    • C09K8/04—Aqueous well-drilling compositions
    • C09K8/14—Clay-containing compositions
    • C09K8/18—Clay-containing compositions characterised by the organic compounds
    • C09K8/22—Synthetic organic compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/02—Well-drilling compositions
    • C09K8/04—Aqueous well-drilling compositions
    • C09K8/14—Clay-containing compositions
    • C09K8/18—Clay-containing compositions characterised by the organic compounds
    • C09K8/22—Synthetic organic compounds
    • C09K8/24—Polymers

Definitions

  • BACKGROUND Formation damage due to invasion by drilling fluids is a well-known problem.
  • Many zones contain formation clays, which hydrate when in contact with water, such as the filtrate from water-based drilling fluids. These hydrated clays tend to block the producing zones, primarily sands, so that oil and gas cannot move to the borehole and be produced.
  • These zones are also damaged by solids, which are carried into the openings with the drilling fluid. The movement of drilling fluids and filtrate through these openings also causes dislodging and migration of solids in place in the formation. These solids can lodge and block movement of produced hydrocarbons.
  • Fluid invasion is caused by the differential pressure between the hydrostatic pressure and fluid viscosity (equivalent circulating density (ECD)) and the formation pressure; differential pressure is especially large in low pressure or depleted zones.
  • the rate of invasion is controlled by the differential pressure, the fluid viscosity, the structure of the pore network in the rock and any fissures in the rock that may be present.
  • Drillers have long used filtrate control mechanisms to reduce the movement of drilling fluids and filtrate into and through the formation openings. The mechanism generally involves the creation of a filter cake along the borehole wall. This technique still allows some fluid in and out of the zone.
  • LSRV Low Shear Rate Viscosity
  • LCM LCM are added to the fluid system so that they may be carried into the loss zone and lodge to form a bridge on which other materials may build a seal akin to a filter cake.
  • LCM themselves are damaging to the zones, and because they often must be carried in the drilling fluid to maintain circulation, solids removal is halted and buildup of solids in the mud results.
  • Methods of correcting lost circulation of drilling fluids by aerating the drilling fluids are set forth in U.S. Pat. No. 2,818,230 (Davis) and U.S. Pat. No. 4,155,410 (Jackson).
  • traditional aerated fluids also have disadvantages. Problems with these fluids include hole cleaning, control of formation fluids and corrosion.
  • novel fluids comprising stabilized colloidal or colloidal-like phases are described herein.
  • One property of fluids comprising aphrons is their ability to seal openings in a formation during drilling or other downhole operations.
  • the aphrons are stabilized through the use of one or more novel primary and secondary Aphron Stabilizers, so that their ability to seal openings in a formation is enhanced significantly.
  • These fluids are capable of being recirculated in the wellbore during drilling or other downhole activities.
  • the fluid composition comprises an aqueous fluid, one or more viscosifiers, one or more surfactants, aphrons, one or more primary Aphron Stabilizers, and one or more secondary Aphron Stabilizers.
  • the primary and secondary Aphron Stabilizers modify the viscosity of the water layer to such an extent that it, in effect, creates an elastomeric membrane.
  • This elastomeric membrane allows the aphrons of the present invention to display improved stability and sealing capability, as compared to previously known aphrons.
  • Methods of use for enhanced aphron containing fluids which include both at least one primary Aphron Stabilizer and at least one secondary Aphron Stabilizer are also described herein.
  • Figure 1 is a schematic drawing of a prior art aphron
  • Figure 2 is a schematic drawing of an enhanced aphron in accordance with a preferred embodiment of the present invention
  • Figure 3 is a graph showing the improved sealing effects of a fluid composition prepared with enhanced aphrons in a high-pressure environment
  • Figures 4a-4h are photographs showing the effect of pressure on survivability of enhanced aphrons as compared to conventional aphrons
  • Figure 5 is a graph showing the improved sealing effects of a fluid composition prepared with enhanced aphrons.
  • Interfacial viscosity is intended to refer to the viscosity at the interface between two fluids in contact with each other (e.g., the viscosified water layer of an aphron and the surrounding bulk fluid).
  • interfacial tension also known as surface tension when applied to the interface between a fluid and air, is intended to refer to the property of liquids arising from unbalanced molecular cohesive forces at or near the surface, as a result of which the surface tends to contract and has properties resembling those of a stretched elastic membrane.
  • the present invention generally relates to compositions comprising stabilized colloidal or colloidal-like phases and methods of using those compositions. Although many detailed embodiments of the present invention will be discussed herein, the fundamental idea is to provide stable, long-lasting compositions and methods for preparing and using such compositions. Some embodiments of the present invention relate to fluid compositions and methods of use of enhanced aphron containing fluids in downhole applications.
  • compositions disclosed herein are circulated in the column while drilling, logging, workover, servicing, or any other downhole operation is occurring.
  • reference to downhole applications is not contemplated as the only use for the compositions of the present invention and should not be so limited.
  • the compositions, form of the compositions, and methods of use for the compositions provided herein are only for the sake of clarity and in the interest of presenting embodiments of the present invention.
  • these fluids have many advantages and uses, such as assisting in the effective sealing of the formation, including sealing microfractured and large fractured zones. Fluid systems containing aphrons are known in the art.
  • an aphron-containing drilling fluid combines the use of LSRV-generating viscosifiers with surfactants to form aphrons.
  • the aphrons can be obtained, for example, by incorporating (1) an aphron-generating surfactant into the fluid and thereafter generating the aphrons in the fluid by introducing into it a gas or (2) generating the aphrons in a liquid compatible with the fluid and mixing the two fluids together.
  • an aphron 10 is typically made up of a spherical core or internal phase 20, which is usually gas 22 encapsulated in a thin shell 30.
  • This shell 30 contains surfactant molecules 32 positioned so that they produce an effective first barrier 34 against a second phase 40 comprised of viscosified water 42.
  • Second phase 40 also contains surfactant molecules 32 positioned so that the hydrophobic portion of the molecules extend into a third phase 44.
  • the latter contains still another layer of surfactant molecules 32 aligned with the hydrophilic (polar) extending into the bulk fluid.
  • phase 44 is a bi-layer of surfactant molecules, which serves as an effective barrier to coalescence with adjacent aphrons (not shown).
  • the gas core is stabilized by three layers of surfactant molecules and a viscosified aqueous layer. It is believed that the outermost surfactant layer is not strongly associated with the rest of the aphron and may be shed when aphrons are forced against each other, thereby leading to agglomeration but not coalescence.
  • Aphron generation can be accomplished by any means known in the art, such as methods described in the book by Felix Sebba mentioned above.
  • Two major components for creating stable aphrons are surfactants and viscosifiers.
  • the surfactants are responsible for the formation of the aphrons' unique layers. These surfactants must be arranged in such a way that the aphron structure is compatible with the base liquid and the viscosifier therein such that the LSRV of the fluid can be maintained.
  • the aphron-generating surfactant may be anionic, nonionic, or cationic depending on compatibility with the viscosifier.
  • Anionic surfactants include, for example, alkyl sulfates, alpha olefin sulfonates, alkyl (alcohol) ether sulfates, refined petroleum sulfonates, and mixtures thereof.
  • Nonionic surfactants include, for example, uncharged species, (e.g.
  • ethoxylated alcohols and zwitterionic molecules (e.g. betaines).
  • Cationic surfactants include, for example, quaternary ammonium salts, alkylamines and polyethylenimines.
  • stable aphron-containing fluids are obtained by increasing the LSRV of the fluid to at least 10,000 centipoise (Brookfield viscosity at 0.06 sec "1 ). Because the stability of the aphrons is enhanced as the LSRV increases, a LSRV of more than 100,000 centipoise may be desired. This is accomplished with appropriate viscosifiers.
  • suitable viscosifiers include organic polymers; inorganic polymers; dispersed clays; dispersed minerals; mixed metal hydroxides, oxyhydroxides and oxides; biopolymers; water-soluble synthetic polymers; other types of polymers; and mixtures thereof.
  • suitable viscosifiers are listed in U.S. Pat. Nos. 5,881,826, 6,123,159, 6,148,917, 6,156,708, 6,390,208, 6,422,326, 6,649,571 and WO 98/36151, and include any water-soluble polymer which increases the low-shear-rate viscosity of the fluid to produce a strongly shear-thinning viscosity profile.
  • biopolymers produced by the action of bacteria, fungi and other microorganisms are particularly useful.
  • Exemplary biopolymers are the polysaccharides produced by the action of Xanthomonas campestris bacteria, which are known as xanthan gums. These are available commercially from several sources including Kelco Oilfield Group, Inc., under such trademarks as 'Xanvis' and 'Kelzan'; Rhone-Poulenc Chimie Fine, under the trademark 'Rhodopol 23-p'; Pfizer Inc., under the trademark 'Shellflo ZA'; and Drilling Specialties Company, under the trademark 'Flowzan'.
  • polysaccharide biopolymers derived from bacterial fermentation which may be useful in the fluids of this invention are the so-called diutan, welan, gellan, scleroglucan and succinoglycan gums.
  • diutan welan
  • gellan gellan
  • scleroglucan succinoglycan gums.
  • palygorskite-sepiolite group clays may be used as an alternative to conventional viscosifiers.
  • the palygorskite-sepiolite clay family comprises a group of fibrous or needle-like hydrous magnesium silicate clays including palygorsMte (commonly known as attapulgite), tuperssuatsiaite, yofortierite, kalifersite, sepiolite, falcondoite, and loughlinite.
  • Palygorskite typically has short ( ⁇ 2 ⁇ m) and low- aspect-ratio ( ⁇ 10: 1) needles.
  • Sepiolite generally has longer, more flexible needles.
  • palygorskite-sepiolite group clays When palygorskite-sepiolite group clays are dispersed in water, they do not swell like smectite clays, but deagglomerate in proportion to the amount of shear applied, and form a random lattice of fibers that entraps the water.
  • This loosely cohesive structure offers shear-thinning rheological properties even greater than those of smectite clays.
  • This fibrous structure allows stable suspensions of high viscosity at relatively low concentration. As a result, suspensions containing palygorskite-sepiolite group clays display non-Newtonian behavior and impart high LSRV to fluids.
  • the present invention provides compositions and methods of use that are an improvement over the existing aphron technology.
  • fluids in accordance with the present invention possess tougher, more resilient surfaces that allow aphrons to survive for long, extended periods of time under severe conditions (e.g., high pressure). Because of their increased stability, the enhanced aphrons are able to seal permeable zones more effectively. All of these added benefits and others can lead to reduced operating costs.
  • Figure 2 a theoretical representation of an aphron 110 in accordance with the present invention is shown. Similar to Figure 1, aphron 110 is thought to include a spherical core or first phase 120, which is usually gas 122 encapsulated in a thin shell 130.
  • this shell 130 contains surfactant molecules 132 positioned so that the hydrophobic (nonpolar) ends extend into the gas core 122 and the hydrophilic (polar) ends extend into a second phase 140 comprised of viscosified water 142, a primary Aphron Stabilizer 143, and a secondary Aphron Stabilizer 145.
  • the second phase 140 also contains surfactant molecules 132 at the outer boundary, as in a conventional aphron, with the hydrophobic ends extending into a third phase 144.
  • This third phase also contains a third layer of surfactant molecules 132 whose hydrophilic ends extend into the bulk fluid.
  • phase 144 is represented as a bi-layer of surfactant molecules, which serves as an effective barrier to coalescence with adjacent aphrons (not shown).
  • the exterior surfactant layer is not strongly associated with the rest of the aphron and may be shed when aphrons come into contact with each other so that they agglomerate rather than coalesce.
  • surfactant molecules are labeled 132, they are not necessarily the same material, i.e., each surfactant layer may be comprised of different types of surfactants.
  • Second phase 140 herein after called the "viscosified water layer," is of particular importance in creating stability in aphrons.
  • the fluid composition in one embodiment of the present invention comprises an aqueous fluid, one or more viscosifiers, one or more surfactants, aphrons, one or more primary Aphron Stabilizers, and one or more secondary Aphron Stabilizers.
  • the stability of bubbles in an aqueous medium is a function primarily of bulk fluid viscosity and interfacial tension.
  • Bulk viscosity is generally derived from polymers or polymer-like molecules, e.g., xanthan gum and/or clays. Interfacial tension is usually lowered with a surfactant.
  • an aphron is stabilized by a very high interfacial viscosity of the second phase.
  • the interfacial viscosity of second phase 40 of the aphron is approximately equal to the bulk viscosity of the liquid, inasmuch as second phase 40 is occupied by the same species that are in the bulk fluid (not shown).
  • Aphron Stabilizer and reactive solids e.g, MgO, and/or (4) the primary Aphron Stabilizer and gas in the spherical core or first phase 120 can increase the interfacial viscosity above that of the bulk viscosity and create a barrier to the transport of air out of the aphron.
  • This strong interaction may be created by various types of bonding, such as polymer cross-linking and hydrophobic- hydrophobic entanglement.
  • the increase in interfacial viscosity imparts increased stability to aphron 110.
  • Various types of materials may be used as the primary Aphron Stabilizer, which may be able to undergo a strong interaction within the viscosified water layer 140 as described above.
  • Suitable primary Aphron Stabilizers include, but are not limited to, the following compositions: cellulose polymer/cross-linker, such as carboxymethylcellulose/aluminum acetate and doubly derivatized HEC/Fe 2+ ; biopolymer/cross-linker, such as xanthan gum/magnesium oxide/sodium chloride and polyacrylamide/chromic acetate; liquid rubber bases; liquid wax bases; water soluble glues (e.g., Elmer's glue); polyvinyl alcohol (PVOH), alone or in combination with a surfactant or surfactants such as alkyl ether sulfates and betaines; and mixtures thereof.
  • cellulose polymer/cross-linker such as carboxymethylcellulose/aluminum acetate and doubly derivatized HEC/Fe 2+
  • biopolymer/cross-linker such as xanthan gum/magnesium oxide/sodium chloride and polyacrylamide/chromic acetate
  • the primary Aphron Stabilizer comprises at least PVOH and a betaine or an alkyl ether sulfate and mixtures thereof. In one embodiment, the primary Aphron Stabilizer comprises from about 0.05% to about 2% of the net weight of the fluid composition, preferably from about 0.1% to 1%. It has been discovered that the addition of one or more secondary Aphron Stabilizers to aphron-containing liquids containing one or more primary Aphron Stabilizers leads to solvation of the viscosified water layer 140.
  • the secondary Aphron Stabilizer functions as a plasticizer, replacing some of the secondary valence bonds of the viscosified water layer 140 with plasticizer-to-polymer bonds. Consequently, polymeric chains within the viscosified water layer 140 have increased freedom of movement, increasing the toughness and flexibility and reducing the permeability of the elastomeric membrane, which results in a reduced tendency for aphrons to lose air under pressure.
  • Suitable secondary Aphron Stabilizers include, but are not limited to, the following compositions: fatty acids, polyols, esters, organic phosphates, ketones, and mixtures thereof.
  • the fatty acids may be derived from oleic and/or linoleic acids.
  • Suitable fatty acids include saturated fatty acids (e.g. stearic acid, butyric acid, lauric acid, and palmitic acid) and unsaturated fatty acids (e.g. oleic acid, linoleic acid, and linolenic acid).
  • An example of a suitable polyol is ethylene glycol.
  • suitable esters include sebacate, adipate, phthalate, glycerol-based esters, and fatty acid-based esters.
  • An example of a suitable organic phosphate is tricresyl.
  • An example of a suitable ketone is camphor.
  • the secondary Aphron Stabilizer comprises at least stearic acid or oleic acid. In one embodiment, the secondary Aphron Stabilizer comprises from about 0.01% to about 0.5 % of the net weight of the fluid composition, preferably from about 0.03% to 0.2%.
  • the surfactant, materials associated with the surfactant, the gas in first phase 120, and any additional viscosifiers may be selected from suitable species known in the art and disclosed above.
  • the fluid compositions may additionally contain weighting agents, corrosion inhibitors, soluble salts, biocide, fungicides, seepage loss control additives, bridging agents, deflocculants, lubricity additives, shale control inhibitors, foam suppressors, and other additives as desired.
  • a biocide including aldehydes, isothiazolones, quaternary phosphonium salts and mixtures thereof; treatment of make-up water with bleach (weak sodium hypochlorite) is also effective to reduce microbiological degradation of the fluid.
  • Bridging agents may also be used to aid in sealing large apertures. These include a vast array of sized particulates, such as CaCO 3 .
  • Shale control inhibitors may also be added to maintain wellbore stability in intervals containing water-sensitive shales. These include a large variety of surface active materials, such as polyamides, e.g.
  • a foam suppressor may be kept on hand during drilling operations; these include such materials as alkylene glycols and glycol ethers.
  • a corrosion inhibitor such as a phosphate ester may be added to the fluid.
  • the aqueous liquid may be fresh water, sea water, or a brine containing soluble salts such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium bromide, potassium bromide, calcium bromide, zinc bromide, sodium formate, potassium formate, cesium formate, and mixtures thereof.
  • the brine may contain one or more soluble salts at any desired concentration.
  • air or other gases can be incorporated into the fluid to entrain more gas for forming aphrons 110.
  • the gas may be any gas which is not appreciably soluble in the liquid phase of the fluid.
  • the gas may be air, nitrogen, carbon dioxide, organic gases, and the like, including air encapsulated in the fluid during mixing.
  • the aphrons 110 can be generated by any means known in the art, including the means taught by Sebba.
  • Aphrons may be generated in the bulk fluid by injecting the gas into the bulk fluid from a higher pressure source through an orifice or a collection of orifices, e.g., a fritted filter; pressurizing a bulk fluid/gas mixture to dissolve the gas and forcing the resulting fluid through an orifice into a lower pressure vessel; creating a vortex in the bulk fluid to draw gas into it using a mixing device, e.g., single-spindle and paddlewheel mixers, blenders, homogenizers (such as Waring or Silverson type); aspirating the bulk fluid into a gas stream, e.g., a Venturi tube; or a combination of any of the above.
  • a mixing device e.g., single-spindle and paddlewheel mixers, blenders, homogenizers (such as Waring or Silverson type)
  • the biopolymer blend used is a xanthan gum-based blend comprised of approximately 70 wt% xanthan gum, 20 wt% starch, 9 wt% oligosaccharide, and 1 wt% magnesium oxide, sold by MASI Technologies L.L.C., a joint venture between M-I L.L.C. and ActiSystems Inc., under the tradename Go Devil ⁇ TM.
  • the polymer blend used is an oligosaccharide-based blend comprised of approximately 90 wt% oligosaccharide and 10 wt% magnesium oxide, sold by MASI Technologies L.L.C, a joint venture between M-I L.L.C.
  • the pH buffer used is a magnesium oxide- based blend comprised of approximately 90 wt% magnesium oxide and 10 wt% oligosaccharide, sold by MASI Technologies L.L.C, a joint venture between M-I L.L.C. and ActiSystems Inc., under the tradename Activator IITM.
  • the surfactant used is an alcohol ether sulfate-based blend comprised of approximately 18 wt% alkyl ether sulfate, 8 wt% cocobetaine, 1 wt% hydroxypropylguar, and 73 wt% water, sold by MASI Technologies L.L.C, a joint venture between M-I L.L.C. and ActiSystems Inc., under the tradename Blue StreakTM.
  • the primary Aphron Stabilizer used is a blend comprised of approximately 50 wt% PVOH, sold by Celanese Ltd.
  • the secondary Aphron Stabilizer used is stearic acid. All the components listed in Table 1 are believed to have a primary function in the resultant fluids.
  • the soda ash is believed to be a hardness buffer and the biopolymer blend is believed to be the primary viscosifier of the bulk fluid.
  • the polymer blend is believed to be a filtration control agent and thermal stabilizer and the surfactant is believed to serve as the aphron generator.
  • the primary Aphron Stabilizer is believed to be a cross-linkable polymer which becomes cross-linked or interacts strongly with the other materials present in the viscosified water layer of the aphrons.
  • the secondary Aphron Stabilizer is believed to be a plasticizer which solvates polymers within the viscosified water layer of the aphrons.
  • the fluid compositions may have a pH in the range from about 7.0 to 11, preferably from about 8.0 to about 10.5.
  • the pH can be obtained (as is well known in the art) by the addition of bases to the fluid, such as potassium hydroxide, potassium carbonate, potassium humate, sodium hydroxide, sodium carbonate, sodium humate, magnesium oxide, calcium hydroxide, zinc oxide, and mixtures thereof.
  • magnesium oxide is a preferred pH buffer.
  • other additives including shale inhibitors, foam suppressors, and thinners may be used if desired.
  • An example of a suitable shale inhibitor is a cottonseed oil-based blend, which is comprised of approximately 61 wt% cottonseed oil and 39 wt% lecithin.
  • suitable foam suppressors include oligomers such as glycol ether and propylene glycol and examples of suitable thinners include causticized lignite and chrome-free lignosulfonate. Aphron generation was accomplished by entraining air under ambient conditions with a Silverson LV-4 mixer with disintegrator head rotating at 7000 rpm for 6 min.
  • Ex. 3 which represents the only composition that contained the surfactant, primary Aphron Stabilizer, and secondary Aphron Stabilizer, possessed a half-life at ambient pressure slightly higher than that of Ex. 2 and considerably higher than that of Ex. 1.
  • the enhanced aphrons also showed improved sealing capabilities, as indicated by Figure 3.
  • a fluid containing enhanced aphrons (with ⁇ 15% Entrained Air) showed a leak-off reduction in a high-permeability core of about 20% compared to an air-free enhanced aphron system or a conventional aphron system, i.e., including no Aphron Stabilizers.
  • Leak-off is herein defined as the magnitude of fluid volume that passes through core over a prescribed period of time at a given temperature and inlet, outlet and confining pressures.
  • the leak-off test parameters used in conjunction with triaxial loading core leak-off tests in 2-inch long 5-darcy Aloxite cores include 100 and 500 psi fore pressures, and 0 and 400 psi backpressures.
  • the leak-off test results for the composition of Ex. 3 are shown in Table 4. In all of the leak-off tests, the dead volume (occupied by a deaerated water spacer between the mud and the face of the core) was approximately 15 mL, with the reported leak-off values not being corrected for dead volume.
  • the % Entrained Air is maintained between about 10% to about 20% of the net volume of the fluid, preferably from about 12% to 18%.
  • the density of the bulk fluid can be monitored and additional surfactant and aphron generator added as necessary to maintain the desired density.
  • conventional surfactant-stabilized bubbles do not survive even low pressures very well. These are bubbles that are stabilized by a monolayer of surfactant and do not possess the viscosified aqueous and surfactant bilayers of an aphron. Pressure has a large effect on solubility of air in water; the diffusion rate of air through a typical surfactant film is generally very fast, so there is little to hold the air in a bubble when the system is pressurized.
  • an aqueous fluid containing 15% v/v entrained air at ambient pressure can potentially lose all of its air to dissolution at a pressure as low as 150 psi. Therefore, it is highly desirable for aphrons to exist at high pressures, e.g., exceeding 500 psi, to aid in drilling operations.
  • Some visualization tests were conducted with a dual sight flow indicator, which show (see Figure 4) that mud containing enhanced aphrons, i.e., produced with both a primary and secondary Aphron Stabilizer, and pressurized to 250 psi survived for a pressurization period of 30 minutes.
  • 4(a) and 4(b) show conventional surfactant-stabilized bubbles at 0 and 250 psi, respectively; 4(c) and 4(d) show aphrons produced without Aphron Stabilizers at 0 and 250 psi, respectively; 4(e) and 4(f) show aphrons produced with a primary Aphron Stabilizer at 0 and 250 psi, respectively; and 4(g) and 4(h) show aphrons produced with both a primary and secondary Aphron Stabilizer at 0 and 250 psi, respectively.
  • the average bubble/aphron size at ambient pressure was between 50-100 ⁇ m.
  • the present invention is intended to help prevent the loss of circulating fluid into the formation by incorporating the enhanced aphrons into a drilling or servicing fluid or any other type of downhole fluid.
  • the present invention is not limited to any particular formation zone.
  • the embodiments of the invention can be useful for promoting sealing of all types of formation zones where fluid can be lost.
  • the present invention can be useful in sealing or enhancing sealing of formation fractures.
  • formation fractures vary in size and shape from microscopic to small caves.
  • the procedure used to determine return permeability is as follows: • Saturate core with 10% by weight NaCl brine. • Mount core in Hassler cell and apply confining stress to 3000 psig. • Raise system pressure to 2000 psig. • Raise core temperature to 150° F. • Flow low-toxicity mineral oil (such as LVT 200 from Conoco Phillips) in the direction of formation to wellbore and establish initial permeability of core. • Apply a 500-psi pressure drop on drilling fluid by flowing from one transfer vessel set at 2,500 psi to another transfer vessel set at 2,000 psi through a back pressure regulator. Maintain system pressure at 2,000 psi.
  • enhanced aphron- containing (with both primary and secondary Aphron Stabilizers) mud also was able to effectively seal fractures with openings as large as 1 mm, as shown in Figure 5.
  • the leak-off test was conducted with a confining pressure of 2500 psi and no back-pressure. An initial inlet pressure of 500 psi was imposed, which was stepped up to 1000 psi after a few minutes, stepped up again to 1500 psi a few minutes later, and finally stepped up to 2000 psi and held there for the duration of the test (30 min total).
  • the total leak-off was approximately 10 mL, of which the first 8 V* mL is primarily the dead volume (occupied by deaerated water) between the mud and the face of the core. This is followed by roughly a 3-rnin period during which the plug/cake is formed in the fracture and leak-off increases by approximately 1 mL (this is the "true" leak-off). Finally, during the pressure step-up all the way to 2000 psi, leak-off increases another 0.7 mL. Because the aphrons have a low density, they will reduce the net density of the fluids they are in and will tend to float in most fluids.
  • aphrons it is critical to keep the aphrons adequately mixed or agitated during preparation and while traveling through the drillstring.
  • Mixing and agitation at the surface is accomplished through any means known in the art, such as paddle mixers and mud guns.
  • piston-type pumps - duplex or triplex - may be used to move the fluid.
  • an additive can be incorporated into the bulk fluid that helps maintain uniform distribution of the aphrons. Additives can also help maintain pumpability of the fluid.
  • the more preferred additives are viscosifiers.
  • Suitable viscosifiers are limited only by their compatibility with the base fluid and the aphrons and should exhibit LSRV and/or suspension properties.
  • any water-soluble viscosifier would suffice, e.g., organic, inorganic or biopolymers, clays, or other polymer-like chemicals.
  • a LSRV biopolymer is added the fluid.
  • the preferred biopolymers according to the present invention comprise a xanthan gum. Also provided herein are methods of using the above-mentioned compositions.
  • a fluid composition comprising an aqueous fluid, one or more surfactants, aphrons, and one or more primary and secondary Aphron Stabilizers, is pumped downhole at elevated pressures, e.g, 2,000+ psi, using a cavitating pump.
  • the aphrons are formed from dissolved gas in the fluid composition or from air entrained at ground level under ambient conditions.
  • the aphrons of the present invention are stable even under elevated pressures of greater than or equal to about 500 psi, preferably stable at pressures of greater than or equal to about 3,000 psi, and more preferably stable at pressures of greater than or equal to about 5,000 psi.
  • the aphrons are compressed due to the excess pressure of the column, and the aphrons enter the formation pore network and/or fractures.
  • the pressure is less within the pores or fractures, thus allowing the aphrons to expand. It is believed that the expansion of the aphrons, coupled with their aggregation within the fracture, can effectively fill and seal the pore throat and/or fracture.
  • the enhanced aphrons preferably have a half-life of greater than or equal to about 15 hours, more preferably have a half-life of greater than or equal to about 100 hours, and still more preferably have a half-life of greater than or equal to about 200 hours, hi some embodiments, the aphrons have a half-life exceeding about 400 hours.
  • a fluid containing aphrons which enters the formation is clean and essentially solids-free such that damage of the formation is significantly less than with solids- containing fluids.
  • solids or particles are not involved in this method, and therefore any solids removal equipment can be used to keep the fluid as clean as possible.
  • the primary and secondary Aphron Stabilizers has been discussed in terms of aphron containing systems, it is fully within the scope of the invention to use the Aphron Stabilizers in any colloidal or colloidal-like phase containing systems to encapsulate, stabilize, or protect in situ various products, including lubricants, spotting fluids, detergents, drilling enhancers, corrosion inhibitors, polymer breakers, fluid loss additives, polymer cross-linkers, etc. It is contemplated that products stabilized with the primary and secondary Aphron Stabilizers may be able to specifically associate with a target surface and that mechanical, thermal, or chemical forces may permit the product to be disgorged at the target surface, thereby performing an enhanced effect of the product.
  • lubricant droplets could be encapsulated using the primary and secondary Aphron Stabilizers, enabling the droplets to reach and attach themselves to drillpipe and casing, where high shear and compressive forces between the drillpipe and casing rupture the aphron stabilized-shell and disgorge the lubricant directly onto the drillpipe and casing surfaces.
  • This contemplated use is a vast improvement over conventional technology, where a large amount of lubricant has to be continuously applied to a mud system because (1) the lubricant becomes tightly emulsified as the mud circulates and therefore does not adsorb easily, and (2) what lubricant does not become tightly emulsified adsorbs on all surfaces regardless of composition.
  • the primary and secondary Aphron Stabilizers may provide some functionality as lubricants, spotting fluids, shale inhibitors, wellbore stabilizers, etc.
  • the Aphron Stabilizers may additionally be able to protect cuttings generated during the drilling process, thereby reducing dispersion of the cuttings and enabling the cuttings to be removed from the mud system more easily. While preferred embodiments of this invention have been shown and described, modification thereof can be made by one skilled in the art without departing from the teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the compositions and methods are possible and are within the scope of this invention.

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Abstract

La présente invention concerne généralement des compositions améliorées contenant des phases colloïdales ou de type colloïdales stabilisées (p. ex., émulsions, aphrons), et des méthodes d'utilisation desdites compositions. Ces compositions contiennent généralement une phase aqueuse continue, un ou plusieurs améliorants de viscosité, un ou plusieurs tensioactifs, des aphrons, un ou plusieurs stabilisateurs d'aphrons primaires et un ou plusieurs stabilisateurs d'aphrons secondaires. Les compositions de l'invention comprennent des aphrons présentant une longévité considérablement accrue à des températures élevées et une capacité améliorée d'étanchéification de formations perméables. Les compositions peuvent en outre être utilisées dans des applications haute pression.
PCT/US2005/011477 2004-04-05 2005-04-05 Systemes colloidaux ou de type colloidaux stabilises WO2005097937A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2220340A1 (fr) * 2007-11-29 2010-08-25 Total Separation Solutions, Llc. Fluides de forage contenant des microbulles
US8808759B1 (en) 2013-09-25 2014-08-19 Chattem, Inc Stabilized colloidal preparations, pre-mix and process for preparing skin care compositions, improved skin care composition, method for treating the skin
CN113122201A (zh) * 2019-12-31 2021-07-16 中石化石油工程技术服务有限公司 一种高温硬胶可循环泡沫钻井液及其制备方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6123159A (en) * 1997-02-13 2000-09-26 Actisystems, Inc. Aphron-containing well drilling and servicing fluids of enhanced stability
US20030201103A1 (en) * 2002-04-30 2003-10-30 Brookey Tommy F. Compositions and methods for sealing formations

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6123159A (en) * 1997-02-13 2000-09-26 Actisystems, Inc. Aphron-containing well drilling and servicing fluids of enhanced stability
US20030201103A1 (en) * 2002-04-30 2003-10-30 Brookey Tommy F. Compositions and methods for sealing formations

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2220340A1 (fr) * 2007-11-29 2010-08-25 Total Separation Solutions, Llc. Fluides de forage contenant des microbulles
EP2220340A4 (fr) * 2007-11-29 2011-08-31 Total Separation Solutions Llc Fluides de forage contenant des microbulles
US8808759B1 (en) 2013-09-25 2014-08-19 Chattem, Inc Stabilized colloidal preparations, pre-mix and process for preparing skin care compositions, improved skin care composition, method for treating the skin
CN113122201A (zh) * 2019-12-31 2021-07-16 中石化石油工程技术服务有限公司 一种高温硬胶可循环泡沫钻井液及其制备方法
CN113122201B (zh) * 2019-12-31 2022-07-29 中石化石油工程技术服务有限公司 一种高温硬胶可循环泡沫钻井液及其制备方法

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