ALKALINE EARTH METAL MINERALS AS CARRIERS FOR SURFACTANTS IN DRILLING FLUIDS

Abstract

The present invention relates to a drilling fluid comprising an alkaline earth metal mineral carrier having an intra-particle intruded specific pore volume of at least 0.8 cm.sup.3/g, a process for producing a drilling fluid and the use of a loaded mineral carrier having an intra-particle intruded specific pore volume of at least 0.8 cm.sup.3/g for the delivery of a surfactant to a drilling fluid.

Claims

1. A drilling fluid comprising: a. an alkaline earth metal mineral carrier having an intra-particle intruded specific pore volume of at least 0.8 cm.sup.3/g, as measured by mercury intrusion porosimetry, b. at least one surfactant, c. a base fluid, d. a thickening agent, and e. a weighting agent.

2. The drilling fluid of claim 1, wherein the alkaline earth metal mineral carrier has a. an intra-particle intruded specific pore volume in the range from 0.8 to 2.5 cm.sup.3/g preferably from 1.2 to 2.1 cm.sup.3/g, and most preferably from 1.5 to 2.0 cm.sup.3/g, as measured by mercury intrusion porosimetry, and/or b. a BET specific surface area in the range from 10 to 100 m.sup.2/g, preferably from 15 to 60 m.sup.2/g, and most preferably from 20 to 40 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277:2010, and/or c. a ratio of the intra-particle intruded specific pore volume, as measured by mercury intrusion porosimetry, to the BET specific surface area, measured using nitrogen and the BET method according to ISO 9277:2010, of more than 0.01 cm.sup.3/m.sup.2, preferably more than 0.05 cm.sup.3/m.sup.2, and most preferably more than 0.06 cm.sup.3/m.sup.2, such as from 0.06 to 0.25 cm.sup.3/m.sup.2, and/or d. a d.sub.50 (vol) in the range from 1 to 1000 μm, preferably from 2 to 75 μm, more preferably from 2.5 to 50 μm, even more preferably from 3 to 20 μm, or from 100 to 1000 μm, preferably from 200 to 800 μm, as determined by laser diffraction.

3. The drilling fluid of claim 1, wherein the alkaline earth metal mineral carrier has a loading capacity in the range from 50 wt.-% to 250 wt.-%, preferably from 60 wt.-% to 220 wt.-%, more preferably from 70 to 200 wt.-%, wherein the loading capacity is defined as the amount of a surfactant, which can be absorbed by the alkaline earth metal mineral carrier, relative to the weight of the dry alkaline earth metal mineral carrier.

4. The drilling fluid of claim 1, wherein the alkaline earth metal mineral carrier is selected from the group consisting of alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal sulphates, alkaline earth metal oxides, alkaline earth metal hydroxides and mixtures thereof, preferably the alkaline earth metal mineral carrier is selected from the group consisting of calcium and/or magnesium carbonates, phosphates, sulphates, oxides, hydroxides and mixtures thereof, more preferably the alkaline earth metal mineral carrier is selected from the group consisting of calcium carbonate, magnesium carbonate and mixtures thereof, and most preferably the alkaline earth metal mineral carrier is selected from the group consisting of precipitated hydromagnesite and surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors in an aqueous medium, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donor treatment and/or is supplied from an external source and mixtures thereof.

5. The drilling fluid of claim 1, wherein the alkaline earth metal mineral carrier further comprises a surface-treatment layer on at least a part of the surface of the alkaline earth metal mineral carrier, wherein the surface-treatment layer is formed by contacting the untreated alkaline earth metal mineral carrier with a surface-treatment composition comprising at least one surface-treatment agent, preferably wherein the at least one surface-treatment agent is selected from the group consisting of a. at least one mono-substituted succinic anhydride and/or mono-substituted succinic acid and/or a salt thereof, preferably wherein the at least one mono-substituted succinic anhydride and/or mono-substituted succinic acid and/or a salt thereof comprises a linear, branched, aliphatic or cyclic group having a total amount of carbon atoms from at least C.sub.2 to C.sub.30 in the substituent, and/or b. at least one carboxylic acid and/or a salt thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C.sub.4 to C.sub.24 and/or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C.sub.12 to C.sub.20 and/or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C.sub.16 to C.sub.18 and/or a salt thereof, and/or c. a phosphoric acid ester blend of one or more phosphoric acid mono-ester and/or salts thereof and/or one or more phosphoric acid di-ester and/or salts thereof, and/or d. at least one aldehyde, and/or e. abietic acid and/or salts thereof, and/or f. at least one polydialkylsiloxane, and/or g. at least one trialkoxysilane, and/or h. mixtures of the materials according to a. to g.

6. The drilling fluid of claim 1, wherein the surfactant is selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants and mixtures thereof, preferably the surfactant is selected from the group consisting of alkyl ethoxylates, quaternary ammonium salts, ethylene oxide/propylene oxide block copolymers, fatty acids and salts thereof, alkyl aryl sulphonates, fatty alcohols, aluminum stearate, non-ionic polyamide emulsifiers and mixtures thereof, and most preferably the surfactant is selected from the group consisting of C.sub.8-C.sub.22 alkyl ethoxylates, C.sub.6-C.sub.12 alkyl phenol alkoxylates, tall oil, tallow oil, salts and derivatives thereof, and mixtures of the foregoing.

7. The drilling fluid of claim 1, wherein the base fluid is an aqueous fluid, an organic fluid, an oil-in-water emulsion comprising an aqueous fluid and an organic fluid, or a water-in-oil emulsion comprising an aqueous fluid and an organic fluid and preferably is a water-in-oil emulsion comprising an aqueous fluid and an organic fluid, and wherein the aqueous fluid is preferably selected from the group consisting of water and aqueous salt solutions, and/or wherein the organic fluid is preferably selected from the group consisting of mineral oils, synthetic oils, synthetic organics, diesel, paraffin, petroleum, olefins, and mixtures thereof.

8. A process for producing a drilling fluid, the process comprising the steps of a. providing an alkaline earth metal mineral carrier having an intra-particle intruded specific pore volume of at least 0.8 cm.sup.3/g, as measured by mercury intrusion porosimetry, b. providing at least one surfactant, c. loading the at least one surfactant onto the mineral carrier to obtain a loaded mineral carrier, d. preparing a base fluid, e. providing a thickening agent, and a weighting agent, f. combining, in any order, the base fluid, the thickening agent, the loaded mineral carrier, the weighting agent and optionally further additives to obtain a drilling fluid.

9. The process of claim 8, wherein in step c. the at least one surfactant is loaded onto the alkaline earth metal mineral carrier in an amount of from 50 wt.-% to 250 wt.-%, preferably from 60 wt.-% to 220 wt.-%, more preferably from 70 to 200 wt.-%, based on the total weight of the dry alkaline earth metal mineral carrier.

10. The process of claim 8, wherein combining step f. comprises the following steps in the following order: f1. adding the base fluid, f2. adding the thickening agent, f3. adding the weighting agent, f4. adding the loaded mineral carrier, wherein steps f3 and f4 may be performed subsequently or simultaneously.

11. A method of using a loaded mineral carrier, comprising the step of: introducing an alkaline earth metal mineral carrier and at least one surfactant, for the delivery of a surfactant to a drilling fluid, wherein the mineral carrier has an intra-particle intruded specific pore volume of at least 0.8 cm.sup.3/g, as measured by mercury intrusion porosimetry.

12. The method of claim 11, wherein the alkaline earth metal mineral carrier has a. an intra-particle intruded specific pore volume in the range from 0.8 to 2.5 cm.sup.3/g, preferably from 1.2 to 2.1 cm.sup.3/g, and most preferably from 1.5 to 2.0 cm.sup.3/g, as measured by mercury intrusion porosimetry, and/or b. a BET specific surface area in the range from 10 to 100 m.sup.2/g, preferably from 15 to 60 m.sup.2/g, and most preferably from 20 to 40 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277:2010, and/or c. a ratio of the intra-particle intruded specific pore volume, as measured by mercury intrusion porosimetry, to the BET specific surface area, measured using nitrogen and the BET method according to ISO 9277:2010, of more than 0.01 cm.sup.3/m.sup.2, preferably more than 0.05 cm.sup.3/m.sup.2, and most preferably more than 0.06 cm.sup.3/m.sup.2, such as from 0.06 to 0.25 cm.sup.3/m.sup.2, and/or d. a d.sub.50 (vol) in the range from 1 to 1000 μm, preferably from 2 to 75 μm, more preferably from 2.5 to 50 μm, even more preferably from 3 to 20 μm, or from 100 to 1000 μm, preferably from 200 to 800 μm, as determined by laser diffraction.

13. The method of claim 11, wherein the alkaline earth metal mineral carrier has a loading capacity in the range from 50 wt.-% to 250 wt.-%, preferably from 60 wt.-% to 220 wt.-%, more preferably from 70 to 200 wt.-%, wherein the loading capacity is defined as the amount of a surfactant, which can be absorbed on the alkaline earth metal mineral carrier, relative to the weight of the dry alkaline earth metal mineral carrier.

14. The method of claim 11, wherein the alkaline earth metal mineral carrier is selected from the group consisting of alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal sulphates, alkaline earth metal oxides, alkaline earth metal hydroxides and mixtures thereof, preferably the alkaline earth metal mineral carrier is selected from the group consisting of calcium and/or magnesium carbonates, phosphates, sulphates, oxides, hydroxides and mixtures thereof, more preferably the alkaline earth metal mineral carrier is selected from the group consisting of calcium carbonate, magnesium carbonate and mixtures thereof, and most preferably the alkaline earth metal mineral carrier is selected from the group consisting of precipitated hydromagnesite and surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors in an aqueous medium, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donor treatment and/or is supplied from an external source and mixtures thereof.

15. The method of claim 11, wherein the surfactant is selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants and mixtures thereof, preferably the surfactant is selected from the group consisting of alkyl ethoxylates, quaternary ammonium salts, ethylene oxide/propylene oxide block copolymers, fatty acids and salts thereof, alkyl aryl sulphonates, fatty alcohols, aluminum stearate, non-ionic polyamide emulsifiers and mixtures thereof, and most preferably the surfactant is selected from the group consisting of C.sub.8-C.sub.22 alkyl ethoxylates, C.sub.6-C.sub.12 alkyl phenol alkoxylates, tall oil, tallow oil, salts and derivatives thereof, and mixtures of the foregoing.

Description

EXAMPLES

1. Description of Alkaline Earth Metal Mineral Carriers Used

[0387] Three alkaline earth metal minerals were assessed as carriers, their properties are listed in Table 1. Materials #C1 and #C2 are inventive, while material #C3 is a comparative example with a non-porous mineral. For material #C3, no intra-particle pore volume could be detected by Hg intrusion porosimetry.

TABLE-US-00001 TABLE 1 List and characterization of the carriers. Carrier V.sub.pore/ d* d** S.sub.BET/ d.sub.50, vol/ Name Description cm.sup.3 g.sup.−1 μm μm m.sup.2 g.sup.−1 μm #C1 PHM Precipitated hydromagnesite 1.711 1.3 13.4 39.5 22 #C2 SRCC Surface-reacted calcium carbonate 1.568 0.6  4.4 92 5.8 #C3 GCC Ground calcium carbonate 0 — — 7.2 1.2 #C4 PHM Precipitated hydromagnesite 1.185  0.83 36.4 55 104

2. Loading of the Carriers

[0388] The loading of the carriers was carried out via manual dosing. 20 g of the carrier was weighed into a beaker and the surfactant was added step-wise. Upon each addition step, the sample was mixed with a spatula, until the morphology of the powder was homogeneous. Once the desired quantity of surfactant was added, a magnetic stirring bar was added to the beaker, and the sample was stirred for at least 30 min, or until it appeared homogeneous.

2.2 Loading of the Carriers Using a Laboratory Mixer

[0389] The carrier was dried at 130° C. for 2 h and then added to the mixing vessel of the laboratory mixer MP-GL/Pharma (Somakon Verfahrenstechnik UG, Lunen, Germany) and mixed at 300 rpm. The surfactant was added dropwise at 25-50 g/min depending on the type of surfactant. After the addition of the surfactant the mixing was stopped, and the product was stored in a closed container.

2.3 Loading of Carrier Using an Overhead Stirrer

[0390] The carrier was dried at 130° C. for 2 h and then added to a beaker. The carrier was stirred at 900 rpm using an overhead stirrer (IKA RW20 digital, IKA®-Werke GmbH & Co. KG, Staufen, Germany). The surfactant was added dropwise at 5-13 g/min depending on the type of surfactant. After the addition of the surfactant the mixing was stopped, and the product was stored in a closed container.

3. Materials and Methods for the Preparation of the Drilling Muds

[0391] The drilling muds were prepared using the ingredients listed in Table 2, following the procedure provided in Table 3. All mixing was carried out using a Polytron PT 10-35 GT with a PT 30/2 EC-F250 homogenizer head. All samples in this report were produced to an approximate volume of 250 mL, using a 600 mL, tall glass beaker to prevent spillage during mixing. After the mud was complete, initial characterization was carried out. After characterization, the sample was transferred to a 260 mL Fann aging cell, the valve stem was attached, and the lid was fastened. After the final mud sample for the day was completed, the aging cells were placed in a Fann 704ET Hot Roller and were aged whilst rolling at 170° F. (76.7° C.) for 14 hours.

TABLE-US-00002 TABLE 2 Materials used to prepare the drilling mud Material Supplier n-Paraffin Oil Hoesch GmbH Nanoclay, surface modified Sigma Aldrich Linoleic Acid, technical grade Sigma Aldrich Calcium Chloride, dihydrate Sigma Aldrich Burnt lime Omya International AG Aduxol TPA-03 D Schaerer & Schlaepfer AG API Barite Steinbock Barite Ltd.

TABLE-US-00003 TABLE 3 Mud preparation instructions # Reagent Instruction 1. Paraffin oil Weigh directly into 600 ml beaker then mix for 5 Linoleic acid min at 11′000 rpm 2. Milk of lime Remove from mixer, weigh constituent directly into beaker, resume mixing for 5 min at 11′000 rpm 3. Brine Weigh constituent in plastic cup, add whilst mixing, continue to mix for 5 min at 11′000 rpm 4. Nanoclay Weigh constituent in weighing tray, add whilst mixing, continue to mix for 5 min at 11′000 rpm. 5. Emulsifier or Remove from mixer, weigh constituent directly into loaded mineral beaker, resume mixing for 5 min at 11′000 rpm carrier 6. Barite Weigh constituent in plastic cup, add whilst mixing, continue mixing for 5 min at 11′000 rpm

4. Description of the Prepared Drilling Muds

[0392] A total of four mud samples were prepared. Mud #M1 is a comparative example with the direct addition of the emulsifier. Muds #M2 and #M3 are inventive examples. Mud #M4 is a comparative sample with ground calcium carbonate. The exact concentration of the solids (in pounds per barrel (ppb) and wt.-%) are summarized in Table 4. The type and loading of the emulsifier is listed in Table 5.

TABLE-US-00004 TABLE 4 Composition of drilling muds #M1-M4 (all muds produced at 16 ppg) Paraffin Linoleic Milk of Oil/ Acid/ lime .sup.a/ Brine .sup.b/ Clay/ Emulsifier/ Barite/ ppb wt. % ppb wt. % ppb wt. % ppb wt. % ppb wt. % ppb wt. % ppb wt. % #M1 127 19.0 2.73 0.41 1.49 0.22 68.2 10.1 8.20 1.22 0.95 0.14 463 68.9 #M2 128 19.0 2.77 0.41 1.38 0.21 68.3 10.2 8.25 1.23 2.28 0.34 461 68.6 #M3 128 19.0 2.75 0.41 1.37 0.20 68.2 10.1 8.23 1.23 1.73 0.26 462 68.8 #M4 126 18.8 2.75 0.41 1.52 0.23 67.5 10.0 8.13 1.21 18.0 2.68 448 66.7 .sup.a 25 wt.-% solids content. .sup.b 25 wt.-% CaCl.sub.2.

TABLE-US-00005 TABLE 5 Emulsifiers used in the drilling muds #M1-M4 Fraction Material Used m.sub.Total .sup.a/ emulsifier/ m.sub.eff, Aduxol .sup.b/ Name Description g — g ppb #MI Aduxol TPA-03 D surfactant 0.54 1.00 0.54 0.95 #M2 Aduxol TPA-03 D on #C1 loaded carrier 1.30 0.44 0.58 1.01 #M3 Aduxol TPA-03 D on #C2 loaded carrier 0.99 0.52 0.52 0.91 #M4 Aduxol TPA-03 D on #C3 loaded carrier 10.3 0.05 0.50 0.88 .sup.a Total mass of loaded mineral carrier added. .sup.b Actual mass of Aduxol in samples.

5. Materials and Methods for the Characterization of the Drilling Muds

5.1 Density

[0393] To determine the effective mud weight/density, a Fann mud balance was used. The sample, shortly after being produced, was filled into the cup of the balance until almost full. The lid was placed on top, such that a small amount of fluid came out of the hole, to ensure the cup was entirely full. The slider weight on the beam was adjusted such that the bubble in the spirit level was centered. The mud weight reading was then read off the beam.

5.2 Rheological Properties

[0394] Before assessing the rheological properties of aged samples, they were re-homogenized for 5 min at 6′000 rpm. For the measurement of viscosity, the sample was transferred into a Fann Thermo-Cup, and heated to 50° C., whilst mixing with a Fann model 35 viscometer at 600 rpm. Once the temperature was stable at 50° C. and the dial was stable, the dial reading was noted. The speed was then changed to 300 rpm and the reading was taken once a stable value was reached. This process was repeated for 200 rpm, 100 rpm, 6 rpm and 3 rpm. From the obtained viscosity values at different speeds, the plastic viscosity (PV) and the yield point (YP) was determined. To measure the gel strength, the sample was mixed at 600 rpm for a minimum of 10 seconds. The speed was switched to the lowest speed position and the viscometer switched off. A timer was started and after 10 seconds, the viscometer was switched on to 3 rpm. The highest dial reading reached was noted down as the 10 second gel strength. This process was repeated, but the wait time was increased to 10 minutes. The highest dial reading reached was noted down as the 10 minute gel strength.

5.3 Filtration

[0395] As filtration trials were carried out after aging and viscosity characterization at elevated temperatures, muds were first allowed to cool to room temperature before testing. A Fann special hardened filter paper (equivalent to Whatman Grade 50) was placed in the testing vessel for the API filter press, the vessel was assembled, and the sample was poured in. The vessel was placed in the API filter mount, and the lid was placed on top. A 25 mL measuring cylinder was placed underneath the nozzle to collect the filtrate, and the pressure was increased to 100 psig (6.9 bar). The pressure was left constant for 30 min, after which the filtrate volume was measured and noted down as the API Fluid Loss (API filtrate volume).

6. Characterization of the Drilling Muds

[0396]

TABLE-US-00006 TABLE 6 Characterization of the drilling muds #M1-M5. Viscosity at_rpm Gel strength API 600 300 200 100 6 3 10 s 10 min PV YP Fluid Loss Dial reading, θ lbs 100 ft.sup.−2 cP lbs 100 ft.sup.−2 mL #M1 Un-aged 61 32 24 16 5 4 6 7 29 3 Aged 67 34 25 17 4 4 5 6 33 1 2.2 #M2 Un-aged 68 38 29 19 6 5 7 8 30 8 Aged 69 38 28 18 5 4 6 7 31 7 4.4 #M3 Un-aged 93 59 48 34 12 10 10 14 34 25 Aged 82 48 37 24 7 6 7 8 34 14 5 #M4 Un-aged 95 63 51 36 13 11 12 16 32 31 Aged 87 52 39 26 7 6 7 8 35 17 6.8

[0397] By comparison of drilling muds #M1 and #M2, it can be gathered that the emulsifier can be dosed as loaded material without impacting the rheology of the fluid, even after aging. In contrast, when utilizing the non-porous carrier in mud #M4, the viscosity is further increased, as is the API fluid loss.

7. Release Trials in Aqueous Media

7.1 Materials and Methods for the Release Trials

[0398] Release experiments were conducted with the additives listed in Table 7 with an additive concentration of 5 g L-1. Based on the indicated additive loading, the desired amount of solids was dispersed in 100 mL water using a magnetic stirrer (300 rpm) for 1 h at room temperature. Afterwards, the suspensions were filtered using a syringe filter (0.2 m) and diluted by a factor of 4. Active concentrations were determined using chemical oxygen demand cuvette tests in an Hach Lange DR 6000 spectral photometer. The concentration was calculated based on the average value of 3 measurements. Linearity of the calibration curve was ensured using 3 samples with individual dilution.

TABLE-US-00007 TABLE 7 Materials used for the release trials in aqueous media Type of # material Description #A1 Emulsifier Nonionic glucamide-based surfactant #A2 Secondary Fatty acid ester-based secondary emulsifier for emulsifier water-in-oil emulsions #A3 Fluid loss 2-Acrylamido-2-methylpropane sulfonic acid- additive based fluid loss additive for aqueous muds

7.2 Results of the Release Trials

[0399]

TABLE-US-00008 TABLE 8 Overview of the conducted experiments. Loading Weigh-in/ Release # Material Used % g % Appearance #E1 #A1 loaded 50 1.00 76.5 cloudy on #C4 using protocol 2.3 solution #E2 #A2 loaded 50 1.00 97.6 clear on #C4 using protocol 2.3 solution #E3 #A3 loaded 50 1.00 97.3 clear on #C4 using protocol 2.3 solution As can be gathered from Experiments #E1-3, the loaded minerals showed a good release performance reaching >75% in all cases, and even >97% for experiments #E2 and #E3.