Lubricant additives for water based drilling fluid

Abstract

The invention relates to powdered lubricants for water based drilling fluids. Conventional liquid lubricants containing particularly divalent ions have the tendency to grease out. The powdered lubricants have excellent dispersion properties and hence do not grease out, when added to the drilling mud in the concentrations, preferably of the order of about 3% or less. The powdered lubricant is a combination of inert fillers with fatty acids that are essentially free from fatty acid esters and metal soaps and have organic acids containing C10-C24 alkyl groups fatty acids. The improved lubricating properties of the drilling muds result in greatly increased life of the rotary drilling bits and marked reduction in torque required to rotate the bit. Solid powdered additives compositions greatly reduce transportation costs and simplify the logistics and environmental concerns associated with shipping large volumes of liquids and overcome the pour point issues associated with liquid additives.

Claims

1. A powdered lubricant additive, comprising: a fatty acid that is free from fatty acid ester and metal soap, said fatty acid comprising organic acids containing C10-C24 alkyl groups fatty acids, wherein the fatty acid is present in a range of about 50% to 70% by weight of the additive; and an inert filler, wherein the inert filler is selected from the group consisting of precipitated silica of particle size about 10-180 microns, diatomaceous earth of particle size about 100-130 microns, expanded perlite of particle size about 10-5000 microns, and combinations thereof, and the inert filler is present in the range of about 30% to 50% by weight of the additive, wherein the powdered lubricant additive does not grease or cheese out in the presence of mono, di or trivalent ions in water based drilling fluids, and the powdered lubricant additive is free from fatty acid ester and metal soap.

2. The powdered lubricant additive as claimed in claim 1 wherein the C10-C24 alkyl group fatty acids are selected from the group consisting of saturated and unsaturated fatty acids, vegetable oil fatty acid, sulfurized vegetable fatty acids or combinations thereof.

3. The powdered lubricant additive as claimed in claim 1 further comprising a hydrocarbon.

4. A water-based drilling fluid having lubricating properties comprising water, viscosifiers, weighing agents, fluid loss control agents and the powdered lubricant additive as claimed in claim 1 and having calcium ions present in concentration greater than 150 parts per million.

5. The water-based drilling fluid as claimed in claim 4 wherein the powdered lubricant additive is present in concentrations of about 0.25% to about 5% weight/volume of drilling fluid, effective to impart lubricity and disperse calcium soaps in the drilling fluid.

6. The water-based drilling fluid as claimed in claim 5 wherein the powdered lubricant additive is present in concentrations of about 1% to about 3% weight/volume of drilling fluid.

7. The water-based drilling fluid as claimed in claim 4 wherein: a. the viscosifier is selected from the group consisting of bentonite, xanthan gum, clay and polymers; b. the weighing agent is selected from the group consisting of barite, hematite and calcium carbonate; and c. the fluid loss reducer is selected from the group consisting of starch, carboxy methylated starch, polyanionic cellulose, polymeric fluid loss additive.

8. A rotary method for drilling a well from a surface through calcium-containing formations in which the water based drilling fluid as claimed in claim 4 is circulated down the well and back to the surface, and contacted with drill bits within the well, said drilling fluid having calcium soaps dispersed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. Thus, the following more detailed description of the embodiments of the present invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the present invention, to set forth the best mode of operation of the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the present invention is to be defined solely by the appended claims.

(2) Many compositions can be prepared according to this invention. It is contemplated that the ratios of the liquid additives to inert filler can vary depending upon final use and method of preparation. Ratios of inert filler to the liquid additive in the powdered lubricant may vary from 10:90 to 90:10. It is noted that the lubricant and inert filler just added separately in the water based drilling fluid will still result in greasing.

(3) The present invention envisages a powdered lubricant additive that does not grease or cheese out in the presence of mono, di or trivalent ions in water based drilling fluids. The powdered lubricant is made of (a) fatty acid that is essentially free from fatty acid ester and metal soap and (b) inert filler. The fatty acids are organic acids containing C10-C24 alkyl groups fatty acids which may be chosen from saturated and unsaturated fatty acids or vegetable oil fatty acid or sulfurized vegetable fatty acids or combinations thereof. The inert filler may be chosen from precipitated silica of particle size about 10-180 microns or diatomaceous earth of particle size about 10-200 microns or expanded perlite of particle size about 10-5000 microns or combinations thereof. Preferably, the ratio of the liquid additive to the inert filler in the powdered lubricant varies from 30:70 to 70:30.

(4) The present invention further envisages a water-based drilling fluid having lubricating properties and made up of water, viscosifiers, weighing agents, fluid loss control agents, calcium ions and the powdered lubricant additive of the present invention in concentrations of about 0.25% to about 5% weight/volume of drilling fluid. Preferably the calcium ions are present in concentrations greater than 150 parts per million. Preferably, the powdered lubricant additive is present in concentrations of about 1% to about 3% weight/volume of drilling fluid. The viscosifier may be chosen from bentonite, xanthan gum, clay or polymers. The weighing agent may be barite or hematite or calcium carbonate. The fluid loss reducer may be chosen from starch, carboxy methylated starch, polyanionic cellulose or polymeric fluid loss additive.

(5) The present invention also envisages a rotary method for drilling a well through calcium-containing formations in which the water based drilling fluid of this invention having calcium soaps dispersed therein is circulated down the well and back to the surface and contacted with the drill bits.

(6) Some of the embodiments according to the invention are described as under.

(7) Embodiment I: In one embodiment, the present invention is a method of preparing a solid lubricant which is used as an extreme pressure lubricant in water based drilling mud. The method comprises spraying liquid extreme pressure lubricant at temperature of about 70-150° C. on inert filler at the rate of about 2-8 LPM.

(8) The method of preparing the solid lubricant involves spraying heated liquid lubricant comprising of a blend of (1) sulfurized fatty acid (2) non-sulfurized fatty acid and (3) a hydrocarbon on inert solid filler, such as precipitated silica of particle size 10-180 μm, diatomaceous earth of particle size 10-200 μm or expanded perlite of particle size 10-5000 μm. The mixture is blended, dried and cooled to obtain the solid lubricant which is further pulverized to particle size of about 500 μm to provide the dried lubricant powder.

(9) An illustrative example of a liquid lubricant is Gel EP Torque Reducer which is commercially available from GUMPRO Drilling Fluids Pyt Ltd.

(10) Embodiment II: Another embodiment of the present invention is a process for preparing solid general purpose lubricant additive. The method comprises spraying liquid lubricant additive at temperature of about 70-150° C. on inert fillers at the rate of about 2-8 LPM.

(11) The method of preparing the solid lubricant additive involves spraying lubricant additive consisting of blend of (1) non-sulfurized vegetable oil and (2) hydrocarbon on inert solid filler such as precipitated silica of particle size 10-180 μm, diatomaceous earth of particle size 10-200 μm & expanded perlite of particle size 10-5000 μm. The method further comprises blending, drying and cooling the mixture to obtain the solid lubricant additive which is further pulverized to particle size of about 500 μm to provide the lubricant additive powder.

(12) A commercially available liquid General Purpose Liquid Lubricant additive is Gel GP Lube from GUMPRO Drilling Fluids Pvt. Ltd.

(13) In the present invention lubricant additives are added in the drilling muds in concentration ranging from about 0.25%-3.0%.

(14) The monovalent or divalent ions causing the formation of the insoluble curds of monovalent or divalent soaps may be added to the drilling mud to give the desired properties. Divalent ions may also have been introduced into the drilling mud as a contaminant as result of penetrating formations or encountering brines.

(15) Laboratory experiments were carried out on drilling mud compositions to determine the effectiveness of dispersants in drilling muds containing monovalent and divalent ions. The test procedure was to prepare a drilling mud and dose it separately with conventional liquid lubricant and the powdered lubricant of the present invention. The resultant drilling mud was tested in each case. The percentage lubricity/torque reduction and greasing out of monovalent and divalent ions was observed for the conventional liquid lubricants and the powdered lubricants of the present invention.

(16) The improved and advantageous properties of the powdered lubricants of the invention are effectively demonstrated by the experiments reported in the ensuing examples. The following terms/abbreviations are used in describing the results of experimentation are explained as follows: “EPTR” is Extreme Pressure Torque Reducer “Liquid EPTR” is conventional Liquid Extreme Pressure Lubricant “Powder EPTR” is powdered Extreme Pressure Lubricant of the present invention. “GP Lube” is General Purpose Lubricant. “AHR” is After Hot Rolling temperature. “Powder GP LUBE” is Powdered General Purpose Lubricant additive of the present invention. “Liquid GP LUBE” is conventional Liquid General Purpose Lubricant.

EXAMPLE 1: KCl MUD SYSTEM

(17) TABLE-US-00001 MUD FORMULATION Hot Rolling For Four Hrs @ 150° F. and 250° F. KCl System Base Mud Formulation Specific Sr. No. Product Gravity Gms Ml Wt % 1 Pac LV 1.6 2 1.25 0.36 2 Xanthan Gum 1.6 1.2 0.75 0.21 3 Starch 1.6 2 1.25 0.36 4 CaCO3-50 2.6 8.45 3.25 0.93 5 KCl 2.47 104.39 40.15 11.47 6 Monoethanol Amine 1.00 0.35 0.35 0.10 7 Biocide 1.00 0.35 0.35 0.10 8 Fresh Water 1 302.654 302.654 86.47 Total 421.4 350.0 100.00

(18) Lubricity and Greasing for the above mud system is studied for 1%, 2% and 3% lubricant dosage.

(19) 1. Comparison of the Lubricity and Greasing of Liquid V/s Powder Extreme Pressure Torque Reducer(EPTR):—

(20) TABLE-US-00002 % Reduction in Lubricity Coefficient LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER EPTR EPTR EPTR EPTR EPTR EPTR 1% Dosage 2% Dosage 3% Dosage AHR- 80.69 24.02 76.97 59.52 79.26 62.86 150° F. AHR- 80.69 78.74 76.97 76.02 77.04 74.58 250° F. Observation on greasing Greas- No Greas- No Greas- No ing Greas- ing Greas- ing Greas- Observed ing Observed ing Observed ing

(21) Conclusion:—

(22) The lubricity of Powder EPTR which is the powdered lubricant of the present invention, increases with increase in dosage at Hot Rolling Temp of 150° F. whereas at 250° F. the lubricity of the Powdered lubricant is comparable to that of Liquid Lubricant. It is observed that the inert filler acts as a good dispersing agent and the powdered lubricant of the present invention prevents greasing out in the drilling mud.

(23) 2. Comparison of the Lubricity and Greasing of Liquid V/s Powder General Purpose(GP) Lube:—

(24) TABLE-US-00003 % Reduction in Lubricity Coefficient LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER GP GP GP GP GP GP LUBE LUBE LUBE LUBE LUBE LUBE 1% Dosage 2% Dosage 3% Dosage AHR- 76.96 70.24 80.6 75.00 78.18 68.59 150° F. AHR- 76.25 71.43 80.74 82.85 81.48 76.84 250° F. Observation on Greasing Greas- No Greas- No Greas- No ing Greas- ing Greas- ing Greas- Observed ing Observed ing Observed ing

(25) Conclusion:—

(26) The lubricity of Powder GP Lube which is the powdered general purpose lubricant of the present invention, is comparable to conventional liquid general purpose lubricant. Inert filler acts as a good dispersing agent and greasing is not observed when the powdered general purpose lubricant of the present invention is used.

EXAMPLE 2: CaCl.SUB.2 .MUD SYSTEM

(27) TABLE-US-00004 MUD FORMULATION Hot Rolling For Four Hrs @ 150° F. and 250° F. CaCl2 System Base Mud Formulation Specific Sr. No. Product Gravity Gms ml Wt % 1 Pac LV 1.6 2 1.25 0.4 2 Tap Water 1 285.897 269.3782 77.0 3 CaC12 3.1 183.465 59.179 16.9 4 Xanthan Gum 1.6 1.2 0.75 0.2 5 Starch 1.60 2 1.25 0.4 6 Calcium carbonate 50 2.6 4.239 17.69231 5.1 7 Monoethanol Amine 1 0.35 0.35 0.1 8 Biocide 1 0.35 0.5 0.1 Total 479.2 350.0 100

(28) Lubricity and Greasing for the above mud system is studied for 1%, 2% and 3% lubricant dosage.

(29) 1. Comparison of the Lubricity and Greasing of Liquid V/s Powder Extreme Pressure Torque Reducer(EPTR) is:—

(30) TABLE-US-00005 % Reduction in Lubricity Coefficient LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER EPTR EPTR EPTR EPTR EPTR EPTR 1% Dosage 2% Dosage 3% Dosage AHR- 27.43 37.07 73.45 38.58 76.11 40.94 150° F. AHR- 29.34 29.89 75.00 40.22 78.26 42.52 250° F. Observation on Greasing Greas- No Greas- No Greas- No ing Greas- ing Greas- ing Greas- Observed ing Observed ing Observed ing

(31) Conclusion:—At 1% dosage, the lubricity of conventional liquid lubricant is comparable to that of the powdered extreme pressure lubricant of the present invention. At 2% and 3% dosage, the lubricity of the powdered lubricant is less than that of liquid lubricant. However, the inert filler acts as a good dispersing agent and greasing is not observed when the powdered extreme pressure lubricant is used.

(32) 2. Comparison of the Lubricity and Greasing of Liquid V/s Powder GP Lube:—

(33) TABLE-US-00006 % Reduction in Lubricity Coefficient LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER GP GP GP GP GP GP LUBE LUBE LUBE LUBE LUBE LUBE 1% Dosage 2% Dosage 3% Dosage AHR- 40.71 29.20 30.97 27.43 26.55 23.01 150° F. AHR- 9.78 40.22 7.60 41.30 3.26 39.13 250° F. Observation on Greasing Greas- No Greas- No Greas- No ing Greas- ing Greas- ing Greas- Observed ing Observed ing Observed ing

(34) Conclusion:—

(35) Lubricity of Powder GP Lube which is the powdered general purpose lubricant of the present invention, is greater than that of conventional Liquid General Purpose lubricant at Hot Rolling Temperature of 250° F., whereas at 150° F. it is comparable to that of the conventional Liquid General Purpose lubricant. Further, the lubricity remains consistent with varying dosages used. However, there is no greasing observed in the powdered general purpose lubricant since the inert filler acts a good dispersing agent.

EXAMPLE 3: NaCl MUD SYSTEM

(36) TABLE-US-00007 MUD FORMULATION Hot Rolling For Four Hrs @ 150° F. and 250° F. NaCl System Base Mud Formulation Specific Sr. No. Product Gravity Gms Ml Wt % 1 Pac LV 1.6 2 1.25 0.36 2 Xanthan Gum 1.6 1.2 0.75 0.21 3 Starch 1.6 2 1.25 0.36 4 CaCO3-50 2.6 8.434 3.24 0.93 5 NaCl 2.79 97.054 34.792 9.94 6 Fresh Water 1.00 308.714 308.71 88.20 Total 419.4 350.0 100.00

(37) 1. Comparison of the Lubricity and Greasing of Liquid V/s Powder Extreme Pressure Torque Reducer(EPTR):—

(38) TABLE-US-00008 % REDUCTION IN LUBRICITY COEFFICIENT LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER EPTR EPTR EPTR EPTR EPTR EPTR 1% Dosage 2% Dosage 3% Dosage AHR- 76.0 77.2 80.0 72.0 79.5 74.4 150° F. AHR- 77.6 79.6 82.9 79.1 82.9 92.8 250° F. Observation on greasing No No No No No No Greas- Greas- Greas- Greas- Greas- Greas- ing ing ing ing ing ing

(39) Conclusion:—

(40) Lubricity of the powdered extreme pressure lubricant of the present invention is comparable to conventional Liquid extreme pressure lubricant.

(41) 2. Comparison of the Lubricity and Greasing of Liquid V/s Powder General Purpose(GP) Lube is:—

(42) TABLE-US-00009 % Reduction in Lubricity Coefficient- POWDER GP LUBE LIQ- POW- LIQ- POW- LIQ- POW- UID DER UID DER UID DER GP GP GP GP GP GP LUBE LUBE LUBE LUBE LUBE LUBE 1% Dosage 2% Dosage 3% Dosage AHR- 82.29 60 83.42 78.49 84.00 83.87 150° F. AHR- 82.19 75 84.25 80.00 84.93 81.25 250° F. Observation on Greasing No No No No No No Greas- Greas- Greas- Greas- Greas- Greas- ing ing ing ing ing ing

(43) Conclusion:—

(44) Lubricity of Powdered general purpose lubricant of the present invention is comparable to conventional general purpose lubricant.

(45) The foregoing description of preferred embodiments of the present disclosure provides illustration and description, but is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosure.