WO2019175649A1

WO2019175649A1 - Environment-friendly lubricant composition for water-based drilling fluids

Info

Publication number: WO2019175649A1
Application number: PCT/IB2018/059212
Authority: WO
Inventors: Mahaboob Subhahani MOHAMED ALI; Mohamed Iqbal Batcha IMAM JAFAR KHAN; Arivudainambi UDAIYAR SHANMUGAVEL EZHIL; Senthilkumar SUNDARARAJ; Rizwan Ahmad
Original assignee: Oren Hydrocarbons Private Limited
Priority date: 2018-03-14
Filing date: 2018-11-22
Publication date: 2019-09-19

Abstract

A lubricant composition for water-based drilling fluids is disclosed. The lubricant composition comprises a synthesized ester obtained by blending at least one polyhydric alcohol and at least one fatty acid, wherein the ratio of said polyhydric alcohol to said fatty acid is in the range of 1:9 to 9:1, and said fatty acid is free of bis-allylic protons. The lubricant composition is environmental-friendly, non-toxic and highly biodegradable.

Description

ENVIRONMENT-FRIENDLY LUBRICANT COMPOSITION FOR WATER-BASED DRILLING FLUIDS

FIELD OF THE INVENTION

The present invention relates to lubricant compositions for fluids used in well drilling or completion operations. More particularly, the present invention relates to lubricant compositions for water-based drilling fluids used in wellbores.

BACKGROUND

Natural resources such as oil and gas present in the subterranean formation are recovered by drilling a wellbore that penetrates the formation. The drilling operation involves driving by rotation a toothed bit fastened to the end of a drill pipe string. During the drilling a fluid, called drilling fluid or mud, is injected at the level of the bit through the inner space of the pipes. The main purpose of the drilling fluid is to cool and lubricate the drill bit as it grinds through the earth’s crust. As the drill bit descends, it generates “cuttings”, or small bits of stone, clay, shale or sand. Other important functions of the drilling fluid are to clean the bit and the well by transporting the cuttings up to the earth’s surface, to provide a hydrostatic pressure to prevent formation fluids from entering into the wellbore, to stabilize the walls of the well, to inhibit reaction of the geologic formations in contact with the fluid, etc.

In recent years, improvements in drilling equipment and fluids has allowed extended reach wells to be drilled with increased effectiveness. However, in most cases, an additional chemical lubricant is required to drill these extended reach wells to total depth. Oil-based and synthetic-based drilling fluids are generally preferred as they produce lower friction and torque values, however, their use may be limited due to the high costs and environment concerns.

Water-based drilling fluids are preferred when combating environmental concerns, however, their use is restricted by disadvantages such as high friction and torque values, and interaction of the water-based drilling fluid with the water-sensitive layers of rock which may lead to unacceptable interference with the drilling process. However, by addition of components having a lubricating effect, water-based drilling fluids may be used advantageously.

Drilling fluid compositions consist of lubricant for the bearing and cutting surfaces of the drill bit and pipe bore. Generally during the well drilling operation friction may occur between the string of drill pipe and well borehole. This friction may interfere with the vertical movement of the pipe into and out of the well borehole. Due to the increased friction between the drill pipe and the bore hole more power may be required to run the drill pipe, further resulting in increased torque and drag. This consequently leads to stress on the drilling pipe, impacting the drilling process and damaging the drilling tools. Hence, a lubricant is an important component of the drilling fluids and completion fluids, and choice of the lubricant is primarily driven by its effectiveness and compliance to environmental regulations.

In the past years, increasingly strict environmental legislation imposed in most parts of the world has changed the choice of chemicals that can be used as lubricants for water- based drilling fluids. Hydrocarbons and fatty acids are known to be traditionally used in practice. The prior art document US Pat. No. 5189012 discloses an oil-based drilling fluid comprising a nonhydrogenated synthetic hydrocarbon oil for improving lubricity. Another prior art document US Pat. 6806235 discloses imparting lubricity to an aqueous drilling fluid by providing a lubricant component containing a partial glyceride derived from a tall oil fatty acid. However, the increasingly stricter regulations with regard to the biodegradability of drilling fluids and their constituents are gradually restricting the use of the commonly used lubricants. At the same time, there is a growing interest in alternatives with better biodegradability, in particular esters. Patent document EP0770661 discloses use of esters of monocarboxylic acids with monohydric alcohols as lubricants for water-based drilling fluid systems. These chemical families are a source of highly lubricious materials that can significantly reduce metal-to-metal and metal-to-rock coefficients of friction in water-based fluid systems by as much as 70%. Typically, the most effective additives have a relatively high degree of surface activity, which improves their adhesion to materials (i.e. metal casing or drilling mud solids), and so enhances the lubricity of the surface. However, this surface activity makes them more capable of reacting with other components of the fluid - whether deliberately added, or present as a contaminant. For example, many effective water-based fluid lubricants may act as an emulsifier in the presence of even small quantities of oil. Under moderate shear conditions, the combination of oil, lubricant and brine can produce ultra- low oil: water ratio invert emulsion with the consistency of cottage cheese. This highly viscous material, also called‘cheese’ is at best a drilling hazard, stripping the lubricant from the fluid and blinding shaker screens. This 'cheese' may damage the production zone or plug the completion assembly, particularly where sand screens are applied.

Another potential problem is the reaction between the lubricant and divalent ions, resulting in the formation of a grease-like precipitate. Depending on the chemical nature of the lubricant, this 'grease' may be formed with relatively low concentrations of calcium or magnesium ions, in some cases with concentrations as low as 1000 mg/L, which may easily be encountered in freshwater or monovalent salt fluids while drilling. The potential consequences of the formation of this grease are similar to those of the creation of the ‘cheese'-like emulsion.

There is therefore felt a need to address the afore-noted drawbacks of the prior art and provide an environment-friendly lubricant composition for use in water-based drilling fluids and completion fluids, importantly to prevent fluid related formation damage.

SUMMARY OF THE INVENTION

Accordingly, a primary object of the present invention is to provide a lubricant composition for water-based drilling fluids which overcomes the afore-noted drawbacks of the known lubricants, and is environmental-friendly, non-toxic and highly biodegradable. Also, the present invention provides a lubricant composition that prevents bit balling, increases the rate of penetration, increases the drilling rate and minimizes differential sticking problems. Further, the present invention provides a lubricant composition that gives high oxidative stability, high hydrolytic stability and excellent low temperature performance.

Other objects, aspects and advantages of the present invention will be more apparent from the following description.

Accordingly, the present invention discloses a lubricant composition for water-based drilling fluids comprising a synthesized ester obtained by blending at least one polyhydric alcohol and at least one fatty acid, wherein the ratio of said polyhydric alcohol to said fatty acid is in the range of 1 :9 to 9: 1 , and said fatty acid is free of bis- allylic protons.

Preferably, according to the present invention, said synthesized ester is obtained by blending said polyhydric alcohol and said fatty acid in the presence of a monobasic acid.

The polyhydric alcohol is selected from the group consisting of pentaerythritol, dipentaeryth ritol, tripentaerythritol, monopentaerythritol, and mixtures thereof, more particularly, pentaerythirotol tetraoleate, pentaerythirotol trioleate, pentaerythirotol dioleate, pentaerythirotol monooleate, and mixtures thereof.

The fatty acid includes at least one acid selected from the group consisting of ricinoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxystearic acid, linoleic acid, linolenic acid, eicosanoic acid, lauric acid and myristic acid. Preferably, the fatty acid is a vegetable oil. The vegetable oil may be selected from the group consisting of tall oil, castor oil, sunflower seed oil, canola oil, palm oil, corn seed oil, cotton seed oil, rapeseed oil, linseed oil, safflower seed oil, oat oil, olive oil, peanut oil, apricot seed oil, almond oil, avocado oil, olive oil, camellia oil, rice bran oil, cotton seed oil, peanut oil, walnut oil, rapeseed oil, rice bran oil, linseed oil, sesame oil, soybean oil, palm kernel oil, and mixtures thereof. The monobasic acid is selected from hydrochloric acid, nitric acid, hydrofluoric acid, hydrobromic acid, and mixtures thereof.

Preferably, according to the present invention, the ratio of said polyhydric alcohol to said fatty acid is preferably 1 : 1.

Typically, the lubricant composition is added to a drilling fluid in a concentration in the range of about 1.5% to 3.0% by volume. The lubricant composition of present invention is dispersible. In the various brine systems, said lubricant composition completely eliminates the greasing and cheesing problems.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting examples in the following description. The examples used herein are intended merely to facilitate an understanding of the ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The description herein after, of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. The present invention is directed to a drilling fluid additive, particularly a lubricant composition. A “lubricant” can be defined as a substance (usually a fluid under operating conditions) introduced between moving surfaces to reduce the friction and wear between them. In drilling fluid system, a lubricant additive is an additive used in drilling fluid to facilitate smooth relative motion of the drilling pipe and the bore hole by minimizing friction and wear between these interacting surfaces. The present invention is an environment-friendly lubricant composition for use as an additive in a drilling fluid system or brine system. The lubricant composition improves drilling fluid performance and efficiency. The lubricant composition is biodegradable, cost-effective and has a low toxicity level. The lubricant composition is an ester-based lubricant derived from natural fats and oils. The lubricant composition when used as an additive in drilling fluid system lubricates the drill bit and the stem, and prevents bit balling, increases the rate of penetration, enhances the drilling rate, reduces the risk of differential sticking and minimizes damage to drilling pipe by twisting or breakage.

An embodiment of the present invention discloses a lubricant composition, preferably for water-based drilling fluid systems or brine systems. The lubricant composition comprises a synthesized ester obtained by blending one or more polyhydric alcohols with one or more fatty acids. The lubricant composition is obtained by blending one or more polyhydric alcohols and one or more fatty acids in a preferred ratio in the range of 1 :9 to 9: 1. Preferably, the ratio of polyhydric alcohol to fatty acid can be taken as 1 : 1. The polyhydric alcohol forms the backbone with the fatty acid group attached to it.

The one or more polyhydric alcohols may be selected from the group consisting of glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol, inositol, volemitol, isomalt, maltitol, lactitol, maltotriitol, maltotetraitol, polyglycitol, and mixtures thereof. Preferably, the polyhydric alcohol is a erythritol selected from the group consisting of pentaerythritol, dipentaerythritol, tripentaerythritol, monopentaerythritol, and mixtures thereof, more particularly, pentaerythirotol tetraoleate, pentaerythirotol trioleate, pentaerythirotol dioleate, pentaerythirotol monooleate, and mixtures thereof. According to a preferred embodiment of the present invention, the fatty acid so employed is free of bis-allylic protons. Due to the absence of bis-allylic protons on the fatty acid chain the lubricant composition so obtained possesses high oxidative stability, high hydrolytic stability, excellent low and moderate temperature performance and relatively high biodegradability. Further, the composition is adapted to form a lubricant film having strong interaction with the metallic surfaces. It is believed that stronger the interaction, better the reduction in friction and wear.

The fatty acid includes at least one acid selected from the group consisting of ricinoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxystearic acid, linoleic acid, linolenic acid, eicosanoic acid, lauric acid and myristic acid. More preferably, the fatty acid is an oleic acid. The one or more fatty acids are typically one or more vegetable oils. Preferably, the vegetable oils may be selected from the group consisting of tall oil, castor oil, sunflower seed oil, canola oil, palm oil, corn seed oil, cotton seed oil, rapeseed oil, linseed oil, safflower seed oil, oat oil, olive oil, peanut oil, apricot seed oil, almond oil, avocado oil, olive oil, camellia oil, rice bran oil, cotton seed oil, peanut oil, walnut oil, rapeseed oil, rice bran oil, linseed oil, sesame oil, soybean oil, palm kernel oil, and mixtures thereof.

In another embodiment, the lubricant composition is a synthesized ester obtained by blending one or more polyhydric alcohols with one or more fatty acids in the presence of a monobasic acid. The monobasic acid is selected from hydrochloric acid, nitric acid, hydrofluoric acid, hydrobromic acid, and mixtures thereof. The proportion of monobasic acid in the blend is about 0.05% to 0.5% by volume.

The lubricant composition is added to a drilling fluid in a concentration in the range of about 1 .5% to 3.0% by volume. When used as an additive in a water-based drilling fluid system, the composition increases lubricity of the fluid system without affecting its rheological properties. The lubricant composition is easily dispersible in any solids-free drilling fluid or brine system. In about 1 .5% to 3.0% by volume, even lower concentrations of about 1.5% to 2.0% by volume, the composition provides excellent results in reducing friction factors by up to 35%, while drilling long reach holes at up to 85° deviations. The composition is designed to be used in situations where drag or the potential for differential sticking are likely, such as when drilling highly deviated or high- differential-pressure wells. This additive is an effective lubricant in low solids, non- dispersed and/or chemically dispersed water-based drilling fluids. In differential sticking situations, it can be added as a concentrated pill in the drilling fluid and displaced and spotted across the sticking zone to free the stuck pipe. In brine systems, the lubricant composition forms a milky white dispersion. After mixing of the lubricant composition in the water-based drilling fluid systems, the lubricant does not separate into an oily layer on the top surface of the mud. Also, the lubricant composition when mixed with divalent ion brine solutions reacts with divalent ions but does precipitate to cause“greasing” or “cheesing”.

The present invention will now be described with the help of the accompanying examples which are only intended to exemplify the invention and shall not be construed to limit the scope and ambit of the invention.

EXAMPLES

The drilling fluid/mud formulations were analyzed using OFITE Extreme pressure and lubricity tester to determine the lubricity coefficient of the drilling fluid. The rheological properties of the fluid were determined by FANN Viscometer as described in "Standard Procedure for Testing Drilling Fluids", American Petroleum Institute, API RP 13B. Other properties such as mud weight, pH, cheesing/greasing effect and foam tendency were also checked.

Example 1

1.4 ppb of Xanthan gum, 17.5 ppb of potassium chloride, 24.5 ppb of Rev dust and 3.5 ppb of lubricant composition (obtained by blending polyol ester and tall oil in a ratio of 1 : 1 ) were added to 330 ml of calcium chloride brine (1.2 g/cc) solution to obtain a mud formulation. Table I below shows the comparative samples. Table II below indicates the lubricant performance in CaCI₂ brine (1.2 g/cc) mud formulation.

Table I

Table II: Lubricant (of example 1 ) performance in CaCI₂ brine (1 .2 g/cc) mud formulation

Example 2

0.7 ppb of Xanthan gum, 17.5 ppb of Rev dust and 10.5 ppb of lubricant composition (obtained by blending polyol ester and castor oil in a ratio of

1 : 1 ) were added to 338 ml of calcium chloride brine (1 .33 g/cc) solution to obtain a mud formulation. Table III below shows the comparative samples. Table IV below indicates the lubricant performance in CaCI₂ brine (1.33 g/cc) mud formulation.

Table III

Table IV: Lubricant (of example 2) performance in CaCI₂ brine (1.33 g/cc) mud formulation

Example 3

24.5 ppb potassium chloride (KCI), 1 ppb of caustic, 1 ppb Xanthan gum, 6 ppb of pregel starch, 10.5 ppb of glycol, 10.5 ppb of lubricant composition (obtained by blending polyol ester and palm oil in a ratio of 1 : 1 in the presence of HCI), 1 ppb of biocide, 15 ppb of CaC0₃ (5 m) and 50 ppb of CaC0₃ (50 m) were added to 285.6 ml of sodium chloride (NaCI) brine (1.03g/cc) solution to obtain a mud formulation. Table V below shows the comparative samples. Table VI below indicates the lubricant performance in NaCI and KCI mud formulation.

Table V

Table VI: Lubricant (of example 3) performance in NaCI and KCI mud formulation

Example 4

80 ppb sodium chloride, 0.8 ppb of xanthan gum, 7 ppb of modified starch, 3.5 ppb of hydrogen sulfide scavenger, 10 ppb of CaC0₃ (fine), 10 ppb of CaC0₃ (medium), 10 ppb of CaC0₃ (5 m) and 10.6 ppb of CaC0₃ (25 m) and 10.5 ppb of lubricant composition (obtained by blending polyol ester and castor oil in a ratio of 1 : 1 in the presence of HN0₃) were added to 322 ppb of water to obtain a mud formulation. Table VII below shows the comparative samples. Table VIII below indicates the lubricant performance in NaCI mud formulation.

Table VII

Table VIII: Lubricant (of example 4) performance in NaCI mud formulation

From the above examples, it is observed that the lubricant composition of present invention significantly improves the lubricity of the mud formulation and reduces torque in water-based drilling fluid systems and brine systems.

Embodiment of the present invention is applicable over a wide number of uses and other embodiments may be developed beyond the embodiment discussed heretofore. Only the most preferred embodiments and their uses have been described herein for purpose of example, illustrating the advantages over the prior art obtained through the present invention; the invention is not limited to these specific embodiments or their specified uses. Thus, the forms of the invention described herein are to be taken as illustrative only and other embodiments may be selected without departing from the scope of the present invention. It should also be understood that additional changes and modifications, within the scope of the invention, will be apparent to one skilled in the art and that various modifications to the composition described herein may fall within the scope of the invention.

Claims

Claims:

1. A lubricant composition for water-based drilling fluids comprising a synthesized ester obtained by blending at least one polyhydric alcohol and at least one fatty acid, wherein the ratio of said polyhydric alcohol to said fatty acid is in the range of 1 :9 to 9: 1 , and said fatty acid is free of bis-allylic protons.

2. The lubricant composition as claimed in claim 1 , wherein said synthesized ester is obtained by blending said polyhydric alcohol and said fatty acid in the presence of a monobasic acid.

3. The lubricant composition as claimed in claim 1 , wherein said polyhydric alcohol is selected from the group consisting of pentaerythritol, dipentaerythritol, tripentaeryth ritol , monopentaerythritol, and mixtures thereof, more particularly, pentaerythirotol tetraoleate, pentaerythirotol trioleate, pentaerythirotol dioleate, pentaerythirotol monooleate, and mixtures thereof.

4. The lubricant composition as claimed in claim 1 , wherein said fatty acid includes at least one acid selected from the group consisting of ricinoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxystearic acid, linoleic acid, linolenic acid, eicosanoic acid, lauric acid and myristic acid.

5. The lubricant composition as claimed in claim 1 , wherein said fatty acid is a vegetable oil.

6. The lubricant composition as claimed in claim 5, wherein said vegetable oil is selected from the group consisting of tall oil, castor oil, sunflower seed oil, canola oil, palm oil, corn seed oil, cotton seed oil, rapeseed oil, linseed oil, safflower seed oil, oat oil, olive oil, peanut oil, apricot seed oil, almond oil, avocado oil, olive oil, camellia oil, rice bran oil, cotton seed oil, peanut oil, walnut oil, rapeseed oil, rice bran oil, linseed oil, sesame oil, soybean oil, palm kernel oil, and mixtures thereof.

7. The lubricant composition as claimed in claim 2, wherein said monobasic acid is selected from hydrochloric acid, nitric acid, hydrofluoric acid, hydrobromic acid, and mixtures thereof.

8. The lubricant composition as claimed in claim 1 , wherein the ratio of said polyhydric alcohol to said fatty acid is preferably 1 :1 .

9. The lubricant composition as claimed in claim 1 , wherein said lubricant composition is added to a drilling fluid in a concentration in the range of about 1.5% to 3.0% by volume.

10. The lubricant composition as claimed in claim 1 , wherein said lubricant composition is dispersible.

11. The lubricant composition as claimed in claim 1 , wherein when added in brine systems said lubricant composition eliminates greasing and cheesing.