WO1995030722A1

WO1995030722A1 - Surfactant composition

Info

Publication number: WO1995030722A1
Application number: PCT/GB1995/001013
Authority: WO
Inventors: Kevin Wall; Pauline William Zard; David James Barclay-Miller; David William Martin
Original assignee: The Burwood Corporation Limited
Priority date: 1994-05-04
Filing date: 1995-05-04
Publication date: 1995-11-16
Also published as: AU2350195A

Abstract

A nonionic surfactant composition for producing a stable aqueous-inorganic emulsion is described. The composition comprises a) at least one organic polyether or organic polyamine; and b) at least one organic acid derivative.

Description

SURFACTANT COMPOSITION

The present invention relates to a surfactant composition suitable for use in or as an invert emulsifier system.

Current technology for producing well drilling muds relies on ionic surfactants. These ionic surfactants require high energy inputs to produce stable invert emulsions and which once formed are difficult to break. In a calcium chloride brine mud svstem, the concentration of calcium chloride is generally limited to about 25 % _W and the maximum content of aqueous phase in organic is approximately 50 % /_w when using ionic emulsifiers. This limits the maximum stable mud density to approximately 1400 kgm^"3 and results in cuttings with high organic loadings. The drill cuttings resulting from muds which use such emulsifiers are difficult to clean, leaving high levels of residual oil associated with the cuttings in spite of the widespread use of chemical compositions which claim to reduce this oil concentration. Ionic emulsifiers are also sensitive to the pH and hardness of the aqueous phase, preferring to work in the alkaline region. Under these conditions careful control of the mud parameters are required during the drilling operation in order to prevent scaling.

Moreover with current oil-based mud drilling methods pollution is created directly in the form of large masses of solids (cuttings) with a tightly-bound retained oil phase discharged onto the sea bed. These give little scope for diffusion of nutrients and bacteria into the cuttings piles to digest the organic phase and hence this practice and technology leads to the accumulation of large inert masses of essentially non- biodegradable effluvia. Subsequent sea bed surveys required by the Offshore Pollution Authorities could lead to retrospective litigation and expensive clean-up costs for the well drilling operators.

The present invention seeks to provide a surfactant system that overcomes some or all of the aforementioned disadvantages. According to a first aspect of the present invention there is provided a nonionic surfactant composition for producing a stable aqueous-inorganic emulsion which composition comprises a) at least one organic polyether or organic polyamine; and b) at least one organic acid derivative.

According to a second aspect of the present invention there is provided a well-bore drilling process comprising the use a nonionic surfactant composition according to the present invention in or as a well-bore drilling formulation and/or a completion fluid.

According to a third aspect of the present invention there is provided the use of a nonionic surfactant composition according to the present invention in the formulation of a well-bore drilling formulation and/or a completion fluid.

According to a fourth aspect of the present invention there is provided the use of a composition according to the present invention as a nonionic surfactant in a well-bore drilling formulation and/or a completion fluid.

With the nonionic surfactant composition of the present invention preferably at least 80% of the functional groups are nonionic functional groups (e.g. esters, amides etc.). More preferred at least 90%, more preferred at least 95%, of the functional groups are nonionic functional groups. With a highly preferred nonionic surfactant composition of the present invention all of the functional groups are nonionic functional groups.

The organic polyether and/or organic polyamine and/or organic acid derivative can be substituted with other functional groups that do not detrimentally affect the preparation and/or properties of the composition of the present invention.

Preferably the nonionic surfactant composition comprises 5-95 %7_W of a); and 5-95 %^w/_w of b). More preferably, the nonionic surfactant composition comprises 5-85

% _W of a); and 15-95 % _W of b). Preferably the organic polyether or organic polyamine is any one of an alkyl, an alkenyl, a cycloalkyl, a cycloalkenyl, or an aromatic polyether or polyamine.

Preferably the organic polyether or organic polyamine is any one of an alkyl, an alkenyl, a cycloalkyl, or a cycloalkenyl polyether or polyamine.

Preferably the organic acid derivative is any one of an alkyl, an alkenyl, a cycloalkyl, a cycloalkenyl, or an aromatic acid derivative.

Preferably the organic acid derivative is any one of an alkyl, an alkenyl, a cycloalkyl, or a cycloalkenyl acid derivative.

Preferably each of the lipophilic segments of each of the components of a) and b) comprises at least 6 carbon atoms, preferably from 6 to 22 carbon atoms.

Preferably component a) is a poly(alkylene amine) or poly(alkylene ether) having from 1 to 12, preferably from 2 to 7, alkylene units in the polyether or polyamine chain.

Preferably component a) comprises a mixture of organic polyethers and/or organic polyamines, such as a mixture of different alkyl, alkenyl, cycloalkyl or cycloalkenyl polyether or polyamines.

Preferably some or all of component b) is an ester, and/or an amide and/or a thioester.

Preferably component b) is a mixture of acid derivatives, such as different alkyl, alkenyl, cycloalkyl or cycloalkenyl acid derivatives.

The composition may additionally comprise up to 25 %7_W of a low molecular weight solvent, soluble in both aqueous and organic liquids.

Preferably the solvent is selected from one or more of C₄-C₁₂ aliphatic or cycloaliphatic alcohols, esters, ethers, ketones or amines or mixtures thereof. The present invention provides a surfactant system which overcomes the aforementioned disadvantages and permits the formation of a stable aqueous-in¬ organic emulsion.

In particular, the present invention provides a readily biodegradable composition which enables stable emulsions to be generated with high ratios of aqueous phase in an organic liquid.

An important advantage of the present invention is that if desired, the emulsions can be made to be stable only at above-ambient temperatures and/or with high ion concentrations in the aqueous phase. This allows the emulsion to be broken at will by dilution with cold water. The property is particularly suited for the production of well drilling muds used, for example, in the exploration of petroleum liquids and gases in environmentally sensitive areas and in oil-based machine tool coolants.

Another important advantage is that the surfactant composition of the present invention requires very low energy inputs in order to produce a stable invert emulsion. Although stable in normal operation, the emulsion can be designed to be broken by cooling and dilution with water. Using the present invention, stable drilling muds have been produced containing 80 %7_W or more of an aqueous phase having a 30

%7_W calcium chloride concentration. Above 70% aqueous phase, the emulsifier system produces a gel structure in the organic liquid thereby reducing or eliminating the need for expensive gelling agents such as amine-treated bentonite. Stable muds have been produced using barite as loading agent with densities in excess of 1400 kgm^-3. Even before washing, the cuttings produced from this system are less environmentally damaging because there is up to 60 %7_W less organic phase present and the emulsifier components are more biodegradable than current systems. The clean-up of the drill cuttings is simpler and more efficient than with current systems and the treatment with demulsifier chemicals can be substantially reduced or even eliminated completely. If an emulsifier package/system is appropriately formulated with the non-ionic surfactant composition of the present invention and used for well-bore drillings, the cuttings from drilled bore-holes will become water-wet when agitated and discharged through the sea water column and therefore less polluting to the offshore marine environment.

Without wishing to be bound by theory it is believed that some of the advantages of the present invention are due to a combination of electrolyte dilution (sea water is typically 16,000-22,000 ppm chloride compared with a minimum of 100,000 ppm from typical drilling mud brine phases) and lowering of the temperature (0-5°C for sea bed temperature compared with temperatures up to 250° C for a deep high temperature, high pressure bore hole). These two factors combine to destabilise the inverted emulsion as the cuttings settle through the sea water column, thus creating a direct emulsion containing most of the organic phase which spontaneously disperses into the sea water column before the bore-hole cuttings and any retained organic phase settle on the sea bed. This then allows aerobic biodegradation of the dispersed bulk volume organics to occur in the large "ocean-sink".

Preferred non-ionic surfactants according to the present invention are generally insensitive to a wide range of pH and water hardness thereby eliminating problems with "scale" formation.

The selection of components and the balance between the components in the invention depends on the liquids to be used in the final application.

In this regard, the use of cycloaliphatic or aromatic derivatives will be favoured by the presence of high aromatic contents in the oil phase. High molecular weight paraffinic liquids will favour the use of high molecular weight aliphatic derivatives.

High salinities in the aqueous phase will favour more hydrophillic derivatives (for example esters or ethers of higher molecular weight polyethers or polyamines).

Increasing the content of hydrophillic components increases the temperature at which the emulsion will break when cooled and/or diluted. Conversely decreasing the hydrophilicity allows the formulation to be used in the production of stable high-aqueous content invert emulsions for use in, for example, low-flammability hydraulic systems.

A preferred embodiment of the present invention relates to a nonionic surfactant composition comprising:

a) 5-95 % _W (preferably 5-85 %7_W) of at least one aliphatic, cycloaliphatic, or less preferably, aromatic polyether or polyamine. The preferred components are alkyl, alkenyl, cycloalkyl or cycloalkenyl poly(alkylene ether)s or the equivalent poly(alkylene amine)s, especially the poly(ethylene oxide), poly(propylene oxide), poly(ethylene amine) and poly(propylene amine) derivatives. Component a) is optionally a blend of these, having various molecular weights, with various numbers and types of side groups on the lipophilic hydrocarbyl structure and combinations of ethoxylation or amination in the hydrophillic chain. The average number of repeat alkylene units in the poly(alkylene oxide/amine) chain is preferably from 1 to 12, more preferably from 2 to 7 units. The lipophilic segments of component a) preferably contain at least 6 carbon atoms and preferably between 6 and 22 carbon atoms.

b) 5-95 %7_W (preferably 15-95 %7_W) of one or more aliphatic, cycloaliphatic or less preferably aromatic acid derivatives, especially esters, amides or thioesters, but may be selected from any combination of other stable hydrophillic acid derivatives. Especially preferred derivatives are the ester derivatives of the poly(alkylene oxide)s, and in particular, poly(e thylene oxide) or poly(propylene oxide). Alternative preferred compounds are amides, alkanolamides (especially monoethanolamide), dialkanolamides (especially diethaπolamides), and poly(alkylene amine)amides (especially poly(ethylene amine)). The lipophilic segments of component b) preferably contain at least 6 carbon atoms and more preferably from 6 to 22 carbon atoms. Additionally the composition optionally comprises:

c) 0-25%7_w of a low molecular weight solvent, soluble in both aqueous and organic liquids. This may consist of one or more aliphatic or cycloaliphatic alcohols, esters, ethers, ketones or amines or it may be a mixture thereof.

Each component the solvent preferably contains from 4 to 12 carbons. Preferred solvents are butoxyethanol, cyclohexanol and cyclohexanone.

A highly preferred nonionic surfactant composition according to the present invention for producing stable aqueous-in-organic emulsions comprises: a) 15-95 %7_W of one or more .^ alkyl, alkenyl, cycloalkyl, cycloalkenyl or less preferably, aromatic derivative of a polyether or polyamine or a blend thereof; and b) 5-85 %7_W of a .^ alkyl, alkenyl, cycloalkyl, cycloalkenyl, or less preferably, aromatic acid derivative (eg. ester, polyether ester, amide etc.) or a blend thereof; and optionally c) up to 25 %7_W of a low molecular weight solvent, which is preferably soluble in both aqueous and organic phases.

The present invention will now be described only by way of example.

Example 1.

Composition A:

30.8 %7_W oleic diethanolamide.

10.2 %7_W an oleic acid poly(oxyethylene)ether ester, having an average poly(oxyethylene) molecular weight of about 308. 20.6 %7_W an oleic acid poly(oxyethylene)ether ester, having an average poly(oxyethylene) molecular weight of about 188. 11.4 %7_W synthetic C₁₃ poly(oxyethylene) ether, having an average poly(oxyethylene) molecular weight of about 440. 19.4 %7_W synthetic C₁₂_₁₃ poly(oxyethylene) ether, having an average poly(oxyethylene) molecular weight of about 28. 7.6 %7_W butoxyethanol.

6 ml of A were added to 200 ml of solvent grade, low aromatic mineral oil and 800 ml of calcium chloride solution containing 30% by weight of calcium chloride. The liquid was warmed to 30-40°C and then agitated to produce a translucent white gel. Barite was then added to increase the solution density to 1410 kgm^-3. Agitation produced an even grey gel which showed no sign of settling after holding the mud in a temperature controlled bath at 40°C for 24 hours. Conductivity measurements on the mud showed that the oil represented the continuous phase. 500 ml of cold water was added to the mud and agitated. After standing for 1 hour at room temperature the mud had separated into a clear upper organic phase and a lower barite containing phase which showed signs of settling. Example 2.

Composition B:

40 %7_W oleic diethanolamide.

10 %7_W Oleic acid - poly(oxy ethylene) ester (having an average poly(oxyethylene) molecular weight of about 176). 18 %7_W 12-hydroxystearic acid- poly(oxyethylene) ester (having an average poly(oxyethylene) molecular weight of about 264). 6 %7_W C₁₂_₁₄ alcohol - poly(oxyethylene) ether, having an average poly(oxyethylene) molecular weight of about 88. 26 %7_W synthetic C.₃_.₅ poly(oxyethylene) ether, having an average poly(oxyethylene) molecular weight of approximately 100.

7 ml of B were added to 100 ml of Finagreen BFDM™ oil (a commercial ester-based synthetic well-bore drilling base oil) and 150 parts of calcium chloride solution containing 20% by weight of calcium chloride. The liquid was agitated to produce a translucent white semi-gel. 1.5 g of amine-treated hectorite were added as a viscosifier and then barite was then added to increase the density to 1,656 kgm^"3. Agitation produced an even grey gel which showed no sign of settling after 24 hours.

Rheology measurements on the mud showed a plastic viscosity of 36 cP, a yield point of 35 lb/lOOft², and a 10 second gel strength of 8 lb/lOOft ². The HTHP filtration test at 250°f gave 23 ml of oil-continuous emulsion filtrate after 30 minutes. Crushed shale (<3mm sieve) was soaked in the mud for 24 hours at room temperature. After sieving the shale was heated in a retort and shown to have associated with it,

4.17%7_W of liquid, of which 40% was oil and 60% water, equating to an oil loading of 1.7%. Example 3.

Composition C:

37.5 %7_W Oleic diethanolamide.

32.3 %7_W Ca, Polyalkenyl succinimide poly(ethylene amine) with an average poly(ethylene amine) molecular weight of approximately 264). 30.2 %7_W Oleyl poly(oxyethylene)amine (average poly(oxyethylene) molecular weight of about 264).

14 ml of C were added to 100 ml of a synthetic olefinic base oil and 150 ml of 20 %7_W calcium chloride brine mixed in. lg of amine-treated bentonite and 170 g of barite added to make a mud with a density of 1,400 kgm^"3. The mud was shown to have a plastic viscosity of 48 cP, a yield point of 13 lb/100ft², and a 10 second gel strength of 3 lb/100ft². The HTHP filtration test at 250°f gave 37 ml. of oil- continuous emulsion filtrate after 30 minutes. Crushed shale (<3mm sieve) was soaked in the mud for 24 hours at room temperature. After sieving the shale was heated in a retort and shown to have associated with it, 7.6%7_W of liquid, of which 40% was oil and 60% water, equating to an oil loading of 3.1%.

Example 4.

For comparison, a commercially available system was made up of 5.7 ml surfactant package Omni-mul (which is a trade mark of and is supplied by Baker Hughes Inteq) and 1.7 ml surfactant package Omni-tec (which is a trade mark of and is supplied by

Baker Hughes Inteq) in 120 ml synthetic olefinic base oil and 80 ml of 20% calcium chloride brine. 5 g of amine-treated bentonite, 7 g of lime and 80 g of barite were then mixed in to give a mud density of 1,175 kgm^"3. The mud was shown to have a plastic viscosity of 44 cP, a yield point of 68 lb/100ft², and a 10 second gel strength of 33 lb/100ft². The HTHP filtration test at 250°f gave 1 ml. of oil-continuous emulsion filtrate after 30 minutes. Crushed shale (<3mm sieve) was soaked in the mud for 24 hours at room temperature. After sieving the shale was heated in a retort and shown to have associated with it, 10.24%7_W of liquid, of which 60% was oil and 40% water, equating to an oil loading of 6.1%.

Other modifications of the present invention will be apparent to those skilled in the art. For example, with the prefered nonionic surfactant compositions comprising 5-95 %7_W of a); and 5-95 %7_W of b), an alternative preferred embodiment is when the nonionic surfactant composition comprises 15-95 %7_W of a); and 5-85 %7_W of b).

Claims

1. A nonionic surfactant composition for producing a stable aqueous-inorganic emulsion which composition comprises:

a) at least one organic polyether or organic polyamine; and

b) at least one organic acid derivative.

2. A composition according to αaim 1 wherein the composition comprises:

a) 5-95 %7_W of at least one organic polyether or organic polyamine; and

b) 5-95 %7_W of at least one organic acid derivative.

3. A composition according to claim 1 or claim 2 wherein the composition comprises:

a) 5-85 %7_W of at least one organic polyether or organic polyamine; and

b) 15-95 %7_W of at least one organic acid derivative.

4. A composition according to any one of the preceding claims wherein the organic polyether or organic polyamine is any one of an alkyl, an alkenyl, a cycloalkyl, a cycloalkenyl, or an aromatic polyether or polyamine.

5. A composition according to claim 4 wherein the organic polyether or organic polyamine is any one of an alkyl, an alkenyl, a cycloalkyl, or a cycloalkenyl polyether or polyamine.

6. A composition according tc any one of the preceding claims wherein the organic acid derivative is any one of an alkyl, an alkenyl, a cycloalkyl, a cycloalkenyl, or an aromatic acid derivative.

7. A composition according to claim 6 wherein the organic acid derivative is any one of an alkyl, an alkenyl, a cycloalkyl, or a cycloalkenyl acid derivative.

8. A composition according tc any one of the preceding claims wherein each of the lipophilic segments of each of the components of a) and b) comprises at least 6 carbon atoms, preferably from 6 to 22 carbon atoms.

9. A composition according to any one of the preceding claims wherein component a) is a poly(alkylene amine) or poly(alkylene ether) having from 1 to 12, preferably from 2 to 7, alkylene units in the polyether or polyamine chain.

10. A composition according to any one of the preceding claims wherein component a) comprises a mixture of organic polyethers and/or organic polyamines, such as a mixture of different alkyl, alkenyl, cycloalkyl or cycloalkenyl polyether or polyamines.

11. A composition according to any one of the preceding claims wherein some or all of component b) is an ester, and/or an amide and/or a thioester.

12. A composition according to any one of the preceding claims wherein component b) is a mixture of acid derivatives, such as different alkyl, alkenyl, cycloalkyl or cycloalkenyl acid derivatives.

13. A composition according to any one of the preceding claims additionally comprising up to 25 %7_W of a low molecular weight solvent, soluble in both aqueous and organic liquids.

14. A composition according to claim 13 wherein the solvent is selected from one or more C₄-C₁₂ aliphatic or cycloaliphatic alcohols, esters, ethers, ketones or amines or mixtures of these.

15. A well-bore drilling process comprising the use a nonionic surfactant composition as defined in any one of the preceding claims in or as a well-bore drilling formulation and/or a completion fluid.

16. Use of a nonionic surfactant composition as defined in any one of claims 1 to 14 in the formulation of a well-bore drilling formulation and/or a completion fluid.

17. Use of a composition as defined in any one of claims 1 to 14 as a nonionic surfactant in a well-bore drilling formulation and/or a completion fluid.

18. A composition, process or use substantially as hereinbefore described.