WO2016025749A1

WO2016025749A1 - Environmentally acceptable paraffin dispersant, and methods for making and using same

Info

Publication number: WO2016025749A1
Application number: PCT/US2015/045119
Authority: WO
Inventors: Kevin Schwartz; Scott SZULC; Ron Anderson; Joe Miller
Original assignee: Lubrizol Oilfield Chemistry, Llc
Priority date: 2014-08-13
Filing date: 2015-08-13
Publication date: 2016-02-18

Abstract

Compositions for reducing paraffin deposits include at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid diester, and methods for making and using same.

Description

PCT SPECIFICATION

TITLE: ENVIRONMENTALLY ACCEPTABLE PARAFFIN DISPERSANT, AND

METHODS FOR MAKING AND USING SAME

INVENTOR: Kevin SCHWARTZ, Scott SZULC, Ron ANDERSON, and Joe MILLER

ASSIGNEE: LUBRIZOL OILFIELD CHEMISTRY, LLC

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] Embodiments of this invention relate to compositions for reducing paraffin deposits, and methods for making and using same.

[0002] More particularly, embodiments of this invention relate to compositions for reducing paraffin deposits, where the compositions include at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester, and methods for making and using same.

2. Description of the Related Art

[0003] One of the most common problems in oil field production involves the formation of paraffin wax deposition within the system. The inner surface becomes fouled with these paraffin deposits, which reduce the space available, plugs off, interfere with stirrer, enhances potential corrosion, and contributes to many other problems which could result in loss of saleable products.

[0004] Paraffin wax precipitates then agglomerates forming deposits, when the temperature of the problematic area drops below the cloud point, such as the temperature at which paraffin wax crystals begin to form. For example, if the pipe is 10°C and the cloud point of crude is 20°C, wax deposition will most likely occur. This temperature can vary over a wide range and is specific to the particular crude oil being produced.

[0005] Chemical remedies such as dispersants and inhibitors may be used to mitigate paraffin issues. Dispersants are chemical additives that prevent the agglomeration of paraffin into amass, which may deposit and become increasingly difficult to produce with the crude. On the other hand, paraffin inhibitors function by taking the place of a paraffin molecule on the edge of the growing crystal. In doing so, the shape of the wax crystal is altered as it precipitates out of solution. The inhibitor will prevent the paraffin molecules from forming needles and will retain the paraffin in the liquid portion of crude leading to a lower viscosity and cloud point.

[0006] While many dispersants and inhibitors have been developed for handling paraffin deposits in and on production tubing, there is still a need in the art for paraffin treatments that do not use solvents and are not inhibitors. .

SUMMARY OF THE INVENTION

Paraffin Reduction Composition

[0007] Embodiments of the present invention provide compositions for reducing paraffin deposits on production tubing, where the compositions include at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

Drilling Fluids

[0008] Embodiments of the present invention provide drilling fluid compositions for reducing paraffin deposits on drill strings, tubing or other tubular members during drilling of oil/gas wells, where the drilling fluid compositions include an effective amount of a paraffin reducing composition including at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

[0009] Embodiments of the present invention provide methods for drilling gas/oil wells, where the methods include circulating a drilling fluid composition while drilling of oil/gas wells, where the drilling fluid compositions include an effective amount of a paraffin reducing composition including at least alkylene modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

Completion Fluids

[0010] Embodiments of the present invention provide completion fluid compositions for reducing paraffin deposits on tubing during oil/gas well completion, where the completion fluid compositions include an effective amount of a paraffin reducing composition including at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

Methods Using Completion Fluids

[0011] Embodiments of the present invention provide methods for completing oil/gas wells, where the methods include circulating a completion fluid composition into an oil/gas well, where the completion fluid composition includes an effective amount of a paraffin reducing composition including at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

Methods Using Production Fluids

[0012] Embodiments of the present invention provide methods for producing oil/gas wells, where the methods include circulating a production fluid composition into an oil/gas well, where the production fluid composition includes an effective amount of a paraffin reducing composition including at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester and where the paraffin reducing composition reduces deposits on production tubing during oil/gas production.

Methods Using Drilling Fluids [0013] Embodiments of the present invention provide methods for drilling oil/gas wells, where the methods include circulating a drilling fluid composition into an oil/gas well, where the drilling fluid composition includes an effective amount of a paraffin reducing composition including at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same:

[0015] Figure 1 depicts a plot of cold point test results for an untreated Blue Rapids oil sample.

[0016] Figure 2 depicts plots of viscosity results for an untreated Blue Rapids oil sample, PDC1 treated Blue Rapids oil sample, PDC2 treated Blue Rapids oil sample, and PDC3 treated Blue Rapids oil sample, respectively

[0017] Figure 3A-D depict photographs of cold fingers of a blank, a solution including PDC1, a solution including PDC2, and a solution including PDC3, respectively.

[0018] Figure 4 A depicts a picture of a wax solution without a dispersant.

[0019] Figures 4B-D depict pictures of a wax solution including the dispersants PDC1, PDC2, and PDC3, respectively.

[0020] Figures 4E-F depict pictures of another wax solution including the dispersants PDC1 and PDC2, respectively.

DEFINITIONS OF TERM USED IN THE INVENTION

[0021] The following definitions are provided in order to aid those skilled in the art in understanding the detailed description of the present invention.

[0022] The term "drilling fluids" refers to any fluid that is used during well drilling operations including oil and/or gas wells, geo-thermal wells, water wells or other similar wellbs.

[0023] The term "completion fluids" refers to any fluid that is used in oil and/or gas well completion operations.

[0024] The term "production fluids" refers to any fluid that is used in oil and/or gas well production operations.

[0025] An over-balanced or conventional balanced drilling fluid means a drilling fluid having a circulating hydrostatic density (pressure) greater than a formation density (pressure).

[0026] An under-balanced and/or managed pressure drilling fluid means a drilling fluid having a circulating hydrostatic density (pressure) lower or equal to a formation density (pressure). For example, if a known formation at 10,000 ft (True Vertical Depth - TVD) has a hydrostatic pressure of 5,000 psi or 9.6 lbm/gal, an under-balanced drilling fluid would have a hydrostatic pressure less than or equal to 9.6 lbm/gal. Most under-balanced and/or managed pressure drilling fluids include at least a density reduction additive. Other additive many include a corrosion inhibitor, a pH modifier and a shale inhibitor.

[0027] The term "gpt" means gallons per thousand gallons.

[0028] The term "ppt" means pounds per thousand gallons.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The inventors have found that compositions for reducing paraffin deposition may be formulated from blends of ethylene oxide and/or propylene oxide modified alcohol surfactants and aminodicarboxylic acid dialkyl esters. The inventors have also found that these blends form suitable alternatives to benzene, toluene, ethylbenzene, and xylene (BTEX) based paraffin deposition inhibitor systems, which are undesirable in the oilfield and bio based solvent systems. The inventors have also found that these paraffin solvent compositions, paraffin reducing compositions, or paraffin deposition inhibitor compositions produce excellent dispersions of various types of paraffins having varying hydrocarbon chain lengths. These paraffin reducing compositions have: 1) improved environmental profiles compared to terpenes and aromatic solvents such as benzene, toluene, and/or xylenes and 2) improved dispersion results compared to terpene solvents and equivalent if not better than aromatic solvents, which carry a negative environmental profile.

[0030] Embodiments of the present invention broadly relate to compositions for reducing paraffin deposition, where the compositions include a blend comprising at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 90 wt.% of at least one alkylene oxide modified alcohol surfactant and 40 wt.% to 10 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 40 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 70 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 30 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the surfactants are ethylene oxide and/or propylene oxide modified alcohols and the aminodicarboxylic acid dialkyl esters are dimethyl esters. In certain embodiments, the alcohol is 2-ethylhexanol and the aminodicarboxylic acid dialkyl esters are dimethyl glutamate, dimethyl aspartate, and mixtures or combinations thereof. In certain embodiments, the blends may also include 1 wt.% to 20 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 20 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 20 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 20 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols.

[0031] Embodiments of the present invention provide production fluid compositions for reducing paraffin deposits on production tubing during oil production, where the production fluid compositions include an effective amount of a paraffin reducing composition including a blend of at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dimethyl ester. In certain embodiments, the blend includes between about 60 wt.% and 90 wt.% of at least one alkylene oxide modified alcohol surfactant and 40 wt.% to 10 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 40 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 70 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 30 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the surfactants are ethylene oxide and/or propylene oxide modified alcohols and the aminodicarboxylic acid dialkyl esters are dimethyl esters. In certain embodiments, the alcohol is 2-ethylhexanol and the aminodicarboxylic acid dialkyl esters are dimethyl glutamate, dimethyl aspartate, and mixtures or combinations thereof. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. The effective amount is between about 50 ppm to about 2 wt.%. In other embodiments, the effective amount is between about 100 ppm and 1 wt.%). In other embodiments, the effective amount is between about 200 ppm and 100,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 10,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 5,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 1 ,000 ppm.

[0032] Embodiments of the present invention provide methods for producing oil from an oil well, where the methods include circulating a production fluid composition into the oil well, where the production fluid composition includes an effective amount of a paraffin reducing composition including a blend of at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dimethyl ester. In certain embodiments, the blend includes between about 60 wt.% and 90 wt.% of at least one alkylene oxide modified alcohol surfactant and 40 wt.% to 10 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 40 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 70 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 30 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the surfactants are ethylene oxide and/or propylene oxide modified alcohols and the aminodicarboxylic acid dialkyl esters are dimethyl esters. In certain embodiments, the alcohol is 2- ethylhexanol and the aminodicarboxylic acid dialkyl esters are dimethyl glutamate, dimethyl aspartate, and mixtures or combinations thereof. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. The effective amount is between about 50 ppm to about 2 wt.%. In other embodiments, the effective amount is between about 100 ppm and 1 wt.%). In other embodiments, the effective amount is between about 200 ppm and 100,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 10,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 5,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 1 ,000 ppm.

[0033] Embodiments of the present invention provide drilling fluid compositions for reducing paraffin deposits on production tubing during drilling, where the drilling fluid compositions include an effective amount of a paraffin reducing composition including a blend of at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dimethyl ester. In certain embodiments, the blend includes between about 60 wt.% and 90 wt.% of at least one alkylene oxide modified alcohol surfactant and 40 wt.% to 10 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 40 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 70 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 30 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the surfactants are ethylene oxide and/or propylene oxide modified alcohols and the aminodicarboxylic acid dialkyl esters are dimethyl esters. In certain embodiments, the alcohol is 2-ethylhexanol and the aminodicarboxylic acid dialkyl esters are dimethyl glutamate, dimethyl aspartate, and mixtures or combinations thereof. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. The effective amount is between about 50 ppm to about 2 wt.%. In other embodiments, the effective amount is between about 100 ppm and 1 wt.%. In other embodiments, the effective amount is between about 200 ppm and 100,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 10,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 5,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 1 ,000 ppm.

[0034] Embodiments of the present invention provide methods for drilling oil from an oil well, where the methods include circulating a drilling fluid composition into the oil well, where the production fluid composition includes an effective amount of a paraffin reducing composition including a blend of at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dimethyl ester. In certain embodiments, the blend includes between about 60 wt.% and 90 wt.% of at least one alkylene oxide modified alcohol surfactant and 40 wt.% to 10 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 60 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 40 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the blend includes between about 70 wt.% and 80 wt.% of at least one alkylene oxide modified alcohol surfactants and 30 wt.% to 20 wt.% of at least one aminodicarboxylic acid dialkyl ester. In certain embodiments, the surfactants are ethylene oxide and/or propylene oxide modified alcohols and the aminodicarboxylic acid dialkyl esters are dimethyl esters. In certain embodiments, the alcohol is 2-ethylhexanol and the aminodicarboxylic acid dialkyl esters are dimethyl glutamate, dimethyl aspartate, and mixtures or combinations thereof. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 10 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 10 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. In certain embodiments, the blends may also include 1 wt.% to 5 wt.% a linear, branched, or cyclic alcohol having between 6 and 20 carbon atoms or a mixture of such alcohols and 1 wt.% to 5 wt.% a linear, branched, or cyclic diol having between 1 and 20 carbon atoms or a mixture of such diols. The effective amount is between about 50 ppm to about 2 wt.%. In other embodiments, the effective amount is between about 100 ppm and 1 wt.%). In other embodiments, the effective amount is between about 200 ppm and 100,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 10,000 ppm. In other embodiments, the effective amount is between about 200 ppm and 5,000 ppm. In other embodiments, _ _ the effective amount is between about 200 ppm and 1 ,000 ppm.

[0035] In certain embodiments, the paraffin solvent compositions of this invention include synergistic blends of ethylene oxide and/or propylene oxide modified alcohol surfactants and aminodicarboxylic acid dimethyl esters. In certain embodiments, the blends include ethylene oxide and/or propylene oxide modified 2-ethyl hexanol surfactants and dimethyl glutamate.

Drilling Fluids

[0036] Generally, a drilling fluid is used during the drilling of a well. Drilling fluids can be designed for so-called over-balanced drilling (a hydrostatic pressure of the drilling fluid is higher than the pore pressure of the formation), under-balanced drilling (a hydrostatic pressure of the drilling fluid is lower than the pore pressure of the formation) or managed pressure drilling, where the hydrostatic pressure of the drilling fluid is managed depending on the nature of the material through which drilling is occurring. Each type of drilling uses different types of drilling fluids. The compositions of this invention are designed to improve dispersion and stability of the resulting drilling fluids so that cuttings remain suspended for longer periods of time or at temperatures up to 450°F. The drilling fluid may be aqueous or hydrocarbon based depending on the base fluid employed.

Completion Fluids

[0037] Generally, a completion fluid is used during the completion of an oil and/or gas well. The completion fluids may be aqueous or hydrocarbon based depending on the base fluid employed.

Production Fluids

[0038] Generally, a production fluid is used during the production of an oil and/or gas well. The productions fluids may be aqueous or hydrocarbon based depending on the base fluid employed.

SUITABLE REAGENTS FOR USE IN THE INVENTION

Alkylene Oxide Modified Alcohol Surfactants

[0039] Suitable alkylene oxide modified alcohol surfactants include, without limitation, compounds of the general formula (I):

R'OiRO)^ (I) where R¹ is a linear, branched, or cyclic hydrocarbyl group including from 6 to 20 carbon atoms, where one or more of the carbon atoms are replaced by oxygen atoms, R^a is a linking group including 1 to 4 carbon atoms, and n is a integer having a value between 1 and 20. In certain embodiments, R¹ is a linear or branched hydrocarbyl group, R^a is a linking group having between 2 and 3 carbon atoms, and n is an integer having a value between 2 and 10. In certain embodiments, the alkylene oxide modified alcohol surfactants include, without limitation, ethylene oxide and/or propylene oxide modified alcohol surfactants of linear or branched alcohols having between 6 and 20 carbon atoms. Exemplary examples of alcohols include, without limitation, 2-methylpentanol, 2-ethylpentanol, 1- hexanol, isohexanol, 2-methylhexanol, 2-ethylhexanol, 1-heptanol, isoheptanol, 2-methylheptanol, 2-ethylheptanol, 1-octanol, isooctanol, 2-methyloctanol, 2-ethyloctanol, 1-nonanol, isononanol, 2- methylnonanol, 2-ethylnonanol, 1-decanol, isodecanol, 2-methyldecanol, 2-ethyldecanol, 1- undecanol, isoundecanol, 2-methylundecanol, 2-ethylundecanol, 1-dodecanol, isododecanol, 2- methyldodecanol, 2-ethyldodecanol, and higher analogs, or mixtures and combinations thereof. The extent of ethylene oxide and/or propylene oxide modification is between 1 and 20 ethylene oxide and/or propylene oxide units.

Aminodicarboxylic Acid Diesters

[0040] Suitable aminodicarboxylic acid diesters include, without limitation, a compound or aplurality of compounds of the general formula (Π):

R² C R^CC O OR⁴ (II) *COOR³

where R² is a hydrogen atom or a linear, branched, or cyclic hydrocarbyl group having from 1 to 20 carbon atoms, R³ and R⁴ are independently linear, branched, or cyclic hydrocarbyl groups having from 1 to 20 carbon atoms, R^b and R^c are independently linear, branched, or cyclic hydrocarbyl linking groups having from 1 to 10 carbon atoms, where in any of the groups, one or more carbon atoms may be replace by an oxygen atom. In certain embodiments, R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 4 carbon atoms. In other embodiments, R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 3 carbon atoms. In other embodiments, R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 2 carbon atoms. In other embodiments, R³ and R⁴ are methyl groups. In other embodiments, the dimethyl esters are compounds of the general formula:

MeOOC-R-CH(NH₂)-COOMe

where R is a hydrocarbyl linking group having between 1 and 10 carbon atoms and Me is methyl. Exemplary dimethyl esters include d and/or / dimethyl glutamate (R is CH₂CH₂), d and/or / dimethyl aspartate (R is CH₂), or mixtures or combinations thereof. In other embodiments, the aminodicarboxylic acid diesters include amino modified diesters of dicarboxylic acid selected from the group consisting of propanedioic acid (malonic acid) (HOOC-CH₂-COOH), butanedioic acid (succinic acid) (HOOC-(CH₂)₂-COOH), pentanedioic acid (glutaric acid) (HOOC-(CH₂)₃-COOH), hexanedioic acid (adipic acid) (HOOC-(CH₂)₄-COOH), heptanedioic acid (pimelic acid) (HOOC-(CH₂)₅-COOH), octanedioic acid (suberic acid) (HOOC-(CH₂)₆-COOH), nonanedioic acid (azelaic acid) (HOOC-(CH₂)₇-COOH), decanedioic acid (sebacic acid) (HOOC-(CH₂)₈-COOH), undecanedioic acid (HOOC-(CH₂)₉-COOH), dodecanedioic acid (HOOC-(CH₂)₁₀-COOH), higher analogs thereof, and mixtures or combinations thereof.

Alcohols

[0041] Suitable alcohols for use in the present composition include, without limitation, linear, branched, or cyclic alcohols having between 1 and 20 carbon atoms. In certain embodiment, the alcohols have between 6 and 20 carbon atoms. Exemplary examples of alcohols include, without limitation, 2-methylpentanol, 2-ethylpentanol, 1-hexanol, isohexanol, 2-methylhexanol, 2- ethylhexanol, 1-heptanol, isoheptanol, 2-methylheptanol, 2-ethylheptanol, 1-octanol, isooctanol, 2- methyloctanol, 2-ethyloctanol, 1-nonanol, isononanol, 2-methylnonanol, 2-ethylnonanol, 1-decanol, isodecanol, 2-methyldecanol, 2-ethyldecanol, 1-undecanol, isoundecanol, 2-methylundecanol, 2- ethylundecanol, 1-dodecanol, isododecanol, 2-methyldodecanol, 2-ethyldodecanol, and higher analogs, or mixtures and combinations thereof.

Diols

[0042] Suitable diols for use in the present composition include, without limitation, linear, branched, or cyclic diols having between 1 and 20 carbon atoms. In certain embodiments, the diols are glycols having between 1 and 20 carbon atoms. Exemplary examples of diols and glycols include, without limitation, methylene glycol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, higher analogs thereof, α,ω-diols, 1,2-diols, 1,3-diols, 1,4-diols, higher analogs thereof, and mixtures or combinations thereof.

General Paraffin Dispersants

[0043] Suitable paraffin dispersants include, without limitation, blends of alkylene oxide modified alcohol surfactants and aminodicarboxylic acid diesters. In certain embodiments, the paraffin dispersants include, without limitation, blends of alkylene oxide modified alcohol surfactants, aminodicarboxylic acid diesters, and alcohols. In other embodiments, the paraffin dispersants include, without limitation, blends of alkylene oxide modified alcohol surfactants, aminodicarboxylic acid diesters, alcohols, and diols. Exemplary examples include ParaClear D600, ParaClear D500, ParaClear D584, and mixtures or combinations thereof; these compositions are blends of alkylene oxide modified alcohol surfactants and aminodicarboxylic acid diesters and may include alcohols and/or diols.

Base Fluids

[0044] Suitable base fluids for use in this invention includes, without limitation, aqueous base fluids, hydrocarbon base fluids, and emulsions including aqueous base fluids and hydrocarbon base fluids.

Hydrocarbon Base Fluids

[0045] Suitable hydrocarbon base fluids for use in this invention includes, without limitation, . synthetic hydrocarbon fluids, petroleum based hydrocarbon fluids, natural hydrocarbon (non-aqueous) fluids or other similar hydrocarbons or mixtures or combinations thereof. The hydrocarbon fluids for use in the present invention have viscosities ranging from about 3^X 10^"6 to about 600^x 10^"6 m²/s (3 to about 600 centistokes). Exemplary examples of such hydrocarbon fluids include, without limitation, poly-a-olefms, polybutenes, polyolesters, biodiesels, simple low molecular weight fatty esters of vegetable or vegetable oil fractions, simple esters of alcohols such as Exxate from Exxon Chemicals, vegetable oils, animal oils or esters, other essential oil, diesel, diesel having a low or high sulfur content, kerosene, jet-fuel, white oils, mineral oils, mineral seal oils, hydrogenated oil such as PetroCanada HT-40N or IA-35 or similar oils produced by Shell Oil Company, internal olefins (10) having between about 12 and 20 carbon atoms, linear alpha olefins having between about 14 and 20 carbon atoms, poly-a-olefins having between about 12 and about 20 carbon atoms, isomerized a- olefins (IAO) having between about 12 and about 20 carbon atoms, VM&P Naptha, Linpar, Parafins having between 13 and about 16 carbon atoms, HF-1000 (produced by Sasol, USA), and mixtures or combinations thereof.

[0046] Suitable poly-a-olefms (PAOs) include, without limitation, polyethylenes, polypropylenes, polybutenes, polypentenes, polyhexenes, polyheptenes, higher PAOs, copolymers thereof, and mixtures thereof. Exemplary examples of PAOs include PAOs sold by Mobil Chemical Company as SHF fluids and PAOs sold formerly by Ethyl Corporation under the name ETHYLFLO and currently by Albemarle Corporation under the trade name Durasyn. Such fluids include those specified as ETHYLFLO 162, 164, 166, 168, 170, 174, and 180. Well suited PAOs for use in this invention include bends of about 56% of ETHYLFLO now Durasyn 174 and about 44% of ETHYLFLO now Durasyn 168. Other examples of PAO's include Chevron Phillips Grades PAO 2, PAO 4, PAO 6 and PAO 8 based on C₁₀ alpha olefins, and PAO 2.5, PAO 5, PAO 7 and PAO 9 based on C₁₂ alpha olefins.

[0047] Exemplary examples of polybutenes include, without limitation, those sold by Amoco Chemical Company and Exxon Chemical Company under the trade names INDOPOL and PARAPOL, respectively. Well suited polybutenes for use in this invention include Amoco's INDOPOL "L" and "H" series, such as H-100, H-300, H-6000, and H-21000.

[0056] Exemplary examples of polyolesters include, without limitation, neopentyl glycols, trimethylolpropanes, pentaerythriols, dipentaerythritols, and diesters such as dioctylsebacate (DOS), diactylazelate (DOZ), and dioctyladipate.

[0048] Exemplary examples of polyolester include, without limitation, neopentyl glycols, trimethylolpropanes, pentaerythriols, dipentaerythritols, and diesters such as dioctylsebacate (DOS), diactylazelate (DOZ), and dioctyladipate. [0049] Exemplary examples of petroleum based fluids include, without limitation, white mineral oils, paraffinic oils, and medium- viscosity-index (MVI) naphthenic oils having viscosities ranging from about 3^χ 10^"6 to about 600 x lO^"6 m²/s (3 to about 600 centistokes) at 40 °C. Exemplary examples of white mineral oils include those sold by Witco Corporation, Arco Chemical Company, PSI, and Penreco. Exemplary examples of paraffinic oils include solvent neutral oils available from Exxon Chemical Company, high- viscosity-index (HVI) neutral oils available from Shell Chemical Company, and solvent treated neutral oils available from Arco Chemical Company. Exemplary examples of MVI naphthenic oils include solvent extracted coastal pale oils available from Exxon Chemical Company, MVI extracted/acid treated oils available from Shell

Chemical Company, and naphthenic oils sold under the names HydroCal and Calsol by Calumet and hydrogenated oils such as HT-40N and IA-35 from PetroCanada or Shell Oil Company or other similar hydrogenated oils.

[0050] Exemplary examples of vegetable oils include, without limitation, castor oils, corn oil, olive oil, sunflower oil, sesame oil, peanut oil, palm oil, palm kernel oil, coconut oil, butter fat, canola oil, rape seed oil, flax seed oil, cottonseed oil, linseed oil, other vegetable oils, modified vegetable oils such as crosslinked castor oils and the like, and mixtures thereof. Exemplary examples of animal oils include, without limitation, tallow, mink oil, lard, other animal oils, and mixtures thereof. Other essential oils will work as well. Of course, mixtures of all the above identified oils can be used as well.

Aqueous Base Fluids

[0051] Suitable aqueous base fluids for use in this invention include, without limitation, water (production water, free water, or other similar waters), or brines such as salt water, sodium chloride brines, calcium chloride brines, phosphate brines, nitrate brines, other alkali metal brines, other alkaline earth metal brines, and mixtures or combinations thereof.

Corrosion Inhibitors

[0052] Suitable corrosion inhibitor for use in this invention include, without limitation: quaternary ammonium salts e.g., chloride, bromides, iodides, dimethylsulfates, diethylsulfates, nitrites, bicarbonates, carbonates, hydroxides, alkoxides, or the like, or mixtures or combinations thereof; salts of nitrogen bases; or mixtures or combinations thereof. Exemplary quaternary ammonium salts include, without limitation, quaternary ammonium salts from an amine and a quaternarization agent, e.g., alkylchlorides, alkylbromide, alkyl iodides, alkyl sulfates such as dimethyl sulfate, diethyl sulfate, etc., dihalogenated alkanes such as dichloroethane, dichloropropane, dichloroethyl ether, epichlorohydrin adducts of alcohols, ethoxylates, or the like; or mixtures or combinations thereof and an amine agent, e.g., alkylpyridines, especially, highly alkylated alkylpyridines, alkyl quinolines, C6 to C24 synthetic tertiary amines, amines derived from natural products such as coconuts, or the like, dialkylsubstituted methyl amines, amines derived from the reaction of fatty acids or oils and polyamines, amidoimidazolines of DETA and fatty acids, imidazolines of ethylenediamine, imidazolines of diaminocyclohexane, imidazolines of aminoethylethylenediamine, pyrimidine of propane diamine and alkylated propene diamine, oxyalkylated mono and polyamines sufficient to convert all labile hydrogen atoms in the amines to oxygen containing groups, or the like or mixtures or combinations thereof. Exemplary examples of salts of nitrogen bases, include, without limitation, salts of nitrogen bases derived from a salt, e.g.: CI to C8 monocarboxylic acids such as formic acid, acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, or the like; C2 to C12 dicarboxylic acids, C2 to C12 unsaturated carboxylic acids and anhydrides, or the like; polyacids such as diglycolic acid, aspartic acid, citric acid, or the like; hydroxy acids such as lactic acid, itaconic acid, or the like; aryl and hydroxy aryl acids; naturally or synthetic amino acids; thioacids such as thioglycolic acid (TGA); free acid forms of phosphoric acid derivatives of glycol, ethoxylates, ethoxylated amine, or the like, and aminosulfonic acids; or mixtures or combinations thereof and an amine, e.g. : high molecular weight fatty acid amines such as cocoamine, tallow amines, or the like; oxyalkylated fatty acid amines; high molecular weight fatty acid polyamines (di, tri, tetra, or higher); oxyalkylated fatty acid polyamines; amino amides such as reaction products of carboxylic acid with polyamines where the equivalents of carboxylic acid is less than the equivalents of reactive amines and oxyalkylated derivatives thereof; fatty acid pyrimidines; monoimidazolines of EDA, DETA or higher ethylene amines, hexamethylene diamine (HMDA), tetramethylenediamine (TMDA), and higher analogs thereof; bisimidazolines, imidazolines of mono and polyorganic acids; oxazolines derived from monoethanol amine and fatty acids or oils, fatty acid ether amines, mono and bis amides of aminoethylpiperazine; GAA and TGA salts of the reaction products of crude tall oil or distilled tall oil with diethylene triamine; GAA and TGA salts of reaction products of dimer acids with mixtures of poly amines such as TMDA, HMDA and 1 ,2-diaminocyclohexane; TGA salt of imidazoline derived from DETA with tall oil fatty acids or soy bean oil, canola oil, or the like; or mixtures or combinations thereof.

Other Additives

[0053] The drilling fluids of this invention can also include other additives as well such as scale inhibitors, carbon dioxide control additives, paraffin control additives, oxygen control additives, or other additives.

Scale Control

[0054] Suitable additives for Scale Control and useful in the compositions of this invention include, without limitation: Chelating agents, e.g. , Na, K or NH₄ salts of EDTA; Na, K or NH₄ salts of NTA; Na, K or NH₄ salts of Erythorbic acid; Na, K or NH₄ salts of thioglycolic acid (TGA); Na, K or NH₄ salts of Hydroxy acetic acid; Na, K or NH₄ salts of Citric acid; Na, K or NH₄ salts of Tartaric acid or other similar salts or mixtures or combinations thereof. Suitable additives that work on threshold effects, sequestrants, include, without limitation: Phosphates, e.g., sodium hexamethylphosphate, linear phosphate salts, salts of polyphosphoric acid, Phosphonates, e.g., nonionic such as HEDP (hydroxythylidene diphosphoric acid), PBTC (phosphoisobutane, tricarboxylic acid), Amino phosphonates of: MEA (monoethanolamine), NH₃, EDA (ethylene diamine), Bishydroxyethylene diamine, Bisaminoethylether, DETA (diethylenetriamine), HMDA (hexamethylene diamine), Hyper homologues and isomers of HMDA, Polyamines of EDA and DETA, Diglycolamine and homologues, or similar polyamines or mixtures or combinations thereof; Phosphate esters, e.g., polyphosphoric acid esters or phosphorus pentoxide (P₂0₅) esters of: alkanol amines such as MEA, DEA, triethanol amine (TEA), Bishydroxyethylethylene diamine; ethoxylated alcohols, glycerin, glycols such as EG (ethylene glycol), propylene glycol, butylene glycol, hexylene glycol, trimethylol propane, pentaeryithrol, neopentyl glycol or the like; Tris & Tetra hydroxy amines; ethoxylated alkyl phenols (limited use due to toxicity problems), Ethoxylated amines such as monoamines such as MDEA and higher amines from 2 to 24 carbons atoms, diamines 2 to 24 carbons carbon atoms, or the like; Polymers, e.g., homopolymers of aspartic acid, soluble homopolymers of acrylic acid, copolymers of acrylic acid and methacrylic acid, terpolymers of acylates, AMPS, etc., hydro lyzed polyacrylamides, poly malic anhydride (PMA); or the like; or mixtures or combinations thereof.

Carbon Dioxide Neutralization

[0055] Suitable additives for C0₂ neutralization and for use in the compositions of this invention include, without limitation, MEA, DEA, isopropylamine, cyclohexylamine, morpholine, diamines, dimethylaminopropylamine (DMAPA), ethylene diamine, methoxy proplyamine (MOPA), dimethylethanol amine, methyldiethanolamine (MDEA) & oligomers, imidazolines of EDA and homologues and higher adducts, imidazolines of amino ethylethanolamine (AEEA), aminoethylpiperazine, aminoethylethanol amine, di-isopropanol amine, DOW AMP-90™, Angus AMP-95, dialkylamines (of methyl, ethyl, isopropyl), mono alkylamines (methyl, ethyl, isopropyl), trialkyl amines (methyl, ethyl, isopropyl), bishydroxyethylethylene diamine (THEED), or the like or mixtures or combinations thereof.

Oxygen Control

[0056] The introduction of water downhole often is accompanied by an increase in the oxygen content of downhole fluids due to oxygen dissolved in the introduced water. Thus, the materials introduced downhole must work in oxygen environments or must work sufficiently well until the oxygen content has been depleted by natural reactions. For system that cannot tolerate oxygen, then oxygen must be removed or controlled in any material introduced downhole. The problem is exacerbated during the winter when the injected materials include winterizers such as water, alcohols, glycols, Cellosolves, formates, acetates, or the like and because oxygen solubility is higher to a range of about 14-15 ppm in very cold water. Oxygen can also increase corrosion and scaling. In CCT (capillary coiled tubing) applications using dilute solutions, the injected solutions result in injecting an oxidizing environment (0₂) into a reducing environment (C0₂, H₂S, organic acids, etc.).

[0057] Options for controlling oxygen content includes: (1) de-aeration of the fluid prior to downhole injection, (2) addition of normal sulfides to product sulfur oxides, but such sulfur oxides can accelerate acid attack on metal surfaces, (3) addition of erythorbates, ascorbates, diethylhydroxyamine or other oxygen reactive compounds that are added to the fluid prior to downhole injection; and (4) addition of corrosion inhibitors or metal passivation agents such as potassium (alkali) salts of esters of glycols, polyhydric alcohol ethyloxylates or other similar corrosion inhibitors. Exemplary examples oxygen and corrosion inhibiting agents include mixtures of tetramethylene diamines, hexamethylene diamines, 1,2-diaminecyclohexane, amine heads, or reaction products of such amines with partial molar equivalents of aldehydes. Other oxygen control agents include salicylic and benzoic amides of polyamines, used especially in alkaline conditions, short chain acetylene diols or similar compounds, phosphate esters, borate glycerols, urea and thiourea salts of bisoxalidines or other compound that either absorb oxygen, react with oxygen or otherwise reduce or eliminate oxygen.

Salt Inhibitors

[0058] Suitable salt inhibitors for use in the fluids of this invention include, without limitation, Na Minus -Nitrilotriacetamide available from Clearwater International, LLC of Houston, Texas.

EXPERIMENTS OF THE INVENTION

[0059] The present examples are designed to compare the performance of various paraffin dispersant compositions of this invention in cold filter plug point (CFPP1) tests. The paraffin dispersant compositions included effective amounts of PDCl, PDC2, and PDC3. PDCl included ParaClear D600. PDC2 included ParaClear D500. And, PDC3 included ParaClear D584. The ParaClear products are available from Aqua-Clear, Inc. of Charleston, WV.

TESTING PROCEDURE

Pour Point Test

[0060] A pour point test was used to ascertain the lowest temperature at which a liquid remains pourable. In oils, the pour point temperature is generally increased by high paraffin content. Wax crystals gradually precipitate, and eventually accumulate until the fluid may no longer flow as the temperature decreases. Procedure

[0061] Selected oil samples were pre-heated in a water bath at 80°C for 60 minutes to make sure that all wax was dissolved back into the solution. The test samples were prepared and pre-sampled in 2 oz bottles. The water supply was opened and the Pour Point Tester was switched on. The samples were treated with various paraffin treating chemistries at 500 ppm. Cups were filled with the samples (untreated and treated) to the marking ring on the inside of the cup. Each filled sample cup was inserted into the holder and rotated until locked in place. The sensor head was lowered into position, and the safety shield was put in place. A program (WinPPT) for runs from 70°C to the pour point was created. The test was initialized by starting the WinPPT program.

Cloud Point Test

[0062] This technique was used to measure the viscosity of supplied oil samples using a temperature gradient. The viscosity measurements are indicative of a cloud point, a point at which the first paraffin wax crystal begins to form and separate from the oil. As the temperature drops further, wax crystallizes and agglomerates, which become visible leading to deposition.

MATERIALS

[0063] The following materials were used in these tests: 15 mL test bottles, 100 to 1000 micropipette, micropipette tips, 50 mL glass syringe, water bath, and 2 oz bottles.

REAGENTS

[0064] The following paraffin treating compositions included PDC 1 , PDC 1 , and PDC3. Hexane was used for cleaning.

PROCEDURE

[0065] The selected oil samples were pre-heated in an 80°C water bath for 60 minutes to make sure that all the waxes were dissolved back into the solution. A computer program controlling the Julabo F 25 water bath Rheocalc was started. The Julabo F 25 chill bath was turned on through the Rheocalc software and the temperature was adjusted to 80°C. The viscometer was turned on and an auto zero process completed. Both the cup and spindle were attached to the water jacket holder, which was connected to the chill bath and heated. After heating, approximately 9 mL of oil sample (treated and untreated) was added to the cup. Viscometer was started by adjusting the rpm number to get a torque of 10%. A computer program recording the data from the viscometer, Rheocalc, was started. The viscosity measurement was then started by initiating a cooling temperature program in Rheocalc software. It essentially steps the temperature down from 80°C to ^_7°C at 1°C per minute.

COLD FINGER TEST

[0066] The Coaxial Shear test was used to evaluate the behaviour of the crude oil with respect to deposition on a surface. This type of test is typical for flow line investigation, but also yields valuable information with respect to the deposition of wax within the system. The device allows the operator to set-up a temperature differential between the bulk crude and the surface in question under either dynamic or static conditions.

Procedure

[0067] The oil samples were pre-heated in water bath at 80°C for 1 hour to dissolve all the wax present in the sample. Nescom 3.0 software was used to control the RTE 740 water bath for cold finger was started. The RTE 740 chill bath was turned on through the Nescom software and the temperature was adjusted to desired temperature. 180 mL of oil sample (treated or untreated) was added into the Co-axial cell. The bulk oil temperature controller was then set to the test temperature and allowed to stabilize. The cold finger attachment was placed in the cell and the cell was pressurized to 300 psi with inert gas (e.g., nitrogen). The magnetic stirring plate was set to 100 rpm. The measurement was then started by initiating a cold finger temperature program in Nescom software and setting the bulk oil temperature to approximately 5°C above the oil's cloud point. The cold finger temperature was set by adjusting the temperature of RTE 740 (reduced temperature from initial temperature to the temperature 5°C above cloud point over the period of 15 minutes. Reduced further from temperature 5°C above cloud point to the coldest system temperature over the period of 165 minutes). The bulk oil temperature controller was adjusted to temperature 5°C above cloud point at the rate that was controlled by the temperature of the cold finger. The cell was depressurized and cold finger was removed for observation. Picture was taken for final results and reporting purposes.

[0068] The oil sample used in these tests was collected from the Blue Rapids field; the oil was fortified to 3% in order to introduce wax that had dropped out of the sample. All tests were performed at a treatment rate of 500 ppm.

RESULTS

Pour Point Test

[0069] The pour point test results are given in Table 1.

TABLE 1

Pour Point Test Results

[0070] PDC1 was the only product that lowered the pour point of the tested oil sample. This product was able to prevent the accumulation of paraffin crystals into a mass, and by doing so was able to slightly lower the pour point and the freeze point of the oil.

Cloud Point Test and Viscosity Test

[0071] Referring now to Figure 1, the cloud point test results are shown for untreated oil, while Figure 2 shows the results for oil treated with 500 ppm PDC2, PDC3 and PDCl also tabulated in Table 1. The cloud point of the oil was measured at approximately 48°C; this is due to the super waxy nature of the oil. PDC3 was able to slightly reduce the viscosity of the oil compared to the other tested products.

[0072] Referring now to Figure 3, all of the tested products were able to mitigate the amount of wax that adhered on the cold finger rod, compared to the untreated oil sample. PDC3 showed good inhibitive behavior as less wax crystals were observed on the cold finger rod at the end of the test. Although PDCl and PDC2 were also able to reduce the amount of wax deposition, more chunks of wax crystals were observed on these cold finger rods compared to the PDC3.

Discussion

[0073] Overall testing results showed that PDC3 was the best product in reducing the viscosity of the oil and in preventing wax deposition on the cold finger rod. PDC2 and PDCl behaved similarly during viscosity and cold finger testing, however, PDCl was the best product at reducing the pour point of the oil sample.

Reference

Addison, G.E. 1984. Paraffin Control More Cost-Effective. Paper SPE 13391 presented at the SPE Eastern Regional Meeting, Charleston, West Virginia, October 31 - November 2 1984.

GLASS JAR PARAFFIN DISPERSION TEST

Procedure

[0074] 5g of paraffin were melted in a 1 % solution of a paraffin dispersant. The solution was shaken and cooled to room temperature over time until either solids disperse or reform paraffin. If the solution was observed to have ground coffee size particles, then the dispersant was determined to have passed the dispersion test. If the solution was observed to have large globs of paraffin sticking to glass or reforming large solid masses, then the dispersant was determined to have failed the dispersion test. The paraffin source was Logan County, WV and was as a blank with no dispersant. With no dispersant, the sample remained a conglomerated wax after cooling as shown in Figure 4A. The addition of PDC 1 at 1 % level caused granulated/ encapsulated coffee grain particles after shaking and cooling of the paraffin solution to room temperature. No waxy paraffin buildup on glass or in the solution was found as shown in Figure 4B. Comparable results were found using PDC2 at 1% as shown in Figure 4C. Comparable results were also found using PDC3 at 1% as shown in Figure 4D. -

[0075] Using a different paraffin with higher melting point from another well location, the test was repeated with PDCl at l% and PDC2. The results of the tests were shown in Figures 4E&F. At the 1% level, the dispersants did not disperse this wax as completely as the previous wax. However, the dispersants were effective.

[0076] All references cited herein are incorporated by reference. Although the invention has been disclosed with reference to its preferred embodiments, from reading this description those of skill in the art may appreciate changes and modification that may be made which do not depart from the scope and spirit of the invention as described above and claimed hereafter.

Claims

CLAIMS We claim:

1. A fluid composition comprising a base fluid and an effective amount of a paraffin dispersant composition comprising at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester, where the effective amount is between about 50 ppm and about 2 wt.% and where the fluid paraffin dispersant composition reduces paraffin deposits on tubing and/or piping.

2. The composition of claim 1 , wherein the alkylene oxide modified alcohol surfactants comprise compounds of the general formula (I):

R'OiRO)^ (I) where R¹ is a linear, branched, or cyclic hydrocarbyl group having from 6 to 20 carbon atoms, R^a is a linking group having 1 to 4 carbon atoms, where one or more of the carbon atoms in R¹ and R^a may be replaced by oxygen atoms, and n is a integer having a value between 1 and 20.

3. The composition of claim 2, wherein R¹ is a linear or branched hydrocarbyl group having from 6 to 12 carbon atoms, R^a is a linking group having between 2 and 3 carbon atoms, and n is an integer having a value between 2 and 10.

4. The composition of claim 2, wherein the alkylene oxide modified alcohol surfactants comprise ethylene oxide and/or propylene oxide modified alcohol surfactants of linear or branched alcohols having between 6 and 20 carbon atoms.

5. The composition of claim 1, wherein the aminodicarboxylic acid diesters comprises compounds of the general formula (II):

R² C R'CGOR⁴ (II)

R^bCGOR³

where R² is a hydrogen atom or a linear, branched, or cyclic hydrocarbyl group having from 1 to 20 carbon atoms, R³ and R⁴ are independently linear, branched, or cyclic hydrocarbyl groups having from 1 to 20 carbon atoms, R^b and R^c are independently linear, branched, or cyclic hydrocarbyl linking groups having from 1 to 10 carbon atoms, where in any of the groups, one or more carbon atoms may be replace by oxygen atoms.

6. The composition of claim 5, wherein R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 4 carbon atoms.

7. The composition of claim 6, wherein R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 3 carbon atoms.

8. The composition of claim 7, wherein R³ and R⁴ are independently linear hydrocarbyl groups including from 1 to 2 carbon atoms.

9. The composition of claim 8, wherein R³ and R⁴ are methyl groups.

10. The composition of claim 9, wherein the aminodicarboxylic acid diesters comprise compounds of the general formula:

MeOOC-R-CH(NH₂)-COOMe

where R is a hydrocarbyl linking group having between 1 and 10 carbon atoms and Me is methyl.

11. The composition of claim 1 , further comprising a linear, branched, or cyclic alcohol having from 1 to 20 carbon atoms.

12. The composition of claim 1, further comprising a linear, branched cyclic diol having form 1 to about 20 carbon atoms.

13. The composition of claim 1 , wherein the fluid is a drilling fluid, a completion fluid, or a production fluid and wherein the base fluid is an aqueous base fluid, a hydrocarbon base fluid, or an emulsion including an aqueous base fluid and a hydrocarbon base fluid.

14. A method comprising the step of:

circulating a fluid composition into a well, where the fluid composition comprises a base fluid and effective amount of a paraffin reducing composition including a blend of at least one alkylene oxide modified alcohol surfactant and at least one aminodicarboxylic acid dialkyl ester, where the effective amount is between about 50 ppm to about 2 wt.%.

15. The method of claim 14, wherein the alkylene oxide modified alcohol surfactants comprises compounds of the general formula (I):

R'OiRO)^ (I) where R¹ is a linear, branched, or cyclic hydrocarbyl group having from 6 to 20 carbon atoms, R^a is a linking group having 1 to 4 carbon atoms, n is a integer having a value between 1 and 20, and where in any of the groups, one or more carbon atoms may be replace by oxygen atoms.

16. The method of claim 15, wherein R¹ is a linear or branched hydrocarbyl group having from 6 to 12 carbon atoms, R^a is a linking group having between 2 and 3 carbon atoms, and n is an integer having a value between 2 and 10.

17. The method of claim 15, wherein the alkylene oxide modified alcohol surfactants comprise ethylene oxide and/or propylene oxide modified alcohol surfactants of linear or branched alcohols having between 6 and 20 carbon atoms.

18. The method of claim 14, wherein the aminodicarboxylic acid diesters comprises compounds of the general formula (II):

R¹ C 'COO ⁴ (II)

R^bCOOR³

19. The method of claim 18 , wherein R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 4 carbon atoms.

20. The method of claim 19, wherein R³ and R⁴ are independently linear or branched hydrocarbyl groups including from 1 to 3 carbon atoms.

21. The method of claim 20, wherein R³ and R⁴ are independently linear hydrocarbyl groups including from 1 to 2 carbon atoms.

22. The method of claim 21, wherein R³ and R⁴ are methyl groups.

23. The method of claim 22, wherein the aminodicarboxylic acid diesters comprise compounds of the general formula:

MeOOC-R-CH(NH₂)-COOMe

24. The method of claim 14, further comprising a linear, branched, or cyclic alcohol having from 1 to 20 carbon atoms.

25. The method of claim 14, further comprising a linear, branched cyclic diol having form 1 to about 20 carbon atoms.

26. The method of claim 15, wherein the fluid is a drilling fluid, a completion fluid, or a production fluid and wherein the base fluid is an aqueous base fluid, a hydrocarbon base fluid, or an emulsion including an aqueous base fluid and a hydrocarbon base fluid.