U.S. patent application number 11/963182 was filed with the patent office on 2008-08-07 for compositions for drilling fluids useful to provide flat temperature rheology to such fluids over a wide temperature range, and drilling fluids containing such compositions.
This patent application is currently assigned to Elementis Specialties, Inc.. Invention is credited to David Dino, Richard Jobbins, Mark Matyi, Jeffrey Thompson.
Application Number | 20080188382 11/963182 |
Document ID | / |
Family ID | 32467762 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080188382 |
Kind Code |
A1 |
Thompson; Jeffrey ; et
al. |
August 7, 2008 |
Compositions for Drilling Fluids Useful to Provide Flat Temperature
Rheology to Such Fluids Over a Wide Temperature Range, and Drilling
Fluids Containing Such Compositions
Abstract
The invention is of oil-based drilling fluids including invert
emulsion fluids that are able to maintain a relatively consistent
rheological profile over a wide temperature range. The invention
also includes new additives that enable the preparation of drilling
fluids with viscosities that are less affected by temperature over
a temperature range from less than about 40.degree. F. to more than
about 250.degree. F. compared to conventional fluids. These
additives are based on reaction products of polyamines and
carboxylic acids with two or more carboxylic moieties combined with
alkoxylated amines and fatty acid amides. In addition, this
invention permits the use of reduced amounts of organoclay
rheological additives in drilling fluids.
Inventors: |
Thompson; Jeffrey; (East
Windsor, NJ) ; Dino; David; (Cranbury, NJ) ;
Jobbins; Richard; (Freehold, NJ) ; Matyi; Mark;
(North Hanover, NJ) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS LLP
1701 MARKET STREET
PHILADELPHIA
PA
19103-2921
US
|
Assignee: |
Elementis Specialties, Inc.
Hightstown
NJ
|
Family ID: |
32467762 |
Appl. No.: |
11/963182 |
Filed: |
December 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10304167 |
Nov 27, 2002 |
7345010 |
|
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11963182 |
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Current U.S.
Class: |
507/251 |
Current CPC
Class: |
C08G 69/34 20130101;
C09K 8/32 20130101 |
Class at
Publication: |
507/251 |
International
Class: |
C09K 8/68 20060101
C09K008/68 |
Claims
1. A composition comprising: a) the reaction product of (i) a
carboxylic acid with at least two carboxylic moieties and (ii) a
polyamine having an amine functionality of two or more; and b) a
chemical selected from the group consisting of (i) alkoxylated
alkyl amines, (ii) fatty acid amides and (iii) mixtures
thereof.
2. The composition of claim 1, wherein the carboxylic acid is a
dimer fatty acid.
3. The composition of claim 2, wherein the dimer fatty acid is
selected from the group consisting of hydrogenated, partially
hydrogenated and non-hydrogenated dimer acids with from about 20 to
about 48 carbon atoms.
4. The composition of claim 1, wherein the polyamine is a
polyethylene polyamine.
5. The composition of claim 4, wherein the polyamine is selected
from the group consisting of ethylenediamine, diethylenetriamine,
triethylenetetramine and tetraethylenepentamine.
6. The composition of claim 4, wherein the polyamine is
diethylenetriamine.
7. The composition of claim 1, wherein the alkoxylated alkyl amine
is an ethoxylated fatty amine.
8. The composition of claim 7, wherein the elkoxylated fatty amine
is an ethoxylated (5) cocoalkyl amine.
9. The composition of claim 1, further comprising an
organoclay.
10. An oil based drilling fluid comprising the composition of claim
1.
11. The drilling fluid of claim 10, further comprising an
organoclay.
12. The drilling fluid of claim 10, further comprising one or more
emulsifiers.
13. A composition comprising the reaction product of (a) a
polyamine having an amine functionality of two or more, (b) a
carboxylic acid with at least two carboxylic moieties and (c) an
alkoxylated alkyl amine.
14. An oil based drilling fluid comprising the reaction product of
claim 13.
15. A composition comprising the reaction product of a) a
carboxylic acid with at least two carboxylic moieties, b) a
polyamine having an amine functionality of two or more, c) an
alkoxylated alkyl amine and d) a fatty acid amide.
16. An oil-based drilling fluid comprising the composition of claim
15.
17. The drilling fluid of claim 16 further comprising an
organoclay.
18. The drilling fluid of claim 15, further comprising one or more
emulsifiers.
19. A composition comprising: a) the reaction product of (i) a
carboxylic acid with at least two carboxylic moieties, (ii) a
polyamine having an amine functionality of two or more and (iii) an
alkoxylated alkyl amine; and b) a fatty acid amide.
20. An oil based drilling fluid comprising the composition of claim
19.
21. The drilling fluid of claim 20 further comprising an
organoclay.
Description
FIELD OF THE INVENTION
[0001] This invention relates to compositions suitable for use as
additives for drilling fluids, and to drilling fluids comprising
said compositions having improved rheological properties. The
invention also relates to additives that provide rheological
properties to drilling fluids relatively independent of the varying
temperatures encountered in oil well drilling operations at various
depths, particularly in deep water drilling.
BACKGROUND OF THE INVENTION
[0002] Drilling fluids have been used since the very beginning of
oil well drilling operations in the United States and drilling
fluids and their chemistry have been and remain an important area
for scientific and chemical investigations. The use and desired
properties of drilling fluids are comprehensively reviewed in
recent U.S. Pat. Nos. 6,339,048 and 6,462,096, issued to the
assignee of this application, the entire disclosures of which are
incorporated herein by reference.
[0003] A drilling fluid is a thixotropic system and exhibits low
viscosity when sheared during cutting of the hole into the ground,
during agitation and circulation but, when such shearing action is
halted, must quickly thicken to among other things hold the
"cuttings" from the drill hole in place without sinking. The fluid
must therefore become thick rapidly, reaching sufficient gel
strength before such suspended materials fall any significant
distance. Importantly, this behavior must be totally reversible at
all temperatures encountered in the borehole. In addition, even
when the drilling fluid is free flowing, it must retain a
sufficiently high viscosity to carry all cuttings and other
particulate matter from the bottom of the hole back up to the
surface.
[0004] Since the end of the second World War, hydrocarbon drilling
for exploratory and production wells has increasingly been done
from platforms located in water settings, often called off-shore
drilling. Such fresh and salt water drilling employs floating
barges and rigs often fixed in some fashion to the submerged
surface of the earth.
[0005] Economic and technical advances have recently pushed these
drilling operations into deeper waters. Although advances in
equipment and engineering have yielded technology capable of
drilling in water depths up to 10,000 feet or more, advances
required in drilling fluid technology have lagged.
[0006] A major problem with oil-based drilling fluids in deepwater
drilling is rheological additive temperature sensitivity over the
temperature range encountered. During circulation, the drilling
fluid typically reaches bottom hole temperatures of about 60 to
80.degree. C. followed by cooling to lower than 5.degree. C. in the
riser during its travel upward (due to the inherent low temperature
of sea water far below the ocean surface). For successful deepwater
drilling, the mud needs to simultaneously suspend the solids and
remain pumpable with proper viscosity over these wide temperature
ranges.
[0007] Drilling fluids thickened with conventional organophilic
clay rheological additives particularly suffer considerable
viscosity build as the drilling fluid is cooled from a temperature
of 60 to 5.degree. C., for example. As a result of this viscosity
increase, the drilling fluid, when it reaches low temperatures, is
more difficult to pump, the equivalent circulating density (ECD) is
increased and losses to the formation (lost circulation) frequently
increase.
[0008] The requirements for drilling fluids with enhanced
temperature properties have also become more complex over the past
two decades as a result of changes in directional drilling
technology, in which a well is drilled at an angle other than
vertical. Such wells are widely known as deviated wells.
[0009] Methods for drilling deviating wells have changed greatly
over recent years with the production of more powerful and reliable
downhole motors, and the invention of more accurate methods
utilizing wireline techniques as well as the highly computerized
downhole, sensing and micro reduction equipment, including
improvements in sounding apparatus and microwave transmission.
These techniques permit the instantaneous acquisition of data
relating to down-hole conditions without the need to remove the
drill string and in fact mean that holes can, and are, drilled at
ever increasing lengths.
[0010] The advantages of directional drilling include (1)
directional drilling allows tapping of fields which cannot
effectively be reached by vertical drilling; (2) such drilling
permits the use of more economical land-based equipment to explore
the immediate off-shore environment; and (3) such drilling make
possible the drilling of multiple wells up to several miles from
one another, sharing the cost of a single site. In addition, in
certain geological formations, increased production can be achieved
by deviating the well off-vertical so as to facilitate perforation
and development of a narrow producing zone, or redevelopment of a
depleted formation.
[0011] Use of a downhole motor allows the hole to be deviated by
the introduction of a fixed offset or bend just above the drill
bit. This offset or bend can be oriented by modern MWD systems
which are capable of reporting accurately the current bit and
toolface hole angle and azimuth (i.e. the orientation with respect
to the upper portion of the hole). It is accordingly possible to
rotate the drill string until the toolface has achieved the desired
direction of deviation, and then to fix the drill string in place
and commence the deviation by starting the motor to extend the hole
in the desired deviated direction.
[0012] There are, however, a number of inherent problems in the use
of directional drilling, which affect the requirements of a
drilling mud; namely: [0013] As in deep water drilling, increased
ranges of temperatures are encountered. [0014] The annulus carrying
the mud to the surface is no longer vertical and extends to far
greater distances versus vertical wells. [0015] Gravity on a
horizontal hole pulls cuttings, weighting material and particulate
matter, not controlled by the drilling fluid, to the bottom side of
the bore (not the bottom of the hole as in traditional drilling)
and results in drag on the bore wall. [0016] The amount of drilling
mud required is increased since the distances are greater, and the
time required for the mud to reach the earth's surface also
increases. [0017] Curves and kinks in the hole's direction can
accumulate cuttings and additives.
[0018] In order to obviate or mitigate these problems, which can
cost oil and gas companies millions of dollars per hole, it is an
object of the invention to provide drilling fluids with rheological
properties particularly appropriate for directional drilling
including the improved viscosity stability with temperature
discussed above.
[0019] For background, it has been long known that organoclays
(also called organophilic clays) can be used to thicken drilling
fluids. See the very early article by the employee of the assignee
hereof J. W. Jordan, "Proceedings of the 10th National Conference
on Clays and Clay Minerals" (1963), which discusses a wide range of
drilling applications of organoclays from high polarity liquids to
low polarity liquids.
[0020] Previously mentioned U.S. Pat. No. 6,462,096 discloses
oil-based invert emulsion drilling fluids that provide more stable
drilling fluid viscosity and anti-settling performance over varying
temperatures when compared to conventional fluids containing
organoclays.
[0021] Patents of the prior art that show developments related to
either drilling fluids or chemistry of additives include the
following:
[0022] U.S. Pat. No. 3,514,399 teaches the use of a mixed dimer
acid-monocarboxylic acid salt of an imidazoline in a drilling
fluid.
[0023] U.S. Pat. No. 5,260,268 describes a product introduced into
a well borehole which encompasses water-based drilling fluids and
shows a composition comprised of a polycarboxylic acrylating agent
reacted with an amine-terminated polyethylene of a molecular weight
average from 600 to 10,000. While ethoxylated amines are discussed
as a surfactant which may be used in conjunction with the
composition, there is no teaching of applications in an oil-based
invert emulsion drilling fluid.
[0024] U.S. Patent Application Publication No. 2001/0009890 shows
an invert emulsion suitable for drilling a subterranean well which
uses an ester of a C.sub.1 to C.sub.12 alcohol and a C.sub.8 to
C.sub.24 monocarboxylic acid--Ethomeen C/15 can be used as an agent
in the invention described in the application.
[0025] U.S. Pat. No. 5,536,871 issued to the assignee hereof
describes a rheological additive which comprises the reaction
product of a polyalkoxylated nitrogen-containing compound such as
polyoxyethylene (5) cocoalkylamine, a polycarboxylic acid including
dimer acids and a liquid diamine.
[0026] U.S. Pat. No. 5,610,110 also issued to assignee hereof shows
an improved drilling fluid containing a reaction product of an
alkoxylated aliphatic amino compound and an organic polycarboxylic
acid and a clay based organoclay.
[0027] U.S. Pat. No. 5,909,779 at Col. 4, lines 55 to Col. 6, line
15 contains a large laundry list of surfactants, wetting agents and
viscosifying agents conventionally used in oil-based drilling
fluids including fatty acids, polyamines, imidazoline derivatives
and polycarboxylic acids and soaps of fatty acids.
[0028] Recent Dow Chemical Company U.S. Pat. No. 6,291,406
describes a well treatment fluid using an amine surfactant to
provide a sufficiently stable emulsion. Ethomeens are discussed,
particularly bis(2-hydroxyethyl) cocamines and oleyamines.
[0029] Commercial rheological drilling fluid additives presently
available on the market, however, tend to have increased viscosity
while the fluid temperature is low, requiring increased pump
pressure which in turn causes increased wear of the drilling gear.
Increased pumping horsepower becomes necessary to pump drilling
muds through long distances, and increased down-hole pressure under
pumping conditions increases fluid loss, fracturing and damage of
the formation. Prior art methods of reducing drilling fluid
viscosity are not satisfactory because the resultant drilling
fluids fail to maintain adequate suspension characteristics when
the fluid temperature changes, for example, at down-hole
conditions.
[0030] There is clearly an unfilled need which has been growing in
the past decade for drilling fluids that are able to maintain a
relatively consistent rheological profile over a wide temperature
range; it is believed that the below unexpected described invention
fills this need.
SUMMARY OF THE INVENTION
[0031] The invention herein covers new additives that enable the
preparation of drilling fluids with viscosities that are less
affected by temperature over a temperature range from less than
about 40.degree. F. to more than about 250.degree. F. compared to
conventional fluids. In addition, this invention permits the use of
reduced amounts of organoclay rheological additives with the
attendant reduction in cost. In fact, in some cases organoclays can
be completely eliminated.
[0032] According to one aspect, this invention provides a mixture
composition comprising as the first ingredient the reaction product
of a di-, tri- or polyamine with an acid containing at least two
carboxyl functional groups to form a polyamide and as the second
mixture ingredient an alkoxylated alkylamine. The alkoxylated amine
can be added to the polyamide before, during, or after its
synthesis or added directly to the drilling mud as a separate
component.
[0033] According to another aspect, this invention provides a
mixture composition comprising the reaction product of a di-, tri-
or polyamine with an acid containing at least two carboxyl
functional groups to form a polyamide and as the second ingredient
either (a) a fatty amide or (b) a mixture of a fatty amide and
alkoxylated alkylamine which can be added to the polyamide before,
during or after its synthesis or added to the drilling mud as a
separate component.
[0034] In yet another aspect, this invention provides a reaction
product comprising a di-, tri- or polyamine, an acid containing at
least two carboxyl functional groups and an alkoxylated
alkylamine.
[0035] In another aspect, this invention provides a reaction
product comprising a di-, tri-, or polyamine, an acid containing at
least two carboxyl functional groups, an alkoxylated alkylamine and
a fatty amide. The fatty amide can be added prior, during or after
the reaction or added directly to the drilling mud as a separate
component.
[0036] A further embodiment of the invention provides for a
drilling fluid composition comprising an oil-based mud in which the
above inventive reaction products are present individually or in
combination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 and FIG. 2 show that when an additive made according
to this invention is added to an oil-based drilling mud, the
viscosity as expressed by a Fann viscometer dial reading is much
less temperature dependent than when organoclays are used alone. It
is also evident that the combination of 2 ppb of BENTONE.RTM. 155
with 0.5 ppb of the invention has a similar viscosity to 4 ppb of
the organoclay at 180.degree. F. and 2 ppb of the clay at
40.degree. F. The value of this phenonenom will be obvious to one
skilled in the art.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0038] The invention provides compositions that reduce the effects
of temperature on the viscosity of an invert emulsion drilling
fluid. The viscosity vs. temperature profile is maintained more
uniformly from less than about 40.degree. F. to greater than about
250.degree. F. for extended periods of time. When used in
combination with organophilic clay, the invention maintains
characteristics associated with organophilic clays in oil and
synthetic based drilling fluids.
[0039] Additionally, the additive has strong value in deep-water
drilling. Among the main positive attributes are the reduced high
and low shear viscosity at sub-ambient temperatures as compared to
a drilling mud exhibiting similar rheological properties at ambient
temperature with just organoclay alone as the rheological agent.
This reduced viscosity at low temperature leads to a greater
ability to control formation pressure while minimizing the risk of
lost returns.
[0040] The term "drilling fluid" conventionally denotes any of a
number of liquid and gaseous fluids and mixtures of fluids and
solids (as solid suspensions, mixtures and emulsions of liquids,
gases and solids) used in operations to drill boreholes into the
earth. It is synonymous with "drilling mud" in general usage.
[0041] This invention particularly covers generally petroleum or
synthetic oil-based drilling fluids we call oil based drilling
fluids. More particularly, it relates to an oil based drilling
fluid often referred to as an invert emulsion drilling fluid, which
is a water in oil emulsion whose continuous phase is oil. The water
phase, or internal phase, is typically a brine for example 25%
calcium chloride. This water or brine phase can range from 0% in
all oil muds to in excess of 50% in invert emulsion drilling
fluids.
[0042] An important embodiment of this invention relates to a
drilling fluid containing a composition which is a mixture or blend
of (1) a reaction product of a specific polyamine and a carboxylic
acid with at least two carboxylic moieties and (2) an alkoxylated
amine. The use of this unique mixture as an additive for an invert
emulsion drilling fluid surprisingly improves the fluid's
rheological properties. The resultant drilling fluids have a
relatively constant viscosity over a wide temperature range. More
surprisingly, the viscosity of the drilling fluid of the invention
is relatively low at reduced temperatures while providing
sufficient viscosity under downhole temperatures to reduce barite
sag and suspend drill cuttings.
[0043] The additive comprises the following. First discussed are
the components of the reaction product and its production.
[0044] Fatty Acids
[0045] Any carboxylic acid with at least two carboxylic moieties
can be used for producing the reaction product component of the
present invention. Dimer acids are preferred; dimer acids of
C.sub.16 and C.sub.18 fatty acid are particularly preferred. Such
dimer acids can be fully hydrogenated, partially hydrogenated, or
not hydrogenated at all. Useful dimer acids also include products
resulting from the dimerization of C.sub.16 to C.sub.18 unsaturated
fatty acids.
[0046] Generally when used, the dimer acids preferably have an
average from about 18, preferably from about 28 to about 48 and
more preferably to about 40 carbon atoms. Most preferably dimer
acids have 36 carbon atoms.
[0047] Useful dimer acids are preferably prepared from C.sub.18
fatty acids, such as oleic acids. Useful dimer acids are described
in U.S. Pat. Nos. 2,482,760, 2,482,761, 2,731,481, 2,793,219,
2,964,545, 2,978,4681, 3,157,681, and 3,256,304, the entire
disclosures of which are incorporated herein by reference.
[0048] Examples of most preferred dimer acids include the
Empol.RTM. product line available from Cognis, Inc., Pripol.TM.
dimer acids available from Uniqema and HYSTRENE.RTM. dimer acids
formerly available from Humko Chemical.
[0049] It is recognized that commercially available dimer fatty
acids contain a mixture of monomer, dimer, and trimer acids.
Preferably, in order to achieve optimal results, the dimer fatty
acid used has a specific dimer acid content as increased monomer
and trimer concentration hinder the additive's performance. A
person of ordinary skills in the art recognizes that commercial
products may be distilled or otherwise processed to ensure certain
dimer content. Preferably, suitable diner acid has a dimer content
of at least 80%, more preferably above 90%.
[0050] Empol.RTM. 1061 with a dimer acid content of 92-96% is the
preferred dimer acid for the present invention.
[0051] Polyamines
[0052] Polyamines having an amine functionality of two or more are
used for the preparation of the reaction product of the present
invention. Most preferably, polyamines from the family of
polyethylene polyamines having a amine functionality of two or more
should be used.
[0053] Di-, tri-, and polyamines and their combinations are most
suitable for use in this invention. Representative such amines
include ethylenediamine, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine and other members of this series. Branched
polyamines and polyamines made with different alkyl groups can be
used.
[0054] Triamines are most preferable, particularly
diethylenetramine (DETA). DETA has been assigned a CAS No. of
111-40-0. It is commercially available from Huntsman
International.
[0055] Making the Reaction Product
[0056] Specifics on processing of polyamines and carboxylic acids
are well known and can be used in making the reaction product of
this invention. Preferably, the molar ratio between the amine
functional group and carboxyl functional group is between 4:1 and
1:1. The preferred range is from 1:5:1.0 to 3:1, most preferably
about 2:1. For example, mixtures of more than one dimer acid and/or
more than one polyamine can be used. A representative manufacturing
process is illustrated in the examples following hereafter. It
should be noted that these reactions may generate imidazolines and
other side products.
[0057] Alkoxylated Amines
[0058] Important to this invention in an important embodiment is
that a suitable alkoxylated alkyl amine is mixed into or blended
into the reaction product produced by the reaction of the
carboxylic acid with the polyamine as described above or is
otherwise added directly to the drilling mud.
[0059] Many alkyl alkoxylated amines are suitable for the present
invention.
[0060] Any alkoxylated amine or similarly derivitized amines may be
used. Suitable alkoxylated amines include amines of various degrees
of alkoxylation. Representative useful chemicals include the entire
Ethomeen.RTM., Propomeen.RTM. and the Ethoduomeen.RTM. product
lines of Akzo Nobel.
[0061] Preferred are amines with up to about 50 units of
alkoxylation per molecule (e.g. Ethomeen.RTM. 18/60). More
preferred are amines with up to about 15-25 units of alkoxylation
(e.g. Ethomeen.RTM. C/25, T/25, S/25, 18/25; Ethoduomeen.RTM.
T/25). Most preferred are amines with up to about 10 units of
alkoxylation (e.g. Propomeen.RTM. C/12, O/12, T/12;
Ethoduomeen.RTM. T/13, T/20; Ethomeen.RTM. C/12, C/15, C/20, O/12,
O/15, T/12, T/15, S/12, S/15, S/20, 18/12, 18/15 and 18/20).
[0062] The most preferred amines are polyoxyethylene (5)
cocoalkylamines, available, for example, under the tradename
Ethomeen.RTM. C/15 from Akzo Nobel (New Brunswick, N.J.).
Ethomeen.RTM. C/15 has a general formula of
RN[(CH.sub.2CH.sub.2O).sub.m[CH.sub.2CH.sub.2O).sub.nH] wherein R
is cocoalkyl, and m+n=5.
[0063] Optionally, the alkoxylated amine may be added prior to the
reaction between the dimer acid and polyamines, or blended after
the reaction step. If added prior to the reaction or at the
reaction temperature, some esters may be formed between the dimer
acid carboxyls and the alkoxylated amine hydroxyls.
[0064] In a preferred embodiment, the two components are mixed or
blended in a weight ratio range of 95:5 to 5:95. The preferred
ratio range is 80:20 to 30:70 and the most preferred ratio is 55:45
reaction product to alkoxylated amine.
[0065] Fatty Amides
[0066] Optionally, additional ingredients such as fatty amides and
related alkoxylated derivatives can be blended into or reacted with
the polyamide reaction product.
[0067] Suitable fatty amides, such as the Armid.RTM. product line
by Akzo Nobel includes high temperature melting amides of fatty
acids that are sparingly soluble in drilling muds. Additionally,
alkoxylated fatty amides, such as the Ethornid.RTM. product line by
Akzo Nobel can be used.
[0068] While the above is the preferred formulation, other
compositions of varying molar ratios of raw materials can be used.
Additionally, alternate commercial dimer fatty acids can be reacted
with various amines to generate the reaction polymer. It however
should also be noted that the alkoxylated amine could be reacted
with the dimer acid/diethylenetriamine polymer generating
compositions which can be further modified by blending amine
derivatives (e.g. fatty amides) and this is intended to be included
in this invention.
[0069] Preparation of the Drilling Fluids
[0070] The compositions of this invention described above will be
used primarily as an additive to oil-based drilling fluids and most
particularly for oil-based invert emulsion drilling fluids employed
in a variety of drilling applications. The term oil-based drilling
fluid is defined as a drilling fluid in which the continuous phase
is hydrocarbon based. Oil-based fluids formulated with over 5%
water or brine are classified as oil-based invert emulsion drilling
fluids. Commonly, oil-based invert emulsion drilling fluids will
contain water or brine as the discontinuous phase in any proportion
up to about 50%.
[0071] A process for preparing invert emulsion drilling fluids (oil
muds) involves using a mixing device to incorporate the individual
components making up that fluid. Primary and secondary emulsifiers
and wetting agents (surfactant mix) are added to the base oil
(continuous phase) under moderate agitation. The water phase,
typically a brine, is added to the base oil surfactant mix along
with alkalinity control agents and acid gas scavengers. Rheological
additives as well as fluid loss control materials, weighting agents
and corrosion inhibition chemicals may also be included, and the
agitation is continued to ensure dispersion of each ingredient and
homogenize the resulting fluidized mixture.
[0072] Suitable Oil Base
[0073] Diesel oil, mineral oil, synthetic oil, vegetable oil, fish
oil, paraffinics, and/or ester-based oils can all be used as single
components or as blends.
[0074] Suitable Brine Content
[0075] Water in the form of brine is often used in forming the
internal phase of these type fluids. Water can be defined as an
aqueous solution which can contain from about 10 to 350,000
parts-per-million of metal salts such as lithium, sodium,
potassium, magnesium, cesium, or calcium salts. The preferred
brines used to form the internal phase of the preferred fluid of
the invention can also contain from about 5 to about 35% by weight
calcium chloride and may contain various amounts of other dissolved
salts such as sodium bicarbonate, sodium sulfate, sodium acetate,
sodium borate, potassium chloride, sodium chloride or formates
(sodium, calcium, or cesium).
[0076] The ratio of water (brine) to oil in the emulsions of the
invention should generally provide as high a brine content as
possible while still maintaining a stable emulsion. Oil/brine
ratios in the range from about 97:3 to about 50:50 have been found
to work satisfactorily, depending upon the particular oil and mud
weight. Thus the water content of a typical drilling fluid prepared
according to the teachings of the invention will have an aqueous
(water) content of about 0 to 50 volume percent.
[0077] Suitable Emulsifiers
[0078] In order to form a more stable emulsion, a emulsifier can
also be added to the external, the internal or both phases of the
drilling fluid. The emulsifier is preferably selected from a number
of organic acids which are familiar to those skilled in the
drilling fluid area, including the monocarboxyl alkanoic, alkenoic,
or alkynoic fatty acids containing from 3 to 20 carbon atoms, and
mixtures thereof. Examples of this group of acids include stearic,
oleic, caproic, capric and butyric acids. Adipic acid, a member of
the aliphatic dicarboxylic acids can also be used. More preferred
surfactants or emulsifiers include fatty acid calcium salts and
lecithin. Most preferred surfactants or emulsifiers include
oxidized tall oil, polyaminated fatty acids, and partial amides of
fatty acids.
[0079] An important class of heterocyclic additives which we
believe assist in regulating the flow properties of the drilling
muds according to the invention are the imidazoline compounds.
Other important members of this heterocylic group are
alkylpyridines.
[0080] Industrially obtainable amine compounds for use as
emulsifiers are often derived from the epoxidation of olefinically
unsaturated hydrocarbon compounds with subsequent introduction of
the N function by addition to the epoxide group. The reaction of
the epoxidized intermediate components with primary or secondary
amines to form the corresponding alkanolamines is of significance
in this regard. Polyamines, particularly lower polyamines of the
corresponding alkylenediamine type, are also suitable for opening
of the epoxide ring.
[0081] Another class of the oleophilic amine compounds useful as
emulsifiers are aminoamides derived from preferably long-chain
carboxylic acids and polyfunctional, particularly lower, amines of
the above-mentioned type. The key factor in their case is that at
least one of the amino functions is not bound in amide form, but
remains intact as a potentially salt-forming basic amino group. The
basic amino groups, where they are formed as secondary or tertiary
amino groups, may contain hydroxyalkyl substituents and, in
particular, lower hydroxyalkyl substituents containing up to 5 and
preferably up to 3 C atoms in addition to the oleophilic part of
the molecule.
[0082] Suitable N-basic starting components for the preparation of
such adducts containing long-chain oleophilic molecule constituents
are monoethanolamine or diethanolamine.
[0083] Weighting materials are also often used to weight the well
bore fluids of the invention to a density in the preferred range
from about 8 to 18 pounds per gallon and greater. Weighting
materials well known in the art include barite, ilmenite, calcium
carbonate, iron oxide and lead sulfide. The preferred weighting
material is commercially available barite.
[0084] Organophilic Clays. Organoclays made from bentonite,
hectorite and attapulgite clays can be added to the inventive
drilling fluids. There are a large number of suppliers of such
clays in addition to Elementis Specialties' BENTONE.RTM. product
line including Rockwood Specialties, Inc. and Sud Chemie GmbH.
Although organoclay can be a useful component, it is not a
necessary component of the drilling fluid.
[0085] Blending Process
[0086] Drilling fluids preparations preferably contain between 1/4
and 15 pounds of the inventive mixture per barrel of fluids, more
preferred concentration is 1/4 to 10 pounds-per-barrel and most
preferably 1/4 to 5 pounds-per-barrel.
[0087] As shown above, a skilled artisan will readily recognize
that additional additives: weighting agents, emulsifiers, wetting
agents, viscosifiers, fluid loss control agents, and other agents
can be used with this invention. A number of other additives
besides rheological additives regulating viscosity and
anti-settling properties, providing other properties, can also be
used in the fluid so as to obtain desired application properties,
such as, for example, anti-settling agents and fluid
loss-prevention additives.
[0088] The drilling fluids of the present invention generally have
a lower viscosity at 40.degree. F. than conventional muds
formulated with sufficient organoclay to provide suspension at
bottom hole temperatures. When used in drilling operations, the
present drilling fluids allow the use of a lower pumping power to
pump drilling muds through long distances, thereby reducing
down-hole pressures. Consequently, fluid loss, fracturing and
damage of the formation are all minimized. Drilling fluids of the
present invention also advantageously maintain the suspension
characteristics typical of higher levels of organoclays at higher
temperatures. The present invention is particularly useful in deep
water drilling when the mud is cooled in the riser. A mud using the
described invention will maintain a reduced viscosity increase in
the riser when compared to drilling fluids containing conventional
rheological additives.
EXAMPLES
Example 1
Preparation of the Polyamide Reaction Product
[0089] Empol.RTM. 1061 (792.9 grams) was placed in a 2 liter,
4-neck, preweighed reactor equipped with a Barrett distilling
receiver and a Friedrichs condenser. The Empol.RTM. 1061 was heated
to 100.degree. C. and then diethylenetriamine (190.6 grams) was
added. The contents were heated to 240.degree. C. under a nitrogen
blanket while mixing at 300 RPM. A reaction occurred with the
liberation of water, which was condensed in a receiver. The
reaction was allowed to continue until the acid value was
.ltoreq.2.0 (mg KOH/gram). The reaction was halted and the reactor
reweighed. A sample was taken, labeled Sample A, and given a lot
number for further studies.
Example 2
Preparation of Inventive Mixture Using the Product of Example 1
[0090] Sample A was allowed to cool to 80.degree. C. under
agitation. Ethomeen.RTM. C/15 (821.8 grams) was added slowly while
mixing at 500 RPM. The composition was mixed for 16 minutes. All of
the Ethomeen.RTM. C/15 was incorporated into the mixture. The
resulting product was poured into an appropriate storage
container.
Example 3
Preparation of Reaction Product 2
[0091] Empol.RTM. 1008 (635.2 grams) and Ethomeen.RTM. C/15 (692.1
gram) were placed in a 2 liter, 4-neck, preweighed reactor equipped
with a Barrett distilling receiver and Friedrichs condenser. The
contents were heated to 240.degree. C. under a nitrogen blanket
while mixing at 300 rpm. The reaction was allowed to continue until
the acid value was .ltoreq.5.0 (mg KOH/grams). Once the acid value
was .ltoreq.5.0, diethylenetriamine (112.6 grams) was charged to
the reactor. The reaction continued for another two hours at
240.degree. C. After this time, Armid.RTM. HT (164.0 grams) was
added to the reactor and cooked for an additional 3 hours at
240.degree. C. The resulting product was poured into storage
containers.
Example 4
Preparation of Drilling Fluid and Various Tests
[0092] A typical test mud was prepared comprised of a synthetic
base oil (186 grams), primary emulsifier (4 grams), secondary
emulsifier (2 grams), 30% calcium chloride brine solution (75
grams) and lime (4 grams). All components were mixed together for
15 minutes. The test additive(s) was charged to the fluid and mixed
for an additional 15 minutes. Barite (215 grams) was next added and
the fluid mixed for another 15 minutes, total mixing time was 45
minutes. Properties of the resulting test mud were measured and
evaluated.
[0093] After initial make up of all the drilling fluid (mud) and
characterization was completed (120.degree. F.), the drilling fluid
(mud) was subjected to a thermal treatment at 150.degree. F. for 16
hours. Drilling fluid (mud) properties were measured at 40.degree.
F., 120.degree. F., and 180.degree. F. as per API RP 13-B standard
practices.
A. Table 1 Summary
TABLE-US-00001 [0094] TABLE 1 Drilling Fluid Formulation Mud
Formulation Lbs./BBL Synthetic Based Oil 186 Primary Emulsifier 4
Secondary Emulsifier 2 30% Calcium Chloride Brine 75 Lime 4
Rheological Additive See Tables for Concentrations Barite 215
[0095] A drilling mud formula for the purpose of evaluating a
rheological additive performance.
B. Table 2 Summary
[0096] This below table represents a Bentone.RTM. 155 concentration
study in a synthetic oil-based invert emulsion drilling fluid
(mud). Table 2 shows that an oil-based drilling mud incorporating
organoclay alone as a rheological modifier exhibits greater than
190% high shear rate viscosity increase at 4 ppb rheological agent
when the temperature is reduced from 120.degree. F. to 40.degree.
F.
[0097] The drilling mud exhibits greater than a 160% low shear rate
viscosity increase at 4 ppb rheological agent when the temperature
is reduced from 120.degree. F. to 40.degree. F.
TABLE-US-00002 TABLE 2 BENTONE .RTM. 155 CONCENTRATION EVALUATION
Rheological Additive BENTONE .RTM. 155 Additive Concentration OFI
800 Viscosity 2 ppb 4 ppb 6 ppb Test Temperature 40.degree. F.
120.degree. F. 180.degree. F. 40.degree. F. 120.degree. F.
180.degree. F. 40.degree. F. 120.degree. F. 180.degree. F. 600 RPM
Reading 113 48 36 169 58 37 215 87 62 300 RPM Reading 69 30 22 110
39 25 158 59 42 200 RPM Reading 53 23 18 88 32 19 133 50 35 100 RPM
Reading 36 16 12 65 24 14 99 38 26 6 RPM Reading 13 6 3 26 10 6 48
20 14 3 RPM Reading 13 5 2 25 9 6 45 18 13 Apparent Visc., cPs 57
24 18 85 29 19 108 44 31 Plastic Visc., cPs 44 18 14 59 19 12 57 38
20 Yield Point, 25 12 8 51 20 13 101 31 22 Lbs./100 Ft.sup.2
C. Table 3 Summary:
TABLE-US-00003 [0098] TABLE 3 Impact of Example 2 on Viscosity:
Temperature Profile Additive Concentration: BENTONE 155 (2.0
ppb)/Example 2 (1.0 ppb) OFI 800 Viscosity Test Temperature
40.degree. F. 120.degree. F. 180.degree. F. 600 RPM Viscosity 84 48
35 300 RPM Viscosity 50 31 24 200 RPM Viscosity 40 25 20 100 RPM
Viscosity 27 19 15 6 RPM Viscosity 12 9 6 3 RPM Viscosity 11 8 5
Apparent Visc., cPs 42 24 18 Plastic Visc., cPs 34 17 11 Yield
Point, Lbs./100 Ft.sup.2 16 14 13
[0099] Table 3 presents the effect of the product of Example 2 on
the viscosity of an oil-based drilling mud. When 0.5 ppb of the
additive is combined with 2 ppb of BENTONE.RTM. 155, the 600 rpm
Fann reading only increases by 75% (48 to 84) when the temperature
is reduced from 120.degree. F. to 40.degree. F. Two ppb of the
BENTONE alone gave rise to a 135% increase (Table 2) under
comparable conditions. The low shear rate viscosity, measured at 6
rpm, showed a 33.3% viscosity increase as the temperature was
reduces whereas the BENTONE alone provided a 115% increase.
D. Table 4 Summary
[0100] Table 4 below presents the effects of the product of Example
3 on the viscosity of an oil-based drilling mud. When 1 ppb of the
additive is used along with 3 ppb of BENTONE.RTM. 155, the 600 rpm
Fann reading only increases by 56.9% (65 to 102) when the
temperature is reduced from 120.degree. F. to 40.degree. F. Four
ppb of the BENTONE alone gave rise to a 190% increase. The low
shear rate viscosity, measured at 6 rpm, showed a 29.4% viscosity
decrease as the temperature was reduced.
TABLE-US-00004 TABLE 4 Impact of Example 3 on Viscosity:
Temperature Profile Additive Concentration BENTONE 155 (3.0
ppb)/Example 3 (1.0 ppb) OPI 800 Viscosity Test Temperature
40.degree. F. 120.degree. F. 180.degree. F. 600 RPM Reading 102 65
50 300 RPM Reading 63 44 36 200 RPM Reading 48 36 30 100 RPM
Reading 31 28 24 6 RPM Reading 12 17 15 3 RPM Reading 11 16 14
Apparent Visc., cPs 51 33 25 Plastic Visc., cPs 39 21 14 Yield
Point, lbs./100 ft.sup.2 24 23 22
[0101] The foregoing description and examples have been set forth
merely to illustrate the invention and are not intended to be
limiting. Since modifications of the disclosed embodiments
incorporating the spirit and substance of the invention may occur
to persons skilled in the art, the invention should be construed
broadly to include all variations falling within the scope of the
appended claims and equivalents thereof.
* * * * *