Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF USE AND COMPOSITION OF POMACE ADDITIVE
BACKGROUND OF THE INVENTION
Field of the Invention
[00011 The invention relates to an improved organic drilling fluid additive
that does not
disrupt electrical stability while simultaneously providing seepage control,
lost circulation
control and fluid loss control of drilling fluid and to the composition of the
drilling fluid with
the particular additives.
Description of the Prior Art
[00021 Numerous organic and inorganic components are known for use as
additives in
drilling operations, both in aqueous fluids and oil muds, to control
detrimental losses such as
gross loss of whole fluid, commonly referred to as lost circulation.
Similarly, additives are
used to control fluid loss and provide seepage control. Organics are often
preferred for their
cost effectiveness as well as functionality. Organics suffer from a drawback
that they
interfere with electrical stability of the drilling fluids and therefore
affect readings for
electrical stability when measuring for hydrocarbons.
[00031 Generally voltage applied across two electrodes is increased until the
drilling fluid
emulsion breaks and a surge of current flows between the two electrodes. The
voltage
required to break" the emulsion is a common measure of the stability of such
an emulsion.
Oil-based muds are used where the use of water-based muds cannot solve
specific problems,
such as: drilling shales which swell or slough; drilling directional holes;
drilling hot, deep
holes; or to prevent or recover stuck pipe and the like. For proper
functioning of oil-based
muds, the small quantities of water used in oil muds must be completely
emulsified in the oil.
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Electrical Stability or voltage break-down (V-B) is measured for oil muds to
determine the
stability of the emulsion. Electrical stability measures the amount of current
required to
achieve the breakdown voltage or the point at which the emulsion becomes
conductive. Pure
oils do not conduct electricity whereas water is a highly effective conductor
of electricity.
High readings indicate stable, oil continuous emulsions, while low readings
indicate poor
emulsions. "E.S.", or electrical stability of the emulsion, is measured by the
test described in
Composition and Properties of Drilling and Completion Fluids, 5th Edition, H.
C. H. Darley,
George R. Gray, Gulf Publishing Company, 1988, pp. 116. Generally, the higher
the number,
the more stable the emulsion.
[00041 Efforts have been continuous in attempting to address the problem of
lost circulation,
seepage, or fluid loss. Patent literature has examples of various agricultural
and cellulosic
waste products being used as lost circulation materials and seepage control
agents designed to
function in specific ways. Yet lost circulation remains a critical issue in
the drilling industry
often directly affecting the profitability of a well.
[00051 Examples of patents addressing this recognized problem of lost
circulation, seepage or
fluid loss include US Patent 5,071,575 and 5,004,553 issued to House for well
working
compositions using ground oat hulls in a certain particle size range with the
possibility of
adding one or more agricultural byproducts including ground citrus pulp. Many
patents teach
the use of specific organic materials. U.S. Patent 5,147,852 issued to Cowan,
discusses the
use of organic materials, specifically cellulose materials, generally
described as those from
wood sources of fibrous materials, indicating generally the benefit of
cellulose. For example
U.S. Patent No. 5,229,018 issued to Forest teaches the use of peanut hulls as
an additive
along with a suitable suspending agent. However, organic additives added to
drilling fluids
generally suffer from certain drawbacks, in particular, interference with the
electrical stability
of oil-based drilling fluid.
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[00061 US Patent No. 6,399,545 recently issued to the current inventor, Rose,
explores the
use of fruit pomace in drilling fluid additives for the purpose of inhibiting
lost circulation,
seepage and/or fluid loss. However, the difficulty in use of various organic
matters relative
to the electrical stability has not previously been explored.
[00071 Common additives tend to drastically alter the properties of the
drilling fluid. One of
the most difficult issues to address is the issue that organic additives tend
to disrupt electrical
stability and the ability to accurately measure hydrocarbon content. This
creates difficulties
with the ability to determine producing formation locations accurately. It
would be
advantageous to provide an additive such that an electrical well-logging tool
when disposed
in the drilling fluid with additive can accurately perform an electrical well-
logging survey or
imaging of a borehole containing the fluid with additive.
[00081 It would be advantageous to provide an additive that functions to
prevent fluid loss,
seepage and lost circulation while at the same time minimizing disruption of
the electrical
stability of the system. It would also be advantageous to create a method for
producing such
an additive. Furthermore, the use of organic waste products would allow for
the advantage of
a cost effective additive.
[00091 The use of an organic additive that otherwise reduces the need to add
further refined
chemical components to the system, such as lignosulfonates and tannins, would
be
advantageous.
[00101 The introduction of an additive that can be used in both water base and
oil base well
working fluids would be advantageous. An additive that provides the desired
control without
interfering with the rheology or the electrical stability of the system would
also be
advantageous.
[00111 The current invention includes certain advantages that will be
appreciated by one
skilled in the art as the description thereof proceeds.
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BRIEF SUMMARY OF THE INVENTION
[00121 The current invention advantageously presents an additive, and the
method of use of
such additive, for use in drilling fluid that does not substantially affect
the electrical stability
of the drilling fluid. The additive of the invention is useful in drilling
fluid for drilling
operation. The additive has the property of inhibiting seepage, lost
circulation, and/or fluid
loss and is useful for this purpose. Also, the additive of the invention
includes an amount of
fruit pomace such that the additive exhibits certain novel characteristics
when added to the
drilling fluid. The fruit pomace is ground to create granules, the granules
being sieved to
define an original size distribution. The amount of fruit pomace in the
additive is such that
the additive, when added to the drilling fluid in a quantity sufficient to
inhibit seepage, lost
circulation, and/or fluid loss, is effective to maintain the electric
stability of the drilling fluid.
This ability to maintain the electric stability is exhibited by no or little
change of the electric
stability experienced upon addition of the additive. Any change experienced as
a result of the
addition of the additive is within a predefined range, the predefined range
being effective
such that an electrostatic measure for hydrocarbon content can be performed
within a
predetermined degree of error.
[00131 Preferred sources of fruit pomace include grape pomace, tomato pomace,
beet pomace
and the like. This pomace is then ground. A preferred embodiment also includes
allowing
the pomace to dry or acquiring dried pomace for grinding. After grinding the
pomace into
granules, the granules are sieved.
[00141 The additive of the invention is advantageously useful in all types of
drilling fluids
including oil mud, synthetic muds and aqueous muds.
[00151 In a preferred embodiment, the amount of fruit pomace included in the
additive is at
least 30% by weight fruit pomace to gain the advantage of maintaining the
electrical stability
within a predefined range, preferably greater than about 400
volts. More preferably, the amount of fruit pomace included in the
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additive is at least 40% by weight fruit pomace. In one embodiment, the
additive of the
invention can include substantially only one fluid loss, lost circulation
and/or seepage control
agent. In that case, the sole fluid loss, lost circulation and/or seepage
control agent is fruit
pomace. Depending upon the particular application, it can be desirable to add
wetting agents,
fungicides, biocides, or rheological agents to the additive. Another preferred
embodiment
includes an additive containing at least 98% by weight fruit pomace.
Furthermore, in a
preferred embodiment, the additive includes only one fruit pomace, such as
only tomato or
only grape pomace.
[00161 The additive of the invention, when not substantially all fruit pomace,
can contain
other materials that are effective to inhibit seepage, lost circulation,
and/or fluid loss.
Inorganic materials are preferred, the inorganic material being ground to
define an original
inorganic size distribution.
[00171 The current invention includes mixing the pomace with organics to
produce different
blends that enhance the organics while maintaining electrical stability. Solid
particles of
organics added to a drilling fluid system tend to interfere with electrical
charges. It has been
observed that the addition of pomace in accordance with the invention
counteracts this effect.
This is regarded to be an enhancement to the performance of the organics.
[00181 The invention also includes a method of performing drilling operations
wherein the
drilling fluid is circulated in a well being drilled in the ground wherein the
invention includes
the steps of preparing additive for addition to the drilling fluid, adding the
additive to the
drilling fluid, and circulating the drilling fluid with additive in the well
while drilling
operations are being carried out. Preparing the additive includes grinding an
amount of fruit
pomace to form granules and adding the amount of fruit pomace to create the
additive. The
amount of fruit pomace added is effective to substantially maintain the
electric stability of the
drilling fluid when added to the drilling fluid. The electric stability is to
be maintained within
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the predefined range, the predefined range being effective such that an
electrostatic measure
for hydrocarbon content can be performed. The additive is also effective to
inhibit seepage,
lost circulation and/or fluid loss and the like. The ground fruit pomace
granules are sieved
such that the granules define an original particle size distribution.
[0019] Another preferred embodiment of the additive includes an amount of a
facilitator
effective to facilitate the incorporation of the additive into the drilling
fluid such that the
additive containing fruit pomaces acts to begin mixing with the drilling fluid
immediately
upon introduction of the additive to the drilling fluid. In this manner, the
additive is
substantially completely incorporated into the drilling fluid prior to
delivery of the drilling
fluid with additive downhole.
[0020] The structure and method of the present invention as well as other
features,
advantages, benefits and objects thereof over other structures and methods
known in the art
can be better understood with reference to the detailed description which
follows.
DETAILED DESCRIPTION OF THE INVENTION
[0021] A pomace, such as tomato, grape or beet, is generally described as the
crushed matter
remaining of the pressed items. This can contain any combination of pulp,
skin, seed or other
naturally occurring substance in the pressed item. These organic products can
be used
individually or in combination with each other or other products.
[0022] In drilling operations, drilling fluid electrical stability of about
350 volts or less,
preferably about 250 volts or less, allows use of an electric logging tool. A
fluid is stable if
the electrical stability is above about 400 volts in a weighted fluid, which
is above 10 pounds
per gallon weight. Electrical stability of an unweighted fluid, which is below
10 pounds per
gallon, is typically considered stable at 200 volts and above. The drilling
fluid, prior to
addition of the additive, is relatively non-conductive. This is true of both
oil based drilling
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fluids and aqueous based drilling fluids or invert emulsions. The presence of
certain organic
additives can interfere with electrical stability, as measured by used in API
RP 13 B-2.
[0023] While it is known in the industry to use organic products to reduce
lost circulation,
each organic product has its own set of characteristics that can be useful or
disruptive to the
drilling fluid system. Fruit pulp products, however, provide surprisingly
efficient results over
other organics and provide the unexpected benefit of maintaining electric
stability, in
contravention to expectations based on behavior of other organic additives. It
is postulated
that the unexpected efficacy results from naturally occurring compounds in
fruit pomace.
This results in increased efficacy.
[0024] Wetting agents such as NOVAWETTM, a product of M-I Drilling fluids, are
useful to
enhance the dispersion of the additive throughout the drilling fluid for
particular drilling
fluids..
[0025] The fruit pomace to be ground is typical a byproduct from other
industries and thus
can be economically obtained. In fact, they are frequently considered waste
materials and
therefore pose a waste disposal problem. After acquiring the fruit pomace,
further drying
and/or pressing can be performed prior to such grinding, depending on the
moisture content
of the pomace. Another preferred embodiment includes heating the products for
a length of
time in order to sanitize the organic products, thus further reducing the
possibility of
undesirable biological activity when the additive is mixed with the drilling
fluid.
[0026] After the organic products of the invention have been. ground, they are
added to the
drilling fluid. There are various apparatuses and methods known in the art for
adding
materials to drilling fluid such that the material is incorporated into the
fluid, all of which are
useful in this invention. A preferred embodiment includes mixing the additive
into the
drilling fluid using a conventional jet-type hopper.
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[0027] The additive is typically ground coarse, medium, fine or ultra fine,
depending upon
the particular usage. Coarse is generally that which will pass through a 4
mesh and retained
on a 60 mesh. Medium is consider that which will pass through a 20 mesh and be
retained on
a 100 mesh. Fine is typically that which will pass through a 60 mesh and be
retained on a
600 mesh. Ultra fine passes through meshes smaller than 600 mesh. There are
general
categories of definitions and include some overlapping sizes of mesh. A
preferred
embodiment of the current invention includes providing two to fifty lbs of
additive per barrel
of mud circulated.
[0028] Following are test results on electrical stability.
ELECTRICAL
STABILITY
COMPARISON
TEST
Sample Description:
Sample A - Grape Pomace Regular
Sample B - Grape Pomace Fine
Sample C - ground corn cob
Sample D - Ground almond hulls
Test Procedure:
A base mud formulation was prepared and the electrical stability measured.
This is reported
below. 25 ppb sample was added and mixed 10 minutes. Samples were then rolled
72 hours
at 150 F. Samples were removed from oven and electrical stability measured
while samples
were still at 150 F. Samples were then cooled to room temperature and the
electrical
stability measured again. Samples were then mixed one minute on multimixer and
the
electrical stability measured again.
Base Mud:
235 mis synthetic base oil
50 mis 10.8 ppg CaC12 brine
6 ppb organoclay
ppb Lime
8 ppb Emulsifier
250 g Barite
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Results:
A .rapt : _~ = ., B Crape C - C oultd` I~ Almond
Pom;cc vt
IECgu(ar -"Pomace Fine Cozri Cob ` Steens
ase Mud 470 494 508 501
Hots olled' 590 550 134 353
Room Temp 647 560 165 411
Imin mix 657 560 160 433
[0029] The additives and the method of their use are useful in drilling fluids
that are oil
muds, including diesel and synthetic oils. The additives and the method of
their use are also
useful in aqueous drilling fluids.
[0030] From the foregoing it will be seen that this invention is one well
adapted to attain all
of the ends and objects hereinabove set forth, together with other advantages
which are
obvious and which are inherent to the apparatus and structure.
[0031] It will be understood that certain features and subcombinations are of
utility and may
be employed without reference to other features and subcombinations. This is
contemplated
by and is within the scope of the claims.
[00321 Because many possible embodiments may be made of the invention without
departing
from the scope thereof, it is to be understood that all matter herein set
forth is to be
interpreted as illustrative and not in a limiting sense.
[0033] For example the additives of this invention for use with drilling
fluids not only
perform as control agents for seepage, lost circulation and lost fluid control
with the novel
benefit afforded by pomace, but they also act as a thinner. The use of these
compounds for
purposes of thinning is encompassed within this invention.
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