U.S. patent application number 12/704333 was filed with the patent office on 2010-12-16 for method of treating oil and gas wells.
Invention is credited to Lloyd Byron Spangle.
Application Number | 20100314112 12/704333 |
Document ID | / |
Family ID | 40340605 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100314112 |
Kind Code |
A1 |
Spangle; Lloyd Byron |
December 16, 2010 |
Method of treating oil and gas wells
Abstract
A two step process for treating an oil or gas well. The first
step uses a cross linking agent, such as borax, as a preliminary
wash for the well following drilling. The cross linking agent
cleans the well of excess mud and pre-coats the tubing and the
formation surfaces with the cross linking agent. The second step
introduces a cement-polymer mixture into the well. A polymer, such
as for example polyvinyl alcohol, that undergoes cross linking when
exposed to the cross linking agent is employed. When the polymer
comes into contact with the cross linking agent in the well, cross
linking of the polymer occurs. This cross linking helps to prevent
fluid loss into the formation. Also, because the cross linking
agent wash previously cleaned the surfaces of the tubing and the
formation, better bonding between the cement and the surfaces of
the tubing and the formation occurs.
Inventors: |
Spangle; Lloyd Byron;
(Claremore, OK) |
Correspondence
Address: |
Novak Druce + Quigg LLP
1000 Louisiana Street, Fifty-Third Floor
Houston
TX
77002
US
|
Family ID: |
40340605 |
Appl. No.: |
12/704333 |
Filed: |
February 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12019933 |
Jan 25, 2008 |
7670994 |
|
|
12704333 |
|
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Current U.S.
Class: |
166/293 ;
523/130; 525/61 |
Current CPC
Class: |
C04B 2103/46 20130101;
C04B 28/02 20130101; C09K 8/512 20130101; C04B 2103/0062 20130101;
C04B 24/2623 20130101; C04B 22/0013 20130101; C04B 28/02 20130101;
C09K 8/487 20130101 |
Class at
Publication: |
166/293 ;
523/130; 525/61 |
International
Class: |
E21B 33/13 20060101
E21B033/13; C09K 8/44 20060101 C09K008/44; C08F 8/00 20060101
C08F008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2008 |
US |
PCT/US08/80838 |
Claims
1.-14. (canceled)
15. A method for inhibiting fluid loss from an oil and gas well,
said method comprising the steps of, separately: washing a well
borehole with a wash composition, said wash composition comprising
a cross linking agent, wherein said cross linking agent at least
partially impregnates a formation's face and pumping a cement
mixture into said well's borehole to cement at least a portion of a
formation face, said cement mixture comprising a polymer
composition, wherein said polymer polymerizes in, on, or about said
formation's face upon exposure to said cross linking agent, thereby
inhibiting fluid loss from said well's borehole to said
formation.
16. The method of claim 15, wherein the step of washing at least
partially cleans the well of excess mud.
17. The method claim 15, wherein the step of washing at least
partially impregnates at least one of said borehole's tubing and
said borehole's formation face with said cross linking agent.
18. The method of claim 15, wherein said cross linking agent is
added to said well borehole along with an oil-based drilling mud or
"spacer".
19. The method of claim 15, wherein said cross linking agent is at
least one of borax, boric acid, water soluble borates, sodium
borates, calcium borates, potassium borates, titanates, zirconates,
and mixtures thereof.
20. The method of claim 15, further comprising the step of: adding
fine particulate material to the polymer composition prior to
mixing it with the cement mixture.
21. The method of claim 20, wherein the fine particulate material
is calcium carbonate.
22. The method of claim 15, wherein the polymer is at least one of
polyvinyl alcohol or a low viscosity partially hydrolyzed polyvinyl
alcohol such as DuPont Elvanol(R) 51-05S8.
23. A method for inhibiting fluid loss from an oil or gas well,
said method comprising the steps of, separately: washing a well
with a reactant agent that creates a thickened reaction product
when a secondary mixture is encountered, and adding secondary
mixture to the well's borehole which forms a thickened reaction
product upon exposure to said reactant, thereby inhibiting fluid
loss from said well's borehole to a formation adjacent to said well
borehole.
24. The method of claim 15, wherein the step of washing is removed
and said cross linking agent is included with a drilling fluid
circulated in said well's borehole prior to adding said cement
mixture.
25. A kit for inhibiting fluid loss from an oil and gas well
comprising: a wash composition, said wash composition comprising a
cross linking agent and a polymer composition, wherein said polymer
polymerizes in, on, or about a formation's face upon exposure to
said cross linking agent, thereby inhibiting fluid loss from said
well's borehole to said formation through said formation's
face.
26. A polymerized well borehole, said polymerized well borehole
formed by a method of claim 15.
27. A method for reducing an amount of fluid loss additive
necessary to inhibit fluid loss from an oil and gas well, said
method comprising the steps of, separately: washing a well borehole
with a wash composition, said wash composition comprising a cross
linking agent, wherein said cross linking agent at least partially
impregnates a formation's face and pumping a cement mixture into
said well's borehole to cement at least a portion of a formation
face, said cement mixture comprising a polymer composition, wherein
said polymer polymerizes in, on, or about said formation's face
upon exposure to said cross linking agent, thereby inhibiting fluid
loss from said well's borehole to said formation through said
formation's face, wherein between about 0.1% and about 90% by
volume of a contemporary fluid loss additive is used to inhibit
fluid loss.
28. The method of claim 27, wherein said fluid loss additive's
components are the same as the components of the contemporary fluid
loss additive.
29. The method of claim 27, wherein the step of washing is removed
and said cross linking agent is included with a drilling fluid
circulated in said well's borehole prior to adding said cement
mixture.
30. The method of claim 15, wherein said cement mixture comprises a
permeable, micro-cluster silica material present in an amount from
about 10 percent to about 30 percent by weight of the cement
mixture, wherein said permeable, micro-cluster silica material has
an average particle size ranging from about 30 to about 80 microns
and a range of distribution from about 1 micron to about 200
microns.
31. The kit of claim 25, further comprising: a permeable,
micro-cluster silica material, wherein said permeable,
micro-cluster silica material has an average particle size ranging
from about 30 to about 80 microns and a range of distribution from
about 1 micron to about 200 microns.
32. The method of claim 23, wherein the step of washing is removed
and said cross linking agent is included with a drilling fluid
circulated in said well's borehole prior to adding said cement
mixture.
33. A polymerized well borehole, said polymerized well borehole
formed by a method of claim 23.
34. The method of claim 23, wherein said cement mixture comprises a
permeable, micro-cluster silica material present in an amount from
about 10 percent to about 30 percent by weight of the cement
mixture, wherein said permeable, micro-cluster silica material has
an average particle size ranging from about 30 to about 80 microns
and a range of distribution from about 1 micron to about 200
microns.
35. The method of claim 27, wherein said cement mixture comprises a
permeable, micro-cluster silica material present in an amount from
about 10 percent to about 30 percent by weight of the cement
mixture, wherein said permeable, micro-cluster silica material has
an average particle size ranging from about 30 to about 80 microns
and a range of distribution from about 1 micron to about 200
microns.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority as a continuation in
part to U.S. Non-provisional patent application Ser. No.
12/019,933, filed on Jan. 25, 2008, now U.S. Pat. No. 7,670,994,
issued Mar. 2, 2010 and International Application No.
PCT/US08/80838, filed Oct. 22, 2008 which further claims priority
to U.S. Non-provisional patent application Ser. No. 12/019,933,
filed on Jan. 25, 2008, now U.S. Pat. No. 7,670,994, issued Mar. 2,
2010.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for treating oil
and gas wells. Various further embodiments relate to enhanced
methods for treating oil and gas wells.
DESCRIPTION OF THE RELATED ART
[0003] Previous methods of fluid loss control have been attempted
by a one step addition of fluid loss control additive to the
cement, which hopefully reduces the ability of the liquid portion
of the slurry from rapidly penetrating a permeable zone at the
formation face. This creates a critical dependence of the fluid
control on the use of a fluid loss control additive that functions
at the temperature of the permeable zone. Also, the cement slurry
must be designed to complement the requirements of the fluid loss
additive for rheology of the fluid portion of the cement slurry.
Most fluid loss control additives thicken the cement slurry into
which they are mixed. Also, they may retard the hardening of the
cement when it reaches its required destination. To deal with such
properties, it is common for service companies to have many
different fluid loss control additives and to select the "best fit"
for the well conditions that are to be encountered.
SUMMARY OF THE INVENTION
[0004] Various embodiments of the present invention generally
relate to methods for treating an oil and/or gas well. In an
embodiment of a method of the present invention generally comprises
washing a well borehole with a wash composition comprising a cross
linking agent, such as, for example, borax, and pumping a cement
mixture into the borehole, to cement at least a portion of the
borehole, the cement mixture comprising a polymer composition, such
as, for example, a polyvinyl alcohol. In various embodiments, the
washing step at least partially cleans the well of excess mud and
at least partially pre-coats the tubing and at least partially
pre-coats the formation face with the cross linking agent.
[0005] The cement polymer mixture undergoes cross linking when
exposed to the cross linking agent. In various embodiments, when
the polymer in the cement mixture comes into contact with the wash
composition's cross linking agent, the polymer undergoes
polymerization or cross linking. This cross linking helps to
prevent fluid loss into the formation. In various embodiments,
increased bonding between the cement mixture and the surfaces of
the tubing and the formation face is exhibited with compositions
and/or methods of the present invention.
[0006] Examples of components useful in the present invention can
be found in U.S. Pat. Nos. 5,009,269; 5,850,880; 5,728,210, the
contents of which are hereby incorporated by reference as if they
were reproduced herein in their entirety.
[0007] As such, in various embodiments, compositions and methods
are disclosed that use a two stage process that allows washing,
with a wash composition, of the permeable zone of the well
borehole's formation face and cementing the well borehole with a
cement mixture comprising a polymer composition.
[0008] This method is not as temperature dependant in down hole
borehole operations, as with the fluid loss additives disclosed in
U.S. Pat. Nos. 5,009,269; 5,850,880; 5,728,210. In traditional
processes using a wash composition comprising a cross-linking agent
and a cement mixture comprising a polymer, operating conditions
above about 200 degrees F. (93.3 degrees C.) results in partial
degradation of the components of the wash composition and/or the
cement mixture. However, surprisingly, embodiments of the present
invention are capable of functioning from near freezing, i.e. about
32 degrees F. (0.0 degrees C.), to above 400 degrees F. (204.4
degrees C.), or the degradation temperature of the polymer.
[0009] In various embodiments, operating temperatures in excess of
400 degrees F. (204.4 degrees C.) are possible. Generally, an upper
temperature limit is at or about the temperature where the
components of the wash composition and/or cement mixture degrade.
In an embodiment, the wash composition's components degrade at
above 400 degrees F. (204.4 degrees C.). In an alternate
embodiment, the wash composition's components degrade at about 250
degrees F. (121.1 degrees C.). In an alternate embodiment, the wash
composition's components degrade above 400 degrees F. (204.4
degrees C.).
[0010] In various embodiments, temperatures below zero degrees
Celsius are difficult to operate in because the components of the
drilling mud begin to change phase or freeze. Typically, such
environments are found in areas with permafrost. Additives can be
included in the drilling mud to lower the freezing point but
attention should be had to interference between the additives and
the various components of the wash composition and/or the cement
mixture, as such, operating conditions below zero are possible with
various embodiments of the present invention.
[0011] In various embodiments, the cross linking agent to be used
for washing, or as a "spacer" additive or drilling mud additive, is
non toxic and environmentally clean. In an embodiment, the cost of
this "spacer" additive for the wash is lower than a traditional
complex chemical wash, as used in contemporary drilling operations.
In various further embodiments, the cross linking agent is capable
of being formulated as a non thickened water base fluid that will
allow turbulent flow in the annulus at very low pump rates into the
well borehole.
[0012] Turbulent flow is capable of producing a churning action
within the well borehole ahead of injected wash, as confirmed by
laboratory studies. Additionally, the detergent action of the cross
linking agent together with the turbulent flow at least partially
granulates excess mud adhering to the pipe and at least partially
granulates the loose mud at the formation face and carries the
material out of the well.
[0013] In various embodiments, during this washing step using a
cross linking agent in the wash, a "seeding" will take place at the
formation face which at least partially impregnates the mud cake
with cross linking agent. The concentration will vary depending on
the permeability at the formation face. Typically, the
concentration of the cross linking agent will increase as the
permeability of the formation face increases.
[0014] In various embodiments, a cross linking agent is capable
being added to drilling mud, or "spacers", to be available for
polymerization with the polymer. In such embodiments, fluid loss
control is capable of being obtained without a washing step, which
step, in certain circumstances, might not be desired, such as when
disposal of a wash composition is an issue. The drilling mud would
impregnate the formation face with the cross linking agent and a
subsequently pumped cement mixtures comprising a polymer would
cross link at or about the formation face.
[0015] In various embodiments, a polymer can be added to the cement
mixture either as a dry component, a liquid component, or as a
combination dry and liquid component. Typically, a polymer is
comparatively low cost to conventional prior art complex fluid loss
compositions. Further, with embodiments of the present invention,
less material than conventional fluid loss compositions is
required. In one embodiment, less composition is required because
of the permeability block occurring at or about the
formation-cement interface, where the reaction of the polymer and
cross linking agent takes place. Accordingly, the application of
the cross linking agent and the polymer is more targeted, producing
less waste.
[0016] Otherwise, in various embodiments, if the reaction of the
cross linking agent and the polymer had taken place in the cement
slurry prior to reaching the permeable formation face, such as when
the cement slurry is injected, the slurry would typically be much
thicker because of the polymerized polymer, thereby requiring more
water to reduce the viscosity of the at least partially polymerized
cement slurry.
[0017] Focusing the reaction at the pressure differential
interface, or formation face, means that a cement mixture of an
embodiment of the present invention requires less loading with
viscosity lowering agents and/or water/fluid.
[0018] In various embodiments, the cement mixtures are suitable for
subterranean applications such as well completion and remedial
operations. It is to be understood that "subterranean applications"
encompass both areas below exposed earth and areas below earth
covered by water such as ocean or fresh water. In various
embodiments, the cement mixtures include a sufficient amount of
water to form a pumpable slurry.
[0019] The density of the cement mixtures may vary. In various
embodiments, the cement mixtures may comprise a density of from
about 4 lb/gallon to about 23 lb/gallon. In alternative
embodiments, the cement mixtures may comprise a density of from
about 12 lb/gallon to about 17 lb/gallon. In other alternative
embodiments, the cement mixtures may be low-density cement mixtures
with a density of from about 5 lb/gallon to about 12 lb/gallon. In
general, the density can be selected for the drilling
operation.
[0020] In various embodiments, the cement mixture comprises at
least one cement such as hydraulic cement, which includes calcium,
aluminum, silicon, oxygen, and/or sulfur and which sets and hardens
by reaction with water. Examples of hydraulic cements include but
are not limited to Portland cements (e.g., classes A, C, G, and H
Portland cements), pozzolana cements, gypsum cements, phosphate
cements, high alumina content cements, silica cements, high
alkalinity cements, and combinations thereof.
[0021] Type I Portland cement is known as common or general purpose
cement. It is commonly used for general construction especially
when making precast and precast-prestressed concrete that is not to
be in contact with soils or ground water. The typical compound
compositions of this type are 55% (C.sub.3S), 19% (C.sub.2S), 10%
(C.sub.3A), 7% (C.sub.4AF), 2.8% MgO, 2.9% (SO.sub.3), 1.0%
Ignition loss, and 1.0% free CaO.
[0022] Type III has a relatively high early strength. Its typical
composition is 57% (C.sub.3S), 19% (C.sup.25), 10% (C.sub.3A), 7%
(C.sub.4AF), 3.0% MgO, 3.1% (SO.sub.3), 0.9% Ignition loss, and
1.3% free CaO. The gypsum level may also be increased a small
amount. This gives the concrete using this type of cement a three
day compressive strength equal to the seven day compressive
strength of types I and II. Finally, other cement types useful in
the cement blend of the present invention include (high-early set)
HE and class C cements.
[0023] In various embodiments, a permeable, Micro-Cluster Silica
Material may be used in the cement mixtures. A Perlite-derived
material capable of use in the present invention comprises
microcellular fillers that are inert, inorganic, hollow glass
particles with irregular spherical geometries. These particles are
commercially available and sold under the name Sil-cell.RTM. by
Silbrico Corporation (Hodgkins, Ill.). Sil-cell.RTM. particles have
a greater tensile strength than the usual spherical bubbles.
Sil-cell.RTM. has a low effective specific gravity (E.S.G.=0.18)
and makes cost effective the manufacture of adhesives, auto body
putty, cultured marble, coatings, wall patching compounds and
stucco in which Sil-cell.RTM. is incorporated. The approximate
composition of Sil-cell.RTM. is 73% silicon dioxide, 17% aluminum
oxide, 5% potassium oxide 3% sodium oxide, 1% calcium oxide and
trace elements.
[0024] The use of a low shear, folding type mixer is desirable to
minimize particle breakage when using Sil-cell.RTM.. Thus, low
shear testing procedures were used to mix compositions with
Sil-cell.RTM.. Tests where high shear was used resulted in break-up
of the structures and release of the entrapped gas. If the
micro-clusters are completely broken-up, they no longer occupy the
space in the liquid slurry needed to eventually intake the excess
water used to initially mix and pump the slurry. The resulting
slurry would be weakened when it hardens into set cement. Silbrico
Corporation product Sil-43BC used in these preferred composition
tests has an average particle size of about 35 microns with a range
of 1 to 150 microns, and at least 95 percent less than 75 microns.
Generally, a grade of micro-cluster silica material has an average
particle size ranging from about 30 to about 80 microns and a range
of distribution from about 1 micron to about 200 microns. More
desirably, the permeable, micro-cluster silica material has an
average particle size ranging from about 30 to about 50 microns and
a range of distribution from about 1 micron to about 200 microns
and even better an average particle size ranging from about 30 to
about 40 microns and a range of distribution from about 1 micron to
about 150 microns.
[0025] The micro-clusters of glass bubbles in Sil-cell.RTM. have
high permeability. The high permeability allows the micro-clusters
to exchange void air space (when hydraulic pressure is applied)
with water from the cement matrix that surrounds the micro-cluster.
On the other hand, when structures that are not permeable (which is
the case with micro-spheres and micro-beads), the micro-clusters
would be subject to collapse under pressure. The use of crushable
structures under high hydraulic pressure results in dramatic
rheology change when collapse takes place. This can render such a
slurry unpumpable or at a severe density change due to the collapse
of the air space.
[0026] The use of the permeable non-crushing, micro-clusters of
glass bubbles avoids this possibility. The Ideal Gas Law can be
used to calculate the density change with pressure. The increase in
pressure is directly related to the decrease in volume of gas.
Also, simulated pressure conditions can be used in unique testing
methods to predict the rheology profile and hydration
characteristics of the cement mixture. Testing has verified the
integrity of the micro-clusters of glass bubbles after water has
invaded the permeable structures under high hydraulic pressure.
Thus, the micro-cluster retains its dimensions while filling with
water from the surrounding fluid.
[0027] A sufficient amount of water is added to the cement mixture
to make the cement mixture pumpable. The water may be fresh water
or salt water, e.g., an unsaturated aqueous salt solution or a
saturated aqueous salt solution such as brine or seawater, or a
non-aqueous fluid. The water may be present in the amount of from
about 16 to about 180 percent by weight of cement, alternatively
from about 28 to about 60 percent by weight of cement. In general,
any amount of water can be used as would be understood by one of
ordinary skill in the art.
[0028] In various embodiments an amount of cross linking agent is
added to adequately cover the formation face. In an embodiment, the
amount of cross linking agent added is in excess of the amount of
cross linking agent needed to impregnate the formation face. In an
alternate embodiment, the amount of cross linking agent added is
50% in excess of the amount of cross linking agent needed to
impregnate the formation face. In an alternate embodiment, the
amount of cross linking agent added is 100% in excess of the amount
of cross linking agent needed to impregnate the formation face. In
an alternate embodiment, the amount of cross linking agent added is
200% in excess of the amount of cross linking agent needed to
impregnate the formation face. In an alternate embodiment, the
amount of cross linking agent added is 500% in excess of the amount
of cross linking agent needed to impregnate the formation face. In
general, any amount of cross linking agent can be used and can be
governed by one of ordinary skill in the art based on coverage,
results, cost, and/or the like.
[0029] In various embodiment an amount of polymer is added to is
added to adequately cover the formation face and/or react with the
cross linking agent, thereby polymerizing. In an embodiment, the
amount of polymer added is in excess of the amount of polymer
needed to polymerize on, in, or about the formation face. In an
alternate embodiment, the amount of polymer added is 50% in excess
of the amount of polymer needed to polymerize on, in, or about the
formation face. In an alternate embodiment, the amount of polymer
added is 100% in excess of the amount of polymer needed to
polymerize on, in, or about the formation face. In an alternate
embodiment, the amount of polymer added is 200% in excess of the
amount of polymer needed to polymerize on, in, or about the
formation face. In an alternate embodiment, the amount of polymer
added is 500% in excess of the amount of polymer needed to
polymerize on, in, or about the formation face. In general, any
amount of polymer can be used and can be governed by one of
ordinary skill in the art based on coverage, results, cost, and/or
the like.
[0030] In various embodiments of the present invention, the total
amount by volume of fluid loss additive need, wherein the fluid
loss additive comprises the polymer in the cement mixture and the
cross linking agent in the wash composition (or drilling mud), is
between about 1.0% and 90% of contemporary fluid loss additive. In
an alternate embodiment, the total amount by volume of fluid loss
additive needed is between about 5.0% and 75% of contemporary fluid
loss additive. In an alternate embodiment, the total amount by
volume of fluid loss additive needed is between about 10% and 50%
of contemporary fluid loss additive. In an alternate embodiment,
the total amount by volume of fluid loss additive needed is between
about 15% and 25% of contemporary fluid loss additive. In an
alternate embodiment, the total amount by volume of fluid loss
additive needed is 0% due to enhancements of various embodiments of
the present invention.
[0031] In various embodiments of the present invention, the total
amount by weight of fluid loss additive need, wherein the fluid
loss additive comprises the polymer in the cement mixture and the
cross linking agent in the wash composition (or drilling mud), is
between about 1.0% and 90% of contemporary fluid loss additive. In
an alternate embodiment, the total amount by weight of fluid loss
additive needed is between about 5.0% and 75% of contemporary fluid
loss additive. In an alternate embodiment, the total amount by
weight of fluid loss additive needed is between about 10% and 50%
of contemporary fluid loss additive. In an alternate embodiment,
the total amount by weight of fluid loss additive needed is between
about 15% and 25% of contemporary fluid loss additive. In an
alternate embodiment, the total amount by weight of fluid loss
additive needed is 0% due to enhancements of various embodiments of
the present invention.
[0032] In various embodiments, a two stage method and also the type
of additives used in the method should be a significant improvement
for fluid loss prevention and permeable interface sealing. Such a
technique or method could be utilized in any type of permeable
situation to minimize leak off of fluid from a well bore, pond,
lake, dam, etc.
[0033] The foregoing has outlined rather broadly the features of
the present disclosure in order that the detailed description that
follows may be better understood. Additional features and
advantages of the disclosure will be described hereinafter, which
form the subject of the claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0034] In the following description, certain details are set forth
such as specific quantities, sizes, etc. so as to provide a
thorough understanding of the present embodiments disclosed herein.
However, it will be obvious to those skilled in the art that the
present disclosure may be practiced without such specific details.
In many cases, details concerning such considerations and the like
have been omitted inasmuch as such details are not necessary to
obtain a complete understanding of the present disclosure and are
within the skills of persons of ordinary skill in the relevant
art.
[0035] The following definitions and explanations are meant and
intended to be controlling in any future construction unless
clearly and unambiguously modified in the following Description or
when application of the meaning renders any construction
meaningless or essentially meaningless. In cases where the
construction of the term would render it meaningless or essentially
meaningless, the definition should be taken from Webster's
Dictionary, 3rd Edition. Definitions and/or interpretations should
not be incorporated from other patent applications, patents, or
publications, related or not, unless specifically stated in this
specification or if the incorporation is necessary for maintaining
validity.
[0036] As used herein, the term "mud cake" means and refers to a
caked layer of clay adhering to the walls of a well or borehole,
formed where the water in the drilling mud filters into a porous
formation during rotary drilling.
[0037] As used herein, the term "lignosulfonate" means and refers
to lignosulfonates, or sulfonated lignins, and are water-soluble
anionic polyelectrolyte polymers.
[0038] As used herein, the term "PVA" or "polyvinyl alcohol" means
and refers to a partially hydrolyzed polyvinyl acetate polymer
having at least about 80 percent of the acetate groups hydrolyzed.
PVA has been a desired fluid loss control agent because of its low
cost, its lack of a set retarding function, and the fact that it is
not totally water soluble, so that its effect on slurry viscosity
is minimal. However, the PVA-based materials previously used have
been less effective at temperatures above about 50 degrees C.
because the PVA becomes essentially water-soluble. Also, PVA has
not been particularly effective in cement slurries formulated with
fresh water.
[0039] As used herein, the terms "cross link" and "polymerize" are
used interchangeably, unless such use would be irrational.
[0040] Various embodiments of the present invention can use any
cross linking agent. The cross-linking agent can comprise a borate
releasing compound or any of the well known transition metal ions
which are capable of creating a cross-linked structure. Examples of
cross-linking agents include, but are not limited to, borate
releasing compounds, a source of titanium ions, a source of
zirconium ions, a source of antimony ions and a source of aluminum
ions. Generally any cross linking agent can be used.
[0041] A cross linking agent can come from any source, such as
sodium tetraborate, potassium tetraborate, boric acid, boron oxide,
or calcium hexaboride, and the like. Titanate and zirconate
cross-linking agents can be used as full or partial substitutes for
the water-soluble borates, but are not as preferred.
[0042] In general, any polymer can be used with various embodiments
of the present invention, such as a polymerization product formed
by polymerizing a 2-acrylamido-2-methylpropane sulfonic acid,
2-methacrylamido-2-methylpropane sulfonic acid, sulfonated styrene,
vinyl sulfonic acid, allyl ether sulfonic acids such as propane
sulfonic acid allyl ether, methallyl ether phenyl sulfonates,
acrylic acid, methacrylic acid, maleic acid, itaconic acid,
n-acrylamidopropyl-n,n-dimethyl amino acetic acid,
n-methacrylamidopropyl-n,n-dimethyl amino acidic acid,
n-acryloyloxyethyl-n,n-dimethyl amino acidic acid,
n-methacryloyloxyethyl-n,n-dimethyl amino acidic acid,
n-acryloyloxyethyl-n,n-dimethyl amino acidic acid,
n-methacryloyloxyethyl-n,n-dimethyl amino acidic acid, crotonic
acid, acrylamidoglycolic acid, methacrylamidoglycolic acid,
2-acrylamido-2-methylbutanoic acid and
2-methacrylamido-2-methylbutanoic acid. Nonionic monomers which can
be used in the formed (synthesized, intercalated) polymer include,
but are not limited to, C.sub.1-C.sub.22 straight or branched chain
alkyl or aryl acrylamide, C.sub.1-C.sub.22 straight or branched
chain n-alkyl or aryl methacrylamide, acrylamide, methacrylamide,
n-vinylpyrrolidone, vinyl acetate, ethoxylated and propoxylated
acrylate, ethoxylated and propoxylated methacrylate, hydroxy
functional acrylates such as hydroxyethylacrylate and
hydroxypropylacrylate, hydroxy functional methacrylates such as
hydroxyethylmethacrylate and hydroxypropylmethacrylate,
n,n-dimethylacrylamide, n,n-dimethylmethacrylamide, styrene,
styrene derivatives and C.sub.1-C.sub.22 straight or branched chain
alkyl, aryl, allyl ethers, poly vinyl alcohol (PVA), and/or the
like.
[0043] In embodiments utilizing PVA, at least in part, while not
intending to be bound, the mechanism by which PVA controls fluid
loss is believed to be different from that of other fluid loss
materials. Most fluid loss additives are high molecular weight
polymers that are totally water-soluble and form some type of a
structure between the cement particles, which reduces the
permeability of the filter cake. PVA is not totally water-soluble
below about 50 degrees C., but is, instead, "water-swellable." The
individual PVA particles swell and soften to form small gel-balls
in the slurry. These gel-balls deform by flattening, and become a
part of the filter cake, greatly reducing the filter cake
permeability, thus giving extremely good fluid loss control.
Because PVA is not totally water-soluble, it does not significantly
increase the slurry viscosity. PVA does not retard the set of
cement.
[0044] Variations in the degree of hydrolysis of the polyvinyl
alcohol, the molecular weight of the polyvinyl alcohol, and the
inclusion of up to 25 percent by weight of substituents on the
polyvinyl alcohol, such as methacrylate, methmethacrylate and the
like are within the scope of the present invention. In addition,
the preferred embodiment can contain calcium sulfate in a form such
as dihydrate or anhydrite, but present in an amount equivalent to
from 0 to 60 percent by weight of calcium sulfate hemihydrate.
[0045] The surfactant can be any of a wide range of materials such
as ethoxylated alkyl phenols, ethoxylated primary or secondary
alcohols, ethoxylated fatty alcohols, ethoxylated amines,
ethoxylated amides, ethoxylated fatty acids, ethoxylated diamines,
and ethoxylated quaternary ammonium chlorides. Suitable surfactants
are described in detail in U.S. Pat. No. 5,105,885, the contents of
which are hereby incorporated by reference as if it was reproduced
herein in its entirety.
[0046] Antifoam materials useful in the present invention are
usually polypropylene glycols but any suitable substitute can be
utilized.
[0047] Cement retarding additives can also be added to the fluid
loss additives. At temperatures above 80 degrees F., cement sets in
a short period of time. Retarders, such as lignosulfonate
materials, lengthen the time the cement slurry will stay liquid,
allowing the slurry to be pumped down the casing and back up the
annulus before setting.
[0048] For embodiments comprising sulfonated polymer dispersing
agents, such materials are capable of being sulfonated
polymelamine, sulfonated polystyrene or vinyl sulfonate polymers or
mixtures of these. Other sulfonated polymer materials can be
substituted provided that materials can be prepared at low pH and
neutralized to form salts of the polymers. The salts can be sodium,
potassium, lithium, ammonium, calcium, magnesium, and the like. The
sulfonated polymer is added in a quantity of 0.05 to 2.0 percent by
weight of the cement. These sulfonated polymers are available in
liquid or powdered form. The weight percent specified is based on
sulfonated polymer only and does not include the weight of any
water that may be present in the liquid form.
[0049] In preparing the low viscosity dry mixed fluid loss control
additive of the present invention, the components to the cement can
be added as a single blend, or as individual components, or in any
combination or order of addition.
[0050] The present invention is both compositions and methods for
treating an oil or gas well and uses a cross linking agent, such as
borax, as a preliminary wash for the well.
[0051] In various embodiments, a preliminary wash is capable of use
to clean the well and pre-coat the tubing and the formation
surfaces with the cross linking agent. In various embodiments,
next, the cement mixture with polymer is pumped into the well. When
the polymer comes into contact with the cross linking agent, the
polymer undergoes polymerization or cross linking A cross linking
agent helps to inhibit fluid loss into the formation. Also, because
the cross linking agent wash cleaned the surfaces of the tubing and
the formation, this results in better bonding between the cement
and the surfaces of the tubing and the formation.
[0052] In various embodiments, the interface of the cross-linker
and polymer forms a wiper that at least partially cleans the
wellbore and/or pipe of excess drilling mud during fluid
circulation through an annulus. In an embodiment, a wiper of
crosslinker and polymer is capable of use before the flow of cement
into the annulus, thereby cleaning the annulus of at least a
portion of the excess mud. In an alternate embodiment, a wiper of
crosslinker and polymer is capable of use immediately preceding the
flow of cement into the annulus, thereby cleaning the annulus of at
least a portion of the excess mud. In various embodiments, the use
of a wiper of the present invention reduces drilling time because a
separate circulation cleaning step is not needed.
EXAMPLES
[0053] This invention has been proven using borax as a common cross
linker for polyvinyl alcohol (PVA) as the cross linking agent
active ingredient by Applicants in the laboratory. These materials
have been used before as fluid loss control agents, but only as a
combined one step package. When used as a pre-blended or combined
fluid loss control agent, the reaction of cross linking occurs in
the cement slurry at the initial mixing time when water is added to
the dry cement materials. As a result of this reaction in the early
slurry life, the cross linking reaction creates a fragile structure
that is temperature limited to about 200 degrees F. and requires a
great excess of fluid loss material to control the fluid loss. Also
the early reaction creates an increase in viscosity and possible
gelatin of the slurry. Such rheology problems increase the demands
on pumping equipment and change the desired state of turbulent flow
to plug flow or laminar flow. Turbulent flow is an accepted method
to increase mud removal and subsequent bond improvement.
[0054] The addition of fine particulate material, such as for
example calcium carbonate, which has been ground or precipitated to
less than 50 micron in average diameter, to the polyvinyl alcohol
prior to mixing it with the cement will be beneficial. These
particles are carried by the polyvinyl alcohol as it begins to
soften in the aqueous slurry and can contribute to the plugging
action of the permeable formation. The addition of fine particulate
material which is initially non-reactive in the early reaction of
cement hydration by has a surface binding to the polyvinyl alcohol
to carry by a gluing action the solid particles which help to crate
the "plug" for fluid loss prevention. The Portland cement particles
cannot usually function in this manner since upon hydration, the
surface of the cement goes into solution in a "sloughing" action.
Also, this is considerably more important if the particular cement
slurry formulation has high gel strength properties. Such a gelled
slurry will usually not allow the cement grains to move the desired
fluid loss plug area.
[0055] Applicants have documented using borax as a pre-wash and
primer for cross linking a following polyvinyl alcohol in testing
done in accordance with American Petroleum Institute procedures as
outlined in API RP 10 publication. Variation from the strict test
procedures were done in regard to simulation of a mud cake
formation face as the permeable interface for fluid loss tests. The
standard filter medium was 3.5 sq. in. in area. A 45 mm screen (No.
325) was supported by a 250 mm screen (No. 60). In order to
simulate a mud covered formation face, the tests were conducted by
sandwiching a 1/16 smear of thick bentonite mud between Whatman No.
1 qualitative filter paper. The mud was soaked with 2 ml of a
solution containing 0.2 grams of borax. This "mud sandwich" was
placed on the standard screen and fluid loss tests were conducted
as outline in the API procedures. To verify the improved control of
the invention, tests were run using the "mud sandwich" without
borax and without the following polyvinyl alcohol.
[0056] Tests show that the polyvinyl alcohol, or other polymer, can
be reduced to less than 0.1 percent by weight of dry cement and
still maintain excellent fluid loss control at the low
temperatures. The conventional pre-cross linked method uses as much
as 10 times as much fluid loss additive. Temperature limits easily
were above the 200.degree. F. (93.3.degree. C.) limit of the
conventional technique and were in fact found to extend to the
break down temperature of the polyvinyl alcohol which is above
300.degree. F. (148.9.degree. C.) for the particular polyvinyl
alcohol tested. It is believed that the temperature could exceed
this for a material with higher temperature stability.
[0057] As such, various embodiments of the present invention
comprise a method for inhibiting fluid loss from an oil and gas
well, said method comprising the steps of, separately:
[0058] washing a well borehole with a wash composition, said wash
composition comprising a cross linking agent, wherein said cross
linking agent at least partially impregnates a formation's face
and
[0059] pumping a cement mixture into said well's borehole to cement
at least a portion of a formation face, said cement mixture
comprising a polymer composition, wherein said polymer polymerizes
in, on, or about said formation's face upon exposure to said cross
linking agent, thereby inhibiting fluid loss from said well's
borehole to said formation. In various embodiments, the step of
washing at least partially cleans the well of excess mud. In
various further embodiments, the step of washing at least partially
impregnates at least one of said borehole's tubing and said
borehole's formation face with said cross linking agent. In various
embodiments, the cross linking agent is added to the well along
with oil-based drilling mud or "spacer". As such, in various
embodiments, the cross linking agent is at least one of borax,
boric acid, water soluble borates, sodium borates, calcium borates,
potassium borates, titanates, zirconates, and mixtures thereof. In
various further embodiments, a fine particulate material is added
to the polymer prior to mixing it with the cement mixture, such as
calcium carbonate. In various embodiments, the polymer is at least
one of polyvinyl alcohol, a low viscosity partially hydrolyzed
polyvinyl alcohol such as DuPont Elvanol.RTM. 51-05S8.
[0060] Various further embodiments disclose a method for inhibiting
fluid loss from an oil and gas well, the method comprising the
steps of, separately:
[0061] washing a well with a reactant agent that creates a
thickened reaction product when a secondary mixture is encountered,
and
[0062] adding secondary mixture to the well's borehole which forms
a thickened reaction product upon exposure to the reactant, thereby
inhibiting fluid loss from the well's borehole to the well
borehole's formation.
[0063] In all embodiments, the step of washing is capable of being
removed and the cross linking agent is included with a drilling
fluid circulated in the well's borehole prior to adding the cement
mixture.
[0064] Various further embodiments disclose a kit for inhibiting
fluid loss from an oil and gas well comprising:
[0065] a wash composition, the wash composition comprising a cross
linking agent and
[0066] a polymer composition, wherein the polymer polymerizes in,
on, or about the formation's face upon exposure to the cross
linking agent, thereby inhibiting fluid loss from the well's
borehole to the formation.
[0067] Various further embodiments disclose a polymerized well
borehole, the polymerized well borehole formed by a method as
herein disclosed.
[0068] A method for reducing an amount of fluid loss additive
necessary to inhibit fluid loss from an oil and gas well, the
method comprising the steps of, separately:
[0069] washing a well borehole with a wash composition, the wash
composition comprising a cross linking agent, wherein the cross
linking agent at least partially impregnates a formation's face
and
[0070] pumping a cement mixture into the well's borehole to cement
at least a portion of a formation face, the cement mixture
comprising a polymer composition, wherein the polymer polymerizes
in, on, or about the formation's face upon exposure to the cross
linking agent, thereby inhibiting fluid loss from the well's
borehole to the formation, wherein between about 0.1% and about 90%
by volume of a contemporary fluid loss additive is used to inhibit
fluid loss. In various embodiments, the fluid loss additive's
components are the same as the components of the contemporary fluid
loss additive.
[0071] In all methods and kits herein disclosed, the cement mixture
is capable of comprising a permeable, micro-cluster silica material
present in an amount from about 10 percent to about 30 percent by
weight of the cement mixture, wherein the permeable, micro-cluster
silica material has an average particle size ranging from about 30
to about 80 microns and a range of distribution from about 1 micron
to about 200 microns.
[0072] Further embodiments of the present invention comprise kits.
Kits of the present invention are capable of containing different
constituents or components of the cement mixture. In an embodiment,
a kit of the present invention comprises a polymer. In an alternate
embodiment, a kit of the present invention comprises a polymer and
a cross linking agent. Further kits may include, alternatively,
retarders, defoamers, fluid loss additives, glass beads, perlite
and/or the like.
[0073] The invention may be embodied in other specific forms
without departing from its spirit or essential characteristics. The
described embodiments are to be considered in all respects only as
illustrative and not restrictive. The scope of the invention is,
therefore, indicated by the appended claims rather than by the
foregoing description. All changes to the claims that come within
the meaning and range of equivalency of the claims are to be
embraced within their scope. Further, all published documents,
patents, and applications mentioned herein are hereby incorporated
by reference, as if presented in their entirety.
Additional Examples
[0074] Previous methods of fluid-loss control has been attempted by
a one-step addition of fluid-loss control additive to the cement,
which hopefully reduces the ability of the liquid portion of the
slurry from rapidly penetrating a permeable zone at the formation
face. This creates a critical dependence of the fluid control on
the use of a fluid-loss control additive that functions at the
temperature of the permeable zone. Also, the cement slurry must be
designed to compliment the requirements of the fluid-loss additive
for rheology of the fluid portion of the cement slurry. Most
fluid-loss control additives thicken the cement slurry they are
mixed into. Also, they may retard the hardening of the cement when
it reaches the destination. To deal with such properties it is
common for service companies to have many different fluid-loss
control additives and to select the "best fit" for the well
conditions that are to be encountered.
[0075] What we have discovered and developed is a composition and
method that uses a two-stage process to allow the use of one
"BorePrime" (such term is not meant as a limitation but as a short
hand identification of the process) composition which can function
as a pre-wash and "seeding" of the permeable zone of the formation
face, and a second or follow-up composition which can be the actual
cement slurry which contains the reactive "PrimeBloc" (such term is
not meant as a limitation but as a short hand identification of the
process) composition. The "Prime" method is not as affected by
temperature as most fluid-loss additives and can function from near
freezing 32.degree. F. (0.0.degree. C.) to above 400.degree. F.
(204.4.degree. C.). Further enhancements of the base bore prime
technology have resulted in the discovery of mixtures, processes
and compositions whereby the fluid loss additive is capable of
being added at about the same time as the cement mixture.
[0076] "BorePrime" is to be used as a pre-wash or as a "spacer"
additive or drilling mud additive that is non-toxic and
environmentally clean. As a chemical wash the cost is very low
compared to complex chemical washes. The "BorePrime" can be
formulated as a non-thickened water base fluid that will allow
turbulent flow in the annulus at very low pump rates. The turbulent
flow has been observed in laboratory simulations that show the
churning action that occurs at the front of the injected wash. The
detergent action of the "BorePrime" together with the turbulent
flow will granulate the excess mud adhering to the pipe and the
loose mud at the formation face and carry the material out of the
well. During this cleaning action a "seeding" will take place at
the formation face which impregnates the mud cake with "BorePrime"
chemical. The concentration will vary depending on the permeability
at the formation face; the higher concentration typically going
into the more permeable zones.
[0077] "BorePrime" can also be used in drilling mud or "spacers" to
be available when later injection of "PrimeBloc" takes place. Thus
fluid-loss control could be obtained without the necessity of the
"BorePrime" wash, which in certain circumstances might not be
desired. There is the possibility that a wash is not always an
option if such things as disposal of fluids is an issue.
[0078] In various embodiments, "PrimeBloc" can be added to the
cement mixture as a dry or liquid fluid-loss control additive that
requires a "BorePrime" wash to be used ahead or to be used when the
drilling mud or "spacer" has previously carried the "BorePrime".
The "PrimeBloc" is also very low in cost compared to complex
fluid-loss control additives and requires an order of magnitude
less material than conventional additives, in various embodiments
because of the permeability block occurring at the formation-cement
interface where the reaction of the "PrimeBloc" and "BorePrime"
takes place. If the reaction had taken place in the cement slurry
prior to reaching the permeable formation, the slurry would be much
thicker and usually have to contain more water to reduce the
viscosity of the reacted chemicals. Concentrating the reaction at
the pressure-differential interface means the cement slurry doesn't
have to carry materials which can cause excessive viscosity or
otherwise excessive amounts of fluid-loss control material.
Likewise this frees the slurry designer from the excess viscosity
of most fluid-loss control methods. Testing at the low temperatures
has shown fluid-loss control with less than 0.1 percent fluid-loss
control additive in the "PrimeBloc" whereas a one stage fluid-loss
test using conventional methods and materials requires 1 percent or
more.
[0079] In various embodiments, the discovery of a two-stage method
and also the type of chemicals in the method should be a
significant improvement for fluid-loss prevention and permeable
interface sealing. Such a technique could be utilized in any type
of permeable situation to minimize leak-off of fluid from a
well-bore, pond, lake, or dam. In alternate embodiments, the use of
an additive should result in significant improvement for fluid loss
prevention and permeable interface sealing.
Description of an Embodiment of Prime Technology
[0080] In various embodiments, this discovery has been proven in an
embodiment using a common crosslinker for polyvinyl alcohol (Borax)
as the "BorePrime" active ingredient. The "PrimeBloc" active
ingredient used in our laboratory work was PVA (polyvinyl alcohol).
These materials have been used before as fluid-loss control agents
but only as a combined one-step package. When used as a pre-blended
or combined fluid-loss control agent the reaction of cross-linking
occurs in the cement slurry at the initial mixing time when water
is added to the dry cement materials. As a result of this reaction
in the early slurry life, the cross-linked reaction creates a
fragile structure that is temperature limited to about 200.degree.
F. (93.3.degree. C.) and requires a great excess of fluid-loss
material to control fluid loss. Also, the early reaction creates
viscosity increase and possible gellation of the slurry. Such
rheology problems increase the demands on pumping equipment and
changes the desired state of turbulent flow to plug flow or laminar
flow. Turbulent flow is an accepted method to increase mud removal
and subsequent bond improvement.
[0081] Using borax as a pre-wash and primer for cross-linking a
following polyvinyl alcohol has been documented in our laboratory
testing under American Petroleum Institute procedures as outlined
in API RP 10 publications. Variations from the strict test
procedures were done in regard to simulation of a mud caked
formation face as the permeable interface for fluid-loss tests. The
standard filter medium is 3.5 sq. in. in area. A 45 mm screen (No.
325) is supported by a 250 mm screen (No. 60). In order to simulate
a mud covered formation face our tests were conducted by
sandwiching a 1/16 smear of thick bentonite mud between Whatman No.
1 qualitative filter paper. The mud was soaked with 2 ml of a
solution containing 0.2 grams of borax. This "mud sandwich" was
placed on the standard screen and fluid-loss tests were conducted
as outlined in API procedures. To verify the improved control of
the invention tests were run using the "mud sandwich" without borax
and without the following polyvinyl alcohol.
[0082] Polyvinyl alcohol contents of less than 0.1 percent by
weight of dry cement used produced excellent fluid-loss control.
The conventional pre-crosslinked method uses as much as 10 times as
much fluid-loss additive. Temperature limits easily were above the
200.degree. F. (93.3.degree. C.) limit of conventional technique
and were in fact found to extend to the break down temperature of
the polyvinyl alcohol which is above 300.degree. F. (148.9.degree.
C.) for the particular polyvinyl alcohol our testing was utilizing.
It is only logical that the temperature could exceed this for a
material with higher temperature stability.
Mud Impregnated Screen
[0083] For testing, a modified filter has to retain Bore Prime
chemical in such a way as to simulate a cementing job that used the
Bore Prime in a pre-wash or spacer type application pumped ahead of
a cement slurry. Simulating a permeable formation face that has a
mud cake imbedded was the objective. To accomplish this a stainless
screen without the 325 mesh but with only the 60 mesh back-up was
used as the base for the simulation filter. Mud cake was a mixture
of bentonite and water at a paste consistency that was layered
across the back of the back-up screen. A dose of approximately 1 ml
of the Bore Prime wash was then applied to the mud face that was
against the 60 mesh. Next, a Whatman filter (cat. # 1003-055) that
had been pre-soaked and air dried was lain on the 60 mesh and
wetted with 1 ml of the Bore Prime wash. The cap of the fluid-loss
cell that the back-up screen attaches to was then pushed against
the mud side of the back-up screen, allowing the mud to move into
the 60 mesh screen and against the Whatman filter paper.
[0084] This prepared filter was then inserted in the fluid-loss
cell and tested as required by API RP10b. If a test at moderate to
high temperature was to be run, then the prepared filter was held
out of the fluid-loss cell until the cell was ready to receive the
cement slurry. This alternate procedure is necessary to avoid
dehydration of the mud cake on the prepared filter before
testing.
[0085] Generally, any mock or simulated mud procedure can be used
as long as a control is run.
Mud Sandwich
[0086] A "mud sandwich" filter can be used instead of the mud
impregnated screen. To prepare this type filter use 60 mm diameter
Whatman #3, which can be cut from (Whatman Cat No 1003 070) using a
circle cutter such as AC-1 circle cutter from
(www.buttonsonline.com). Use two papers with a layer of mud paste
(100 g bentonite in 500 ml water) between them approximately 2 mm
thick. The mud and papers should be dosed with Bore Prime wash made
from 1 gram of Bore Prime in 100 ml of fresh water. This "mud
sandwich" should be attached to the stainless screen using mud as
an adhesive to hold the sandwich during assembly of the fluid-loss
cell prior to running the fluid-loss test. As before mentioned, do
not preheat this sandwich since it will dehydrate. Add it to the
cell just before adding the cement slurry.
Results
[0087] Slurry and mud compositions:
TABLE-US-00001 Prime Bloc: Lehigh class H cement Retarders HR-5,
HR-12, SCR-100, Prime Bloc 1 PVA (polyvinyl alcohol) about
55%-about 65% Albaglos PCC about 35%-about 45% A precipitated
calcium carbonates (PCCs) designed for coated paper and paperboard
applications. Defoamer about 1% 40208pva (3 parts Elvanol 71-31
pva, 3 parts Elvanol 50-42s8pva, 4 parts precipitated CaCO.sub.3)
Filters: 32008a(Whatman qualitative #3), EX-1(0.4 parts borax, 100
parts water), 40408a (12 parts boric acid, 300 parts water), 40408c
(16 parts borax, 4 parts dish detergent WalMart GV), mud was made
from bentonite/water paste, salty mud had 40 parts bentonite paste
+ 10 parts NaCl) Filters were permeable paper or mud smears that
had Bore Prime chemical. PVA: Dupont Elvanol 50-42S8 Wilmington,
DE. 302-478-5491 Eliot Echt (1-302-478-5491) Albaglos PCC:
Specialty Minerals Inc.Adams, MA. 413-743-0591 Mark Spurlock
(1-281-658- 6954) Defoamer DF: BASF Global Oilfield Solutions,
Houston, Tx. 281; 820-0955 Bore Prime: Borax Decahydrate Granular
about 65%-about 85% Auto Dish Detergent about 15%-about 35% Borax:
U.S. Borax Inc., 26877 Tourney Road, Valencia, CA 91355-1847, Larry
Jayroe, Rio Tinto Minerals, U.S. Borax, Inc./Luzenac P.O. Box 1093,
Forrest City, AR 723336, Phone 870.630.0895, Auto Dish Detergent:
Wal-Mart Great Value Automatic Dishwashing Detergent Huish
Detergents, Inc. 3540 W/ 1987 S.. Salt Lake City, UT 84104
Experiment 1
TABLE-US-00002 [0088] Fluid Loss Viscosity Sample Slurry
Composition Temp .degree. F. (ml/time) (Bearden units) LW540-3
Lehigh + 0.5% (Primebloc 1) + 150 47/103 sec. 6 (initial) 17
(final) 0.2% HR-5 + 44% water (32008a filter used) LW540-4 Lehigh +
0.75% (Primebloc 1) + 150 34/30 min. 6 15 0.2% HR-5 + 44% water
(32008a filter used) LW540-6 Lehigh + 0.75% (Primebloc 1) + 190
41/18 sec. 12 34 0.08% HR-12 + 54% water (32008a filter used)
LW540-7 Lehigh + 1% (Primebloc 1) + 190 39/45 sec. 12 36 0.08%
HR-12 + 54% water (32008a filter used) LW540-8 Lehigh + 1.25%
(Primebloc 1) + 190 41/43 sec. 12 35 0.08% HR-12 + 54% water
(32008a filter used) LW540-9 Lehigh + 1.25% (Primebloc 1) + 190
32/165 sec. 13 23 0.08% SCR-100 + 54% water (32008a filter used)
LW541 Lehigh + 1% (40208pva) + 0.08% 190 44/25 sec. 12 35 HR-12 +
35% silica flour + 54% water (using 32008a filter) LW542 Lehigh +
1.25% (Primebloc 1) + 190 42/43 sec. 11 22 0.08% SCR-100 + 35%
silica flour + 54% water (using 32008a filter) LW540b Lehigh + 1.5%
(Primebloc 1) + 190 26/1126 sec. 12 20 0.08% SCR-100 + 35% silica
flour + 54% water (using 32008a filter) LW540b-2 Lehigh + 1.25%
(Primebloc 1) + 190 37/81 sec. 12 20 0.08% SCR-100 + 35% silica
flour + 54% water (using 32008a filter) LW540b-3 Lehigh + 1.75%
(Primebloc 1) + 190 47/30 min. 12 20 0.08% SCR-100 + 35% silica
flour + 54% water (using 32008a filter) Lehigh + 1.67% (Primebloc
1) + 190 33/307 sec. -- -- 0.08% SCR-100 + 35% silica flour + 54%
water (using 32008a filter) LW543 Lehigh + 1.58% (Primebloc 1) +
190 30/865 sec. 21 30 0.08% HR-12 + 35% silica flour + 54% water
(using EX-1 filter) LW540b-5 Lehigh + 2.25% (Primebloc 1) + 230
76/32 sec. -- -- 0.5% HR-12 + 35% silica flour + 54% water (using
3200a filter) Lehigh + 2.25% (Primebloc 1) + 230 33/30 min. -- --
0.5% HR-12 + 35% silica flour + 54% water (using 40408a filter 1)
LW540c Lehigh + 2.5% (Primebloc 1) + 270 12/30 min. 15 10 0.67%
HR-12 + 35% silica flour + 54% water (using 40408c filter) LW540c-2
Lehigh + 2.5% (Primebloc 1) + 300 115/552 sec. 15 10 0.83% HR-12 +
35% silica flour + 54% water (using 40408c filter) LW540c-4 Lehigh
+ 2.75% (Primebloc 1) + 325 1.7/30 min. -- -- 0.83% HR-12 + 35%
silica flour + 54% water (using 40408c filter against mud smear on
60 mesh wire screen without 325 wire screen) LW540c-5 Lehigh +
2.75% (Primebloc 1) + 350 70/66 sec. -- -- 0.83% HR-12 + 35% silica
flour + 54% water (using 40408c filter against mud smear on 60 mesh
wire screen without 325 wire screen) LW540c-6 Lehigh + 3.25%
(Primebloc 1) + 350 94/171 sec. -- -- 0.83% HR-12 + 35% silica
flour + 54% water (using 40408c filter against mud smear on 60 mesh
wire screen without 325 wire screen) LW540 Incor HE + 0.25%
(Primebloc 1) + 80 47/30 min. 20 40 48% water (using 32008a filter)
LW540-2 Incor HE + 0.25% (Primebloc 1) + 100 24/30 min. 15 40 50%
water (using 32008a filter) LW540-5 Incor HE + 0.16% (Primebloc 1)
+ 80 55/30 min. 12 30 50% water (using 32008a filter) LW540d Lehigh
+ 2.5% (Primebloc 1) + 310 55/30 min. -- -- 0.83% HR-12 + 35%
silica flour + 54% water (using 40408c filter sandwiched on mud
smear) LW540b-6 Lehigh + 2% (Primebloc 1) + 0.5% 250 16/30 min. --
-- HR-12 + 35% silica flour + 54% water (using 40408c filter
sandwiched on mud smear) LW540b-7 Lehigh + 0% (Primebloc 1) + 0.5%
250 148/65 sec. -- -- HR-12 + 35% silica flour + 54% water CONTROL
TEST (using 40408c filter sandwiched on mud smear) LW540b-8 Lehigh
+ 2% (Primebloc 1) + 0.5% 230 4/30 min. -- -- HR-12 + 35% silica
flour + 54% water (using 40408c filter sandwiched on mud smear
using 60 mesh wire, no 325 mesh) LW540b-9 Lehigh + 1.5% (Primebloc
1) + 230 55/30 min. -- -- 0.5% HR-12 + 35% silica flour + 54% water
(using 40408c filter sandwiched on mud smear) LW540c-7 Incor HE +
0.125% (Primebloc 1) + 80 blew out too rapidly -- -- 48% water to
measure (using 40408c filter with mud smear against 60 mesh back-up
screen) 2.sup.nd test (using 40408c filter with 80 70/30 min. -- --
mud smear against standard back- up screen, 60 mesh on 325 mesh)
LW540c-8 Incor HE + 0.167% (Primebloc 1) + 80 43/1123 sec. -- --
50% water (using two 40408c filters against standard back-up
screen, 60 mesh on 325 mesh) 2.sup.nd test (using two 40408c
filters 80 45/85 sec. -- -- against standard back-up screen, 60
mesh on 325 mesh)- LW540c-9 Incor HE + 0.125% (Primebloc 1) + 80
38/303 sec. -- -- 50% water (using two 40408c filters against 60
mesh back-up screen) LW540c- Incor HE + 0.25% (Primebloc 1) + 80
47/121 sec. -- -- 10 50% water (using two 40408c filters against 60
mesh back-up screen) 2.sup.nd test (using two 40408c filters 80
52/30 min. -- -- against standard 60 mesh on 325 mesh)- LW540c-
Incor HE + 0.25% (Primebloc 1) + 80 44/30 min. -- -- 11 50% water
(using two 40408c filters as a sandwich on mud smear against 60
mesh without 325 mesh) 2.sup.nd test (using two 40408c filters 100
45/30 min. -- -- as a sandwich on mud smear against 60 mesh without
325 mesh)- LW540c- Lehigh + 3.25% (Primebloc 1) + 350 blew out
gummy liquid in 69 sec, used 12 0.83% HR-12 + 35% silica flour +
500 psi test pressure 54% water (using two 40408c filters as a
sandwich on mud smear against 60 mesh without 325 mesh) LW540c-
Lehigh + 3.25% (Primebloc 1) + 350 blew out gummy liquid in 79
sec., used 12 0.83% HR-12 + 35% silica flour + 500 psi test
pressure 54% water (using two 40408c filters as a sandwich on salty
mud smear against 60 mesh without 325 mesh)
Experiment 2
TABLE-US-00003 [0089] tests at Lab 1000 psi Viscosity Work Fluid
Loss (Bearden ID Composition (ml/time)* units)** LW511 Prime Bloc 2
(21% PVA, 78% CaCO.sub.3, 1% defoamer) NA NA LW512 Lafarge + 0.7%
(Primebloc 2) + 46% water (using Bore Prime 1.sup.st 58/ 12 20
filter EX1) test 30 min (initial) (final) 2.sup.nd 38/ -- -- test
30 min LW513 Lafarge + 0.7% (Primebloc 2) + 46% water (using Bore
Prime 1.sup.st 37/ 11 17 filter EX2) test 30 min 2.sup.nd 41/30 min
-- -- test LW521 Lafarge + 0.7% (Primebloc 2) + 46% water (using
Bore Prime filter 1.sup.st 34/ 10 18 31208) test 30 min (tested at
2.sup.nd 49/ -- -- 110.degree. F.) test 30 min LW531 Lafarge + 0.7%
(Primebloc 2) + 46% water (using Bore Prime filter 1.sup.st 50/ 12
18 32008b) test 30 min (tested at 2.sup.nd 36 ml/ -- -- 125.degree.
F.) test 337 sec. LW533 Lafarge + 0.7% (Primebloc 2) + 0.067% HR-4
+ 46% water (tested 39 ml/ 10 31 at 125.degree. F., using 32008a
filter) 1345 sec. Lafarge + 0.7% (Primebloc 1) + 0.067% HR-4 + 46%
water (tested 29/30 min 10 25 at 125.degree. F., using 32008a
filter) LW534 Lafarge + 0.7% (Primebloc 2) + 0.067% HR-4 + 48%
water (tested 63/30 min 9 21 at 125.degree. F., using 32008a
filter) Lafarge + 1% (Primebloc 2) + 0.067% HR-4 + 48% water
(tested at 55/30 min 10 21 125.degree. F., using 32008a filter)
LW535 Lafarge + 0.7% (Primebloc 2) + 0.1% HR-4 + 48% water (tested
at 46 ml/15 sec. 5 20 175.degree. F., using 32008a filter) Lafarge
+ 1% (Primebloc 2) + 0.1% HR-4 + 48% water (tested at 57 ml/18 sec.
5 18 175.degree. F., using 32008a filter) Note: Test temperature
was 80.degree. F. unless otherwise noted. Primebloc 2; 0.7% Prime
Bloc 2 is about the equivalent of 0.147% PVA. Prime Bloc 1 is a
higher PVA composition (sample 389, 59% PVA, 40% precipitated
CaCO3, 1% defoamer) Lafarge type I cement was used in the tests.
Test LW527 was held at 1000 psi for 15 min before opening valve
stem very slightly attempting to study effect on fluid loss rate.
IRF-105 is a Tucker Energy Services fluid loss additive seen as a
competitive product. HR-4 is a retarder, as might be available from
Halliburton. Defoamer was commercial powder grade. *Fluid loss was
conducted according to API RP 10 with the exception of when "Prime"
filters were used to apply reactive chemical to the fluid as it
entered the permeable membrane (filter screen). Control tests have
shown the "Prime" filter offers no blockage to fluid without the
PVA containing secondary reaction product entering the screen.
**Viscosity was taken from the atmospheric consistometer that was
used to stir the cement slurry before testing in the high pressure
fluid loss cell.
* * * * *