U.S. patent application number 13/136237 was filed with the patent office on 2013-01-31 for preserving oil gravity.
This patent application is currently assigned to Conlen Surfactant Technology, Inc.. The applicant listed for this patent is Larry W. Gatlin. Invention is credited to Larry W. Gatlin.
Application Number | 20130025857 13/136237 |
Document ID | / |
Family ID | 47596280 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130025857 |
Kind Code |
A1 |
Gatlin; Larry W. |
January 31, 2013 |
Preserving oil gravity
Abstract
Volatile organics in newly produced oil and gas, and/or
condensates and distillates from produced oil and gas, are treated
to depress vapor pressure to preserve light hydrocarbons in them
when they are in storage vessels. The loss of volatile organics
during storage of high gravity oil is minimized by forming a
flowable or pumpable gel in the high gravity oil, (and/or
condensates and distillates), as they are introduced to a storage
vessel. The gel-former may comprise a phosphate ester of one or
more low molecular weight alcohols, and a crosslinker including a
source of iron or aluminum. Although the gels are flowable and
pumpable, they can be broken for transportation from the production
site or at another desirable time, returning the hydrocarbon
product to its original properties.
Inventors: |
Gatlin; Larry W.; (San
Antonio, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gatlin; Larry W. |
San Antonio |
TX |
US |
|
|
Assignee: |
Conlen Surfactant Technology,
Inc.
|
Family ID: |
47596280 |
Appl. No.: |
13/136237 |
Filed: |
July 27, 2011 |
Current U.S.
Class: |
166/267 |
Current CPC
Class: |
F17C 11/007
20130101 |
Class at
Publication: |
166/267 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. Method of inhibiting volatilization of light hydrocarbons from a
liquid mixture of hydrocarbons in a storage vessel comprising, (1)
prior to placing said liquid mixture of hydrocarbons in said
storage vessel, adding to said liquid mixture (a) a
phosphorous-containing gel former and (b) a source of polyvalent
metal crosslinking agent in an amount effective to form a pumpable
gel comprising said liquid mixture of hydrocarbons, and (b) pumping
said pumpable gel into said storage vessel.
2. Method of claim 1 wherein said liquid mixture of hydrocarbons is
a newly produced mixture of hydrocarbons from a producing oil
well.
3. Method of claim 1 wherein said liquid mixture of hydrocarbons is
a newly produced mixture of hydrocarbons from a producing gas
well.
4. Method of claim 1 wherein said pumpable gel has a Reid vapor
pressure in said storage vessel at lest two pounds per square inch
lower than said liquid mixture of hydrocarbons would have had
without said gel former and said crosslinking agent.
5. Method of claim 1 wherein said source of multivalent metal
crosslinking agent comprises a source of aluminum.
6. Method of claim 3 wherein said mixture of hydrocarbons from a
producing gas well comprises condensates from produced gas.
7. Method of storing and transporting newly produced high gravity
oil comprising (a) converting said high gravity oil to a weak gel,
(b) placing said weak gel in a storage vessel, (c) storing said
weal gel in said storage vessel, (d) breaking said weak gel to
render said high gravity oil substantially free of said weak gel,
and (e) transporting said high gravity oil to a new location.
8. Method of claim 7 wherein said transporting in step (e) is
conducted in a pipeline.
9. Method of claim 7 wherein said weak gel stored in step (c) has a
Reid vapor pressure no greater than 2 psi.
10. Method of claim 7 wherein said weak gel is broken in step (d)
by adding at least one aminoalcohol in an amount effective to break
said weak gel.
11. Method of storing newly produced high gravity oil to inhibit a
reduction in its high gravity by vapor loss comprising (a) adding
to said newly produced high gravity oil 0.001 to 0.02 parts by
volume phosphate ester of C.sub.2-C.sub.6 alcohol per cubic meter
of high gravity oil, (2) adding to said newly produced high gravity
oil containing said phosphate ester 0.001 to 0.02 parts by volume
of a crosslinker for said phosphate, thereby forming a pumpable
gel, and (c) introducing said newly produced high gravity oil in
the form of said pumpable gel to a storage vessel.
12. Method of claim 11 wherein said newly produced high gravity oil
has a Reid vapor pressure in said storage vessel in step (c) no
greater than 2 pounds per square inch.
13. Method of claim 11 wherein said high gravity oil has an API
gravity of 33.degree. or higher.
14. Method of claim 11 wherein said high gravity oil is a
condensate from natural gas.
15. Method of claim 11 wherein said newly produced high gravity oil
flows substantially continuously from a producing well to said
storage vessel and the additions of steps (a) and (b) are made into
said substantially continuously flowing high gravity oil .
16. Method of claim 15 wherein the adding of phosphate ester in
step (a) is conducted by adding said phosphate ester to said newly
produced high gravity oil as said oil flows from said producing
well to said storage vessel.
17. Method of claim 16 wherein said adding of said crosslinker of
step (b) is conducted after said phosphate is added in step (a) and
before said oil reaches said vessel in step (c).
18. Method of claim 11 wherein said phosphate ester is
predominantly a diester.
19. Method of claim 11 wherein said crosslinker contains iron.
20. Method of claim 11 wherein said crosslinker includes a
nitrogen-containing compound selected from amines, amides, and
imidazlines, and an oil selected from animal and vegetable oils.
Description
TECHNICAL FIELD
[0001] The invention relates to the conservation of volatile
organics in oil and gas, and/or condensates and distillates from
produced oil and gas, in storage vessels generally, but most
usefully as they are recovered from the earth. The loss of volatile
organics during storage of high gravity oil is minimized by forming
a flowable or pumpable gel in the high gravity oil, (and/or
condensates and distillates), as they are introduced to a storage
vessel. The gel-former may comprise a phosphate ester of one or
more low molecular weight alcohols, and a crosslinker including a
source of iron or aluminum. Although the gels are flowable and
pumpable, they can be broken after transportation from the
production site or at another desirable time, returning the
hydrocarbon product to its original properties.
BACKGROUND OF THE INVENTION
[0002] The American Petroleum Institute's system of classifying
crude oils includes designations by gravity, relating the oil to
the density of water. By this system, a high gravity oil is one
which contains a high concentration of volatile, low molecular
weight hydrocarbons, and a lower gravity oil will contain fewer
such components.
[0003] When a high gravity oil is recovered from the ground and
placed in a tank or other vessel not equipped with a special seal
or vent designed to contain or minimize vapor emissions,
substantial losses of light hydrocarbons can be incurred simply
from evaporation and volatilization. This not only represents an
economic loss but also is environmentally undesirable; moreover,
some of the volatile components--for example, benzene, toluene and
xylene in the atmosphere--could be hazardous for nearby
workers.
[0004] Liquid storage is also commonly provided for liquid
components removed from natural gas, sometimes known as
"condensates and distillates." Although in the liquid phase at the
time of removal from the produced gas, they tend to include
significant concentrations of readily volatilized light
hydrocarbons, which are especially vulnerable to loss.
[0005] Some tanks and other storage vessels are equipped with
special seals, pressure controls, or vents made to suppress
emissions not only during static storage conditions, but also when
the tanks are being filled or when the contents are being removed,
and otherwise when there may be a degree of turbulence in them.
Variations in head space when the vessels are low or near filled
are of course important factors in volatilization, as are
variations in temperature, which affect vapor pressures. Numerous
storage tanks in the field--in the vicinity of producing wells--are
not equipped with the expensive vents necessary to adjust to such
variations. A simple way of inhibiting volatilization in such
storage vessels is needed.
SUMMARY OF THE INVENTION
[0006] Although this invention is applicable to lower gravity oils,
it is most useful for high gravity oils, designated 33.degree. API
or higher, and is well suited for oils in the range of
40-45.degree. API. Perhaps the most beneficial use is with respect
to "condensates and distillates," typically produced with natural
gas, and sometimes described as "natural gas liquids," having API
gravities of 45.degree. to 60.degree.. For my purposes in this
application, a high gravity oil is defined as one having a gravity
of 33.degree. API or higher, including an API value higher than
60.degree., regardless of whether it is a crude oil or is derived
from natural gas; for example, a condensate (I consider
"condensate" and "distillate" to be interchangeable for my
purposes) from natural gas.
[0007] I are able to preserve the high gravity rating of high
gravity oils and condensates in storage by forming a weak gel in
the high gravity oil or condensate as it is conducted from the
producing well to the storage tank, it being understood that other
steps, such as filtration, may be practiced also during transport.
By a weak gel I mean one which is flowable and pumpable, so that
the normal passage from well to storage, including whatever
equipment or treatment steps are between, will not be unduly
retarded by a suddenly induced high viscosity. A strong gel is not
necessary to retard emissions in storage, and would require further
treatment to remove from the storage vessel. My weak gel is
substantially formed in the conduit prior to introduction to the
storage vessel.
[0008] Hydrocarbon gels are commonly used for fracturing fluids,
the gelling agents having been found to be excellent aids for
suspending propping agents. Virtually any gelling agent useful in a
hydrocarbon fracturing fluid may be used in my invention. Well
known gelling agents have two basic components--a
phosphorous-containing gelling agent, and a crosslinking agent
including a source of polyvalent metal; by a polyvalent metal, I
mean iron or aluminum.
DETAILED DESCRIPTION OF THE INVENTION
[0009] I may use any known gelling agent for hydrocarbons used in
fracturing fluids.
[0010] Generally I may use any of the combinations of
phosphorous-containing gelling agents and crosslinkers containing a
source of polyvalent metal described in the following patents, all
of which are incorporated herein specifically in their entirety:
[0011] Monroe U.S. Pat. No. 3,505,374, describing gels made with a
reaction product of Fe.sub.3O.sub.4 and an alkyl oleyl diester of
orthophosphoric acid. Other diesters of phosphoric acid may be
used. [0012] Crawford U.S. Pat. No. 3,757,864 uses aluminum salts
of alkyl aliphatic orthophosphate diesters as friction reducers in
flowing hydrocarbons. [0013] Griffin, in U.S. Pat. No. 4,153,649,
lists, in just a few lines of column 1, eighteen US patents said to
describe organic phosphoric acid esters used to thicken organic
liquids, and summarizes his invention in claim 1 as an organic
phosphate ester composition having as a property the ability to
increase the viscosity of kerosene when admixed in kerosene with
sodium aluminate, said composition being prepared by the process
which comprises the reaction of: [A] a pentavalent phosphorus
compound selected from the group consisting of P.sub.2O.sub.5 and a
mixture of P.sub.2O.sub.5 with polyphosphoric acid; [B]. a hydroxy
ether of the formula ROR.sub.1OH wherein R is a C.sub.1 to C.sub.6
alkyl group, R.sub.1 is a C.sub.2 or C.sub.3 alkylene group and the
total carbon atoms of R and R.sub.1 range from 3 to about 8; and
[C]. when the total carbon atoms of R and R.sub.1 and is 3 or 4, a
long chain substantially unsubstituted monohydric aliphatic alcohol
containing at least 5 carbon atoms, but when the total carbon atoms
of R and R.sub.1 is 5 to 8, an alcohol selected from the group
consisting of a long chain substantially unsubstituted monohydric
aliphatic alcohol containing at least 5 carbon atoms, a short chain
substantially unsubstituted monohydric aliphatic alcohol containing
from 1 to 4 carbon atoms and a mixture of said alcohols, the
individual mole ratios of the hydroxy ether, the long chain alcohol
and the short chain alcohol to total P.sub.2O.sub.5 being within
the ranges of 0.4:1 to 4.5:1; 0:1 to 4.0:1 and 0:1 to 5.0:1
respectively, said reaction being conducted at temperature ranging
from about 70.degree. to about 90.degree. C. for a period of time
of from about 1.5 to about 6 hours, and said pentavalent phosphorus
compound, hydroxy ether, and alcohol or alcohols being provided in
molar ratios and admixed in a sequence effective to provide a
reaction product suitable for use in increasing the viscosity of
kerosene. See also Griffin's U.S. Pat. Nos. 4,174,2283 and
4,152,289 disclosing additional aluminum salts of phosphate esters
useful for gelling fracturing fluids.
[0014] In U.S. Pat. No. 4,316,810; Burnham uses the term "pumpable"
as desirable for gelled fracturing fluids. He describes a class of
aluminum oxaalkyl phosphates useful for the purpose.
[0015] As indicated in Smith & Persinski U.S. Pat. No.
5,571,315 and related patents, a common orthophosphate diester may
be expresses as HPO.sub.4RR' where R is a straight or branched
chain alkyl, aryl, alkoxy, or alkaryl group having about 6 to about
18 carbon atoms and R' is hydrogen or an aryl, alkaryl, alkoxy, or
alkyl group having up to about 18 carbon atoms. These phosphates
are combined with ferric aluminum citrate to make gels in
hydrocarbon based fracturing fluids.
[0016] More complicated phosphorous-containing gelling agents are
described by Jones et al in U.S. Pat. No. 5,990,053 and U.S. Pat.
No. 6,147,034. Generally, they are two-component systems, one
providing a phosphorous-containing gelling agent and the other
providing a polyvalent metal, typically aluminum or iron. But see
also Taylor et al U.S. Pat. No. 7,534,745, who utilize as the
phosphorous-containing gelling agent various organophosphonic acid
esters and organophosphinic acid esters, again together with a
polyvalent metal.
[0017] For my purposes, while any orthophosphate diester of the
formula HPO.sub.4RR' where R is a straight or branched chain alkyl,
aryl, alkoxy, or alkaryl group having about 6 to about 18 carbon
atoms and R' is hydrogen or an aryl, alkaryl, alkoxy, or alkyl
group having up to about 18 carbon atoms may be used as the
phosphorous-containing material, I can use a product of the
reaction of orthophosphoric acid (PO.sub.4) with an excess of a
mixture of C.sub.2 to C.sub.6 alcohols to maximize the formation of
diesters.
[0018] For the crosslinker, while any known aluminum crosslinker
may be used, such as sodium aluminate or polyaluminum chloride, any
of the iron crosslinkers mentioned in the above patents or used
commercially in formation fracturing may be applied. For example, I
may use an iron solution such as ferric sulfate dispersed with a
mixture of imidazolines, amides and alkanolamides derived from
primarily vegetable oils and dimethylaminopropylamine and
diethanolamine. Vegetable oils include but are not limited to,
coconut, palm kernel, palm, soya, safflower, sunflower, linseed,
tall oil, rapeseed(high and low euric), and blown versions of the
above, or oxidized oil versions. Other non vegetable oils, as
tallow of swine, sheep(including lanolin), and beef or other
mammals, as well as aquatic species of fish, mammals, encompassing
many water living species.
[0019] The crosslinking composition may contain a coconut(food
grade) diethanolamide. The properties of this well known emulsifier
in the cosmetic and detergent-market is also used in the oilfield,
typically having a TAV of about 137 from diethanolamine, as the
amine equivalent weight of the amide is infinity. Stabilizers for
the crosslinking composition can be cellosolves, glycerin and/or
ethanols.
[0020] If the storage vessel is discharged into a sales line,
transmission line, or other pipeline of some length, the user may
wish to break the gel just prior to beginning discharge in order
not to unnecessarily consume energy in pumping because of the
viscosity of the gel, even though it is a weak gel. If the storage
vessel is discharged into a truck, it may be more efficient to wait
until the truck arrives at its destination; the benefits of high
gravity preservation will thereby be obtained while the truck holds
the weakly gelled hydrocarbons. The gel can be broken in either
case by adding a small amount of aminoalcohols, and especially in
the form of hexahydro triazines, aminoalcohol(reactions of glycidyl
ethers and secondary amines). Addition of the gel breaker can be
made either to the holding vessel or truck or directly to a pipe or
other conduit. Addition can be "batch" or substantially continuous
if the material is flowing, and may be coordinated with a
stabilizer or other system where light ends are deliberately
separated.
[0021] While viscosity is objectively measurable and useful in
evaluating my gels, it should be observed that our invention is not
simply a matter of increasing the viscosity of the stored
hydrocarbons, since it is normally desirable to break the gel on
termination of storage. In other words, I do not use polymeric
viscosifiers that cannot be readily broken down to restore the
original viscosity of the hydrocarbons. Moreover, crosslinked gels
are more efficient at suppressing emissions than are linear
polymers because they inhibit the formation of bubbles below the
surface of the stored hydrocarbons, while linear polymers may only
temporarily divert the ascent of small bubbles to the surface. A
crosslinked network on or near the liquid surface also physically
alters the phase interface, resulting in vapor pressure effects
favorable to retention of the lighter components of the stored
material. My gels containing butanes, pentanes, and other C5s to
C8s exhibit Reid Vapor pressure of <2 psi, while ungelled
hydrocarbon liquids and vapors have Reid vapor pressures of 3 to 8
psi or even higher. My method will frequently provide a Reid vapor
pressure is a hydrocarbon storage vessel at least two Reid vapor
pressure units lower than it would be without my invention.
[0022] My invention includes inhibiting volatilization of light
hydrocarbons from a liquid mixture of hydrocarbons in a storage
vessel comprising, (1) prior to placing said liquid mixture of
hydrocarbons in said storage vessel, adding to said liquid mixture
(a) a phosphorous-containing gel former and (b) a source of
polyvalent metal crosslinking agent in an amount effective to form
a pumpable gel comprising said liquid mixture of hydrocarbons, and
(b) pumping said pumpable gel into said storage vessel.
[0023] My invention also includes a method of storing and
transporting newly produced high gravity oil comprising (a)
converting said high gravity oil to a weak gel, (b) placing said
weak gel in a storage vessel, (c) storing said weal gel in said
storage vessel, (d) breaking said weak gel to render said high
gravity oil substantially free of said weak gel, and (e)
transporting said high gravity oil to a new location.
[0024] In another aspect, my invention includes a method of storing
newly produced high gravity oil to inhibit a reduction in its high
gravity by vapor loss comprising (a) adding to said newly produced
high gravity oil 0.001 to 0.02 parts by volume phosphate ester of
C.sub.2-C.sub.6 alcohol per cubic meter of high gravity oil, (2)
adding to said newly produced high gravity oil containing said
phosphate ester 0.001 to 0.02 parts by volume of a crosslinker for
said phosphate, thereby forming a pumpable gel, and (c) introducing
said newly produced high gravity oil in the form of said pumpable
gel to a storage vessel.
* * * * *