U.S. patent application number 10/772561 was filed with the patent office on 2004-10-07 for method and product for cementing hydrocarbon wells.
This patent application is currently assigned to Diversity Technologies Corp.. Invention is credited to Jabs, William.
Application Number | 20040194957 10/772561 |
Document ID | / |
Family ID | 33035039 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040194957 |
Kind Code |
A1 |
Jabs, William |
October 7, 2004 |
Method and product for cementing hydrocarbon wells
Abstract
A method of and product for use in cementing the annulus of a
hydrocarbon well having a casing centered within a hole bored from
a surface. The method comprises the steps of introducing an
effective amount of colouring agent contained in a water-soluble
bag into a portion of spacer or scavenging fluid, pumping the
spacer or scavenger and a then cementing slurry down the casing to
the bottom of the hole to displace drilling mud upwardly through
the annulus to the surface, until the colouring agent becomes
visible at the surface, displacing the casing volume and then
stopping the pumping and allowing the pumped cement slurry to
harden.
Inventors: |
Jabs, William; (Edmonton,
CA) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Assignee: |
Diversity Technologies
Corp.
|
Family ID: |
33035039 |
Appl. No.: |
10/772561 |
Filed: |
February 5, 2004 |
Current U.S.
Class: |
166/250.14 ;
166/250.01; 166/291; 507/269; 507/271; 507/928; 73/152.18;
73/152.57 |
Current CPC
Class: |
E21B 33/14 20130101;
C04B 40/0641 20130101; C04B 40/0641 20130101; C04B 40/0641
20130101; C09K 8/424 20130101; C04B 28/02 20130101; C04B 2103/54
20130101; C04B 14/022 20130101; C04B 14/30 20130101; C04B 14/304
20130101; C04B 14/308 20130101; C04B 28/02 20130101; C04B 14/307
20130101; C04B 2103/0077 20130101; C04B 16/00 20130101 |
Class at
Publication: |
166/250.14 ;
166/291; 166/250.01; 073/152.18; 073/152.57; 507/269; 507/271;
507/928 |
International
Class: |
E21B 047/10; E21B
033/16 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2003 |
CA |
2,424,800 |
Claims
1. A method of cementing the annulus of an oil or gas well having a
casing centering within a hole bored from a surface, the method
comprising the steps of introducing an effective amount of
colouring agent contained in a water-soluble bag into a water-based
separating fluid, pumping said water-based separating fluid ahead
of a cementing slurry down the casing to the bottom of the hole to
displace drilling mud upwardly through the annulus to the surface,
until the colouring agent becomes visible at the surface,
displacing the casing volume and then stopping the pumping and
allowing the pumped cement slurry to harden.
2. A method according to claim 1 wherein the water-based separating
fluid is a spacer or a scavenger fluid.
3. A method according to claim 2, wherein the water-soluble bag is
made from polyvinyl alcohol, the colouring agent being sealed in
the bag to keep it dry until use.
4. A method according to claim 2, wherein the colouring agent is a
powder selected from dyes or pigments conventionally used to colour
concrete.
5. A method according to claim 4, wherein the dye is selected from
the group comprising carbon black, iron oxide, phthalocyanine,
umber, chromium oxide, titanium oxide, and cobalt blue.
6. A method according to claim 4, wherein the dye is a powder
selected from dyes conventionally used to colour concrete.
7. A product for carrying out the method of claim 1, which product
comprises an effective amount of colouring agent contained in a
water-soluble bag, the colouring agent being sealed within the bag
to keep the colouring agent dry until use.
8. A product according to claim 7, wherein the colouring agent
comprises a powdered admixture used to colour concrete.
9. A product according to claim 8, wherein the admixture comprises
one or more pigments selected from the group comprising carbon
black, iron oxide, phthalocyanine, umber, chromium oxide, titanium
oxide, and cobalt blue.
10. A product according to claim 7, wherein about 2.5 lbs of
colouring agent are contained in the bag.
11. A product according to claim 7, wherein the bag is made of
sheets of polyvinyl alcohol.
12. A product according to claim 11, wherein the sheets are of
thickness of about 2 mil.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an improved method of
cementing the annulus of a hydrocarbon well.
BACKGROUND OF THE INVENTION
[0002] Conventionally the process of cementing an oil well (or
other bored holes in earth or rock) requires the on-site
preparation of the spacer (or scavenger) and cement slurry, which
are then pumped under pressure to the tubing or casing at the well
head. The casing or tubing typically runs the full length of the
well, top to bottom, except in special cases which are not
described herein.
[0003] Cement slurry design is not a simple task. It is essential
to isolate the drilling mud from the cementitious materials for
incompatibility reasons. For this purpose, either a mechanical
device or spacer is used to prevent contamination of these fluids.
For purely economic reasons, typically a spacer or scavenger fluid
is used.
[0004] In this case, cement slurries or water-based separating
fluids or "spacers" are pumped to the tubing or casing. Ideally a
water-based spacer fluid is used, although in many instances no
spacer will be used but a dilute, first portion of the cement
slurry, called the "scavenger" is pumped ahead of the regular
portion of cement slurry.
[0005] These fluids perform two main functions, the first being to
"displace" the drilling mud efficiently, and the second being to
prevent any contact between the cement and the mud. Here
rheological, density and velocity profile characteristics are of
vital importance, as are fluid loss control and stability or
settling control.
[0006] As the spacer and the cement slurry or scavenger and cement
slurry are pumped down the casing to the bottom of the hole, they
are displacing the drilling mud which rises via the annulus (i.e.
the gap between the exterior of the casing and the inner face of
the bored hole), and are discharged to a retaining vessel at the
surface (mud tank) for the disposal.
[0007] Once all of the slurry has been pumped, it is propelled or
displaced by an inert fluid, i.e. water, or drilling mud. Pumped
volumes are typically calculated in such a manner that pumping is
halted when the cement slurry has replaced all of drilling mud in
the annulus, and the interior of the casing is filled with the
inert fluid. The volume of spacer and cement slurry are based on a
number of different calculations, well-known to those skilled in
the art. This annular volume is often very difficult to calculate.
Thus, in many cases, the oilwell operator will mix cement slurry
and pump it down the casing until the annular volume between the
casing and the wellbore is entirely full, at which time the cement
slurry in the casing will be displaced by the inert fluid.
[0008] In order to accomplish this, without a volume calculation
relating the annular volume to the volume of cement slurry pumped
into the casing, a method of knowing when the annulus is full is
needed for the oilwell operator. In this context, it should be
understood that cement and mud are typically difficult to discern
visually.
SUMMARY OF INVENTION
[0009] Thus, in accordance with the present invention, a method is
provided of cementing the annulus of a hydrocarbon well having a
casing centering within a hole bored from a surface. A method
comprises steps of introducing an effective amount of colouring
agent contained in a water-soluble bag into a water-based
separating fluid, pumping the separating fluid ahead of a portion
of cementing slurry down the casing to the bottom of the hole to
displace drilling mud upwardly through the annulus to the surface;
until the colouring agent becomes visible at the surface displacing
the remaining cement inside the casing with an inert material such
as drilling mud or water, and then stopping the pumping and
allowing the pumped cement slurry to harden.
[0010] The bags are made of sheets of polyvinyl alcohol or any
other water soluble material. These are of preferably very thin,
for example 2 mil thickness, since they require and receive very
little agitation to dissolve in the spacer or scavenger fluid.
[0011] It will be understood that when the colouring agent reaches
the upper surface of the annulus, the oilwell operator then
displaces the casing with the certainty that the entire annular
space between casing and bore hole is full of cement, thus ensuring
the maximum hydraulic seal between various hydrocarbon layers in
the ground around the casing.
[0012] Although the colouring agent technology used in the present
case is not unique, the delivery of colouring agents to the spacers
or scavengers by way of a water soluble bag is. The bag containing
the colouring agent is made of fast dissolving polyvinyl alcohol
and is sealed in a "zip-lock" type bag, or otherwise sealed, to
keep it dry until use. Upon contact with any of the fluids
described above, the bag deteriorates rapidly, releasing a powder
material to the water phrase, to be quickly dispersed with minimal
mechanical agitation and providing good colour difference from the
surrounding fluids.
[0013] The colouring agent is preferably in powder form, is almost
inert and has no effect on varying components contained within a
cement slurry or spacer. Its sole purpose is to provide colour to
the fluid being pumped, so that as it is returning from the
wellbore, it can be discerned from the drilling fluid, to alert the
operator that the certain slurry, returning to the surface via the
annulus is close to the surface. The powder is usually an admixture
composed of dyes or pigments conventionally used to colour concrete
such as for example carbon black, iron oxide, phthalocyanine,
umber, chromium oxide, titanium oxide, and cobalt blue.
[0014] It should be noted that colouring agents in water soluble
bags have been added to aqueous cementitious mixtures in the past,
as described and illustrated for example in Smith et al U.S. Pat.
No. 5 120367, issued Jun. 9, 1992. When that has been done in the
past however, the purpose has been to completely colour a load of
concrete in a concrete wet mixer so that the resultant concrete
product will have a uniform colour. Such prior art usage has not
suggested Applicant's use of water soluble bags to colour spacer or
scavenger fluid in a well environment. Moreover, because of the use
to which the colouring agent/water soluble bag is applied, in
accordance with the present invention, much smaller amounts of
colouring agent are required in the bags, than would be the case
for application in colouring cement in a wet mixer. As well, the
significant agitation required in a wet mixer environment, to
ensure that the dye permeates the concrete being mixed, is not
needed in the context of the present invention since, in accordance
with the present invention, the bag containing the colouring agent
deteriorates to enable the spacer or scavenger to show colour just
through normal passage of the bag containing spacer or scavenger
down the casing or up the annulus.
EXAMPLE
[0015] A polyvinyl alcohol pouch was made up of sheets of 2 mil
thickness that were formed into pouches to contain about 2.5 lbs of
iron oxide powder as colouring agent. The colouring agent was
sealed in the bag. At a test site well head, one of the pouches was
placed into a water-based spacer and pumped into the well casing,
ahead of cement slurry. The pumping of cement slurry into the
casing was continued, displacing drilling mud from the bottom of
the hole, at the bottom end of the casing, upwardly through the
annulus to the surface. When the distinctive reddish colour of the
iron oxide was noted in the displaced fluid at the surface (meaning
that the drilling mud had been completely displaced from the casing
and annulus about the casing), the remaining cement slurry within
the casing was then displaced with water. The pumping was then
stopped and the pumped cement slurry remaining in the annulus was
allowed to harden.
[0016] It was found that there was no trace of the sheet material
of the pouches in the spacer and colouring agent which became
displaced back to the surface during the pumping process.
[0017] Also it was found that, by using the pouch of colouring
agent and the process in the manner described, an immediate and
accurate indication of when the annulus was filled with cement
slurry was achieved, resulting in a more efficient use of cement
slurry and a faster completion of the annulus cementing
process.
[0018] Thus, there has been provided in accordance with the
invention of an improved method and product for cementing
hydrocarbon wells that fully satisfies the objects, aims and
advantages set forth above. While the invention has been described
in conjunction with specific embodiments thereof, it is evident
that many alternatives, modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. Accordingly, it is intended to embrace all such
alternatives, modifications and variations as fall within the
spirit and broad scope of the invention.
* * * * *