U.S. patent application number 10/651642 was filed with the patent office on 2004-04-15 for apparatus and method for minimizing solids deposited in a reserve pit.
This patent application is currently assigned to Rocky Mountain Fluid Technologies, Inc.. Invention is credited to Cowan, Michael.
Application Number | 20040069536 10/651642 |
Document ID | / |
Family ID | 32073313 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040069536 |
Kind Code |
A1 |
Cowan, Michael |
April 15, 2004 |
Apparatus and method for minimizing solids deposited in a reserve
pit
Abstract
A method of minimizing the quantity of solids deposited in a
reserve pit of the type used in drilling oil and gas wells. The
method is applicable to well sites where drilling is facilitated by
the use of drilling fluid and cuttings are generated by a drill
bit, lifted to the surface and deposited at a well bore. The method
consists of separating cuttings from associated drilling fluid and
conveying larger cuttings to a solids storage location, thus
bypassing the reserve pit for a good deal of the solid waste
generated at a drilling site. Residual drilling fluid is directed
to a reservoir such as a suction tank where it can be reused in
further drilling operations. Over time the residual drilling fluid
in the suction tank will increase in viscosity to the point where
the residue is no longer suitable as drilling fluid. Thereupon, a
portion of the residue may be discarded from the suction tank to
the reserve pit and water or drilling chemicals added to the
suction tank to revitalize the drilling fluid.
Inventors: |
Cowan, Michael; (Arvada,
CO) |
Correspondence
Address: |
SWANSON & BRATSCHUN L.L.C.
1745 SHEA CENTER DRIVE
SUITE 330
HIGHLANDS RANCH
CO
80129
US
|
Assignee: |
Rocky Mountain Fluid Technologies,
Inc.
|
Family ID: |
32073313 |
Appl. No.: |
10/651642 |
Filed: |
August 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60411263 |
Sep 17, 2002 |
|
|
|
Current U.S.
Class: |
175/66 ;
175/207 |
Current CPC
Class: |
E21B 21/066
20130101 |
Class at
Publication: |
175/066 ;
175/207 |
International
Class: |
E21B 021/06 |
Claims
What is claimed is:
1. A method of minimizing the quantity of solids deposited in a
reserve pit of the type used in drilling oil or gas wells where
drilling is facilitated by the use of drilling fluid and cuttings
are generated by a drill bit, lifted to the surface and deposited
at a well bore, the method comprising the steps of: a. directing
the cuttings and associated drilling fluid from the well bore to a
coarse separating means; b. separating larger cuttings from a
residue comprising drilling fluid and associated smaller cuttings
by action of the coarse separating means; c. conveying the larger
cuttings from the coarse separating means to a solids storage
location; d. directing the residue from the coarse separating means
to a reservoir; e. returning the residue from the reservoir to the
well for use as drilling fluid in further drilling operations; and
f. discarding a portion of the residue from the reservoir to the
reserve pit when the viscosity of the discarded portion renders it
no longer suitable as drilling fluid.
2. The method of claim 1 wherein the coarse separating means is a
rig shaker.
3. The method of claim 1 wherein the larger cuttings are conveyed
from the coarse separating means an auger.
4. The method of claim 1 wherein the coarse separating means
separates cuttings too large to fit through a 100 micron screen
from the residue.
5. The method of claim 1 wherein step c. comprises: conveying the
larger cuttings from the coarse separating means to a means for
drying solids; drying the larger cuttings in the means for drying
solids creating dried solids; and conveying the dried solids to the
solids storage location.
6. The method of claim 7 wherein the means for drying solids is a
High-G dryer.
7. The method of claim 1 wherein step d. comprises: directing the
residue from the coarse separating means to a medium separating
means; separating smaller cuttings from the residue by action of
the medium separating means; directing the residue from the medium
separating means to the reservoir; and conveying the smaller
cuttings from the medium separating means to the solids storage
location.
8. The method of claim 7 wherein the medium separating means is a
hydrocyclone.
9. The method of claim 7 wherein the medium separating means
separates cuttings too large to fit through a 50 micron screen from
the residue.
10. The method of claim 7 wherein the residue is further conveyed
to a fine separating means prior to the reservoir, the method
further comprising: separating fine cuttings from the residue by
action of the fine separating means; directing the residue from the
fine separating means to the reservoir; and conveying the fine
cuttings from the fine separating means to the solids storage
location.
11. The method of claim 10 wherein the fine separating means is a
centrifuge.
12. An apparatus for handling the cuttings associated with the
drilling of an oil or gas well where drilling is facilitated by the
use of drilling fluid and cuttings are generated by a drill bit,
lifted to the surface and deposited at a well bore, the apparatus
comprising: coarse separating means receiving the cuttings and
associated drilling fluid from the well bore and separating the
larger cuttings from a residue comprising smaller cuttings and
drilling fluid; a solids storage location receiving the larger
cuttings from the coarse separating means; a reservoir receiving
the residue from the coarse separating means; means for returning
the residue from the reservoir to the well for use as drilling
fluid in further drilling operations; and a reserve pit receiving a
discarded portion of the residue from the reservoir when the
viscosity of the discarded portion renders it no longer suitable as
drilling fluid.
13. The apparatus of claim 12 wherein the coarse separating means
is a rig shaker.
14. The apparatus of claim 12 wherein the means for conveying the
larger cuttings from the coarse separating means is an auger.
15. The apparatus of claim 12 further comprising a solids dryer
receiving the larger cuttings from the separating means.
16. The apparatus of claim 12 further comprising a medium
separating means receiving the residue from the coarse separating
means.
17. The apparatus of claim 16 wherein the medium separating means
is a hydrocyclone.
18. The apparatus of claim 16 further comprising a fine separating
means receiving the residue from the medium separating means.
19. The apparatus of claim 18 wherein the fine separating means is
a centrifuge.
20. An apparatus for handling the cuttings associated with the
drilling of an oil or gas well where drilling is facilitated by the
use of drilling fluid and cuttings are generated by a drill bit,
lifted to the surface and deposited at a well bore, the apparatus
comprising: a rig shaker receiving the cuttings and associated
drilling fluid from the well bore and separating the larger
cuttings from a residue comprising smaller cuttings and drilling
fluid; an auger conveying the larger cuttings from the rig shaker
to one of a solids dryer and a three sided tank; a reservoir
receiving the residue from the rig shaker; a return loop in fluid
communication with the reservoir and the well bore for returning
the residue in the reservoir to the well for further drilling
operations; and a reserve pit receiving a discarded portion of the
residue from the reservoir when the viscosity of the discarded
portion renders it no longer suitable as drilling fluid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/411,263, "Apparatus and Method for Minimizing
Solids Deposited in a Reserve Pit," filed Sep. 17, 2002,
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention is directed toward the handling of
waste materials generated during the drilling of an oil or gas
well, and more particularly toward a method of minimizing the
quantity of solids deposited in a reserve pit of the type used in
drilling oil or gas wells.
[0004] 2. Background Art
[0005] The exploration for oil and gas dates back over 100 years in
the United States. The technology to drill wells faster and deeper
is constantly being enhanced to reduce costs and improve profit
margin for the oil companies. Exploring for these resources takes a
tremendous amount of money and cooperation between the oil
companies and the service industry employed to look for oil and
gas.
[0006] While drilling a well, cuttings (earth) generated by the bit
are brought back to the surface by a drilling fluid comprised of
water, bentonite, and polymers and other assorted chemicals. The
disposal of these cuttings has always been a significant well site
issue. Historically, cuttings have been disposed of into a waste
pit called a reserve pit. Recently, the practice of drilling more
then one well from a single pad and environmental concerns have
made the size and existence of a reserve pit a liability.
[0007] Presently, wastes generated at a well site are handled by
the implementation of one or two mutually exclusive site management
methods. The two methods are broadly categorized as open loop
systems and closed loop systems. The most common and traditional
mode is an open loop system. In a typical open loop system, a
reserve pit is dug adjacent to the well site to hold excess cement
from casing designs, rig water used to clean the rig, excess
drilling fluids, and most importantly for the disposal of drill
cuttings. A typical open loop system is quite cost effective,
however, it requires a large reserve pit which raises significant
environmental concerns. In many instances, the size of the reserve
pit is dictated by the volume of drill cuttings dumped therein. The
size of a reserve pit sufficient to handle multiple wells drilled
from a single pad can be environmentally prohibitive.
[0008] The second, more costly alternative to an open loop system
is to drill with a closed loop mud system eliminating the need for
a reserve pit. The hallmark of all closed loop systems is the use
of a rather complex apparatus and methodology to separate drilling
fluid from drill cuttings and other waste matters associated with
the drilling process. After separation, the cuttings and waste are
removed from the drilling site in solid form, and the drilling
fluid is reused. Numerous examples of closed loop systems are
taught in the prior art. Each of these systems is more or less
effective at facilitating the handling of waste generated at a
drill site, yet each is relatively expensive. The increased cost
arises from both additional equipment expenses and significantly
increased manpower costs in order to monitor and operate the
relatively sophisticated closed loop equipment. Examples of closed
loop systems include Summers, U.S. Pat. No. 4,636,308, which
teaches a series of rig shakers, rig de-sanders, rig de-silters,
and centrifuges to effectively remove solids from the drilling
fluid. It is an expressly stated purpose of the Summers invention
to eliminate the reserve pit at a drilling site, thus reducing the
area required and an environmental pollution problem.
[0009] Similarly, Rowney, et al., U.S. Pat. No. 6,059,977, teaches
a closed loop system featuring a settling tank which decreases the
reliance on a battery of centrifuges. McIntyre, U.S. Pat. No.
6,530,438, features a closed loop system using a desorption unit
that vaporizes the liquids from the cuttings, then condenses the
vapor for reuse as drilling fluid. Other closed loop systems are
based upon flocculation tanks or other chemical methods to
effectively separate undesirable solids from the drilling
fluid.
[0010] Although the above closed loop technologies are effective
and environmentally sound, each involves significant cost. In
addition, the elimination of a reserve pit can cause site
management problems. In particular, it is customary to wash solid
contaminants off of the drilling rig and associated equipment into
the reserve pit. For example, a cement truck which might need to be
cleaned can simply be hosed off with the excess cement being washed
into the reserve pit of an open loop system. On the other hand,
there is no facility available for routine maintenance chores such
as this in conjunction with a closed loop system.
[0011] The present invention is directed to overcoming one or more
of the problems discussed above.
SUMMARY OF THE INVENTION
[0012] In one aspect of the present invention, a method of
minimizing the quantity of solids deposited in a reserve pit of the
type used in drilling oil and gas wells is disclosed. The method is
applicable to well sites where drilling is facilitated by the use
of drilling fluid and cuttings are generated by a drill bit, lifted
to the surface and deposited at a well bore. The method consists of
the following steps:
[0013] 1. Directing the cuttings and associated drilling fluid from
the well bore to a coarse separating means such as a rig
shaker;
[0014] 2. Separating larger cuttings from a residue consisting of
drilling fluid and associated smaller cuttings by action of the rig
shaker;
[0015] 3. Conveying the larger cuttings from the rig shaker to a
solid storage location, thus bypassing the reserve pit for a great
deal of the solid waste generated at the drilling site;
[0016] 4. Directing the residue from the rig shaker to a reservoir
such as a suction tank where it can be reused as drilling fluid in
further operations;
[0017] Implementation of the above steps will, over time, cause the
residue in the suction tank to increase in viscosity to the point
where the residue is no longer suitable as drilling fluid.
[0018] 5. Discarding a portion of the residue from the suction tank
to the reserve pit.
[0019] Water or drilling chemicals may then be added to the suction
tank to revitalize the drilling fluid.
[0020] The large cuttings may alternatively be directed from the
rig shaker to a drying apparatus prior to depositing the larger
cuttings at the solids storage location. If the size of the reserve
pit is to be minimized and the useful lifespan of the reserve pit
maximized, hydrocyclones and/or centrifuges may be used in series
with the rig shaker to remove relatively finer materials from the
residue prior to return of the residue to the suction tank for
reuse as drilling fluid. Implementation of the above method assures
that a reserve pit will be available at the drilling site for
ancillary uses such as cleaning equipment.
[0021] An alternative embodiment of the present invention is an
apparatus for handling the cuttings associated with the drilling of
an oil or gas well. The apparatus is suitable for implementation of
the above method and has the following components: a device for the
coarse separation of cuttings from a residue of fine cuttings and
drilling fluid, such as a rig shaker; a solids storage location
receiving the cuttings from the rig shaker; a suction tank
receiving residue from the rig shaker; a plumbed loop for returning
the residue from the suction tank to the well for use as drilling
fluid in further operations; and a reserve pit for receiving a
discarded portion of the residue from the suction tank when the
viscosity of the discarded portion renders it no longer suitable as
drilling fluid.
[0022] The apparatus may alternatively have devices for separating
medium and fine particles from the residue such as hydrocyclones or
centrifuges of various sizes in series with the rig shaker.
Implementation of these supplemental devices in the apparatus can
further minimize the amount of solids ultimately deposited into the
reserve pit. Preferably, the larger cuttings are conveyed from the
rig shaker by a mechanical device such as a conveyor belt or
auger.
[0023] A system designed and implemented as described above will
not be as costly as a closed loop mud system without a pit. By
removing the drill cuttings with the solids control equipment and
avoiding disposal into the reserve pit, a much smaller pit is
needed. By keeping the solids out of a standard reserve pit, the
basic pit can be reduced in size by 66% for a given operation. Some
of the advantages to a smaller pit are the following:
[0024] 1. Less water needed;
[0025] 2. Construction costs of the pit will be less;
[0026] 3. Reduction of the expense incurred for reclaiming the
larger pit;
[0027] 4. Significantly decreased operating costs compared to a
closed loop pitless system;
[0028] 5. Small pit available to recycle waste fluids such as rig
wash down water and FRAC flow back;
[0029] 6. The smaller pit will minimize environmental surface
damage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic representation of an apparatus for
minimizing solids deposited in a reserve pit;
[0031] FIG. 2 is a flow chart representation of the method of the
present invention; and
[0032] FIG. 3 is a flow chart of the method of the present
invention featuring hydrocyclones and centrifuges in series to
remove relatively finer solids.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033] An apparatus for minimizing the deposit of solids in a
reserve pit 10 is illustrated schematically in FIG. 1. The
apparatus receives combined drilling fluid and drill cuttings from
a well bore 12 through a flowline 13. The combined cuttings and
drilling fluid are directed to a rig shaker 14 which separates
larger cuttings (e.g. 100 micron or bigger) from the drilling
fluid. The drilling fluid may then be directed through a flowline
tank 15 to a suction tank 16. Alternatively, the drilling fluid
recovered from the rig shaker 14 may be directed by line 18 to a
hydro cyclone 20 for removal of smaller sized particulate matter
(e.g. 50-100 micron or bigger). The separated drilling fluids may
then be directed through the flowline tank 15 to the suction tank
16, and from there through line 17 to the well bore 12 for reuse as
drilling fluid. Alternatively, the drilling fluid separated by the
rig shaker 14 and the hydro cyclone 20 may be directed by line 24
to a centrifuge 26 for separating even smaller particulate (e.g. 50
micron or smaller) material from the drilling fluids. Drilling
fluid recovered from the centrifuge is then returned by line 28 to
the suction tank 16. As should be apparent to one skilled in the
art, whether the hydro cyclone 20 or centrifuge 26 are used in
combination with the rig shaker for further removal of solids is a
function of the need to remove particulate material of a size
smaller than that separated by the rig shaker 14 from drilling
fluid being returned to the suction tank 16. Either the hydro
cyclone 20 or the centrifuge 26 may be omitted from the apparatus
when removal of particulate material of the size removed by these
devices is unnecessary.
[0034] As shown in FIG. 1, solids separated from the rig shaker 14
are collected by solids transport device 30 which may be a conveyer
belt or, preferably, an auger. The solids transport device 30 may
also receive solids separated from the hydro cyclone 20 when the
hydro cyclone 20 is part of the apparatus 10. The solids are
transported from the rig shaker 14 and hydro cyclone 20 to a solids
dryer 32 to remove residual drilling fluids from the solids and the
solids are preferably outputted to a three sided tank 34. The three
sided tank 34 facilitates removal of the separated solids by a
front end loader or the like for transport from the vicinity of the
well bore or for deposit near the well bore. Alternatively, the
solids dryer 32 may be omitted and the wet solids captured at the
solids transport device outlet may then be air dried either in the
vicinity of the well bore or elsewhere. Where a centrifuge 26 is
used, solids extracted by the centrifuge are deposited in a three
sided tank 36 for disposal in the same manner as the solids
deposited in the three sided tank 34.
[0035] As described above, the suction tank 16 receives a residue
of drilling fluid and fine cuttings through the flowline tank 15
from the rig shaker 14, hydrocyclone 20 and centrifuge 26 (if the
hydrocyclone 20 and centrifuge 26 are implemented). Over time, as
the residue is pumped through line 17 to the well bore 12 for reuse
as drilling fluid, the viscosity of the residue in the suction tank
16 will increase to a point where the residue is no longer suitable
for use as drilling fluid. As shown in FIG. 1, a discard portion of
the thickened residue can then be directed to the reserve pit 38
through discard line 40. The drilling fluid/residue mixture in the
suction tank 16 can be recharged with additional drilling fluid or
water after the discarded portion of the residue has been
removed.
[0036] The rig shaker 14, hydrocyclone 20, solids transport device
30, solids dryer 32 and centrifuge 26 may be selected from various
known manufactures and may be off the shelf units. A representative
rig shaker model is the Flo-Line Cleaner, manufactured by Derrick.
Representative hydro cyclones are models 4"-10" cones, manufactured
by Derrick. A representative auger is the Screw Conveyor model,
manufactured by Martin. A representative solids dryer is the High G
Dryer, manufactured by Derrick. A representative centrifuge is
model DE-1000, manufactured by Derrick.
[0037] In an alternative configuration, the solids transport device
30 may be omitted if the solids from the rig shaker 14 and hydro
cyclone 20 fall directly into the solids dryer 32. However, there
must be enough room behind the flowline tank 15 and the reserve pit
38. This may require an unconventional routing trench system to
allow access to the reserve pit 38. However, in most applications,
use of a solids transport device 30 to remove the solids from the
drilling platform is preferred.
[0038] The apparatus described above can be used to implement a
method of managing the cuttings generated at an oil or gas well
drill site. The method is represented by the flowchart of FIG. 2.
The method commences with cuttings and drilling fluid being forced
to the surface of a drill bore as drilling operations progress
(step 100). The combined cuttings and drilling fluid are routed to
a device for separating coarse cuttings from a residue of drilling
fluid and finer cuttings (step 110). A typical device for
separating coarse cuttings from the residue is a rig shaker 14.
Following step 110, the large cuttings are conveyed to a solid
storage location (step 112) contemporaneously the residue of
drilling fluid and finer cuttings are routed to a reservoir such as
a suction tank 16 (step 114). Typically, the drilling fluid and
finer cuttings flow through a flowline tank 15 situated in close
proximity to the suction tank 16. The residue of drilling fluid and
finer cuttings is recycled to the well bore 12 for use as drilling
fluid in further drilling operations (step 116). As a result of
this continual cycle of reuse and with the continuous addition to
the residue of fine cuttings, over time the residue in the suction
tank 16 will thicken to an unusable viscosity (step 118). At the
point in time where the viscosity of the residue renders it no
longer suitable for use as drilling fluid, the operator can direct
a discard portion of the residue in the suction tank to the reserve
pit (step 120). This step will substantially or partially drain the
suction tank 16 which can be recharged with fresh drilling fluid or
water.
[0039] In addition to the basic method of FIG. 2, certain
enhancements to the process are represented in flowchart form on
FIG. 3. In particular, the residue of smaller cuttings and drilling
fluid from the rig shaker 14 may be directed to an apparatus for
removing smaller cuttings such as a hydrocyclone (step 122). If it
is desired to remove even finer materials from the residue, the
fine cuttings and associated drilling fluid can be directed to a
centrifuge 26 (step 124) before the residue flows to the suction
tank 16. As described above, the larger cuttings from the rig
shaker 14 and the smaller cuttings from the hydrocyclone 20 may be
placed at an appropriate location for air drying. Alternatively,
these solids can be delivered to an apparatus for drying solids,
such as a high-g solids dryer 32 (step 126). Subsequently, the
dried solids may be routed to a 3-sided tank 34 for temporary
storage (step 128) prior to delivery to a final solids storage
location (step 112).
[0040] The reserve pit 38 of the invention can be substantially
smaller than the reserve pit associated with a conventional open
loop drilling system. This decrease in size is facilitated by the
removal and processing of the solid cuttings which traditionally
are dumped into the reserve pit 38. The availability of the small
reserve pit 38 has advantages as water from well site wash down,
associated equipment wash down and frac flow back can be directed
to the reserve pit 38 for safe and efficient storage (step
130).
[0041] The objects of the invention have been fully realized
through the embodiments disclosed herein. Those skilled in the art
will appreciate that the various aspects of the invention may be
achieved through different embodiments without departing from the
essential function of the invention. The particular embodiments are
illustrative and not meant to limit the scope of the invention as
set forth in the following claims.
* * * * *