Note: Descriptions are shown in the official language in which they were submitted.
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DRILL CUTTING SAMPLER
Field of the Invention
This invention relates to methods and apparatus for taking samples from the
cuttings contained in effluent including circulation fluid from a drill hole
used for exploratory
drilling and in particular to a sampling device mountable in cooperation with
a vibratory
separator used conventionally in the art for separating drill cuttings from
fluid so that the fluid
may be recycled for reuse.
Background of the Invention
As stated by Barrett in his United States Patent No. 4,718,289 which issued
January 12, 1988 for a Drill Cuttings Sample Collector, exploratory wells are
drilled to
evaluate penetrated rock formations for producible hydrocarbons. In drilling
such wells (and
in drilling production wells), circulation fluid is pumped down a string of
drill pipe and
through a drill bit at the lower end thereof. Such fluid thereafter circulates
upwardly in the
annulus between the drill pipe and the wellbore and thus flushes drill
cuttings, such including
drilled rock grains and fragments, from the wellbore.
In the usual operation, the drill cuttings are separated from the circulation
fluid
at the surface of the wellbore. The circulation fluid is thereafter
recirculated through the drill
string. Typically, such separation is done by a vibratory screening device;
what is referred to
in the industry as a shale shaker. The shale shaker comprises one or more
vibrating screens.
Fluid containing the drill cuttings is poured onto the screen(s) which permit
the fluid to pass
therethrough for recirculation. The screen(s) are inclined and vibrate the
drill cuttings off one
end, that is the lower end thereof. The drill cuttings are disposed of by
burial on land or maybe
put in a barge when drilling offshore.
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Samples of drill cuttings which are separated from circulation fluid as
described
above are examined by geologists to evaluate the penetrated rock formations.
Such
examination is particularly important in connection with exploratory wells
which are drilled
for the purpose of determining the nature of the formation. It is important to
collect samples
from all penetrated depths so that the lithology of the formations from the
surface of the well
to the bottom of the bore may be accurately determined. The importance of such
samples are
increased when, after drilling is complete, a wireline log cannot be acquired
or is of poor
quality because of a damaged bore. In such cases, the cutting samples and
related hydrocarbon
records are the only results to show for the expense of drilling the well. It
is desirable to
screen out larger cuttings, which are typically referred to as cavings, and
which are less likely
to have been drilled during the interval of interest. Smaller sized cuttings
are more likely to
have been transported up the annulus at the same rate as the drilling fluid,
the lag rate of which
can be determined by the geologist.
As reported by Barret, in the past drill cuttings samples were collected by
placing a container in the flow of drill cuttings which fell from lower end of
the shale shaker.
The container was periodically emptied and collected samples examined. Such
prior art
sample collectors suffered from several disadvantages. First, the container in
which the
samples accumulated would often fill to the top and overflow. Drill cuttings
falling from the
shale shaker when the container was full were not sampled and the record for
such drill
cuttings lost. This was especially true in the case of a drilling operation
which was drilling at a
fairly rapid rate and thus generating a high volume of drill cuttings per unit
time.
Loss of drill cutting samples may also occur when fluids are accidentally
introduced into the container collecting the samples. Such may occur as a
result of a blinded
shaker screen; that is, the screen becomes clogged and permits circulation
fluid to flow with
the drill cuttings into the container. gamples may also be lost as a result of
water from a hose,
which is used to clean the shale shaker, entering the container. In addition,
heavy rain and, in
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offshore drilling operations, waves may introduce water into the container,
thus greatly
reducing or destroying the information obtainable from the samples.
The present invention addresses the problem in the prior art where often drill
cuttings are allowed to accumulate in a stationary collector underneath the
downstream end of
the shale shaker, the problem being that sampling from such a collector quite
often means an
assistant merely scooping cuttings from the top of the collector or digging
into the layered
contents of the collector, whether or not mixed so that the actual sample
taken by the assistant
is not necessarily representative of the particular drilling interval which it
is desired to sample.
As disclosed by Barrett in his patent referred to above, it is known to place
a
container under the outflow end of a so-called shale shaker, itself
conventionally used in the
art for removing drilling fluid from drilling cuttings. The container of
Barrett is placed so as
to capture drilling cuttings falling from the end of the shale shaker which as
known in the art is
a vibratory inclined screen conveyor which transports drill cuttings down
along the inclined
surface by means of vibrating the otherwise stationary surface of the screen
whilst allowing
circulation fluid to pass through the vibratory surface for collection and
reuse. What Barrett
fails to disclose, and which is one object of the present invention to
provide, is an improved
method and apparatus for screening, filtering or culling a selectively smaller
volume of the
drill cuttings exiting the shale shaker so that the sample still represents a
uniform sampling of
the desired drilling cross-section exhibited by the drilling cuttings exiting
the shale shaker.
Other prior art of which applicant is aware include:
Canadian Patent No. 1,280,740 which issued to Hoeft on February 26, 1991 for
a Chip Sampler. Canadian Patent No. 1,079,229 which issued to Huff on June 10,
1980 for a
Mud Metering Testing and Cleansing System. United States Patent No. 5,571,962
which
issued to Georgi on November 5, 1996 for a Method and Apparatus for Analyzing
Drill
Cuttings. United States Patent No. 5,372,037 which issued to Butt on December
13, 1994 for
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Soil Sampling Apparatus. United States Patent No. 3,563,255 which issued to
Morris on
February 16, 1971 for an Apparatus for Collecting and Washing Well Cuttings.
United States
Patent No. 3,135,685 which issued to Tanner on June 2, 1964 for a Device for
Collecting
Cutting Samples From Well Drilling Operations. United States Patent No.
2,336,539 which
issued to Gilbert on December 14, 1943 for a Sampling Device. -
Summar,y of the Invention
In summary, the present invention may be characterized in one aspect as a
device for sampling drill cuttings which includes a frame, an inclined
perforated member, a
sprayer, and a removable cuttings collector. The frame is pivotally mountable
to, so as to
cooperate with, a downstream end of a vibratory screen over which drill
cuttings are passed in
a downstream flow direction so that vibratory motion of the vibrating screen
is transmitted at
'least in part to the fiame. The inclined perforated member, preferably a
planar member, is
mounted on the frame, the planar member including a plate or sieve screen
having perforations
over at least a portion thereof between an upstream end and a downstream end
of the planar
member.
The perforations are sized to screen out those cuttings exceeding a pre-
determined size and to allow to pass through the perforations those cuttings
equal to or less
than the pre-detennined size. The sprayer is mounted adjacent the upstream end
of the planar
member so as to direct fluid spray downstream along the planar member and over
the
perforations. - . -
The open-topped cuttings collector is removably mounted under the frame so as
to be insertable under the frame into a collecting position disposed beneath
the perforations on
the perforated planar member, and removable from the frame so that the
cuttings may be
removed from the collector for analysis.
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The planar member is covered by adjustable plates so that only a pre-selected
ratio of the cuttings on the vibratory screen are entrained onto the
perforated portion of the
planar member. The drill cuttings for any particular drill-hole cross-section
may thus be
uniformly sampled and the resulting sample of a selectively pre-determined
volume for ease of
and efficient removal for analysis.
In one embodiment the collector is a perforated container for straining fluid
from the cuttings passing into the collector through the perforations in the
planar member.
The collector may be a rigid walled container having a base comprising a mesh
screen. The
mesh screen of the base of the collector may have a sieve screen mesh size
which allows fluids
and any particles smaller than the sieve screen mesh size to pass through the
mesh screen,
while retaining on the mesh screen cleaned cuttings larger than the sieve
screen mesh size.
The planar member may include a sieve screen having uniformly sized mesh.
The planar member may be a plate, and the plate may be inclined in the range
of substantially 10-30 degrees from the horizontal -so as to elevate the
upstream end of the
planar member to cooperate with the downstream end of the vibratory screen
when the frame
is mounted adjacent the downstream end of the vibrating screen so that the
cuttings translating
in the flow direction flow from the vibrating screen onto the plate. The plate
is inclined so that
cuttings travel from the upstream end to the downstream end and subsequently
off the
downstream end. In one embodiment the planar member is inclined substantially
15 degrees
from the horizontal. The device further comprises a hinged mount rotatably
mounted to the
frame for releasable mounting to the downstream end of the vibratory screen
and adapted so as
to selectively pivot the frame and the planar member relative to the vibratory
screen.
The frame may define a drawer support and the collector may be a perfora.ted
drawer for draining fluid from the cuttings while retaining the cuttings in
the drawer. The
drawer may be selectively drawn out from under the planar member and
selectively slid back
into the frame so as to align an open top of the drawer under the perforations
on the planar
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member. The collector may be a first collector and removable from the frame so
that a second,
empty collector may be inserted into the frame in place of the first collector
oiice the first
collector has accumulated a sample of the drill cuttings passing through the
perforations in the
planar member. The drawer may be entirely removable from the frame.
Brief Description of the Drawings
Figure 1 is, in perspective view, a cutting sampler according to one
embodiment of the present invention mounted at the downstream end of a shale
shaker.
Figure la is an enlarged perspective view of Figure 1 showing the cutting
sampler in the open position.
Figure 2 is the view of Figure 1 with the removable cutting collector which
forms part of the cutting sampler according to the present invention partially
removed.
Figure 3 is, in perspective view, the cutting sampler of Figure 1.
Figure 3a is, in plan view, the perforated plate of the cutting sampler of
Figure
3.
Figure 4 is, in bottom perspective view, the removable cutting collector of
the
cutting sampler of Figure 1.
Detailed Description of Embodiments of the Invention
As may be seen in the accompanying figures wherein like characters of
reference denote corresponding parts in each view, the drill cutting sampler
according to one
embodiment of the present invention includes a supporting frame 10 adapted to
be mounted in
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cooperation with the downstream end of a shale shaker 12 for supporting a
perforated plate or
sieve screen (also collectively herein referred to as perforated plate 14) in
the outflow path of
drill cuttings exiting the shale shaker. The perforated plate 14 cooperates
with a removable
cutting collector 16 removably mounted beneath perforated plate. 14 for
collecting a sampling
of cuttings passing over perforated plate 14 wherein a percentage of the
cuttings 18 are washed
by spray water from a sprayer 20 through perforations 14a of perforated plate
14. Perforated
plate 14 allows cuttings of a desired size to pass through into the collector
16 while all
undesired larger cuttings are rejected and pass over the plate, being both
washed away and
vibrated off. That is, the sample washer according to the present invention,
and in particular
perforated plate 14 is mounted so as to utilize the vibration from the shale
shaker in order to
aid in separation of the desired size of particle. The desired size or sizes
of particle fall
through the apertures or perforations 14a in perforated plate 14 so as to fall
into collector 16.
Thus the desired size or sizes of particles are separated from larger sized,-
undesired cuttings
which are vibrated and washed off the lower end of perforated plate 14.
Thus drill cuttings 18 on the shale shaker translate downwardly along the
downwardly inclined vibrating screen of the shale shaker in direction A so as
to exit from the
downstream-most end of the shale shaker.
Supporting frame 10 is pivotally mounted at the downstream end of shale
shaker 12 by a hinge or pivot means that rotatably supports it in place. The
frame includes a
vertically disposed pair of parallel, laterally spaced apart uprights 10a. The
uprights l0a may
be clamped directly to the downstream end of the shale shaker by clamps 26.
Clamps 26 are
rotatably mounted to uprights l0a on hinges 13a. Screw-type adjusting bars 13b
adjustably fix
the uprights at a desired angle relative to the shale shaker. Lower ende of
bars 13b are
mounted to the free ends of clamps 26. The upper ends are mounted to the upper
ends of
uprights 10a. The lower end of supporting frame 10 is free hanging.
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Drawer supporting rails 10b are rigidly mounted to vertical uprights l0a so as
to extend cantilevered therefrom. Rails 10b are in opposed facing relation and
are mounted
under perforated plate 14. Flanges 16a extend laterally outwardly from the
sides of collector
16 and are slidably mounted within rails lOb so that collector 16 may be slid
in direction B
into and out of the rails. Collector 16 may thus be easily removed from, and
replaced back
into, rails lOb.
The uppermost end of perforated plate 14 is mounted adjacent, that is, so as
to
be in the flow path of cuttings leaving the downstream-most end of shale
shaker 12 so that drill
cuttings 18 vibrating downwardly in direction A along the downward incline of
shale shaker
12, will, if aligned with the adjustable opening between side walls 15a on
cover plates 15, fall
onto or otherwise transfer onto the perforated portion of perforated plate 14.
Cover plates 15
may be laterally adjusted to vary the inlet width w by upstanding bolts 17a
sliding in slots 15b.
Slides 15 are releasably locked in place by tightening of nuts 17b down onto
bolts 17a and
washers 17c so as to clamp cover plates 15 down onto plate 14.
Sprayer 20 sprays fluid such as water from nozzles 20a, , to thereby flush
cuttings 18 in direction C to urge the cuttings 18 over the perforations 14a.
The spray cleans
the cuttings and those which are of desired size fall into the collector 16,
and also flushes
undesired cuttings off perforated plate 14. The spray also washes away any
remnant drilling
fluid which was not separated from cuttings by the shale shaker, resulting in
a much cleaner
sample. The remainder of the cuttings 18 exiting the downstream end of shale
shaker 12, if
they fall outside of the spacing w between sidewalls 15a, merely fall as waste
from the shale
shaker and are disposed of conventionally. Consequently, the percentage of
cuttings
transported along shale shaker 12 which are to be sampled may be initially
governed by the
selectable and adjustable width w between sidewalls 15a, that is, the ratio of
the width w to the
overall width d of the downstream outflow end of shale shaker 12. By way of
example, width
w may be less than or equal to six inches.
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The upstream end of perforated plate 14 may have an un-perforated infeed area
under spray nozzles 20a which may be approximately three inches long measured
in the
direction of flow, and may have an un-perforated area at the downstream-most
end of
approximately two inches. These dimensions may advantageously correspond to
the position
of the open-topped removable collector 16 mounted in rails 10b, that is,
positioned so that the
open top of collector 16 is mounted vertically under the perforations 14a.
Perforated plate 14
may also be a sieve screen of a standard mesh size (that is 10 mesh, 20 mesh,
etc). When
uprights 10a are attached to shaker 12 using clamps 26, perforated plate 14
hangs just below
the downstream end of shaker 12 in the path of cuttings falling from the
shaker.
The flow rate of cuttings 18 passing over apertures 14a for example is
governed
by the pressure and volume of spray from nozzles 20a, the vibration from
shaker 12, the
inclination from the horizontal of perforated plate 14 and the width w between
walls 15a.
These factors as well as the aperture size of perforations 14a, that is, in
the case of sieve
screens including the mesh size of the sieve screen govern the volume and rate
at which
cuttings 18 pass through perforations 14a in direction F and thus the sample
rate of, and the
volume of, the samplirig of cuttings 18. In the illustrated embodiment,
advantageously,
perforated plate 14 may be inclined in the range of 10-30 degrees from the
horizontal, and in
particular may be inclined approximately 15 degrees.
Thus, after a pre-determined drilling interval has been accomplished, for
example every five metres, the corresponding sample of desired size of drill
cuttings 18 may
be collected for storage and later analysis, by removing collector. 16 from
underneath
perforated plate 14 and by inserting a second empty collector 16 so as to
commence collecting
samples from the next drilling interval. Advantageously, the base 16b of
collector 16 may be a
fine screen or mesh, for example, 120 mesh screen supported by, for example, a
metal support
grate. Mesh screen allows the fluid from nozzles 20a to drain from collector
16 leaving only
washed cuttings 18.
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As will be apparent to those skilled in the art in the light of the foregoing
disclosure, many alterations and modifications are possible in the practice of
this invention
without departing from the spirit or scope thereof. Accordingly, the scope of
the invention is
to be construed in accordance with the substance defined by the following
claims.
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