FORMATION I NC
APPARATUS, SYSTEMS, AND METHODS
Background
Sampling programs are often conducted in the oil field to reduce risk.
For example, the more closely that a given sample of formation fluid represents
actual conditions in the formation being studied, the lower the risk of inducing
error during further analysis of the sample. This being the case, down hole
samples are usually preferred over surface samples, due to errors which
accumulate during separation at the well site, remixing in the lab, and the
differences in measuring instruments and techniques used to mix the fluids to a
composition that represents the original reservoir fluid. However, down hole
sampling can a o he costly in terms of time and money, such as when sampling
time is increased because sampling efficiency is low.
FIG. 1A is a top plan view, and FIGs. IB-I D are sectioned side views of
geological fonnation sampling and guard probes, according to vario
embodiments of the invention.
FIGs. 2A and 2B illustrate top plan views of additional embodiments of a
geological fonnation sampling and guard probe according to various
embodiments of the invention.
P'IG. 3A is a block diagram of a data acquisition system and a down hole
too according to various embodiments of tire invention.
FIG. 3B illustrates down hole tools according to various embodiments of
the invention.
FIG. 4 illustrates a wireline system embodiment of the invention.
FIG. 5 illustrates a while-drilling system embodiment of the invention.
FIG. 6 is a flow chart illustrating several methods according to various
embodiments of the invention.
FIG. 7 is a block diagram of an article of manufacture, including a
specific machine, according to various embodiments of the invention.
Detailed Description
The oil and gas industry uses formation pressure testing tools to measure
the pressure of fluids (including gases) and their mobility in subterranean
geological formations. These i clude wireline or drill pipe-conveyed devices,
such as the Halliburton^ RDT and HSFTTI tools, and the Halliburton*
GeoTap* tool.
Geological formations can present a wide range of pressures, fluid
characteristics (e.g., viscosity), and permeability. To facilitate rapid, accurate
measurements, down hole sampling tools sometimes have !he capability to vary
the drawdown volume and rate to achieve a selectable drawdown pressure and
pressure build-up profile. For example, drawdown volume and rate can be
controlled to reduce the chance of plugging flow lines, which sometimes occurs
when the pressure differential during the drawdown is large and the rock in front
of the sample probe fails, driving rock particles to enter the sample f ow line.
The drawdown rate can be used during sampling to control pressures a d avoid
phase changes in the fluid. Thus, when sampling, pressure adjustments can be
ade by varying the drawdown rate to keep the sample fluid above the bubble
point.
n a conventional drawdown sampling sequence, a sampling probe is
retracted and the probe conveyance (e.g., a formation testing tool) is moved
dowi hole to a depth where the test point is located. An equalization valve is
opened to make i t possible o measure the well bo e hydrostatic pressure prior to
testing. When the formation tester is located at the testing depth, the sampling
probe is extended to make a sealing engagement with the borehole rock face.
Before or while the sampling probe is deployed, the equalization valve is closed
to isolate the flow line (which is hydraulically connected to a pressure gauge,
probe, and pretest chamber) from the borehole.
During sealing engagement of the sampling probe with the rock face,
there is frequently a pressure change (e.g., a slight increase) measured by the
pressure gauge, which can be caused by the sealing action of the sampling probe
and/or the equalization valve closure. Then a pretest piston is moved at a
controlled rate to reduce pressure in the flo line and at the sampling probe,
starting the drawdown time. As the piston moves, the pressure decreases and
ideally stabilizes at a desired drawdown pressure, which is primarily controlled
by the rate the pretest piston moves. This is also the case when sampling, where
a lo g pumping period is used to remove we l bore fl d in the formation in the
vicinity of the probe so that a relatively uneontaminated sample can be obtained.
In some cases the for atio tester pump is used to perform a pressure test, uch
ike a pretest.
After the pretest piston stops moving, the pressure buildup begins, which
marks the end of the drawdown time. Other mechanisms can be used to
terminate the drawdown activity, such as closing a valve to isolate the pretest
piston, or pumping from the flowline - this may be known as a "shut-in".
Usually, the pressure buildup rate mirrors the drawdown rate and the pressure
stabilizes fairly quickly in a permeable for atio (i.e., a formation having a
mobility of greater than 1rmlhdarcy/centipoise). The pressure buildup normally
continues for several minutes until the final buildup pressure has stabilized.
n a formation with low permeability, such as a formation having a
mobility of less than 1 millidarcy/centipoise, the fluid does not flow as easily
into the sampling probe. Thus, when the pretest piston moves, most of the
pressure decrease during drawdown is governed by expansion of the fluids in the
flow line, so that the volume of fluid that actually flows into the formation
represents only a fraction of the piston volume displaced.
When the piston stops moving or the flowline is shut-in, the pressure
increases more slowly than the drawdown pressure decreases. This is because
formation fluid is moving into the formation tester from the sa pli g probe sand
face and recompressing the flow line fluids. Once the piston displacement
volume has entered into the flow line the pressure eventually stabilizes, but this
can take mo e than an hour, depending on several factors.
Equations have been developed to characterize the time i takes to change
drawdown pressure (Fdd) a d buildup pressure (Pbu). These are summarized as
follows:
Phu(t) P - b e £
14696where the system time constant m < . (seconds), and the
drawdown magnitude b
The variables in these equations are known to those of ordinary skill in
the art, and are defined as follows:
q = cc/sec, flow rate
q = cc/sec, drawdown flow rate
r = cm, ro e ra us
r - cm, probe radius
Ms = millidarcy/centipoise, mobility
= psi, formation pressure
ts_ - start of drawdown time
~ end of drawdown time
t ' —T - = seconds of drawdown time
t = T - te_ d = seconds of buildup ti e
T = sec, actual test time
probe shape factor
c = 1/psia, total compressibility
V i cc, flowline volume
i =see, drawdown time
These equations and variables demonstrate that tool design can change
the volumes and rates used to achieve a desired drawdown pressure. Because
the inlet area of conventional sample probes is fixed in size, the standard method
of controlling the drawdown pressure involves changes in the pretest volume and
rate of movement. However, in low permeability, weak rock conditions,
achieving a desired drawdown pressure can be difficult when the pretest volume
and rate of movement are the only accessible variables.
The inventors have discovered a mechanism that can be used to achieve
selected drawdown pressures even when low permeability conditions are
present. This is accomplished by surrounding the sample probe with an
adjustable guard probe to vary the total inlet size. While the prior art permits the
guard probe inlet size to be selected statically, y retrieving the down hole tool
to change out larger and smaller guard probes according to the anticipated
formation testing conditions, various embodiments of the invention permit
changing the size of the guard probe inlet size incrementally, and dynamically,
without retrieving the tool, to accommodate a much wider range of such
conditions.
Another advantage of the adjustable guard probe is improvements that
can be achieved in the sampling process itself. n the prior art, there has been
typically one guard probe used so focus the flow field near the probe to reduce
sampling time. In some embodiments, having more than one guard probe, or
flow rings around the sample probe, can eniiance sampling capabilities when
compared to a single guard ring.. The focusing effect can be further timed to
improve sample quality or reduce sampling time. Furthermore, the shape of the
guard does not necessarily need to be a simple ring around the sample probe a
variable i let size and shape may be implemented to optimize both sampling and
pressure testing based on the formation and fluid properties.
For example, in a low permeability formation, lower flow rates are often
desirable. However there are limits to the rate control on most formation testers
At these times, a larger cross-sectional area on the guard probe can enhance the
ability to control the drawdown pressure. If the guard probe surface inlet area
size ca also be made smaller, this has the same effect as flowing at a higher rate
for more permeable formations, further extending the range of useful operation
associated with the attached formation testing tool.
Thus, an enhancement to varying pretest volume and rate is to vary the
cross sectional flow area through which the fluid is drawn into the sampling
device. a addition to the size of the guard, the guard shape can be varied - from
a circular ring to an elliptical shape. Large packers that extend to seal the well
bore above and below the sampling probe are used in some embodiments. These
and other embodiments of the invention will now be described in more detail.
n some embodiments, a variable guard probe inlet area size can be
achieved by controlling the guard probe inlet area (e.g., adjusting the effective
radius of the guard probe inlet area, where the guard probe inlet area is
mathematically equivalent to that possessed by a guard probe having a
substantially circular inlet area configiiration). One method of varying the guard
probe inlet area size comprises controlling the size of one or more sealing areas
through which formation f d is drawn into the flow line t is a combination of
the guard probe sealing areas, which may have a variety of shapes, that make up
the total guard probe inlet area size.
Thus, the guard probe inlet area size can be varied by using more than
one sealing area, each having a fixed and/or variable size. Thus, i some
embodiments, sealing surfaces are employed as circular sealing elements (e.g.,
arranged as a series of concentric or non-concentric sealing areas) comprising
flexible sealing lips which are engaged, or disengaged with the borehole wall to
create a equivalent guard probe inlet radius that matches the desired inlet area -
one that is useful with respect to the particular formation conditions that are
encountered. As a result, when down hole conditions change, the overall guard
probe i let area can be changed to match the changing conditions, to achieve the
desired drawdown and buildup in a dynamic fashion, without moving the
formation testing tool to physically change out the probe.
In another embodiment separate pretest pistons or pu ps can b
connected to each guard probe to control tlow rates and pressures individually.
By controlling the individual drawdown rates associated with each guard probe,
pressures can be varied between the rings to achieve improved testing results.
For example, by observing the different rates and pressures from the sampling
probe and guard probes, it is possible to determine localized formation rock
properties, such as the permeability, mobility, skin factor, and anisotropy. In
this way, greater control of the flow field in the formation near the probes mayoperate
to further improve sampling
FIG. A is a top plan view 100, and F Gs. B- ID are sectioned side
views 100' 100", 100'" of a geological formation sampling and guard probes,
according to various embodiments of the invention. Each of the sectional views
of the sampling and guard probes 100', 100", 100"' illustrates a different
combination of engaging and disengaging a concentric series of sealing elements
2, effectively forming an inlet area 4 of variable size. This is a feature of
many embodiments: the ability to change the probe flow inlet area while the
testing tool is positioned at a single depth. The result of such flexibility is an
expansion of formation testing and sampling capability, saving rig time.
Referring now to FIGs. 1A-1D, it can be seen thai a central sampling
probe 4 is surrounded by concentric sealing elements 12 which can be
sealingly engaged with the wall of the well bore. The sealing elements 1 2 may
comprise a metallic base with an elastomeric lip 16, where the Hp 116 ay be
made of rubber. The flow through the inlet area 104 is adjustable using the
sealing elements 12, which can be activated by advancing them to engage the
sealing area against the well bore, or retracting them to expose an additional
amount of flow inlet area using a control mechanism in the sampling and guard
probe 00, or a tool attached to the sampling and guard probe 100. One or more
sealing pads 108 may surround the inlet area 104, to include one or more
selectable sealing elements 2 .
Valves 32, internal or external to the formation sampling and guard
probe 100. can be used to control the flow of fluid in some embodiments (e.g., in
sampling and guard probe 100'"). Fluid flow is guided by the seaiing eiemenis
, through the flow inlet area(s) 4 . The valves 132 can be automatically
activated to achieve a desired drawdown pressure and flow area, perhaps using
embedded sensors P, such as pressure sensors. The sealing elements 1 2 and/or
the valves 132 may be used to selectively couple one or more fluid passages 8
from the inlet area(s) 104 to a single fluid flow line 124. One or more pumps
(see pumps 344 in FIG. 3) may be coupled o one or more of the sealing
elements 12, via the valves 132 or directly, to adjust the pumping pressure for
each sealing element 1 , if desired .
FIGs. 2A and 2B illustrate top plan views of additional embodiments of a
geological formation sampling and guard probe 200 according to various
embodiments of th invention. Here it can be seen thai the probe inlet area 104
cars also be varied by using multiple sealing elements 212 (surrounding multiple
sampling probes 4, if desired) with different apertures, shapes, and relative
locations. Tn these sampling and guard probes 200', 200" an elongated oval
shape (e.g., a stadium shape) is shown to include various sealing element 2
configurations.
/
n the example of sampling and guard probe 200', an elongated oval
shaped aperture defined by the sealing pad 08 is used with multiple sampling
probes 4 a d concentric sealing elements 212 to vary the guard probe inlet
area 104 and thus, the equivalent inlet radius. In the example of sampling and
guard probe 200", several non-concentric sealing elements 2 2 and probes 4
are located within the area defined by the sealing pad 108. In each ease, the
effective inlet area 04 of the geological formation sampling and guard probe
200 can be varied y engaging one or more sealing elements 2 12 that cooperate
to define the inlet area 4 . This can be accomplished b advancing the sealing
elements 2 2 into sealing engagement with the well bore, by using mechanical
movement, valves, and or pumps, as described previously. When individual
sampling probes 1 4 are surrounded by one or ore larger probe sealing areas,
the respective inlets , 2 can be engaged separately, or in combination with
the individual sampling probes 14. Again valves and/or pumps ay be use to
effectively vary the composite inlet area 104 for the geological formation
sampling and guard probe 0, 200.
In some cases, a plurality of no -concentric slots 236 are disposed as
sealing elements within the i let area 04 (one or more sampling probes 4 can
be disposed within each of the slots 236). The longitudinal axis of each slot 236
may be substantially parallel to the longitudinal axis 220 of the sampling and
guard probe 200. as well as the longitudinal axis of the down hole tool.
Although not shown, the longitudinal axis of each slot 2 may also be
substantially perpendicular to the longitudinal axis220 of the sampling and guard
probe 200. Each slot 236 may be separately activated for sealing engagement
with the well bore, perhaps using an. eiastomeric material to line the outer edge
of the slot 2 .
FIG. 3A is a block diagram of a data acquisition system 300 and a down
hole tool 304' according to various embodiments of the invention, FIG. 3
illustrates down hole tools 304", 304" ' , 304"" according to various
embodiments of the invention.
An apparatus that operates in conjunction with the system 300 may
comprise a down hole tool 304 (e.g., a pumped formation evaluation tool) that
includes one or more formation sampling a d guard probes 00, 200, valves 132,
straddle packers 340, a d pumps 344. t should be noted that, while the down
hole tool 304 is shown as such, some embodiments of the invention may be
implemented using a wireline logging tool body. However, for reasons of clarity
and economy, and so as not to obscure the various embodiments illustrated, this
latter implementation has not been explicitly shown in this figure.
The system 300 may include logic 342, perhaps comprising a sampling
control system. The logic 342 can be used to acquire flow line drawdown and
buildup pressure data, as well as formation fluid property data.
The data acquisition system 300 ay be coupled to the tool 304, to
receive signals and data generated by the sampling and guard probes 0, 200, as
well as from other sensors that may be included in the probe seals (e.g., sensors
P in FIG. 1). The data acquisition system 300, and/or any of its components,
may be located down hole, perhaps in a tool housing or tool body, or at the
surface 366, perhaps as part of a computer workstation 356 in a surface logging
facility.
In some embodiments of the invention, the down hole apparatus can
operate to perform the functions of the workstation 356, and these results ca be
transmitted to the surface 366 and/or used to directly control the down hole
sampling system, perhaps using a telemetry transceiver (transmitter-receiver)
344. Processors 330 may operate on data that is acquired from the sampling and
guard probes 00, 200 and stored in the memory 350, perhaps in the form of a
database 334. The operations of the processors 330 ay result in the
determination of various properties of the formation surrounding the tool 304.
in some embodiments, the action of variable inlet area sampling and
guard probes 100, 200 can he combined with the operation of straddle packers
340. In this case the sampling and guard probes 100, 200 can be any of the types
shown previously. Here the packers 340 can be individually activated to
perform multiple tests at the same location, if desired. In addition, several sets
of straddle packers 340 can be used with varied spacing, to vary the effective
volume of fluid available to the sampling and guard probe(s) 100. 200.
Combining the action of multiple straddle packers 340 can greatly
increase testing flexibility. A variety of smaller intervals, or even one large
interval can all be tested, along with combinations of intervals. Examples of
these types of variation can be seen with respect to the embodiments illustrated
with respect to the down ho e tools 304', 304", 304"', a d 304"". Having this
variety available ca sometimes be used to better identify the strata and
variations of permeability over a give formation testing interval. These
configurations can also enhance sampling activity, since the isolated interval
surrounding the probe acts as a guard, drawing in the majority of invaded fluids,
so the center sample probe can be used to collect tbe sample, as desired.
The use of multiple valves 132 and pumps 344, as shown, provides a
variety of different fluid flow paths. For example, while it has been shown
previously that the flow lines can be connected to a single pretest cylinder or
pump (e.g., via the single flow line 124 i FIG. 1), it is also possible to connect
each section and/or inlet of a sampling and guard probe 0, 200 or the packer
interval to a separate pump 344 or pretest chamber, perhaps using individual
fluid passages 2 8. Probes similar to thoses in Fig. 1 can also be used to
increase the testing and sampling flexibility. This enables regulating the
drawdown/buildup flow and pressure at each exposed portion of the well bore.
This combined mechanism sometimes permits fluid sensors to detect
contamination a d fluid types within each section, further enhanc g the
sampling capability of the interval of the tool 304. in essence, this configuration
provides independently selectable sample chambers 348. For example, various
analysis methods can be employed using separate flow paths, such as
interference testing between exposed flow areas to determine permeability
aaisotropy. Thus, referring now to FIGs. 1-3, it can be seen that many
embodiments may be realized.
For example, an apparatus may comprise a geological formation
sampling and guard probe 100, 200 having at least one sealing element 12, 212
to provide an inlet area 104 of selectable incrementally variable size. For the
purposes of this document, an inlet area that is "incrementally variable" in size
means that the guard probe inlet area size is designed to be adjusted upward or
downward in a finite number of fixed increments, as occurs w th the use of
multiple sealing elements defining sealing areas that ca be selectively applied to
the borehole wall in sealing engagement per se veral embodiments described
herein. It is not meant to include guard probes, if such exist, with a continuously
variable i let size, providing a substantially unlimited number of possible area
combinations.
The selection of inlet area size may be controlled by a processor. Thus,
the apparatus may comprise a processor 330 to adjust the size, based o a
drawdown pressure sensor response (e.g., from the sensor P)
The sampling and guard probes 100, 200 may have more than one sealing
pad, or only one sealing pad. Thus, the apparatus may comprise a single sealing
pad 108 surrounding the inlet area 04 containing at least one selectable internal
sealing element. These elements may comprise the sealing elements 2 212.
Thus, the inlet area 104 of the apparatus may comprise a plurality of
independently movable, concentric sealing elements 1 2, 2 Ϊ 2 (see FIGs. IA and
2A) or non-concentric sealing dements 242 (see FIG. 2B).
The inlet area 1 4 may have multiple movable or stationary sealing
elements (e.g., when the sealing elements 1 2, 212, 242 are not extendable or
retractable), of e same or differing size. Each of the sealing elements, whether
movable or stationary, can be activated independently by coupling one or more
of them to a flo line 4 Thus, in some embodiments, the inlet area 04
comprises a plurality of non-concentric, movable or non-movable, sealing
elements (e.g., sealing elements 242, fabricated as stationary inlets in FIG 2B),
disposed within the inlet area 4.
Separate inlets may be disposed along a line within the inlet area (e.g.,
along the longitudinal axis of the probe 220, which may be substantiaily parallel
to the longitudinal axis of the down hole tool). Thus, in some embodiments the
plurality of non-concentric inlets 242 is substantially linearly disposed within the
inlet area 104,
The inlet area 104 may be constructed in a variety of shapes, perhaps
comprising a combination of smaller areas. For example, an inlet area 4
having a substantially circular shape (see FIG. A) ay e relatively easy to
fabricate, whereas an inlet area 104 formed as a stadium (see FIG. 2.A) may be
more difficult to make, but also more effecti ve in sealing the probe (e.g., using
less suction over a given area) from its surrounding environment within the bore
hole. An oblong or elliptical design (e.g., the stadium shape) may also provide
stratification information that is otherwise unavailable when a non-oblong (e.g.,
rou d or square) inlet area 104 is used.
Multiple fluid passages from the guard probe to the flow line in the tool
ay be determined by the physical construction of the inlet area 104, and the
relative location of inlet area parts (e.g., concentric sealing elements), to direct
fluid samples from the probe face 134 to the internal flow line 24 . Thus, in
some embodiments, a plurality of fluid passages 128 ca be selectively coupled
from the inlet area 104 to a single fluid flow line 124 via moving concentric
sealing elements toward, or away from, a sealing contact point on the face
134 of the sampling a d guard probe 00, 200.
Multiple fluid passages 128 from the sampling and guard probe 100, 200
to the flow line 124 may be opened/closed by valves 132, a d are generally used
to direct fluid samples from the probe face 134 to the internal flow line 124,
either sequentially, or substantially simultaneously. Thus, an apparatus may
comprise a plurality of valves 132 to selectively couple a corresponding plurality
of fluid passages 128 fro the inlet area 104 to a single fluid flow line 124.
One or ore sensors P can be embedded in the seal , the passage 8,
and/or the flow line 124 Thus, the apparatus may comprise o e or more sensors
F, such as a drawdown/buildup pressure sensor. Still further embodiments may
be realized.
For example, F G. 4 illustrates a wireline system 464 embodiment of the
invention, and FIG. 5 illustrates a while-drilling system 564 embodiment of the
invention. Thus, the systems 464, 564 may comprise portions of a tool body 470
as part of a wireline logging operation, or of a down hole tool 524 as part of a
down hole drilling operation.
FIG. 4 shows a well during wireline logging operations A. drilling
platform 486 is equipped with a derrick 488 that supports a hoist 490.
The drilling of oil and gas wells is commonly carried out using a string of
drill pipes connected together so as to form a drilling string that is lowered
through a rotary table 410 into a wellbore or borehole 412. Here it is assumed
that the drill string has been temporarily removed from the borehole 412 to allo
a wireline logging tool body 470, such as a probe or sonde, to be lowered by
wireline or logging cable 474 into the borehole 412. Typically, the tool body
470 is lowered to the bottom of the region of interest and subsequently pulled
upward at a substantially constant speed.
During the upward hip, at a series of depths the tool movement can be
paused and the tool set to pump fluids into the sampling and guard probes 100,
200 included in the tool body 470. Various instruments (e.g., sensors) may be
used to perform measurements on the subsurface geological formations 414
adjacent the borehole 412 (and the tool body 470). The measurement data ma
be stored and/or processed down hole (e.g., via subsurface processors) 330,
logic 342, and memory 3 0) or communicated to a surface logging facility 492
for storage, processing, and analysis. The logging facility 492 may be provided
with electronic equipment for various types of signal processing, which may be
implemented by any one or more of the components of the system 300 in FIG. 3.
Similar formation evaluation data may be gathered and analyzed during dri ling
operations (e.g., during logging while drilling (LWD) operations, and by
extension sampling while drilling).
In some embodiments, the tool body 470 comprises a formation testing
tool for obtaining and analyzing a fluid sample from a subterranean formation
through a wellbore. The formation testing tool is suspended in the wellbore by a
wireline cable 474 that connects the tool to a surface control unit (e.g.,
comprising a workstation 6 as depicted in FIG. 3 or the like). The formation
testing tool may be deployed in the wellbore on coiled tubing, jointed drill pipe,
hard-wired drill pipe, or via any other suitable deployment technique.
Turning now to FIG. 5, it can be seen how a system 564 may also form a
portion of a drilling rig 502 located at the surface 504 of a well 506. The drilling
rig 502 may provide support for a drill string 508. The drill string 508 may
operate to penetrate a rotary table 4 0 for drilling a borehole 412 through
subsurface formations 414. The drill string 508 may include a ke y 5 , drill
pipe 518, and a bottom hole assembly 520, perhaps located at the lower portion
of the drill pipe 518.
The bottom hole assembly 520 may include drill collars 522, a down hole
tool 524, and a drill bit 526. The drill bit 526 may operate to create a borehole
412 by penetrating the surface 504 and subsurface formations 414. The down
33
hole tool 524 may comprise an of a number of different types of tools including
MWD (measurement while drilling) tools, LWD tools, and others.
During drilling operations, the drill string 508 (perhaps including the
ke y 51 , the drill pipe 8, and the bottom hole assembly 520) may be rotated
by the rotary table 410. In addition to, or alternatively, the botto hole assembly
520 ay also be rotated by a motor (e.g., a mud motor) that is located down
hole. The drill collars 522 may be used to add weight to the drill bit 526. The
drill collars 522 may also operate to stiffen the bottom hole assembly 520
allowing the bottom hole assembly 520 to transfer the added weight to the drill
bit 526, and in torn, to assist the drill bit 526 in penetrating the surface 504 and
subsurface formations 414.
During drilling operations, a mud pump 532 may pump drilling fluid
(sometimes known by those of skill in the art as "drilling mud") from a mud pit
534 through a hose 536 into the drill pipe 5 and down to the drill bit 526. The
drilling fluid can flow out from the drill bit 526 and be returned to the surface
504 through an annular area 540 between the drill pipe and the sides of the
borehole 412. The drilling fluid may then be returned to the mud pit 534, where
such fluid is filtered. In some embodiments the drilling fluid can be used to
cool the drill bit 526, as well as to provide lubrication for the drill bit 526 during
drilling operations. Additionally, the drilling fluid may he used to remove
subsurface fom a ion cuttings created by operating the drill bit 526.
Thus, referring now to FIGs. 1-5, it may be seen that in some
embodiments, a system 464, 564 may include a down hole tool 304, 524, and/or
a wireline logging tool body 470 to house one or more apparatus and/ot systems,
similar to or identical to the apparatus and systems described above and
illustrated in FIGs. 1-3. Wireline tools are frequently adapted for use in a drill
siring when wireline conveyance is not possible. For example, this may be the
case to accommodate highly deviated boreholes or horizontal wells. Thus, for the
purposes of this document, the term "housing" may include any one or more of a
down hole tool 304, 524 or a wireline logging tool body 470 (each having an
outer wall that can be used to enclose or attech to instrumentation, sensors, fluid
samp ng devices, such as probes, pressure measurement devices, such as
sensors seals, processors, a d data acquisition systems). The down hole tool
304, 524 may comprise an LWD tool or MWD tool. The tool body 470 may
comprise a wireline logging tool, including a probe or sonde, for example,
coupled to a logging cable 474. Many embodiments may thus be realized.
For example, i some embodiments a system 464, 564 ay comprise a
housing and o e or more geological formation sampling and guard probes 100,
200 mechanically coupled to the housing. The geological formation probes 0
200 may have one or more fluid inlets with an inlet area of selectable,
incrementally variable size.
The probes 100, 200 described herein can thus be attached to a variety of
housings. For example, the housing may comprise a wireline tool body 470 or a
down hole tool 304, 524, such as an MWD tool.
n some embodiments, the system 464, 564 may include straddle packers
to capture fluid between the housing and the borehole wall. Thus, the system
464, 564 may comprise independently activated straddle packers 340
mechanically coupled to the housing, the packers 340 configurable to isolate
fluid along a selected length of the housing a d/or to bound the fluid volume
available for intake by the probes 100, 200 when the probes 100, 200 are not in
contact with the borehole wall (e.g., see FIG. 3).
In some embodiments, a system 464, 564 may include a display 496 to
present the pumping volumetric flow rate, measured saturation pressure, seal
pressure, probe pressure, and other information, perhaps in graphic form.. A
system 464, 564 may also include computation logic, perhaps as part of a surface
logging facility 492, or a computer workstation 454, to receive signals from fluid
sampling devices (e.g., probes 00, 200), multi-phase flow detectors, pressure
measurement devices (e.g.,sensors P), probe displacement measurement devices,
and other instrumentation to determine adjustments to be made to the seal
placement: and pu p in a fluid sampling device, to determine the quality of the
borehole sea contact, as well as various formation characteristics.
The geological formation sampling and guard probes 100, 200; sealing
pads 08; sealing elements 2, 2 12; sampling probes 4 ; fluid line 24; fluid
passages 128; valves 132; slots 236; systems 300, 464, 564; down hole tool 304,
524; processors 330; database 334; straddle packers 340; logic 342; pumps 344;
memory 350; workstation 356; rotary table 410; tool body 470; drilling platform
486; derrick 488; hoist 490; logging facility 492; display 496; drilling rig 502;
drill string 508; ke y 516; drill pipe 518; bottom hole assembly 520; drill collars
522; down hole tool 524; drill bit 526; mud pump 532; hose 536; and sensors P
may all be characterized as "modules" herein.
Such modules may include hardware circuitry, a processor, memory
circuits, software program modules a d objects, firmware, and/or combinations
thereof, as desired by the architect of the apparatus and system s 300, 464, 64
and as appropriate for particular implementations of various embodiments. For
example, in so e embodiments, such modules may be included in an apparatus
and/or system operation simulation package, such as a software electrical signal
simulation package, a power usage and distribution simulation package, a
power/heat dissipation simulation package, and/or a combination of software and
hardware used to simulate the operation of various potential embodiments.
It should also be understood that the apparatus and systems of various
embodiments can be used in applications other than for logging operations, and
thus, various embodiments are not to be so limited. The illustrations of
apparatus and systems 300, 464. 564 are intended to provide a general
understanding of the structure of various embodiments, and they are not intended
to serve as a complete description of al the elements and features of apparatus
and systems that might make use of the structures described herein.
Applications that may include the novel apparatus and systems of various
embodiments may include electronic circuitry used in high-speed computers,
communication and signal processing circuitry, modems, processor modules,
embedded processors, data switches, application-specific modules, or
combinations thereof. Such apparatus and systems may further be included as
sub-components within a variety of electronic systems, such as televisions,
cellular telephones, personal computers, workstations, radios, video players,
vehicles, signal processing for geothermal tools and smart transducer interface
node telemetry systems, among others. Some embodiments include a number of
methods.
For example, FIG. 6 is a flow chart illustrating several methods 6 1 of
operating guard probes with selectable and incrementally variable inlet area size.
Thus, a processor-implemented method 6 to execute on one or more
processors that perform the method may begin at block 62 with advancing (as
needed) a geological formation guard probe w th a surrounding pad to seal the
pad against a borehole wall.
The method 6 may continue on to block 625, to determine whether
feedback is being used o ad st the inlet area size. For example, pressure sensor
feedback can be used to adjust the size of the inlet area. If feedback is not used,
the method 6 may advance directly to block 633 with adjusting the size of at
least one inlet area of the guard probe, perhaps using a series of sealing
elements, where the size of the inlet area selectabiy and incrementally
variable.
If feedback is used to adjust the inlet area size, then the method 6 may
continue from block 625 on to block 629 with operating to determine the amount
of feedback, and then go on to block 633 with adjusting the size of the inlet area
based on the feedback. For example, the feedback can be pro vided by a sensor,
such as a drawdown pressure sensor.
some embodiments, the guard probe sealing elements are concentric,
and the inlet area size is adjusted by advancing/retracting one or more of the
sealing elements. Thus, the activity of adjusting the inlet area size at block 633
may comprise advancing some of a set of concentric sealing eielements included
in the inlet area toward the borehole wall and/or retracting some of the set of
concentric sealing elements included in the inlet area away from the borehole
wall.
The method 6 1may continue on to block 637 to include drawing fluid
into the fluid inlet area by activating at least one pump coupled to at least one
fluid passage in the guard probe.
Fluid can be drawn through one or more selected sealing elements - one
at a time, or substantially simultaneously. Thus, the activity at block 637 may
comprise selectively drawing the fluid through an electronically selected number
of multiple non-concentric sealing element included in the inlet area.
The selection of fluid drawn into the inlet area can be controlled via
separate pumps and/or valves. Thus, the activity at block 637 may comprise
operating more than one pump or more than one valve coupled to the nonconcentric
sealing elements.
Straddle packers can be activated to capture fluid between the housing
and the borehole wall; the captured fluid can then be taken i to the probe
without having the probe contact the borehole wall. Thus, the activity at block
637 can include drawing fluid captured by straddle packers into the fluid inlet
area f or more guard probes.
At block 641, the method 6 may include determining whether fluid
sampling is complete. If so, the method may continue on to block 649, or to
block 62 in some embodiments.
f fluid sampling is not complete, in some embodiments, the method 1
may continue on to block 645 to include activating at least two straddle packers
to capture the fluid as captured fluid between the straddle packers, a borehole
tool, and the borehole wall.
n some embodiments, fluid can be drawn through the borehole wal , and
from an area isolated by straddle packers, at different rates. The difference in
pressure between the two activities can be used to determine formation
permeability. Thus, the activity at block 637 may he accomplished with or
without straddle packers at a first flow rate and a first fluid pressure, and then go
on to activating (or re-ac ating) the straddle packers at block 645, and returning
to block 637 to capture some of the fluid as captured fluid, drawing the captured
fluid through the fluid inlet at a second rate different from the first rate, to
determine a permeability of a formation associated with the borehole wall.
The method 611 may continue on to block 649 to include retracting the
geological formation guard probe away from the borehole wall to break the seal
of the pad against the borehole wall. Fluid may then be drawn into the guard
probe, if straddle packers are used to isolate the probe, or the tool may be moved
to a different depth in the bore hole, depending on the sampling process desired.
It should be noted that the methods described herein do not have to be
executed in the order described, or in any particular order. Moreover, various
activities described with respect to the methods identified herein can be executed
in iterative, serial, or parallel fashion. Information, including parameters,
commands, operands, and other data, can be sent and received in the form of one
or more carrier waves.
The apparatus 00, 200 a d systems 300, 464, 564 may be implemented
in a machine-accessible and readable medium that s operational over one or
ore networks. The networks may be wired, wireless, or a combination of
wired and wireless. The apparatus 100, 200 and systems 300, 464, 564 ca be
used to implement, among other things, the processing associated with the
methods 6 11 of FIG. 6. Modules may comprise hardware, software, and
firmware, or any combination of these. Thus, additional embodiments may be
realized.
For example, FIG. 7 is a block diagram of an article 700 of manufacture,
including a specific machine 702, according to various embodiments of the
invention. Upo reading and comprehending the content of this disclosure, one
of ordinary skill in the art will understand the manner in which a software
program can be launched from a computer-readable medium in a computerbased
system to execute the functions defined in the software program.
One of ordinary skill in the art will further understand the various
programming languages that ay be employed to create one or more software
programs designed to impiement and perform the methods disclosed herein. For
example, the programs may be structured i an object-orier.tated format using an
object-oriented language such as Java or C++. In another example, the programs
can be structured in a procedure-oriented format using a procedural language,
such as assembly or C. The software components ay communicate using any
of a number of mechanisms well known to those of ordinary skill in the art, such
as application program interfaces or interprocess communication techniques,
including remote procedure calls. The teachings of various embodiments are not
limited to any particular programming language or environment. Thus, other
embodiments may be realized.
For example, an article 700 of manufacture, such as a computer, a
memor system, a magnetic or optical disk, some other storage device, and/or
any type of electronic device or system may include one or more processors 704
coupled to a machine-readable medium 708 such as memory (e.g., removable
storage media, as well as any memory including an electrical, optical, or
electromagnetic conductor) having instructions 712 stored thereon (e.g.,
computer program instructions), which when executed by the one or more
9
processors 704 result its. the machine 702 performing any of the actions described
with respect to the methods above,
The machine 702 may take the form of a specific computer system
having a processor 704 coupled to a number of components directly, and/or
using a bus 7 . Thus, the machine 702 may b e incorporated into the apparatus
100, 200 or system 300, 464, 564 shown in FIGs. 1-5, perhaps as part of the
processor 330, or the workstation 356.
Turning now to FIG. 7, it can he seen that the components of the machine
702 may include ai memory 720, static or non-volatile memory 724, and
mass storage 706. Other components coupled to the processor 704 may include
an input device 732, such a s a keyboard, or a cursor control device 736, such as a
mouse. An output device 728, such as a video display, may be located apart
from the machine 702 (as shown), or made as a integral part of the machine
702,
A network interface device 740 to couple the processor 704 and other
components to a network 744 may also be coupled to the bus 716. The
instructions 12 ay h e transmitted or received over the network 744 via the
network interface device 740 utilizing any one of a number of well-known
transfer protocols (e.g.. Hypertext Transfer Protocol). Any of these elements
coupled to the bus 716 may b e absent, present singly, or present in plural
numbers, depending on the specific embodiment to be realized.
The processor 704, the memories 720, 724, and the storage device 706
may each include instructions 712 which, when executed, cause the machine 702
to perform any o e or more of the methods described herein, in some
embodiments, the machine 702 operates as a standalone device or may be
connected (e.g., networked) to other machines. I a networked environment, the
machine 702 may operate in the capacity of a server or a client machine in
server-client network environment, or as a peer machine in a peer-to-peer (or
distributed) network environment.
The machine 702 may comprise a personal computer (PC), a tablet PC, a
set-top box (STB), a PDA, a cellular telephone, a web appliance, a network
router, switch or bridge, server, client, or a y specific machine capable of
executing a set of instructions (sequential or otherwise) that direct actions to be
taken by that machine to implement the methods and functions described herein.
Further, while only a single machine 702 is illustrated, the term "machine" shall
also be taken to include any collection of machines that individually or jointly
execute a set (or multiple sets) of instructions to perform any one or more of the
methodologies discussed herein.
While the machine-readable medium 708 is shown as a single medium,
the term "machine-readable medium" should be taken to include a single
medium or multiple media (e.g., a centralized or distributed database, and'or
associated caches and servers, and or a variety of storage media, such as the
registers of the processor 704, memories 720, 724, and the storage device 706
that store the one or more sets of instructions 712. The term "machine-readable
medium" shall also be taken to include any medium that is capable of storing,
encoding or carrying a set of instructions for execution by the machine and that
cause the machine 702 to perform any one or more of the methodologies of the
present invention, or that is capable of storing, encoding or cartying data
structures utilized by or associated with such a set of instructions. The terms
"machine-readable medium" or "computer-readable medium" shall accordingly
be taken to include tangible media, such as solid-state memories and optical and
magnetic media.
Various embodiments may be implemented as a stand-alone application
(e.g., without any network capabilities), a client-server application or a peer-tcpeer
(or distributed) application. Embodiments may also, for example, be
deployed by Software-as-a-Service (SaaS), an Application Service Provider
(ASP), or utility computing providers, in addition to being sold or licensed via
traditional channels.
Using the apparatus, systems, and methods disclosed herein may afford
formation evaluation clients the opportunity to more intelligently choose
between repeating measurements and moving the tool Additional data on rock
properties that can be collected using various embodiments can inform the
selection of future testing locations within the same formation and wellbore, as
well as determining how to adjust the guard probe inlet area to enhance sealing
and/or prevent rock failure. Increased client satisfaction may result.
The accompanying drawings that form a part hereof, show by way of
illustration, a d not of limitation, specific embodiments in which the subject
matter may be practiced. The embodiments illustrated are described in sufficient
detail to enable those skilled in the art to practice the teachings disclosed herein.
Other embodiments may be utilized and derived therefrom, such that structural
and logical substitutions and changes may be made without departing from the
scope of this disclosure. This Detailed Description, therefore, is not to be taken
in a limiting sense, and the scope of various embodiments is defined only by the
appended ciainis, along with the full range of equivalents to which such claims
are entitled.
Such embodiments of the inventive subject matter may be referred to
herein, individually and/or collectively, by the term "invention" merely for
convenience and without intending to voluntarily limit the scope of this
application to any single invention or inventive concept if more than one s in
fact disclosed. Thus, although specific embodiments have been illustrated and
described herein, it should be appreciated that any arrangement calculated to
achieve the same purpose may be substituted for the specific embodiments
shown. This disclosure is intended to cover any and all adaptations or variations
of various embodiments. Combinations of the above embodiments, and other
embodiments not specifically described herein, will be apparent to those of skill
in the art upon reviewing the above description.
The Abstract of the Disclosure s provided to comply with 37 C.F.R.
§1-72(b), requiring an abstract that will allow the reader to quickly ascertain the
nature of the technical disclosure. It is submitted with th understanding that it
will not be used to interpret or limit the scope or meaning of the claims n
addition, in the foregoing Detailed Description, it can be seen that various
features are grouped together in a single embodiment for the purpose of
streamlining the disclosure. This method of disclosure is not to be interpreted as
reflecting an intention that the claimed embodiments require more features than
are expressly recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single disclosed
embodiment. Thus the following claims are hereby incorporated into the
Detailed Description, with each claim standing on its own as a separate
embodiment.
Claims
What is claimed is:
. An apparatus, comprising:
a geological formation probe having at least one fluid flow inlet with an
inlet area of selectable, incrementally variable size.
2. The apparatus of claim , further comprising:
a processor to adjust the size, based on a drawdown pressure sensor
response.
3. The apparatus of clai 1 farther comprising:
a single sealing pad surrounding the inlet area, the inlet area containing at
least one selectable internal sealing element.
4 . The apparatus of claim 1, wherein the inlet area comprises:
a plurality independently movable, concentric sealing elements.
5. The apparatus of claim 1. wherein the inlet area comprises:
a plurality of non-concentric, movable sealing elements, disposed within
the inlet area.
6. The apparatus of claim 5, wherein the; plurality of non-concentric i lets is
substantially linearly disposed.
7. The apparatus of claim 1, wherei n the 'm et area is formed as a stadium.
8. The apparatus of claim , wherein a plurality' of fluid passages can be
selectively coupled from the inlet area to a single fluid flow line via moving at
least one concentric sealing element toward, or away from, a sealing contact
point on a face of the probe.
9. The apparatus of claim 1, further comprising:
a plurality of valves to selectively couple a corresponding plurality of
fluid passages from the inlet area to a single fluid flow line.
10. A system, comprising:
a housing; a d
a geological formation probe mechanically coupled to the housing, the
geological formation probe having at least one fluid flow inlet with an inlet area
of selectable, incrementally variable size.
. The system of claim , wherein the housing comprises one of a wireline
tool or measurement while drilling tool.
12. The system of claim 10, wherein the inlet area comprises:
a plurality of non-concentric slots disposed as sealing elements within the
inlet a rea, a longitudinal axis of each slot being substantially parallel to a
longitudinal axis of the hou sing.
3. The system of claim 0, further comprising:
independently activatible straddle packers mechanically coupled to the
housing, the packers configurable to isolate fluid along a selected length of the;
housing, to bound a fluid volume available for intake by the guard probe when
the guard probe is ot in contact with the borehole wall.
14. A processor-implemented method to execute on one or more processors tha
perform the method, comprising:
advancing a geological formation probe with a surrounding pad to seal
the pad against a borehole wall;
adjusting a size of at least one inlet area of a fluid flow inlet of the probe,
the size of the inlet area being selectably and incrementally variable: and
drawing fluid into the fluid flow inlet by activating at least one pump
coupled to at least one fluid passage in the probe.
5. The method of claim 4, wherein the adjusting comprises:
adjusting the size based on feedback from a drawdown pressure sensor.
16. The method of claim 14, wherem the adjusting comprises:
advancing some of a set of concentric sealing elements included in the
inlet area toward the borehole wail, and-'or
retracting some of the set of concentric sealing elements included in the
inlet area away from the borehole wall.
1 . 'Hie method of claim 14, further comprising:
activating at least two straddle packers to capture the fluid as captured
fluid between the straddle packers, a borehole tool, and the borehole wall;
retracting the guard probe away from the borehole wall to break the seal
of the pad against the borehole wall; and
drawing the captured fluid into the fluid flow inlet.
18. The method of claim 14, wherein the drawing comprises:
selectively drawing the fluid through an electronically selected number of
multiple non-concentric sealing elements included in the inlet area.
19. The method of claim S, wherein selectively drawing further comprises:
operating more than one pump or more than one valve coupled to the
non-concentric sealing elements.
20. The method of claim 14, wherem drawmg the fluid is accomplished at a first
flow rate at a first fluid pressure, further comprising:
activating straddle packers to capture some of the fluid as captured fluid;
and
drawing the captured fluid through the fluid flow inlet at a second rate
different from the first rate, to determine a permeability of a formation
associated with the borehole wa l.