INTEGRATED WELL SURVEY MANAGEMENT AND PLANNING TOOL
TECHNICAL FIELD
[0001] This disclosure relates to well survey management and planning.
BACKGROUND
[0002] A well plan describes the well trajectory to be followed to to take a
well successfully from its surface position to the end of the well trajectory. Based on
factors such as an expected use of a well (e.g., observation, production, injection, or
multi-purpose well), parameters (e.g., production parameters, completion
requirements, well dimensions, location), an expected life of the well, and conditions
of the geological target (e.g., the subterranean reservoir) to be reached by the well,
and other factors, the well plan outlines well objectives to be achieved during well
drilling and well use. When drilling commences based on the well plan, the well can
be periodically surveyed to obtain information describing the well being drilled and
the obtained information interpreted, e.g., to compare a planned position and a
determined position of the well. An operator can respond to deviations between the
planned position and the determined position, e.g., by adjusting the drilling operations
or by re-defining the well objectives (or both).
DESCRIPTION OF DRAWINGS
[0003] FIG. 1 illustrates an example computer system to implement an
integrated well survey management and planning tool.
[0004] FIG. 2 is a flowchart of an example process to implement the
integrated well survey management and planning tool during a planning stage.
[0005] FIG. 3 illustrates an example user interface provided by the example
computer system of FIG. 1 in response to implementing the integrated well survey
management and planning tool.
[0006] FIG. 4 is a flowchart of an example process to implement the
integrated well survey management and planning tool during an execution stage.
[0007] FIG. 5 illustrates an example schematic of the example computer
system of FIG. 1.
[0008] Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0009] This disclosure describes an integrated well survey management and
planning tool. The tool can be implemented as a comprehensive, interactive survey
management computer software application that can enable better planning and
evaluation of survey strategy. The tool can bring different aspects of survey
management, e.g., outputs determined by different survey tools that need to be
considered during planning and executing a well into a single interactive environment.
By implementing the tool, results of some analysis and actual interference effects can
be viewed during the planning stage and the execution stage, respectively.
[0010] As described below, the tool can display multiple elements that affect
well planning and surveying in a single interactive user interface on a display device.
The interactive user interface can display the effect of a change in one parameter on
other parameters, as applicable. Based on the outputs displayed in the user interface,
an operator can adjust the choice of survey tools resulting in a well survey that
achieves the well objectives, e.g., drill a well that reaches the intended geological
target. In this manner, the tool can be implemented as an all-in-one interactive tool
that can illustrate and optimize a survey for a well, platform, pad or field. For
example, the tool can enable implementing as few surveys as necessary with survey
tools that are as inexpensive as practicable. The tool can be implemented before or
after commencing drilling operations (or both). Implementing the tool can enable
operators to match the survey program with well objectives. The tool can be used to
perform what-if analysis to determine the optimum length of non-magnetic material
required in the BHA and to monitor the effects of variations in the earth magnetic
field, due to solar storms for instance, on survey accuracy and allow for early
determination if re-surveying is needed. Also the tool allows for the instantaneous
verification that the correct earth magnetic model is being used and that the input
variables are correct, the same applies for the declination correction being applied.
FIG. 1 illustrates an example computer system 100 to implement the integrated well
survey management and planning tool. In some implementations, the tool can be
implemented as a computer software application including computer instructions
stored on a computer-readable medium 102 and executable by data processing
apparatus 104 (e.g., one or more computer processors). The computer system 100 can
be connected to a display device 106 and to one or more input devices 108 (e.g., a
mouse, a keyboard, a touchscreen, a stylus, an audio input device, or other input
devices). In some implementations, the computer system 100 can be a desktop
computer, a laptop computer, a tablet computer, a smartphone, a personal digital
assistant, a client computer of a server-client computer system, or other computer
system.
[00 11] The computer system 100 can be connected to one or more well survey
and planning computer systems (e.g., a first computer system 110a, a second
computer system 110b, a third computer system 110c) over one or more wired or
wireless networks 112 (e.g., a local area network, a wide area network, the Internet).
Each well survey and planning computer system can execute a respective well survey
and planning computer software application that receives survey information obtained
from survey tools connected to each well survey and planning computer system. The
computer system 100 can receive the survey information from the well survey and
planning computer software applications over the one or more wired or wireless
networks 112. In some implementations, the one or more well survey and planning
computer systems can be implemented as entities that are separate from the computer
system 100 that implements the integrated well survey management and planning
tool. Alternatively, the computer system 100 can implement the computer software
applications implemented by each of the one or more well survey and planning
computer systems.
[0012] FIG. 2 is a flowchart of a process 200 to implement the integrated well
survey management and planning tool during a planning stage, i.e., before drilling
commences. In some implementations, the computer system 100 can implement the
process 200. At 202, the computer system 100 can receive multiple parameters. For
example, the parameters can describe a location and a shape of a well and can be
received, e.g., from a well operator. At 206, the computer system 100 can receive a
survey plan indicating the number, position and survey type of surveys to be
performed on the well while drilling the well.
[0013] At 204, the computer system 100 can receive a trajectory of the well
from a surface to a subterranean geological target to be reached by drilling the well.
For example, an operator can provide the trajectory as an input to the computer
system 100. Alternatively, another computer system, which stores the trajectory, can
provide the trajectory as an input to the computer system 100. At 208, the computer
system 100 can receive a selection of a survey tool from among multiple survey tools.
A survey tool can be a physical type of surveying tool that can be carried into the
well. For example, the tool can be carried into the well on a wire (e.g., a wireline, eline,
or other tool) or tubing. The survey tool can measure the location in threedimensional
space of the well. For example, either the computer system 100 or one
or more of the well survey and planning computer systems (or both) can be connected
to the survey tool that surveys the well to be drilled along the received trajectory. In
some implementations, the computer system 100 can also receive the number,
position and survey type of surveys to be performed on the well while drilling the
well.
[0014] At 210, the computer system 100 can apply multiple error models to
the survey tool. An error model can be implemented as a computer software
application as computer instructions stored on the computer-readable medium 102 and
executable by the data processing apparatus 104. Each error model can define a
respective uncertainty in reaching the subterranean geological target by drilling the
well along the received trajectory. Some error models can determine the respective
uncertainty by accounting for influences of different error sources. In some
implementations, the computer system 100 can receive the error models, e.g., as
inputs from an operator or from another computer system (or both). At 212, the
computer system 100 can display, in a user interface 114 (e.g., displayed in the
display device 106), the multiple parameters, the received trajectory of the well, an
identifier identifying the survey tool and an uncertainty indicator determined by
applying the one or more error models. The uncertainty indicator indicates an
uncertainty in drilling the well on the received trajectory.
[0015] The uncertainty indicator represents a combination of respective
uncertainties defined by the multiple error models. In other words, the uncertainty
indicator is an uncertainty of the well that represents a combination of uncertainties of
each survey and spacing between the surveys. For example, each of multiple survey
tools that are (or can be) implemented during a well survey is associated with a
respective uncertainty. The uncertainty indicator described in this disclosure
represents a combination of the multiple uncertainties associated with the multiple
survey tools. The computer system 100 can determine the uncertainty indicator
based, in part, on the locations of the survey tools. The uncertainty represented by the
uncertainty indicator is more than the uncertainty in the accuracy of the tool itself.
The uncertainty in the accuracy of the tool is determined by errors in the tool's ability
to make measurements. In addition to the uncertainty of the tool, the uncertainty for
the well represented by the uncertainty indicator represents an uncertainty in drilling
the well along the target trajectory without being able to see the three-dimensional
drilling space, i.e., without survey points and using measurements made by the survey
tools during the previous survey. The uncertainty represented by the uncertainty
indicator can increase as a time between successive surveys increases because the
possible error builds. In some implementations, the uncertainty indicator can be
determined based on the intended well trajectory and the survey tools that will be used
(and the locations of the survey tools). The operator can then plan more or fewer
survey points, different survey points, different survey tools (or combinations of
them) based on a confidence (provided by the uncertainty indicator) that the well will
hit the geological target.
[0016] In this manner, the computer system 100 can provide the user interface
114 as a comprehensive, interactive survey management module. The operator can
use the user interface 114 to evaluate an effect of different numbers, positions and
survey types of surveys that affect the uncertainty indicator. The operator can also
use the user interface 114 to evaluate an effect of different error models and
combinations of error models, measurement corrections (e.g., sag correction), drill
string configuration (e.g., the NMDC), well configurations and factors including well
location and drilling time of the year. For example, the computer system 100 can
provide each of the factors that affect the uncertainty indicator as a selectable option
in the user interface 114. The operator can create combinations of selectable options
(e.g., a combination of a first error model, a first correction, a first drill string
configuration, a first location, a first drilling time, another combination of first and
second error models, no correction, a second drill string configuration, the first
location, a second drilling time, or other combinations) to determine the uncertainty
indicator. In this manner, the operator can select/unselect available options and
determine an effect on the uncertainty indicator. The operator can use the tool
implemented by the computer system 100 to determine a survey program (i.e., the
number, position and survey types) that will enable the operator to drill a well that
will reach the geological target.
[0017] In the planning stage, the computer system 100 can receive the
multiple parameters, receive the trajectory of the well, receive the selection of the
survey tool, apply the one or more error models and display the multiple well survey
parameters before the well is drilled along the received trajectory. In an execution
stage, the computer system 100 can additionally receive actual drilling data and show
the trajectory based on actual drilling data, as described below.
[0018] FIG. 3 is an example of the user interface 114 provided by the
computer system 100 in response to executing the integrated well survey management
and planning tool. The user interface 114 includes multiple regions. In each region,
the computer system 100 displays either an input to or an output of the integrated well
survey management and planning tool implemented by the computer system 100. In
some implementations, the user interface 114 includes a region 304 in which the
computer system 100 displays multiple parameters, e.g., a length of a non-magnetic
drill collar (NMDC) to be positioned in the well, a sensor position in the NMDC at
which a survey tool is to be positioned, and casing information describing at least one
of a casing size, distance, or direction from the sensor position. The computer system
100 can receive the multiple parameters, which can also include a location and a
shape of the well, either from an operator of the computer system 100 or from one of
the well survey and planning computer systems.
[0019] The user interface 114 includes a region 308 in which the computer
system 100 displays the trajectory of the well from the surface to the subterranean
geological target based, in part, on the parameters. In the region 308, the computer
system 100 can also display the uncertainty indicator described above. In some
implementations, the computer system 100 can display the uncertainty indicator as
including multiple ellipses, each occupying a different area. As described above, each
ellipse represents a combination of uncertainties associated with different multiple
survey tools. A change in an uncertainty associated with information obtained by one
of the survey tools affects an uncertainty associated with information obtained by
another of the survey tools. Each ellipse of the multiple ellipses accounts for the
different uncertainties associated with the different survey tools. For example, an area
occupied by each ellipse is a measure of uncertainty in drilling on the target trajectory
at a respective depth that cannot be visualized by relying on survey points obtained
from the survey tools during a previous survey. In addition, each ellipse is associated
with a respective depth of the well from the surface to the subterranean geological
target. The computer system 100 can display the multiple ellipses at multiple
respective depths along the trajectory in the region 308 of the user interface 114.
[0020] In some implementations, the computer system 100 can determine a
confidence level for each ellipse that represents a confidence that an actual trajectory
of the drilled well will match the predicted trajectory. The computer system 100 can
determine the confidence level for each ellipse based, in part, on uncertainties
associated with the information obtained by the survey tools, as described above. The
computer system 100 can additionally determine an uncertainty threshold at a
respective depth that represents an acceptable deviation between the actual and
predicted trajectories. The uncertainty threshold is a potential uncertainty that is so
great that the target trajectory could possibly miss the geological target. The
computer system 100 can also determine whether the possible actual trajectory will
reach the geological target. The computer system 100 can determine that a first
ellipse at a first depth does not satisfy an uncertainty threshold at that depth. In
response, the computer system 100 can display the first ellipse in the region 308 in a
manner that is visually distinguishable from a second ellipse that satisfies the
uncertainty threshold at a second depth. For example, the computer system 100 can
display ellipses that satisfy respective uncertainty thresholds in a color (e.g., green)
and ellipses that do not satisfy the respective uncertainty thresholds in another color
(e.g., red).
[0021] In some implementations, multiple survey tools can be available and
can be connected to (e.g., operated by) the well survey and planning computer
systems. The operator of the computer system 100 can select one or more survey
tools, which can include, e.g., a single shock magnetic survey tool, a MWD magnetic
survey tool with multi-shock type survey, or other survey tools. If the inaccuracies
determined for the survey tools are higher than acceptable thresholds, then additional
corrections can be applied. The corrections can include, e.g., SAG corrections to
correct errors in the alignment of the survey tool, corrections to correct errors
associated with the presence of magnetic components in the drill string, corrections
due to earth's magnetic field based on geographic location (e.g., closer to the north or
south poles), and other corrections.
[0022] As described above, the computer system 100 can receive a selection
of one or more survey tools, e.g., from a user of the computer system 100 or from one
or more of the well survey and planning computer systems. In addition, the computer
system 100 can receive one or more error models to be applied to the selected survey
tool through the user interface 114. For example, the user interface 114 can include a
region 302 in which the computer system 100 displays multiple error models
including, e.g., at least one of an interpolation in-field referencing (IIFR) model, an
in-field referencing (IFR) model, and a measurement while drilling (MWD) model.
In this region, the user interface 114 can also include a correction applied to the
readings, e.g., a sag correction. A user of the computer system 100 can select one or
more of the error models through the user interface 114. The computer system 100
can apply the selected one or more error models to the selected survey tool. In some
implementations, the computer system 100 can include an "Accuracy" field that
specifies an acceptable deviation (e.g., 1-sigma, 2-sigma, 3-sigma) in the region 302.
The computer system 100 can apply the selected one or more error models to the
selected survey tool to determine that the errors fall within the deviation specified in
the "Accuracy" field.
[0023] In some implementations, the multiple parameters can include a
geographic location at which the well is to be drilled and a drilling time, i.e., a time of
the year when drilling operations are to be performed. A well survey and planning
computer system can implement a geodetic model that can determine the earth's
gravitational field and magnetic field strength at the location and at the drilling time.
The user interface 114 can include a region 306 in which the computer system 100
displays an identifier identifying the geodetic model. The user interface 114 can also
include a region 312 in which the computer system 100 can display the earth's
gravitational field strength and magnetic field strength, and a dip angle of the
magnetic field.
[0024] In some implementations, the multiple parameters can include
magnetics representing variations in the earth's magnetic field due to solar effects
during the drilling time. The user interface 114 can include a region 314 in which the
computer system 100 displays the magnetics during the drilling time. For example,
one of the well survey and planning computer systems can determine and provide the
magnetics to the computer system 100 for display in the region 314. The computer
system 100 can display a plot of the magnetics over a time that includes the drilling
time in the region 314. Either the computer system 100 or a well survey and planning
computer system can compare the magnetics with a threshold magnetics for drilling
the well. In some implementations, the computer system 100 can display the
magnetics at a particular time that satisfy the threshold magnetics to be visually
distinguishable from magnetics at a different time that does not satisfy the threshold
magnetics. For example, the computer system 100 can display the magnetics that
satisfy the threshold magnetics in a first color (e.g., green) and the magnetics that do
not satisfy the threshold magnetics in a second, different color (e.g., red). Moreover,
some of the survey tools measure orientation relative to the earth's magnetic field.
The computer system 100 can account for the effect of the magnetics on the readings
of the magnetic survey tools.
[0025] Additional survey and planning information that the computer system
100 can display in the user interface 114 can include an image of a SAG correction
for the well (e.g., in a region 318), an axial and cross-axial interference (e.g., in a
region 310) representing a disturbance in a magnetic field due to low magnetic
permeability components in the well, and an output of the IFR/IIFR error models
(e.g., in a region 316). As described above, the user interface 114 is interactive. For
example, when the computer system 100 receives a change to an uncertainty defined
by an error model (or any input to the integrated well survey management and
planning tool) that results in a change to an uncertainty defined by another error
model, the computer system 100 can automatically and without user intervention
update the uncertainty indicator (or any other aspect of the well plan or survey
displayed in the user interface 114). The computer system 100 can display the
updated uncertainty indicator in the user interface 114. An operator of the computer
system 100 can make changes and see, e.g., in real time or near real time, an effect of
the changes on the ellipse. In this manner, the operator can create different scenarios
while designing the well survey plan.
[0026] The techniques described above related to implementing the integrated
well survey management and planning tool during the planning stage of well. After
drilling has commenced, one or more survey tools can be implemented to monitor the
drilling operation as described below with reference to FIG. 4. The computer system
100 can implement the integrated well survey management and planning tool to
receive information determined by the one or more survey tools, and, in real time,
update appropriate regions in the user interface 114. By doing so, the operator can
compare the actual drilling information with the predicted drilling information, and
make adjustments as necessary, e.g., to the drilling conditions, the survey tools, the
error models (or combinations of them). In addition, the operator can visualize an
effect of the actual drilled well on the ellipses. For example, if the as-drilled well
lands at a center of a predicted ellipse, the subsequent ellipses over undrilled portions
will not be as large as predicted.
[0027] FIG. 4 is a flowchart of an example process to implement the
integrated well survey management and planning tool during an execution stage. In
some implementations, the computer system 100 can implement the process 400. At
402, the computer system 100 can receive survey data describing a well being drilled.
For example, after the well drilling has commenced, a survey tool positioned at a
location between the surface and the geological target to be reached by drilling the
well can be implemented to obtain survey data that includes a trajectory of the well
being drilled. The survey tool can be moved to different locations in the well. For
example, after drilling for a certain period, drilling can be stopped and the survey tool,
which can be near the drill bit, can be operated to take a survey. As described above,
the computer system 100 can receive a target trajectory along the well to be drilled to
the geological target. At 404, the computer system 100 can determine an uncertainty
indicator indicating an uncertainty in drilling the well on a target trajectory. For
example, the computer system 100 can determine the uncertainty indicator based at
least in part on the survey data and the target trajectory. The uncertainty indicator can
indicate an uncertainty (e.g., a confidence measure) in reaching the geological target
by drilling the well along the target trajectory.
[0028] At 406, the computer system 100 can display the uncertainty indicator
in a user interface, e.g., in the user interface 114. As described above, in certain (but
not all) instances, the computer system 100 can have previously determined an
uncertainty indicator for the well during a planning stage, i.e., before drilling
commences. By implementing process 400, the computer system 100 can determine a
revised uncertainty indicator for the well based, in part, on survey data that describe
the well being drilled. The revised uncertainty indicator measured during the drilling
stage, therefore, is an update to the uncertainty indicator determined during the
planning stage. In some implementations, the computer system 100 can receive at
least a portion of a measured trajectory (i.e., the actual trajectory) of the well being
drilled and compare the portion of the measured trajectory with the target trajectory
determined during the planning stage. The computer system 100 can determine the
revised uncertainty indicator based on the comparison. For example, upon
determining that the as-drilled well lands at or near a center of an ellipse, then the
computer system 100 can determine that the uncertainty that the well will land in a
subsequent ellipse in an undrilled portion is low. Consequently, the computer system
100 can determine the revised ellipse to be smaller than a current ellipse.
Alternatively, upon determining that the as-drilled well lands at or near a periphery of
the ellipse, the computer system 100 can determine the revised ellipse to be larger
than or at least the same size as the current ellipse.
[0029] The uncertainty indicator determined during the drilling stage, like the
uncertainty indicator determined during the planning stage, can include multiple
ellipses, each occupying a different area. Each ellipse is associated with a respective
depth of the well from the surface to the subterranean geological target. One or more
of the ellipses represents an uncertainty associated with a portion of the well that has
not yet been drilled. The computer system 100 can display the multiple ellipses at
multiple respective depths of the well in the user interface. In some implementations,
the computer system 100 can replace an ellipse at a depth determined during the
planning stage with another ellipse at the depth determined during the drilling stage.
In this manner, the computer system 100 can replace one or more ellipses at
respective one or more depths based on the survey data and the target trajectory. In
some situations, the computer system 100 can determine that an ellipse determined
during the planning stage matches (e.g., occupies the same area as) an ellipse
determined during the drilling stage. In such situations, the computer system 100 may
not replace the ellipse determined during the planning stage.
[0030] In response to viewing ellipses associated with the revised uncertainty
indicator, an operator may change aspects of a survey plan, e.g., to adjust the target
trajectory from the as-drilled well and the plan such that the newly updated ellipses
land at the geological target. At 408, the computer system 100 can receive a change
to the survey plan that indicates the number, position and survey type of surveys to be
performed on the well while drilling the well. As described above, the change can be
responsive to the uncertainty indicated by the revised uncertainty indicator. For
example, upon viewing the revised uncertainty indicator, an operator can determine to
change the number, position, survey type, error models (or a combination) that was
previously defined in the survey plan. The operator can, e.g., select a survey tool that
the operator had not selected during the planning stage before drilling commenced. In
some implementations, the computer system 100 can display, in the user interface,
multiple survey tools from among which the operator can make one or more
selections.
[0031] At 410, the computer system 100 can apply multiple error models
based on the received change to the survey plan. Each error model defines a
respective uncertainty in reaching the subterranean geological target by drilling the
well. The uncertainty is based on a survey performed while the well is being drilled
as well as the remaining target trajectory. The revised uncertainty indicator represents
a combination of the respective uncertainties defined by the multiple error models. A
change to an uncertainty defined by one of the error models can affect an uncertainty
defined by another of the error models and the revised uncertainty indicator itself. At
412, the computer system 100 can determine such a change to the uncertainty
indicator, and, at 414 display the revised uncertainty indicator in the user interface
114.
[0032] After the operator has adjusted the survey plan, well drilling can
continue. The computer system 100 can continue to receive the survey data and
determine the uncertainty indicator. For example, the computer system 100 can
receive the data in real time (or near real time) or concurrently with the well drilling
(or both). Based on a change or changes to the uncertainty indicator (e.g., if the
uncertainty indicator fails to satisfy an uncertainty threshold), the operator can
provide changes to the survey plan resulting in the computer system 100 revising the
uncertainty indicator. In this manner, during the drilling stage, the computer system
100 can be implemented as a tool that the operator can use to monitor and adjust
drilling operations to reach the geological target by implementing as few and as
inexpensive survey tools as practicable.
[0033] FIG. 5 illustrates a schematic of the example computer system 100 of
FIG. 1. The example computer system 100 can be located at or near one or more
wells and/or at a remote location. The example computer system 100 includes a data
processing apparatus 104 (e.g., one or more processors), a computer-readable medium
102 (e.g., a memory), and input/output controllers 170 communicably coupled by a
bus 165. The computer-readable medium can include, for example, a random access
memory (RAM), a storage device (e.g., a writable read-only memory (ROM) and/or
others), a hard disk, and/or another type of storage medium. The computer system
100 can be preprogrammed and/or it can be programmed (and reprogrammed) by
loading a program from another source (e.g., from a CD-ROM, from another
computer device through a data network, and/or in another manner). The input/output
controller 170 is coupled to input/output devices (e.g., the display device 106, input
devices 108, and/or other input/output devices) and to a network 112. The
input/output devices receive and transmit data in analog or digital form over
communication links such as a serial link, wireless link (e.g., infrared, radio
frequency, and/or others), parallel link, and/or another type of link.
[0034] The network 112 can include any type of data communication network.
For example, the network 112 can include a wireless and/or a wired network, a Local
Area Network (LAN), a Wide Area Network (WAN), a private network, a public
network (such as the Internet), a WiFi network, a network that includes a satellite
link, and/or another type of data communication network.
[0035] A number of implementations have been described. Nevertheless, it
will be understood that various modifications may be made without departing from
the spirit and scope of the disclosure.

CLAIMS
1.A computer-implemented well survey method comprising:
receiving survey data describing a well being drilled from a surface to a
subterranean geological target to be reached by drilling the well, wherein the well is
associated with a target trajectory on which the well is to be drilled from the surface to
the subterranean geological target;
based, at least in part, on the survey data and the target trajectory, determining an
uncertainty indicator indicating an uncertainty in drilling the well on the target trajectory;
and
displaying, in a user interface, the uncertainty indicator.
2. The method of claim 1, wherein the survey data is obtained by a survey tool moved to
respective locations in the well being drilled.
3. The method of claim 1, wherein determining the uncertainty indicator based, at least in
part, on the survey data and the target trajectory comprises:
receiving at least a portion of a measured trajectory of the well being drilled; and
comparing the portion of the measured trajectory and the target trajectory.
4. The method of claim 1, wherein the uncertainty indicator includes a plurality of
ellipses, each occupying a different area, each ellipse associated with a respective depth
of the well from the surface to the subterranean geological target, the method further
comprising displaying the plurality of ellipses at a plurality of respective depths in the
user interface.
5. The method of claim 1, wherein the uncertainty indicator is determined for a portion of
the well that has not yet been drilled.
6. The method of claim 1, further comprising:
receiving a change to a survey plan that indicates the number, position and survey
type of surveys to be performed on the well while drilling the well, the change being
responsive to the uncertainty indicated by the uncertainty indicator;
applying a plurality of error models based on the received change to the survey
plan, each error model defining a respective uncertainty in reaching the subterranean
geological target by drilling the well.
7. The method of claim 5, wherein receiving the change to the survey plan
comprises receiving a selection of a survey tool from among a plurality of survey tools,
the survey tool to be implemented to survey the well to be drilled.
8. The method of claim 7, wherein the survey tool was unselected before displaying
the revised uncertainty indicator.
9. The method of claim 6, wherein the uncertainty indicator represents a
combination of respective uncertainties defined by each error model of the plurality of
error models.
10. The method of claim 9, wherein a respective uncertainty defined by an error
model is based on a survey performed while the well is being drilled and is included in
the received survey data.
11. A non-transitory computer-readable medium storing instructions executable by data
processing apparatus to perform operations comprising:
receiving survey data describing a well being drilled from a surface to a
subterranean geological target to be reached by drilling the well, wherein the well is
associated with a target trajectory on which the well is to be drilled from the surface to
the subterranean geological target;
based, at least in part, on the survey data and the target trajectory, determining an
uncertainty indicator indicating an uncertainty in drilling the well on the target trajectory;
and
displaying, in a user interface, the uncertainty indicator.
12. The medium of claim 11, wherein the survey data is obtained by a survey tool moved
to respective locations in the well being drilled.
13. The medium of claim 11, wherein determining the uncertainty indicator based, at
least in part, on the survey data and the target trajectory comprises:
receiving at least a portion of a measured trajectory of the well being drilled; and
comparing the portion of the measured trajectory and the target trajectory.
14. The medium of claim 11, wherein the uncertainty indicator includes a plurality of
ellipses, each occupying a different area, each ellipse associated with a respective depth
of the well from the surface to the subterranean geological target, the operations further
comprising displaying the plurality of ellipses at a plurality of respective depths in the
user interface.
15. The medium of claim 11, wherein the uncertainty indicator is determined for a portion
of the well that has not yet been drilled.
16. A system comprising:
a data processing apparatus; and
a medium storing instructions executable by the data processing apparatus to
perform operations comprising:
receiving survey data describing a well being drilled from a surface to a
subterranean geological target to be reached by drilling the well, wherein the well is
associated with a target trajectory on which the well is to be drilled from the surface to
the subterranean geological target;
based, at least in part, on the survey data and the target trajectory,
determining an uncertainty indicator indicating an uncertainty in drilling the well on the
target trajectory; and
displaying, in a user interface, the uncertainty indicator.
17. The system of claim 1, the operations further comprising:
receiving a change to a survey plan that indicates the number, position and survey
type of surveys to be performed on the well while drilling the well, the change being
responsive to the uncertainty indicated by the uncertainty indicator;
applying a plurality of error models based on the received change to the survey
plan, each error model defining a respective uncertainty in reaching the subterranean
geological target by drilling the well.
18. The system of claim 17, wherein receiving the change to the survey plan
comprises receiving a selection of a survey tool from among a plurality of survey tools,
the survey tool to be implemented to survey the well to be drilled.
19. The system of claim 18, wherein the survey tool was unselected before displaying
the revised uncertainty indicator.
20. The system of claim 17, wherein the uncertainty indicator represents a
combination of respective uncertainties defined by each error model of the plurality of
error models, and wherein a respective uncertainty defined by an error model is based on
a survey performed while the well is being drilled and is included in the received survey
data.