Sperry Drilling
MWD/LWD
Services
Sperry Drilling MWD/LWD Services
Measurement-while-drilling (MWD) and loggingwhile-drilling (LWD) systems employ instrumented
drill collars and a downhole-to-surface data telemetry
system to provide wellbore directional surveys,
petrophysical well logs and drilling information in real time
while drilling. The term “MWD” is used generally to refer to
all measurements acquired downhole while drilling or
specifically to describe directional surveying and drillingrelated measurements; “LWD” refers to petrophysical
measurements, similar to openhole wireline logs, acquired
while drilling. The decision to use MWD/LWD services is
usually based on the need for better decisions based on
real-time information and on improved economics. This
economic improvement may reflect direct cost savings or
increased productivity resulting from better well placement.
These applications affect economics through:
• Elimination of the rig time required for conventional
directional surveying by using MWD directional surveys
and toolface measurements, as well as the realization
of savings associated with better well placement.
• LWD replacement of wireline logs, eliminating the rig
time required for wireline logging; this is particularly
applicable in high-angle wells where wireline tools
would have to be deployed on drillpipe.
• Improved production from better well placement.
Sperry Drilling services’ MWD/LWD measurements
provide information to a host of new well planning and
drilling software applications that enable planning and
steering the well directly in the earth model. These
tools together with new directional drilling systems
and Real-Time Operations (RTO) are enabling new
interactive workflows that have a dramatic effect on
upstream economics.
Sperry Drilling’s MWD/LWD services feature modular
sensors that can be tailored to your drilling and formation
requirements and well economics. They are compatible
with all our drilling tools, including the Pilot™ fleet of
rotary steerable systems.
Real-time data applications include:
• Faster directional survey and toolface information for
directional drilling
• Timely drilling efficiency and safety information for
drilling decisions, e.g., annular pressure, pore
pressure, drillstring vibration
• Improved stratigraphic correlation and geological
certainty for geosteering, hazard avoidance and
casing/coring point selection
• Accurate petrophysical measurements with a minimum of
formation damage, fluid invasion and washout
Our commitment to providing superior service quality
and reliability is reflected in our MWD/LWD system
development. The shock, pressure and heat of the
downhole drilling environment make survival of any
electronic instrument difficult. Our electronic designs are
subjected to extreme heat, vibration and pressure tests
until they meet Sperry Drilling’s stringent standards of
reliability. Entire systems are then re-tested. Continuous
improvements in design, inspection, failure analysis and
certification have enabled Sperry Drilling MWD/LWD
systems to continue to lead the industry in reliability.
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Telemetry Systems
Four MWD telemetry systems are available from Sperry
Drilling: positive mud pulse, negative mud pulse,
electromagnetic and via wired drillpipe. The mud pulse
systems use valves to modulate the flow of drilling fluid in
the bore of the drillstring, generating pressure pulses that
propagate up the column of fluid inside the drillstring and
then are detected by pressure transducers at the surface.
The positive pulse system momentarily restricts mud
flow through the downhole tool, resulting in a pressure
increase, or positive pressure pulse, that propagates to
the surface. With the negative pulse system, mud is
momentarily vented from the bore of the drill collar
directly to the annulus, bypassing the bit jets and creating
a brief pressure drop, or negative pressure pulse, inside
the drillstring, which propagates to the surface. In both
mud pulse systems, data from downhole sensors are
encoded and transmitted by varying the time between
consecutive pressure pulses.
The electromagnetic telemetry (EMT) MWD system
transmits data via low-frequency electromagnetic waves
that propagate through the earth and are detected by a
grounded antenna at the surface. It provides higher data
rates and greater reliability than traditional mud pulse
systems. Electromagnetic telemetry is particularly
applicable for drilling with air, foam or aerated muds that
preclude the use of mud pulse. It is also widely used in
geothermal drilling, as well as in areas with high mud
losses. Previously constrained to shallow land
applications, this electromagnetic telemetry service has
recently been enhanced by Sperry and successfully
deployed offshore and in deep shale wells.
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The InSite IXO interface is the link that connects
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the Sperry MWD/LWD systems to NOV’s IntelliServ
Network. The IntelliServ Network provides two-way
communication between downhole MWD/LWD
sensors and the surface at speeds up to 10,000
times faster than current mud pulse telemetry rates.
It is built on the industry’s first commercial highbandwidth drillstring.
In addition to transmitting data in real time, data can
also be recorded in downhole memory and retrieved
after each bit run as the tool returns to the surface.
The use of downhole memory is important for multisensor LWD services in which much more data are
acquired downhole than can be transmitted in real
time. The parameters vital for real-time applications
are selected for transmission, while the remainder of
the information, including raw data and diagnostic
parameters, is recorded in downhole memory and
accessed at the end of each bit run.
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MWD Sensors
Fundamental to our MWD services are sensors that
provide directional survey and drilling information to
facilitate accurate wellbore placement along with safe
and efficient drilling.
Directional surveying sensors consist of tri-axial
accelerometers and magnetometers that determine the
orientation of the drillstring with respect to the earth’s
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magnetic and gravitational fields. The Evader MWD gyro
service utilizes high accuracy rate-gyro steering in place of
magnetometers making the sensor’s measurement
unaffected by magnetic influences. Directional sensors
provide the following data:
• Wellbore inclination
• Wellbore azimuth
• Magnetic and gravity toolface orientation
Drillstring vibration sensors are the tri-axial DDS™
(drillstring dynamics sensor), the two-axis SVSS
(sonde-based vibration severity sensor), and the
single-axis VSS (vibration severity sensor). The
DDS sensor measures torsional, lateral and axial
accelerations, whereas the SVSS responds to lateral
and axial accelerations and the VSS detects lateral
drillstring vibrations. These sensors can record both
the average and the maximum accelerations over a
given interval. The DDS sensor can also record full
time-series acceleration data for spectral analysis.
When drillstring vibration exceeds pre-set thresholds,
real-time alarm information is transmitted to the
surface to facilitate immediate corrective action.
These measurements help determine the wellbore path
and position in three-dimensional space; true vertical depth;
the bottomhole location; and the orientation of directional
drilling systems, such as steerable mud motors and rotary
steerable systems.
Sperry Drilling’s ABI™ (at-bit inclination) sensor is a
tri-axial accelerometer package that mounts on the bit box
of a steerable mud motor assembly and communicates
data across the motor to the main MWD tool via an
acoustic telemetry link. This means improved reliability over
special power sections with feed-through wires. The ABI™
service provides immediate feedback to the directional
driller on inclination changes. This knowledge of the
bottom-hole assembly’s (BHA) tendency removes much of
the uncertainty in steering and reduces wellbore tortuosities
and resulting torque and drag.
The following MWD sensors are also employed by the
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Sperry ADT (applied drilling technology) optimization
service specialists. Our experienced ADT service
personnel model, measure and optimize drilling
performance using a suite of advanced software and
hardware tools.
Downhole pressure measurements are provided by the
PWD (pressure-while-drilling) service, which consists of
high-accuracy quartz pressure gauges measuring annular
and bore pressure. The PWD data have a number of
valuable applications, including:
• Accurate downhole measurement of ECD (equivalent
circulating density)
• Kick detection, including shallow water flows
• Swab/surge pressure monitoring while tripping and
reaming
• Monitoring of hole cleaning
• Accurate downhole measurement of hydrostatic
pressure and effective mud weight
• Accurate LOT (leak-off test) and FIT (formation integrity
test) data without circulating to condition the mud
Borehole diameter measurements are provided
in real time by the AcoustiCaliper™ sensor.
This sensor has three acoustic standoff
measurement transducers oriented 120 degrees
apart azimuthally to provide borehole diameter
when rotating or sliding. Real-time caliper logs
provide immediate feedback on borehole stability
conditions, as well as detect such conditions as
undergauge bits, sloughing shales and washouts.
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LWD Sensors
LWD sensors provide petrophysical information similar
to that obtained from openhole wireline tools but with
the added benefits of delivering the data in real time
while drilling and typically acquiring the data before
significant invasion or washout has occured. LWD tools
are particularly well suited to logging high-angle and
horizontal wells, where real-time geosteering
applications are often important and where wireline
logging can be difficult, time-consuming and costly.
LWD logging is also particularly applicable on high-cost
drilling projects where the savings in rig time while
replacing wireline are substantial.
The ABG™ (at-bit gamma ray) sensor provides a
gamma ray measurement within 3 feet of the bit as part
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of the 7600 and 9600 series Geo-Pilot rotary steerable
systems. Multiple gamma ray sensors allow the ABG
sensor to produce a near bit real-time gamma ray
image for geosteering.
Neutron porosity and formation density sensors
are available in 4-3/4-, 6-3/4-, and 8-inch tool sizes and
can log boreholes ranging from 5-7/8- to 12-1/4-inches
in diameter.
The CTN™ (compensated thermal neutron) porosity
sensor uses helium-3 detectors to provide a thermal
neutron porosity measurement. The 6-3/4- and 8-inch
CTN tools also incorporate the AcoustiCaliper sensor
(see above) that facilitates accurate borehole size
and standoff corrections and provides a borehole
caliper log.
This LWD quad-combo log shows deep, water-based filtrate
invasion in a pay sand. A bit trip in the middle of the sand resulted
in a long formation exposure time and thus, deep invasion.
However, the INVAMOD™ program provided Rt, Rxo and Di to
facilitate accurate calculation of Sw and movable oil.
Gamma ray measurements of the formation’s natural
gamma ray activity are provided by the dual-detector,
insert-based DGR™ (dual gamma ray) sensor or the
sonde-based GM (gamma module) or PCG
(pressure case gamma) sensors. Although these
sensors provide a wireline-quality natural gamma ray
log, the DGR and GM sensors also have multiple
gamma ray sensors for redundancy. Additionally,
gamma ray measurements are available with the
AGR™ (azimuthal gamma ray) sensor, which is part
of the EWR™-M5 integrated resistivity sensor. The
AGR has multiple gamma ray sensors for redundancy,
but also has the capability to azimuthally measure the
formation's natural gamma ray activity to produce realtime gamma ray images for geosteering.
The GABI™ (gamma/at-bit inclination sensor)
provides at-bit azimuthal gamma ray and inclination
measurements for improved geosteering and optimum
well placement. The sensor also produces a borehole
image both while rotating and sliding that can be used
to interpret the bed dip and determine the location of an
approaching bed. The GABI sensor can be mounted
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within any SperryDrill positive displacement motor
below the power section. It is a powerful tool for drilling
long horizontals and staying in the pay.
The SLD™ (stabilized lithodensity) spectral sensor
provides compensated formation density and Pe
measurements. The SLD tool design employs a
stabilizer blade that emulates a wireline density tool
detector pad. In in-gauge holes, a standard spine-andrib compensation technique corrects for minor standoff.
In enlarged boreholes or when directional drilling
considerations require an undergauge stabilizer, a
rapid-sampling rotational binning technique and
statistical analysis algorithm isolate data acquired at
minimal standoff distances, producing high-quality
density and Pe logs even when detector pad contact is
not maintained continually. The SLD tools are being
retrofitted and phased out, replaced by the more
advanced sensor electronics and azimuthal capability
of the ALD sensor.
The ALD™ (azimuthal lithodensity) sensor
incorporates all of the features of the SLD sensor but
also provides azimuthally oriented density and Pe data
for geosteering and borehole imaging applications. At
high relative dip angles, such as those typically
encountered when drilling high-angle and horizontal
wells, formation structural dip may be determined from
the ALD borehole image data. The azimuthally oriented
data also permit real-time determination of relative dip
angle for geosteering applications and provide an
alternative method for optimizing log quality in
enlarged boreholes.
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Resistivity measurements are provided by the following
sensors:
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The EWR -PHASE 4™ multi-spacing propagation
resistivity sensor provides eight independent formation
resistivity measurements from four different transmitterreceiver spacings (four phase-shift measurements and
four attenuation measurements). The EWR-PHASE 4
sensor is available for logging boreholes ranging from 35/8- to 30 inches in diameter and can operate in waterand oil-based muds, as well as in air- and foam-drilled
boreholes.
The EWR™-M5 integrated resistivity sensor measures
resistivity using three frequencies (2 MHz, 500 kHz, 250
kHz) and five compensated spacings. This provides very
deep resistivities for bed boundary detection while
geosteering, as well as a greater number of resistivity
measurements to cover the broadest range of
applications. With both phase-shift and attenuation
measurements, the EWR-M5 sensor provides 30 unique
compensated resistivity measurements. The M5 tool also
incorporates an AGR™ azimuthal gamma ray sensor, a
drilling mud resistivity sensor, a pressure-while-drilling
sensor and a drilling motion sensor.
The InSite ADR™ azimuthal deep resistivity sensor
combines a deep-reading geosteering sensor for
distance to bed boundary determination with a traditional
multifrequency compensated resistivity sensor for accurate
azimuthal resistivity measurements. This one tool provides
more than 2,000 unique measurements for both precise
wellbore placement and more accurate petrophysical
analysis. Deep-reading (up to 18 feet), directional and
high-resolution images give early warning of
approaching bed boundaries before the target zone is
exited, allowing you to keep the wellbore in the most
productive part of the reservoir.
The full benefits of the InSite ADR sensor can be
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realized when run as part of our StrataSteer 3D
geosteering service. Using the industry’s most
powerful and intuitive software, our experienced
geosteering specialists provide valuable
recommendations based on a thorough understanding
of sensor physics, geology and directional drilling. The
bottom line is that this comprehensive service can
increase reservoir exposure up to 100 percent while
refining the understanding of the geology in and around
the reservoir.
The InSite AFR™ azimuthal focused resistivity
sensor provides high-resolution borehole images,
omni-directional laterolog-type resistivity
measurements, azimuthal laterolog-type resistivity
measurements and an at-bit resistivity measurement.
The high-resolution, detailed images of structural and
stratigraphic features allow for accurate determination
of dip and fracture orientation. The InSite AFR sensor
is ideal for picking casing points and for obtaining
accurate resistivities where propagation-type tools have
difficulty, such as when drilling with highly conductive
muds or where the ratio of formation resistivity to mud
resistivity (Rt/Rm) is very high. The at-bit resistivity
measurement uses the BHA below the InSite AFR
sensor as a measurement electrode. The AFR
measurement is particularly useful for detecting
conductive beds as the bit penetrates them.
Sonic log measurements of both compressional and
shear slowness (∆tc and ∆ts) are provided by the
BAT™ (bi-modal acoustic) LWD dipole sonic tools.
BAT tools are available in 4-3/4-, 6-3/4-, 8-, and 9-1/2inch tool sizes and can log boreholes ranging from 57/8- to 30-inches in diameter. The dual transmitter and
dual, seven-element receiver array configuration of the
BAT tool provide a superior signal/noise ratio, as well
as measurement redundancy for service reliability. BAT
tool applications include:
• Real-time pore pressure interpretation
• Real-time synthetic seismograms
• Porosity
• Gas detection from Vp/Vs
• Bit wear calculation
• Rock strength and mechanical properties
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The QBAT™ multipole LWD sonic tool has several
significant design improvements over the original BAT
tool. It delivers accurate shear and compressional velocity
measurements in a wider range of formation types –
including very soft formations – and under more
challenging drilling conditions.
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The InSite GeoTap IDS fluid identification and
sampling sensor revolutionizes the industry by allowing
downhole capture, identification and surface recovery of
representative fluid samples on LWD. Only available on
wireline before, formation fluid sampling is now possible
using LWD technology. The GeoTap IDS sensor delivers
real-time reservoir characterization and helps eliminate
the time and cost of wireline sampling.
LWD NMR (nuclear magnetic resonance)
measurements are provided by the MRIL-WD™ sensor,
which is an LWD adaptation of the successful MRIL
wireline NMR logging tool. While drilling, the MRIL-WD
sensor’s T1 acquisition mode provides logs of total
porosity, bound water and free fluid enabling real-time
evaluation of shaly sands and fine-grained formations
with high irreducible water saturation. The unique
implementation of the T1 acquisition mode, specifically
designed for measurement while drilling, is virtually
unaffected by lateral tool motion, rotation and drilling
vibration. For more detailed evaluation of potential
reservoir intervals, the MRIL-WD tool’s evaluation mode
emulates the wireline MRIL tool measurements, providing
a complete T2 decay spectrum with variable TE and TW
modes for permeability logging, direct hydrocarbon
detection and gas identification.
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With the GeoTap LWD formation pressure tester, it
is possible to obtain direct pore pressure measurements
as the well is drilled, with accuracy and precision
comparable to that of wireline formation testers. GeoTap
tools are available in 4-3/4-, 6-3/4-, 8-, and 9-1/2-inch tool
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sizes. The GeoTap service also eliminates the rig time,
risk and cost that would otherwise be incurred by running
wireline or pipe-conveyed wireline formation test tools
to acquire critical reservoir pressure and mud density
information.
Formation pressure tests may be performed while mud
circulation is maintained (if there is no motor in the BHA),
facilitating real-time transmission of pressure data and test
quality control information, while reducing the risk of tool
sticking or well control problems.
MRIL-WD™ sensor evaluation log from a run made at the Catoosa
(Oklahoma) test facility with the first MRIL-WD prototype tool,
Discovery 1.
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MWD/LWD Service Tool Size Availability
2-3/8-in.
61 mm
3-1/8-in.
79 mm
3-3/8-in.
86 mm
3-½-in.
89 mm
4-¾-in.
121 mm
6-½-in.
165 mm
6-¾-in.
171 mm
7-¼-in.
184 mm
7-¾-in.
197 mm
8-in.
203 mm
9-½-in.
221 mm
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Sensors
Directional (PM, DM, PCD)
At-bit inclination (ABI™)
Drillstring vibration (DDS™)
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Vibration severity (SVSS)
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Annular/bore pressure (PWD)
At-bit gamma (ABG™)
Gamma ray (GM, PCG)
Gamma ray (DGR™)
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Gamma/at-bit inclination
(GABI™)
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Azimuthal gamma ray (AGR™)
Resistivity (EWR-PHASE 4™)
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Resistivity (M5™)
Azimuthal deep resistivity
(InSite ADR™)
Azimuthal focused resistivity
(InSite AFR™)
Formation density (SLD™)
Azimuthal density (ALD™)
Neutron porosity (CTN™)
Caliper (AcoustiCaliper™)
Sonic (BAT™)
Sonic (QBAT™)
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Formation pressure (GeoTap )
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Fluid sampling and
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identification (GeoTap IDS)
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NMR (MRIL-WD™)
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Telemetry Systems
Positive pulse (DWD)
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Negative pulse (MPT)
Electromagnetic (Mercury™)
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InSite IXO interface for NOV
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IntelliServ Network
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the contract between Halliburton and the customer that is applicable to the sale.
H07333 7/10 © 2010 Halliburton. All Rights Reserved.
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