Open Hole Services

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Gamma Ray (MCG) Tool

gamma ray (MCG) tool combines gamma ray, temperature, and casing-collar locator (CCL) logs with power conversion and surface communications for all other measurements in a Compact tool string. It is always the top tool in the string. The auxiliary gamma sub (MGS) is shorter and can be placed anywhere in the string, enabling gamma radiation and temperature to be recorded close to the bottom of the well. An integral power conditioner in the MCG tool automatically converts a wide range of cablehead voltages to a standard value for all tools in the Compact string. This feature adds to the system’s flexibility and reliability by eliminating the need to match surface power to particular logging cables. The MCG tool also processes data from the following auxiliary measurements: spontaneous potential originating from the array induction (MAI) and dual laterolog (MDL) tools; tension from the tension cablehead (MCB-A and MCC); tension and compression from the tension compression sub (TCS); external temperature; and CCL.

Applications

Determining the volume of shale content in simple lithologies, such as shaly sand

Correlating well-to-well details in open and cased hole

Providing primary log for depth correlation of other logging tools in the same well

Features, Advantages and Benefits

The NaI detector is rugged, reliable, and sensitive, providing a full range of accurate data for quantitative analysis and repeatability.

The tool’s 2- to 3-ft (0.61- to 0.91-m) depth of investigation enables the detection of gamma rays through several strings of casing.

The tool’s 3-ft (0.91-m) vertical resolution enables accurate identification of formation contacts and is widely used for well-to-well correlation and between log runs.

Spectral Gamma Ray (SGR) Tool

spectral gamma ray (SGR) tool provides superior clay type and volume analysis by measuring gamma ray energy from the naturally occurring radioactive elements potassium, uranium and thorium. The SGR tool measures naturally occurring radioactive elements in formations to provide clay type and volume analysis. The tool contains a large scintillation crystal which provides higher detection efficiency and sensitivity. The result is a detailed spectrum of 256 discrete data channels. Surface processing uses five energy windows to “strip” relative concentrations of potassium, uranium and thorium from the raw spectra. The resulting log displays potassium content as a percentage of uranium and thorium contents in ppm. A total gamma curve equivalent to a regular natural gamma ray is also displayed, along with a uranium-free gamma ray curve. The tool is almost always run in combination with the Spectral Pe Density (SPeD) and Compensated Neutron Tool (CNT). These tools also can be combined with other services.

Applications

Quantitative measurement of actual radiation and separation into its three predominant components: potassium, uranium and thorium

Determination of clay and shale volumes

Clay typing

Heavy mineral identification

Input for complex lithology analysis

Differentiation between radioactive pay zones and shales

Identification of fractured and highly permeable zones where high uranium concentrations are present

Detailed well-to-well correlation

Features, Advantages and Benefits

The highly sensitive NaI detector provides accurate spectral analysis of natural gamma ray energies.

Detailed spectrum determines Potassium, Uranium, and Thorium weight concentrations in the formation.

Compensated dual neutron

A compensated neutron log is useful for identifying zones of interest and determining perforating depths, tracking gas cap movement and gas encroachment under shale layers, as a correlation between open and cased hole where a gamma ray is not indicative, and to measure overall porosity of the well.

Density/photo electric effect (PE)/Caliper

The photoelectric effect, or Pe, measures a formation's ability to absorb gamma rays. The absorptive abilities of formations vary with lithology. The photoelectric absorption is recorded as a supplementary measurement to the formation density measurement, using common detectors and radioactive sources. Since this measurement is part of the density measurement, the tool is a pad contact tool and is subject to borehole wall rugosity. The measurement is not valid in muds weighted with barite. The recording can be used both for correlation of formations between wells and for determining lithology.

Array Induction (MAI) Tool

Weatherford’s Compact array induction (MAI) tool acquires and records data that can be used to determine true formation resistivity (Rt ) in openhole environments. The MAI tool provides raw data from multiple subarrays, which are integrated vertically and radially with environment-dependent processing to produce five depths of investigation. This data is provided in a broad range of borehole environments. When the MAI tool is run with a high vertical-resolution-proximity device, such as the shallow-focused electric (MFE) tool—a mandrel-type tool—or with the flushed-zone resistivity (MMR) tool—a standard pad-type tool—the advanced processing includes true formation resistivity and enhances vertical resolution to 4 in. (10.00 cm).

Applications

Determining formation conductivity Determining water saturation (Sw) Providing well-to-well correlation Identifying moveable fluids

Identifying fluid contacts

Creating an invasion profile

Providing thin-bed analysis

Features, Advantages and Benefits

The enhanced vertical resolution and radial profiling improve accuracy in Rt determination, resulting in more accurate reserve estimates.

The unique profile of the tool facilitates flexible deployment, in wireline or memory mode, to mitigate the risk of bridging events and reduce nonproductive time.

Weatherford’s Compact shallow-focused electric (MFE) tool provides an invaded
zone resistivity measurement with high vertical resolution in conductive mud
environments. Designed for use with other Compact resistivity tools, it enhances
vertical resolution and provides a shallow, penetrating, resistivity measurement
that aids in the determination of true formation resistivity (Rt

), as well as in the

detection of moveable fluids.
The MFE tool has one radial, current-emitting electrode with a set of focusing
electrodes, which achieves a vertical resolution of less than 12 in. (304.8 mm)
and is immune to the effects of borehole wall rugosity.
The resulting MFE output curve can be used to increase the vertical resolution
of the array induction (MAI) or dual laterolog (MDL) curve.

Applications

• Determining flushed zone resistivity (Rxo)
• Creating an invasion profile
• Delineating thin beds for improved thin-bed analysis and reserve estimates
• Detecting moveable fluids

Features, Advantages and Benefits

• The direct-current electrode emits a concentrated, radial current to provide
measurement at a shallow depth of investigation. Because the tool works
by sending current to the formation without making contact, it is immune to
rugosity-induced noise.
• The MFE tool, combined with other Compact resistivity tools, enhances vertical
resolution and improves the accuracy of Rt

determination.

Focused electric (MFE/shallow resistivity)

Laterlog (DLL/salt system resistivity)

The dual laterlog tool (DLL) simultaneously measures formation resistivity
at two depths of investigation and at ranges up to 40,000 ohm-m. The tool
offers excellent resolution of thin beds down to 24 in. (61 cm).
The DLL tool contains an array of nine electrodes to focus current into
the formation and produce two advanced laterolog measurements
with different current paths and frequencies. The tool often is run in
combination with the MSFL tool to obtain an extra-shallow resistivity
measurement which allows calculation of Rt and Rxo in invaded conditions.
The DLL continuously monitors current and voltage to the measurement
electrode. This ensures that the tool’s drive power consistently provides a
wide, dynamic range of measurement. Conductive fluids must be present
in the borehole for the DLL tool to work.

Applications

• Wells drilled with salt muds
• Wells with high formation resistivity

Features, Advantages and Benefits

• Determines true formation resistivity (Rt

), flushed zone resistivity (Rxo) and

the diameter of invasion (Di
)

• Provides inputs required to calculate water saturation
• Generates quantitative evaluation of invasion
• Excellent thin-bed resolution
• Uses bucking electrodes to focus measured current into the formation
instead of the borehole

Spontaneous Potential (SP)

The SP tool is one of the simplest tools and is generally run as standard when logging a hole, along with the gamma ray. SP data can be used to find:

Depths of permeable formations
The boundaries of these formations
Correlation of formations when compared with data from other analogue wells
Values for the formation-water resistivity

The SP curve can be influenced by various factors both in the formation and introduced into the wellbore by the drilling process. These factors can cause the SP curve to be muted or even inverted depending on the situation.

Formation bed thickness
Resistivities in the formation bed and the adjacent formations
Resistivity and make up of the drilling mud
Wellbore diameter
The depth of invasion by the drilling mud into the formation

Borehole Navigation (MBN/surveys in open hole only)

Weatherford’s Compact borehole navigation (MBN) tool measures orthogonal
components of the earth’s magnetic and gravitational fields along a wellbore.
These measurements are used to compute instantaneous tilt and azimuth of a tool
string, enabling derivation of the well trajectory below the casing shoe. Results
are presented as a table of measured depths (MD) and true vertical depths (TVD),

supported by a polar plot and vertical section plots showing north-south and east-
west projections.

When the Z-axis accelerometer is sampled at a higher rate, instantaneous speed of
the tool string can be determined. When run as part of a CompactSM memory logging
(CML) service, the information can be used to fine-tune MDs and to correct any
irregular tool movements.
MBN data is also used to confirm the rotational position of other tools in a

measurement string; for example, when auxiliary equipment, such as a downward-
pointing density shoe, is used to achieve a particular orientation in a horizontal well.

Applications

• Determining borehole trajectory
• Determining TVD
• Applying speed corrections to formation evaluation data

Features, Advantages and Benefits

• The robust three-axis magnetometers and accelerometers provide precise and
reliable tool-string orientation measurements, even in extreme borehole and
logging conditions.

Measure flushed-zone resistivity (RXO) with Weatherford’s microresistivity
tool (MRT). An interchangeable pad allows this versatile tool to function either
as a microspherically focused laterolog (MSFL) or a microlog (MEL) device.
The MSFL measures flushed-zone resistivity (RXO), which can be used
to calculate flushed-zone water saturation (SXO). The difference between
undisturbed water saturation and flushed-zone water saturation indicates the
volume of hydrocarbons flushed during the invasion process.
This pad-type microresistivity device uses a concentric arrangement of five
electrodes to force the tool’s measurement current into a hemispherical
pattern. This arrangement helps to eliminate errors generated by wellbore
conditions such as mudcake on the borehole wall.
The three-electrode array on the MEL pad provides the shallow-reading
micro inverse (m. inverse) and deeper-reading micro normal (m.normal)
measurements. The amount of mudcake present on the borehole wall
can be indicative of permeability in the adjacent zone, with the variation in
mudcake thickness primarily affecting the response of the shallow-measuring
m. inverse curve. Positive separation between the curves (m. inverse >
m. normal) denotes the presence of mudcake, providing a high-resolution
permeability indicator.

Applications

• In MSFL mode, the MRT provides excellent high-vertical resolution and
flushed-zone resistivity (RXO) measurements.
• With a pad change, the MRT can also provide a high-quality
permeability indication with an MEL measurement.

Features, Advantages and Benefits

• The borehole-corrected MSFL provides accurate Rxo measurements
necessary to estimate moveable-hydrocarbon volumes, reducing
estimation errors and associated costs.
• High-resolution measurements from the MSFL and MEL improve
bed-boundary delineation in narrow beds, increasing accuracy in
determination of hydrocarbon reserves.
• The uncomplicated MEL measurement provides an efficient indication
of permeability, enabling timely selection of zones for testing or
potential completion.

Weatherford’s Compact microresistivity (MMR/MML) tool, consisting of the microlog
(MML) pad or microlaterolog (MMR) pad, provides resistivity measurements with high
vertical resolution and shallow penetration. Each type of measurement is derived from a
single conformable pad held against the borehole wall by a sturdy caliper mechanism. The
pads are interchangeable. The tools can be stacked when both sets of measurements are
required.
The MML pad provides micronormal and microinverse curves, which are highly sensitive
to mudcake thickness and provide an important permeability indicator.
The MMR measurement is made with a focused-current beam that penetrates mudcake,

making it sensitive to the invaded zone. This measurement is used to correct the deep-
penetration curve from the Compact dual laterolog (MDL) tool and to detect moveable

fluids when used in calculating the flushed-zone saturation (Sxo).
The electrode configuration within each pad matches that used in conventionally sized
tools, providing similar response characteristics.

Applications

• Determining the flushed-zone resistivity (Rxo) of the formation
• Providing the invasion correction in conductive-mud environments
• Creating an invasion profile
• Indicating permeability
• Providing detailed well-to-well correlation
• Delineating thin beds for improved thin-bed analysis and reserve estimates
• Detecting moveable fluids

Features, Advantages and Benefits

• The MMR/MML tool produces a high-resolution Rxo measurement to improve thin-
bed delineation and enhance the vertical resolution of resistivity tools for improving

reserve estimates.
• The MMR/MML tool can be run in combination with the MDL tool to provide an
independent, shallower measurement for improved accuracy in determination of
Rxo and true formation resistivity (Rt

) in complex invasion profiles.

• The small diameter of the tool facilitates flexible

Weatherford’s compensated neutron tool (CNT) provides a borehole-compensated, high-
resolution porosity measurement that can be logged in both open and cased wellbores.

Knowledge of formation porosity is vital to reservoir evaluation. The CNT incorporates an
AmBe241 radioactive source, which bombards the formation with high-energy neutrons. As
these neutrons disperse throughout the rock matrix, their interaction with hydrogen atoms
slows them to thermal energies.
Two detectors, located at different spacings from the source, count thermal neutrons
traversing the formation. Count rates measured at the detectors are proportional to
hydrogen content of the adjacent formation.
The CNT’s proprietary source-to-detector spacings are designed so that the ratio of count
rates at each detector accurately determines hydrogen content compensated for borehole
and casing effects.
A set of empirical algorithms converts this ratio into porosity units, assuming one of three
rock lithologies. This neutron porosity (øN) is the principal curve displayed during logging.
In the open-hole environment, the CNT is typically run with the universal gamma ray
(UGRTM) tool, spectral Pe

density (SPeDTM) tool and a resistivity service to provide
triple-combo logging capability. This logging suite provides porosity and water saturation
analysis, lithology identification and gas detection, and can be combined with other tools
for further versatility.
As a cased-hole service, the CNT is commonly run in combination with a UGR tool
and casing collar locator. This provides through-casing porosity determination and gas
detection. Other services also can be combined, including enhanced gas detection with the
monopole-dipole array sonic tool.

Applications

• Determining porosity and lithology
• Identifying formation gas, shale volume and mineral properties
• Providing input to advanced FE programs, seismic programs, water saturation
calculations, and determination of mechanical properties of rock
• Providing detailed well-to-well correlation and reservoir delineation

Features, Advantages and Benefits

• Measures formation porosity.
• Identifies lithology and detects gas when used in combination with other services.
• Indicates shale volume.
• Operates in open- and cased-hole environments.
• Provides input for water saturation calculations.

Microresistivity (MRT/ borehole image which requires processing via Weatherford or other)

Microresistivity log (MMR/MML mud cakes, or mud logs)

Compensated Neutron
Tool (CNT)

The Dipole Sonic Imager Tool (DSI)

combines high-speed telemetry with simultaneous, 12-bit dynamic range digitization of an eight-receiver array. The sonde incorporates both monopole and crossed-dipole transmitters with an eight-station array of electronically configurable hydrophones for monopole and dipole reception. Combining new dipole-based technology with the latest monopole developments into one system provides the best method available today for obtaining borehole compressional, shear and Stoneley slownesses (slowness is the reciprocal of velocity and corresponds to the interval transit time measured by standard sonic tools).

The transmitter section of the DSI contains three transmitter elements: one omnidirectional monopole ceramic transducer and two unidirectional wide-band electrodynamic dipole transducers oriented perpendicular to each other. Wide-band transducers are preferable to a single narrow-band source because they allow examination of the entire frequency spectrum without phase-matching problems at their resonant frequencies and are not subject to reduced output because of aging. A low-frequency pulse drives the monopole transducer for Stoneley wave excitation, and a high-frequency pulse drives it for compressional and shear measurements. A low-frequency pulse drives each dipole transducer for the creation of shear waves. In addition, a new low-frequency source option provides excitation below 1 kHz for extremely large holes and for very slow formations and shear waves.

The receiver section contains eight receiver stations spaced 6 in. apart and spanning 3.5 ft. Each station contains two hydrophone pairs: one oriented in line with the upper dipole transmitter and the other in line with the lower dipole transmitter. The outputs from each pair are differenced for dipole reception and summed for monopole reception. Receivers are carefully matched during manufacture and the receiver array provides more spatial samples of the propagating wavefield for full waveform analysis. The arrangement of the transmitters and receivers allows measurement of wave components propagating deeper into the formation.

The acquisition cartridge contains the circuitry to perform automatic gain control, digitize eight separate waveforms simultaneously, stack these waveforms from more than one firing and then transmit the signals uphole. Threshold detectors for recording amplitude threshold crossing times for each waveform are also present. These are for compressional first-motion detection and allow derivation of compressional slowness in a manner similar to the analog threshold detection scheme used in conventional sonic tools.

Dipole technology allows borehole shear measurements to be made in “soft” rock as well as “hard” rock formations. Limited by borehole physics, monopole tools can detect only shear velocities that are faster than the borehole fluid velocity — or in hard rocks only. Dipole tools overcome this fluid velocity barrier.

Cross-Dipole
Sonic (CXD)

Weatherford’s Compact cross-dipole sonic (CXD) tool combines monopole
and cross-dipole sonic technology, providing acoustic data for a wide variety of
geophysical, petrophysical, and geomechanical applications. The data obtained by
the CXD tool assists in improving reservoir characterization and ultimately maximizes
well and reservoir productivity.
The tool incorporates three high-powered transmitters—one monopole and two
wideband, low-frequency, dipole transmitters perpendicular to each other. The
receiver section has an array of eight receiver stations. Each receiver station consists
of four gain-matched, piezoelectric hydrophones that are aligned with the dipole
transmitters. Ninety-six, high-fidelity, wideband waveforms are recorded, ensuring
excellent quality control.
Patented isolator technology prevents direct flexural wave transmission to the
receivers through the tool body and provides a rugged tool for flexible conveyance.
Anisotropic orientation data is produced by combining the CXD with either the
Compact borehole navigation (MBN) tool or the Compact microimager (CMI) tool.

Applications

• Geophysics
– Velocity calibration, time/depth conversion
– Amplitude variation with offset (AVO) calibration
• Petrophysical
– Porosity estimation and lithology
– Gas identification
• Geomechanical
– Anisotropic presence, magnitude, and orientation
– Elastic properties
– Hydraulic-fracture design
– Sanding potential

Features, Advantages and Benefits

• Propriety transmitter and receiver design produces high-data quality over a broad range
of environmental conditions.
• The small diameter and length of the tool facilitate flexible deployment, in wireline or
memory mode, to mitigate the risk of bridging events and reduce nonproductive time.
• The CXD records all waveform data into flash memory, independently from the data
communicated by wireline, for data assurance.

Enables quantification of mineralogy, lithology, and organic carbon for improved saturations and reservoir characterization

Applications

Mineralogical quantification, including clay types
Detailed lithological analysis
Matrix density and matrix-corrected porosity
Enhanced porosity and oil saturation calculation
Total organic carbon (TOC) determination
Formation sigma

Features and Benefits

The geochemical spectroscopy instrument (GSI) functions as an integrated answer product that generates mineralogy and detailed lithology.
The service combines 15 elements: 12 from the GSI (Al, Ca,C, Cl, Gd, H, Fe, Mg, O, Si, S, Ti) with three from spectral gamma ray (K, Th, and U) for complete mineralogy determination.
Diffusion-corrected sigma aids in formation evaluation and reservoir characterization.
Real-time lithology and elemental concentrations are available at the wellsite, which enables time-sensitive decision-making.
A 14 MeV pulsed-neutron generator provides for comprehensive inelastic and capture gamma ray detection.
No chemical radioactive source is required, which enhances safety in the case of a fishing incident or lost-in-hole event.
The lanthanum bromide (LaBr3) detector exhibits enhanced energy resolution with fast emission and temperature linearity characteristics.
The instrument can be deployed using advanced Assure™ conveyance techniques.
Memory capabilities enable cost-effective horizontal logging.

Tool Description

The geochemical spectroscopy instrument (GSI) uses a pulsed-neutron generator to induce inelastic and capture gamma rays. Measuring the gamma rays enables identifying key formation elements. The final lithological and mineralogical interpretation is guided by these elemental concentrations, as well as by the measurement of intrinsic sigma. The interpretation software processes the input, analyzes the lithology, and improves the identification of matrix properties for use in further reservoir characterization.

Geochemical Spectroscopy Tool

TM Formation Pressure
Tester (MFT)

Weatherford’s Compact formation pressure tester (MFT) measures formation fluid
pressures for use in permeability and fluid-contact determinations. The tool contains a
high-accuracy, quartz-pressure gauge and a high-precision, strain gauge.
Its unique design automatically centers the body of the tool to give optimal pad
application for reliable seals and reduced risk of differential sticking, yet it allows the tool
to pass restrictions smaller than 3 in. and to operate in wells up to 14 in. in diameter.
A conformable pad seals part of the borehole wall from the mud column, and formation
fluid is produced at a programmable rate into a pre-test chamber. Typically an initial
fall in pressure is followed by a buildup to the formation value. Permeability can be
computed from both the drawdown and buildup behaviors. Multiple tests can be
performed at each depth station, and an unlimited number of stations can be tested.
As the MFT arm mechanism closes at the end of each test, the risk of differential
sticking is reduced further by the application of a positive fluid pressure from the pad.

Applications

• Providing measurements for formation pressure and formation-pressure gradient to
identify fluid contacts and determine permeability

Features, Advantages and Benefits

• The MFT can operate on third-party wireline, including monocore cable.
• The slim design of the MFT enables thru-drillpipe conveyance past restrictions as
small as 3 in., reducing the risk of nonproductive time associated with key-seated
cable.
• The self-centering design reduces the total contact area, thereby reducing the risk
of differential tool sticking.
• The MFT generates positive pressure at the pad at the end of each test.
• Setting and closing time in an 8.5-in. borehole is 10 seconds (from one-half to a
quarter of the time required for conventional formation testers).
• If tool power is lost, a fail-safe mechanism enables the tool to collapse when
overpull is applied.

High Resolution 40- and 60-Arm
Multi-Sensor Caliper Tool (MSC)

The Weatherford high-resolution 40- and 60-arm multi-sensor caliper (MSC) tools provide an
accurate internal casing profile from an array of precision-calibrated feeler arms. Each arm
provides independent, radial measurements. The high-resolution MSC tools deliver 400 data
samples per meter compared to the industry standard of 40 samples per meter provided by
legacy MSC tools. No other caliper tools in the market can deliver equivalent resolution at
equivalent logging speeds. The high-resolution 40- and 60-arm MSC tools are combinable with
other Weatherford high-speed telemetry well integrity tools, such as the Casing Imaging Tool
(CIT), the Ultrasonic Radial Scanner (URS), and the 3-ft/5-ft Cement Bond Tool (CBT).
The wellbore measurement and onboard inclinometers supply a rigorous eccentricity correction
algorithm enabling the high-resolution 40- and 60-arm MSC tools to provide data for the analysis
of casing deformation and bending. Real-time monitoring of tool response enables the operator
to perform multiple passes over anomalous features on the casing profile. TVision analysis
software classifies each casing joint with respect to the worst case defect found, providing a
convenient joint-by-joint well summary. The analysis package can also graphically portray the
casing as a 2D cross section or 3D image to highlight anomalies.

Applications

• Monitoring internal casing corrosion or scale buildup
• Evaluation of drilling wear
• Inspection of marine risers (with available extended-reach kit)
• Identification of split, parted, or deformed casing
• Evaluation of pipe deforrmation due to geomechanical issues
• Axis deformation, clearance circle analysis, ovality analysis)

Features, Advantages, and Benefits

• Selectable high-resolution, independent radii measurements from each caliper arm provide
highly accurate wellbore profile.
• Tool is combinable with Casing Imaging Tool, Ultrasonic Radial Scanner, and 3-ft/5-ft
Cement Bond Tool.
• Eccentricity algorithm and onboard inclinometer package provide advanced cross-sectional
analysis methods to improve geomechanical deformation interpretation.
• TVision software produces graphical cross-sectional and 3D plots of casing ID for easy
identification of anomalies and advanced interpretation of deformation.
• Temperature sensor improves identification of casing anomalies by highlighting sources of
fluid entry.

Two-Arm Caliper
(MTC)

Weatherford’s Compact two-arm caliper (MTC) is used to orient and/or eccentralize
specific tool strings and to produce logs of the borehole diameter. It also provides
powered eccentralization in situations where conventional eccentralizers cannot be
used (for example, through-drillpipe logging).
The lateral force from the MTC exceeds that of the photodensity (MPD) caliper;
therefore, when the MTC and MPD are combined, the density shoe is forced to run up
the short axis of an oval hole. This axis is usually less rugose and closer to bit size,
resulting in optimal density and Pe log responses. The consequential X-Y caliper logs
also provide more accurate hole-volume estimations.
By removing one of the two caliper arms, the MTC can be used as a powered
eccentralizer. Complex tool string geometries can be constructed using multiple MTCs,
which can be configured at 60 or 90 degrees to one another.
The MTC is also used in tool strings that contain no other caliper measurement in order
to provide hole-size input for environmental corrections and hole-volume calculations.

Applications

• Providing borehole volume calculations
• Ensuring tool orientation with powered eccentralizer

Features, Advantages and Benefits

• The dual (X-Y) caliper provides data for a more accurate analysis of the
borehole shape and volume.
• The powered eccentralization enables short-axis orientation to provide more
accurate measurements in a rugose hole.

Dual Laterolog (MDL) Tool

laterolog (MDL) tool is the resistivity tool of choice in wells drilled in high-contrast, true formation resistivities (Rt ) / mud resistivities (Rm) environments. The MDL tool provides individually optimized deep- and shallowpenetration curves that share a common 2-ft (0.6-m) vertical resolution. Optimizedelectrode geometry and digital-measurement sequence control give the tool excellent environmental performance over a wide range of Rm and hole sizes and virtually eliminate electrode-polarization effects. The voltage reference and simultaneous SP electrodes are incorporated into a stiff bridle at the top of the tool string to optimize reliability. The cableless logging variant enables the MDL to be run without a wireline. The Groningen curve is used with the deep measurement to detect anomalous responses as the tool approaches nonconductive formations, such as salt caps. The MDL tool is normally run with the microlaterolog (MMR) or microlog (MML) tool to determine the invaded-zone resistivity

Applications

Determining formation resistivity in conductive-mud environments Determining water saturation (Sw) Providing well-to-well correlation Identifying moveable fluids Identifying fluid contacts Creating an invasion profile to indicate permeability, when used with the flushed-zone resistivity (Rxo) MMR tool

Features, Advantages and Benefits

The arrangement of the electrodes on the MDL tool detects the Groningen effect for quality control to provide accurate, real-time, deep-resistivity readings. The MDL can be run in combination with the microresistivity (MMR/MML) tool to obtain an independent, shallower measurement for improved accuracy in determining Rxo and Rt in complex invasion profiles.

Data from the microresistivity (MMR) or the shallow-focoused electric (MFE) tool can be used to significantly enhance the vertical resolution of the MDL to less than 1 ft (0.3 m) for improved thin-bed analysis and reserve estimates. The small diameter of the tool facilitates flexible deployment in wireline or memory mode to mitigate the risk of bridging events and reduce nonproductive time.

Photodensity (MPD) Tool

photodensity (MPD) tool provides bulk density, caliper, and photoelectric (Pe ) factor for porosity and lithology determination in conventional and slim wells. The unique profile of the tool enables it to pass through restrictions as small as 2.5 in. (57 mm). The density and Pe detection and processing system are contained in an articulated shoe, which maintains closer contact with the formation over caved intervals, eliminating the gross errors typical of mandrel tools in similar conditions. The highly optimized shoe has smaller borehole size corrections than many conventional tools. A connector at the bottom of the tool can be rotated 180° to provide 0.5 in. (13 mm) of standoff to tools below. It is normally used to eccentralize the induction (MAI) tool and eliminates the need for an intersonde crank.

Applications

Determining formation porosity and lithology

Logging through-drillpipe past severe hole conditions

Determining fluid density (in combination with other measurements) Identifying formation gas

Identifying mineral properties Providing input to advanced formation-evaluation programs Providing input to determine mechanical properties of rock Providing input to seismic programs Providing detailed well-to-well correlation

Delineating the reservoir

Features, Advantages and Benefits

The MPD uses an articulated shoe that reduces the effects of borehole size and rugosity and provides a high-quality density measurement.

The unique profile of the tool facilitates flexible deployment, in wireline or memory mode, to mitigate the risk of bridging events and reduce nonproductive time.

Dual Neutron (MDN) Tool

dual neutron (MDN) tool provides a boreholecompensated porosity measurement. The MDN is fully characterized for air and mud-filled environments in both open- and cased-hole wells. The tool design minimizes sensitivity to environmental effects; for example, borehole size corrections are smaller than those for conventionally sized tools. Full environmental corrections are applied automatically during data acquisition. Porosity is recorded simultaneously in apparent limestone, sandstone, and dolomite porosity units. Enhanced resolution processing is available when acquiring data at a high sample rate. The MDN tool is usually run with a V-bow spring, which forces the tool against the borehole wall for maximum porosity sensitivity. In oval boreholes, this doublespring eccentralizer can keep the photodensity (MPD) tool, which is normally placed below the MDN, aligned along the short axis.

Applications

Determining porosity and lithology Gas identification (with density porosity)

Determining shale volume Providing input for water-saturation calculations

Providing detailed well-to-well correlation

Delineating the reservoir Determining porosity in open- and cased-hole environments

Features, Advantages and Benefits

The MDN tool is designed with the latest advances in modeling and detector technologies to deliver excellent porosity sensitivity and a 65 percent reduction in radioactive source activity for safer operation and simpler transportation.

The tool’s small diameter enables flexible deployment.

The tool is characterized for air- and mud-filled environments.

Cross-Dipole Sonic (CXD)

cross-dipole sonic (CXD) tool combines monopole and cross-dipole sonic technology, providing acoustic data for a wide variety of geophysical, petrophysical, and geomechanical applications. The data obtained by the CXD tool assists in improving reservoir characterization and ultimately maximizes well and reservoir productivity. The tool incorporates three high-powered transmitters—one monopole and two wideband, low-frequency, dipole transmitters perpendicular to each other. The receiver section has an array of eight receiver stations. Each receiver station consists of four gain-matched, piezoelectric hydrophones that are aligned with the dipole transmitters. Ninety-six, high-fidelity, wideband waveforms are recorded, ensuring excellent quality control. Patented isolator technology prevents direct flexural wave transmission to the receivers through the tool body and provides a rugged tool for flexible conveyance. Anisotropic orientation data is produced by combining the CXD with either the Compact borehole navigation (MBN) tool or the Compact microimager (CMI) tool.

Applications

Geophysics – Velocity calibration, time/depth conversion – Amplitude variation with offset (AVO) calibration

Petrophysical

– Porosity estimation and lithology

– Gas identification Geomechanical – Anisotropic presence, magnitude, and orientation

– Elastic properties

– Hydraulic-fracture design

– Sanding potential

Features, Advantages and Benefits

Propriety transmitter and receiver design produces high-data quality over a broad range of environmental conditions.

The small diameter and length of the tool facilitate flexible deployment, in wireline or memory mode, to mitigate the risk of bridging events and reduce nonproductive time.

The CXD records all waveform data into flash memory, independently from the data communicated by wireline, for data assurance.

Sonic Sonde (MSS)

sonic sonde (MSS) measures formation compressional slowness (inverse velocity) at five spacings with 1- and 2-ft (0.30- and 0.61-m) vertical resolution. In cement bond log (CBL)/variable density log (VDL) mode, the MSS tool records a waveform (normally from the 5-ft [1.52-m] receiver) and up to four first-arrival amplitude logs. The ratio of two amplitude curves defines an attenuation log that is sensitive to cement bond quality. Data quality is maintained at high levels over a broad range of environmental conditions from a combination of high transmitter output, real-time despiking, and cycle-stretch compensation. Cycle-stretch compensation gives improved accuracy and consistency by adjusting transit times based on information about waveform shapes close to the first arrivals.

Applications

Determining secondary porosity and lithology

Providing formation mechanical properties

Providing fracture detection Providing gas detection Integrating seismic, time-to-depth corrections

Providing a synthetic seismogram (when used with the MPD tool) Providing a CBL

Features, Advantages and Benefits

Unlike traditional 3- to 5-ft (0.91- to 1.52-m) sonic tools, the MSS uses a single-sided array with depth-derived, cave compensation and tilt correction. This feature, together with a short electronics package, makes the tool unusually short and light.

The MSS passes through restrictions as small as 2.5 in. (63 mm), enabling throughdrillpipe logging for increased operational efficiency