EnvironmentalMeasurement Sonde

Borehole PropertiesAnalysis

Applications■ Calculation of borehole

radius and cement volume

■ Stress analysis and boreholestability evaluation

■ Automatic analysis ofborehole shape

■ Environmental correctionand depth matching ofother measurements

Benefits■ Precise borehole-shape

evaluation to determinedrilling performance

■ Accurate estimation ofcement volume to optimizecementing cost

■ Combined operations withother measurements savesrig time

■ Real-time environmentalcorrections for other loggingtools to yield accurate results

■ Real-time depth matchingof other logging tool data toenhance log interpretation

Features■ Six independent borehole

radii measurements

■ Mud temperature, mudresistivity and toolacceleration measurements

■ Centralized or eccentralizedoperation

■ Modular design to suitindividual application needs

■ Flexible configurationand setup

■ Combinable with mostformation evaluation tools

New dimension for borehole evaluationThe Environmental MeasurementSonde (EMS) dramatically increasesthe ability to determine the preciseshape of the borehole. Supported bythe MAXIS* Multitask Acquisition andImaging System, the EMS tool usessix independent arms to make calipermeasurements around the borehole.These caliper readings provide exten-sive drilling and petrophysical infor-mation. Using an ovality algorithm,the measurements determine the defi-nite shape of the borehole for stressanalysis studies. In addition, the EMStool measures mud resistivity, mudtemperature and acceleration alongthe tool axis for real-time environ-mental correction of downhole meas-urements.

Better borehole geometry evaluationOver a wide range of borehole sizes,the six independent arms of the EMStool precisely measure the boreholecross section to give detailed informa-tion on borehole geometry. The resultis better environmental correction ofthe imaging tool data, improved bore-hole stress analysis and more preciseestimation of the cement volume, evenif the tool is eccentered.

Improved mud resistivity measurement With multiple voltage monitoringelectrodes, the EMS mud resistivitysensor provides robust and accurate

mud resistivity measurements underadverse conditions. Even with mud-cake on the tool surface or in narrowboreholes, the EMS tool delivers reli-able and precise measurements.

Real-time environmental correctionsThe improved caliper, mud resistivityand temperature measurements allowreal-time environmental correction ofmeasurements obtained from imagingtools such as the AIT* Array InductionImager Tool, the IPL* IntegratedPorosity Lithology tool and the ARI*Azimuthal Resistivity Imager. Sincethe EMS tool is combinable with allimaging tools, environmentally cor-rected wellsite logs can be producedwithout an extra trip in the hole.

Better depth matchingThe EMS tool incorporates a singleaxial accelerometer. Data from theaccelerometer can be used to provideaccurate depth matching of the bore-hole measurements, correct tool speedand estimate hole deviation.

AdaptabilityDesigned to suit individual applicationrequirements, the EMS tool incorpo-rates three modules, the environmentalmeasurement cartridge (EMC), theenvironmental measurement sondeadapter (EMA) and the environmentalmeasurement mechanical sub (EMM).These modules can be run in different

Mudcakecoveringthe sensor

Mud resistivitymeasurement

Current path

Sensor

Boreholewall

Equipotentialsurfaces

The mud resistivity measurement is not affected by the presence of mudcake in front of the tool.

configurations depending on the toollength and data requirements. The toolcan be run centered or eccentered witheach of the six caliper arms independ-ent of each other. In conditions wheretool eccentering is crucial for othermeasurements in the same tool string,an optional fixed caliper operation isavailable that features three adjacentarms locked.

Detailed borehole geometry data The six independent caliper readingssupply data for both drilling and petro-physical studies. An algorithm, basedon all six oval-radii measurements,gives the best-fit ovality and providesborehole geometry with long- andshort-axis diameters, their orientationand the tool arm positions.

The computed long- and short-axisdiameters are more precise than rawmeasurements, which may be affectedby tool eccentralization and boreholeovality. The log presentation can betailored to specific needs, and the loganswers can be customized to give agood visual indication of the boreholeprofile to enhance decision making.Precise cement volumes can also becalculated.

Digital telemetrycartridge (DTC)

Environmental measurementsonde adapter (EMA)

Environmental measurementcartridge (EMC)

Environmental measurementmechanical sub (EMM)

Other tools

DTC

EMC

EMM

Other tools

DTC

EMA

EMC

Adapter head

Other tools

DTC

EMCAdapter head

Other tools

Measurements provided

Mud resistivityTemperatureBorehole diametersTool acceleration

Borehole diametersTool acceleration

Mud resistivityTemperatureTool acceleration

Tool acceleration

The EMS tool has three modules that can be easily configured to the required measurement need and tool length limitation.

XO25

XO50

XO75

4.59

8.52

7.22

3.63

5.53 9.67

4.464.22

9.09 9.436.13

4.93 10.32

3.82

6.79 10.0713.88

4.86 6.11

7.86 8.9410.37

8.685.18

5.20 9.787.335.59

5.855.32 4.58

10.274.635.93

4.945.20 5.03

3.69

4.174.88

Depth(ft)

OvalizationLong axis diameter

10 0 10(in.)

Short axis diameter10 0 10

(in.)Bit size

10 0 10(in.)

From the EMS log, the driller can easily select the best setting depth for an openhole packer.

SMP-5883 ©Schlumberger

July 2002 *Mark of Schlumberger

www.connect.slb.com

The EMS tool has six independent arms thatprecisely gauge the borehole cross sectionover a wide range of borehole sizes.

EMS Tool Specifications

Length 14.1 ft [4.5m]Diameter 3.375 in. [85.7 mm] without caliper section

4.000 in. [101.6 mm] with caliper sectionWeight 296 lbm [133 kg]Temperature rating 175°F [350°C]Pressure rating 20,000 psi [137,895 kPa]Mud resistivity

Range 0.01 to 5 ohm-mAccuracy ±10% (0.02 to 0.5 ohm-m)

±7% (0.5 to 5.0 ohm-m)Depth of investigation 0.3 to 1.0 in. [7.62 to 25.4 mm]

Mud temperatureResolution 0.1°C (0.2°F)Accuracy ±1°C or 1% (±2°F)

CaliperMaximum diameter 40 in. [1016 mm] with extension arms

30 in. [762 mm] without extension armsResolution 0.06 in. [1.5 mm]Accuracy ±0.1-in. [2.5-mm] radius

AccelerationAccuracy +4 cm/s2 Resolution 1 cm/s2