Logging-While-Drilling EcoScope* Tool

lwd_ecoscopeThe Logging-While-Drilling-EcoScope (LWD-EcoScope) is the first Schlumberger LWD multifunction tool that provides a complete set of formation evaluation measurements without using the traditional chemical sources. A pulsed neutron generator (PNG) replaces the americium-berillium (AmBe) source commonly used for porosity measurements, while an optional neutron gamma density measurement is performed with out the traditional side-mounted Cesium source. This feature considerably reduces the risk previously associated with transportation and operations at the borehole site. Also, the PNG produces more high-energy neutrons than the traditional chemical source, which results in a deeper depth of investigation and therefore more accurate measurements of the properties of the formation. In addition to density and porosity measurements, the EcoScope offers the first LWD measurement of neutron-induced elemental gamma ray spectroscopy and sigma; these data provide mineralogy, lithology and matrix properties. Phase and attenuation resistivity at two frequencies (originally from ARC tool) and gamma ray, as well as some drilling parameters such as annular pressure-while-drilling, caliper, and shock complete the suite of measurements provided by the EcoScope.

All drilling and measurement sensors are mounted on a single collar mounted close to the bit that can be deployed faster than conventional LWD tools; all EcoScope measurements are delivered in real-time to the surface via TeleScope high speed telemetry. The EcoScope large memory capacity allows for the recording of data at 2 points/ft (30.48 cm) at penetration rates up to 450 ft/hr (137 m/hr).


• Formation lithology and physical property evaluation
• Formation mineralogy from elemental gamma spectroscopy
• Drilling performance evaluation

Tool Specifications

Temperature rating: 300° F (149° C)
Pressure rating: 20 kpsi (138 MPa)
Length: 28 ft (8.5 m)
Weight: 3,200 lbs (1,453 kg)
API nominal collar outside diameter: 6.75 in (17 cm)
Maximum outside diameter: 7.875 to 9.375 in (20 to 23.8 cm)
Minimum bit size: 8.375 in (21.3 cm)
Maximum bit size: 9.875 in (32.5 cm)
Flow range: 250-800 gpm
Maximum curvature – sliding: 16 deg/100 ft (16 deg/31 m)
Minimum operating RPM: 30 rpm
Uphole connection: 5-1/2 FH box
Downhole connection: 5-1/2 FH box
(*) pressure drop = [mudweight in ppg] x [flow in gpm]²/C

Measurement Specifications

Gamma Ray 
    Range: 0-250 GAPI
    Accuracy: 7%
    Vertical resolution: 6 in (15.24 cm)
    Range: 0.2-3,000 ohm-m
    Accuracy: 2% (<6 ohm-m); ±0.3 msec/m (>6 ohm-m)
    Vertical resolution: 8.4 in (21.33 cm)
    Range: 1.7-3.05 g/cm³
    Accuracy: 0.015 g/cm³
    Vertical resolution: 6 in (15.24 cm)
    Range: 0-100 pu
    Accuracy: ±0.5 pu (<10 pu); ±5% (10-50 pu)
    Vertical resolution: 12 in (30.48 cm)
Photoelectric Effect
    Range: 1-10 barns/e-
    Accuracy: 5%
    Vertical resolution: 2 in (5.08 cm)

Major Outputs

RHOB: Bulk Density (g/cm³) 
DRHO: Density Correction (g/cm³)
DRRT: Correction for rotational density (g/cm³)
IDDR: Image Derived Density Correction (g/cm³)
IDPE: Image Derived Photoelectric Effect (g/cm³)
PEF: Photoelectric Effect (barns/e-)
TNPH: Thermal Neutron Porosity (%)
BPHI: Best Thermal Neutron Porosity, Average (%)
DCAL: Differential Caliper (in)
GRMA: Gamma Ray, Average (GAPI units)
PnB: Phase Shift Resistivity Blended, n=16, 22, 28, 34, 40 in (ohm-m)
PnH: Phase Shift Resistivity, 2 MHz, n=16, 22, 28, 34, 40 in (ohm-m)
PnL: Phase Shift Resistivity, 400 KHz, n=16, 22, 28, 34, 40 in (ohm-m)
AnB: Attenuation Resistivity Blended, n=16, 22, 28, 34, 40 in (ohm-m)
AnH : Attenuation Resistivity, 2 MHz, n=16, 22, 28, 34, 40 in (ohm-m)
AnL: Attenuation Resistivity, 400 KHz, n=16, 22, 28, 34, 40 in (ohm-m)
APRS: Annulus Pressure (psi)
ATMP: Annulus Temperature (degC)
ECD: Equivalent Circulating Density (lb/gal)
DWAL_WALK2: Dry Weight % Pseudo Aluminum (Walk2 Mode)
DWCA_WALK2: Dry Weight % Pseudo Calcium (Walk2 Mode)
DWFE_WALK2: Dry Weight % Pseudo Iron (Walk2 Mode)
DWGD_WALK2: Dry Weight % Pseudo Gadolinium (Walk2 Mode)
DWK_WALK2: Dry Weight % Pseudo Potassium (Walk2 Mode)
DWSI_WALK2: Dry Weight % Pseudo Silicon (Walk2 Mode)
DWSU_WALK2: Dry Weight % Pseudo Sulfur (Walk2 Mode)
DWTI_WALK2: Dry Weight % Pseudo Titanium (Walk2 Mode)
AGTM: Gamma Ray Time After Bit (s)
ARTM: Resistivity Time After Bit (s)
TAB_DEN: Density Time after Bit (s)
TAB_NEU: Neutron Time after Bit (s)
ROP5_RM: Rate of Penetration, average over last 5 ft (m/hr)
RPM: Tool Rotational Speed (rpm)

* ®trademark of Schlumberger