Spectral Density Log

In order to use the latest techniques in wireline logging and for more accurate lithology & porosity identification for sedimentary and basement rock, from 1997 Vietsovpetro L&TD has been using Halliburton’s Spectral Density Log Tools (SDL-T).

Spectral Density Log provides superior formation bulk density (r_b) and borehole Compensated photoelectric factor (Pe) measurements. These measurements are key factors for

Accurate determination of formation bulk density
Reliable identification of formation lithology, regardless of formation fluid type
Precise delineation of thinly bedded formations (the unfiltered Pe curve is used)
Excellent indication of gas when used in combination with a neutron log
Excellent effect of basement dyke identification when used in combination with a neutron log

Tool specification

Buck Density

Pe High resolution

Max Temp	3500F (1750C
Max Press	20 000psi (137 900 kPa)
Max hole	20.75 in. (528.7 mm)
Min hole	4.5 in (115 mm)

Vertical Resolution	Standard 33in (83cm) Inhanced 5.5in (14cm	4in (12.7cm	2in (5.1cm)
Depth of Investigation (50%)	1.5 in. (3.8 cm)	0.5 in. (1.3 cm)	0.5 in. (1.3 cm)

Precision (1 SD)

0.37%

1.6%

5.3%

Accuracy	5%
Max hole	20 in (508 mm)
Primary Curve	RHOB, DRHO, Pe
Secondary Curve	DP e , P e Q, QLS, QSS, GR, Caliper, Standoff

Basement Dyke detection when used in combination with a neutron log

Benefits and Features

Consistent, high-quality measurements. Field engineers perform precise calibration and wellsite checks.

Accurate rb with minimal statistical variation. The tool’s rigid tungsten pad incorporates a 1.5- curie cesium-137 source and two high-efficiency scintillation detectors designed to maintain high gamma counts.

Real-time assessment of the validity of rb and Pe measurements. Curves that indicate data quality are displayed on a computer screen in real time and are recorded on the log.

Reliable performances, even under hostile conditions. The tool’s rugged construction and advanced gain-stabilization help maintain measurement integrity under varying temperature conditions.

Valid log response in weighted borehole fluids. An advanced correction algorithm is applied to density data.

Single-pass, comprehensive formation evaluation. The SDL tool is combinable with a complete family of tools that operates under Digital Interactive Telemetry System.