DDS - Dual Downhole System
from Geotomagraphie

The Dual Downhole System (DDS) consists of two geophone receivers, both fitted with a minimum of 3 geophone elements, separated by a fixed distance. When deriving interval velocities the receiver geometry is extremely important. A fixed receiver separation reduces geometry and trigger errors which can be an issues when using two independent downhole geophones.

Dual Downhole System (DDS) with two 3 component geophones separated with a 2m interval.
Dual Downhole System (DDS) with two 3 component geophones separated with a 2m interval.

To aid orientate the receivers a fluxgate magnetic compass is installed in the casing of the low receiver. The heading of the receiver is then reported on a LCD screen fitted in the hub of the cable reel. The pneumatic air line and signal cables are integrated within a jacketed Kevlar weave allowing the tool to be easily deployed by hand. The Kevlar weave also prevents the cable from stretching.

Each receiver is supported against the borehole side wall by a pneumatic bladder. The pneumatic system is adequate for exploration depths of 100m and the air bladders will inflate to fill a 75mm diameter borehole. In larger diameter boreholes spacers can be fitted to the DDS receivers.

The stainless steel receiver casing is sealed to allow the tool to operate in dry or water filled boreholes.

Product Dimensions

Physical Dimensions (L x W x H) Weight
DDS - Dual Downhole System (instrument only) 55cm x 50cm x 50cm 32kg

Technical Specifications

Natural sensor frequency: 4.5, 10, 15, 28 or 30Hz
Sensor arrangement: DDS3 - 1 vertical & 2 horizontal (90º spacing)
DDS5 - 1 vertical & 4 horizontal (45º spacing)
Operational depth: 100m
Number of stations: 2
Station interval: 2m
Station length: 620mm
Station diameter: 65mm
Station weight: 2.5kg
Cable weight per metre: 145g
Cable strength: 2150N
Borehole diameter: 75mm
Clamping system: Inflatable bladder
Orientation: Magnetic compass (+/-2.5°)
Seismograph: Any (requires adapter cable)

Shipping

Contents Dimensions (L x W x H) Weight
Case1
DDS, pump and Seismogrph adaptor cable
117cm x 70cm x 42cm 75kg
Shipping Notes:

If dispatched with a Geode seismograph then the system will be collated onto a pallet. The courier will require a fork lift or tailgate flit.