Borehole RIM-6:

The Radio Imaging Method (RIM) was developed in the early 1980’s as a means of interrogating geological conditions between boreholes and drives in underground mines. The technique utilizes medium frequency radio wave transmission to map variation in conductivity between transmitter and receiver. RIM has been used extensively in the coal and minerals industry over the past twenty years. The current version of the Bore-Hole RIM System (termed RIM-6) was designed specifically for advanced horizontal crosswell and deep borehole applications. Compared to older systems the new RIM-6 uses electronics and antenna assemblies which provide a signal-to-noise improvement of 5 to 35 dB (frequency dependant).

Shallow and Deep-Borehole Mapping

  • Application-Specific Packaging and Performance RIM-6M and RIM-6D
  • 2-D and 3-D Crosswell Tomography
  • Greater “dynamic range” allows for longer signal range over RIM-5 (50% improvement)
  • Higher imaging frequencies, increases resolution
  • Rapid Data Collection and Processing
  • 4-year commercial history, +100 surveys

General RIM Borehole System Description

A complete borehole RIM imaging system consists of a transmitter (TX) unit and a receiver (RX) unit. Each unit consists of a fiber-optic hoist, unit controller and a down-hole imaging probe. The probe systems (TX and RX) include multiple stainless steel tube enclosures and stainless end-adaptors (probe interconnects). The magnetic-dipoles use ferrite-core antennas and their housings are a fiberglass composite. The borehole system block diagram is shown in the following figure.

Borehole RIM-6 uses low-wattage RF signals, propagated and received from adjacent sub-surface boreholes, to produce tomographic images of the earth between the boreholes. The signals are very low power and safe. Operational specifications, electrical ratings, and size and weight specifications, can be provided for each system with approved request.

A fully assembled RIM-6 Hoist contains some variable length of fiber optic cable, a DC motor and controller, onboard power distribution box, and a central processing unit. All onboard electronics run on 15V DC, the hoist motor uses 120 or 240 VAC, and downhole sensors are powered by a 15 VDC downhole battery pack. The probe electronics are kept inside a steel holster for transport and storage. Each central processing unit consists of a Pocket PC interface (with GUI), the Central Processing Modem, and a Depth Counter. An accessory Wi-Fi link can also make the Pocket PC fully wireless. To create a synchronous connection between the TX and RX hoists, radio-modems are utilized for field set-up.

Each RIM-6 hoisting units, which is driven by 90-VDC electric motors (3/4 HP), is designed to lower and raise the borehole probes over a range of its fiber optic cable length. This hoist system includes an electronic counter to measure the depth of the probes and has speed control as well as an electric directional switch. The motor drives the fiber optic spool via a gear reduction box and beltdrive (fully guarded). The front guide wheels are engineered to allow cable winding and positive cable tension. The motor power has protection switches built into the upper spring-mounted guide wheel (for over-tension protection) and an Emergency Cut-Off Switch near the User Interface Console. The cutoff switches provide added protection to the equipment in case of excess fiber-optic cable stress such as probe “hang-ups” during extraction.

There are many borehole hoist designs available for use by SGM field operations. The type of system used is based on the required imaging depth (to end-of-hole) and the nature of the field logistics and deployment requirements. The hoisting systems range from 150-meters of fiber optic cable, to 1500-meters of cable. Some hoisting systems are specifically designed to be used for horizontal-borehole applications (gravity-independent) where a secondary spooling system is required for “double-takeup” capability. A list of available RIM-6 hoisting systems is provided below.

• Standard International A-Hoist (630-meters, 240VAC)
• Standard North American B-Hoist (2200-ft, 120VAC)
• Deep Borehole D-Hoist (1500-meters, 240VAC)
• Mini North American M-Hoist (700-ft, 120/240VAC)
• Compact C-Hoist (1900-ft, 120/240VAC)
• Standard USGS-Model Hoist (1900-ft, 120VAC)

The RIM-6 borehole probe set consist of (from top to bottom): fiber optic interface probe, rechargeable battery pack, receiver or transmitter electronics, and a ferrite-core magnetic dipole antenna and tuning chassis with fiberglass tube housing. Each of these probe sections are housed in sealed stainless steel tubes with end adapters. These four sections plug into one another to make up either the down-hole transmitter or receiver probes. Assembled length is 9 to 10 feet; assembled weight is between 25 and 30 pounds (depending on type of probe). The fiber optic cable adds additional down-hole weight. Some downhole probe photos are provided.

The fiber-optic interface sub-module is permanently attached to the fiber optic cable (i.e. always connected to the hoist unit). However, all other components are removable for packaging in a “gun case” for transport and storage. These include the down-hole battery packs, the receiver and transmitter electronics, the magnetic dipole antennas, and the probe assembly kits. The Pocket PCs and chargers each have their own travel cases as well.

D-Hoists (Deep System) (RX and TX)

  • Powered by 240-volt AC
  • Spool capacity: 1500 meters (5500 feet)
  • Forklift, heavy truck mobile



































M-Hoists (Mobile System) (RX and TX)

  • Powered by 120 volts AC, or DC battery pack
  • Spool capacity:  700 Feet
  • SUV mobile, or two-man carry

























A-Hoists (Australia System) (RX and TX)

  • Powered by 240 volts AC, or DC battery pack
  • Spool capacity: 630 meters
  • Ute-portable, wheeled, can be towed or one-man pulled














B-Hoists (North American System) (RX and TX)

  • Powered by 120 volts AC, or DC battery pack
  • Spool capacity: 2200 feet
  • Trailer or pickup portable, can be towed or one-man pulled


























C-Hoists (Compact System) (RX and TX)

  • Powered by 120 volts AC, or DC battery pack
  • Spool capacity: 1900 feet
  • SUV portable, or one-man mobile
















USGS-Model Hoist Set (RX and TX)

  • Utilizes RIM-5 technology
  • Powered by 120 volts AC
  • Spool capacity, 1900 feet









































Each Borehole System uses specialized Graphical User Interface (GUI) software to control the RIM-6 unit on its PDA computer. The application has seven main operating pages for command, control, diagnostics, noise analysis, data graphics, and multi-frequency operation. A collection of PDA screens are shown below.

Final Note:  Stolar has extensive experience over the last 30 years investigating the susceptibility of men, machinery, and explosive sources to its radiowave transmission devices. These studies include the susceptibility of various types of mining equipment to electromagnetic (EM) fields, their effects on blasting caps and remote detonation devices, the biological effects of EM waves from RIM equipment, and methane ignition susceptibility to radiating magnetic diploes. More detailed discussion of these issues can be provided upon specific request.