SDS Telemetry System

The SDS Telemetry System consists of a Simple Telemetry Board (STB) and an optional Downhole Power Supply Board (DHPS) . The purpose of the STB is to convey data from downhole tools on the tool bus (RS232), Transmit/Receive the data and Commands to/from the surface via a reliable digital telemetry system facilitating communication between the Warrior Surface System and downhole tools. Typical applications have been for conventional logging tools (including digital acoustic and spectral data), hybrid tools (telemetry and memory simultaneously), intervention tools (relying heavily on surface to downhole control) and fast mobilization for the development of new tools and sensor testing where "off the shelf" and simple to setup and interface telemetry can save substantial development time and costs.

SDS Simple Telemetry Circuit Board (STB)

General Specifications: Maximum Temperature 350ºF (177°C), operating Voltages (dependent on power supply) range +0 +450V DC, Current consumption at 200V 15mA, Tool Bus data rate 115kbps, Wireline Uplink data rates currently 12 kbps to 67 kbps, and Downlinks rates 1 kbps to 5 kbps. Input Voltage Requirements are typically +15Vdc, -15Vdc and +5Vdc.

SDS Simple Telemetry circuit Board (STB)

The STB consists of 5 main functional blocks as shown in the block diagram below

SDS STB block diagram

Wireline Uplink Modem

The Wireline Uplink Modem forms the hardware interface between the Rx Tool Bus RS232 Modem and the Wireline mono-cable which transmits data to the surface system. Uplinks are modulated onto the line as pulsed RS232 at a selectable bit rate currently ranging from 12 kbps to 67 kbps with amplitude of +/- 15Vpk. The Wireline Uplink Modem rate can be changed via downlink command. The Wireline Uplink Modem uses half duplex transmission.

Rx Tool Bus RS232

The Rx Tool Bus RS232 Modem forms the hardware interface between the Downhole Tools and Wireline Uplinks Modem. Rx is modulated TTL input (5Vdc), onto Rx Tool Bus RS232 Modem at 115kbps. The Rx Tool Bus RS232 Modem rate can be change for downlinks commands via I2C Bus.

Wireline Downlink Modem

A half duplex downlink allows the user to configure and control operations from the surface prior to and during logging. Control is exercised by means of commands, which may be destined for the Wireline Downlink Modem, Rx Tool Bus RS232 Modem, and /or passed on to other tools via the Tx Tool Bus RS232 Modem. Where command execution generates a response, this is generally uplinked to the surface via Wireline Uplinks Modem, downlink status is monitored and reported by the system.

Tx Tool us RS232 Modem

The Tx Tool Bus RS232 Modem forms the hardware interface between the Wireline Downlinks Modem and the Downhole Tools. Tx is modulated TTL output, onto the Tool Bus as RS232 at 115kbps (5Vdc). The Tool Bus rate can be changed for downlinks commands via I2C bus.

Analog Bus Inputs

The Analog Bus Inputs received signals between 0 to 4 VDC. The Tool Head Voltage, Internal Downhole Temperature, and Tool Bus Voltage are sensed and sent to the surface to facilitate setting the appropriate operating voltage.

SDS Simple Telemetry Board Specification:

Uplink Data Rate over Wireline

50 Kbits/sec (on most cables); actual rate controlled from surface

Downlink Data Rate over Wireline

5 Kbits/sec

Tool Bus

RS232 serial port at logic levels (3.3V to 5.0V); rate configurable but aggregate must be lower than the selected wireline rate.

Power Requirements

Plus/minus 12VDC to 15VDC and +5VDC

Temperature Rating

177°C (350°F) for 1 hour

Board Dimensions

7.5 inches x 1.0 inch

SDS Downhole Power Supply (DHPS)

The voltage entering the down-hole system is usually 100VDC, but it can range from 80VDC to 120VDC. To minimize interference with the telemetry signals, a filtering circuit is used. The specifications are: Output voltage: 12V DC with a tolerance of ±0.1V, Maximum current: 250mA, Voltage ripple: 100mV peak-to-peak.

To apply power the tool, the power supply goes through an unstable transition zone between 10 to 75 volts, where currents of 150 to 250 mA can appear, depending on the load connected at the VOUT (12V) output. However, once it passes into the stable zone, the current will be much lower, reaching up to 100V, with a current of 12mA without load at the 12V output or 32mA with load at the output. That's why the values in Fig. 8 for current and voltage at 130V are for protection. If the operator accidentally exceeds this voltage (130V), the line is immediately disabled to protect the power supply.

A high-efficiency step-down DC/DC regulator with an internal power switch draws a typical DC supply current of decimas of μA while maintaining a regulated output voltage even when there is no load.

The power supply provides one output of 12VDC with a maximum current of 0.2A to the customer and is designed to operate efficiently at high temperatures. There are three regulators: +15VDC at 60mA, -15VDC at 60mA, and +5VDC at 100mA, to supply power to the telemetry system. The power supply has protection to prevent incorrect polarity at the input.

The Cable Head Voltage is 100V (LINE), and a sample signal (HV_S) is taken at 1VDC. Similarly, the Tool Power Bus Voltage is 12VDC, and its sample signal (LV_S) is at 1.2VDC. These sampled signals are sent to the telemetry board.

The entire system operates within a maximum temperature limit of 177°C for one hour.

SDS Downhole Power Supply (DHPS) Board

SDS Power Supply Board Specification:

Head Voltage (Input)

80-120 VDC

Outputs

Plus/minus 15VDC @ 60ma and +5VDC @ 100ma (normally for telemetry board) 12VDC @ 0.2A general purpose. Higher output is possible with use of chassis mount components.