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Permanent downhole              MONITORING systems

For real-time downhole pressure and temperature monitoring

Unique Quartz sensors without downhole electronic components provide high reliability, guaranteeing up to 15 years of operational life

Improved hydrodynamic reservoir characterisation

Reservoir development dynamics data acquisition for production control

Determination of optimal well operating conditions and production stimulation effectiveness


Permanent downhole monitoring systems are used in dual-completion production wells

Downhole measurements

Conducted using two quartz sensors for absolute pressure and temperature measurements inside and outside the tubing (in the annulus)

Operating principle 

Tubing measurements determine reservoir parameters at the bottom hole, while measurements outside tubing determine the integrity of the annulus isolated from the reservoir by a packer. The sensor/mandrel connection can be pressure-tested.

Pressure and temperature measurements 

Bottom-hole pressure and temperature measurements with Tota Systems' PDMS enable control of the main hydrodynamic parameters, such as bottom-hole and reservoir pressures, calculated skin factors (contamination of the near-wellbore reservoir zone), productivity, hydrodynamic communication with nearby wells, etc. Bottom-hole pressure and temperature monitoring data acquired by Tota Systems' PDMS can be used to control well operating conditions and maintain a certain ratio between well production rate and bottom-hole pressure. 

Surface Recorder

Includes a surface recording system and an independent power supply system (IPSS) utilising environmental energy from a wind power generator and solar panels


Surface Recorder records data from downhole pressure and temperature measurement modules to store them in non-volatile memory and is compatible with Supervisory Control and Data Acquisition (SCADA) systems through RS232 and RS485 buses. Supports the Modbus RTU/ELAM protocol.

Depending on customer requirements, Surface Recorder can be manufactured in vandal-, climate- and ignition-proof versions with a heating and heat-insulation system or in an explosion-proof version with a separate rechargeable battery unit. The equipment package includes a stand-by uninterrupted power supply unit for 30 days of power-independent operation.

Data are transferred through mobile communication channels

Pressure and temperature data are transferred into the Client's telematic data system at a sampling rate from 1 s for permanent 220 V power supply to 4 times a day for an independent power supply system (IPSS). Alternatively, Tota Systems can set up and use its own telematic system based on GSM modems or radio communication. At the same time, data are recorded into the internal memory of the surface recorder.

Independent power supply system (IPSS)

Designed for independent power supply of various electrical equipment at a constant voltage of 24 V with a power consumption of no more than 3 kW/d.

Independent power supply system

Constant voltage is supported by the main and stand-by generators.

Mono-crystalline solar panels are used as the main generator, and a vertical-shaft wind power generator as a stand-by one. 

Combination of various types of generators allows year-round use of the system under different weather conditions. Due to the wide operating temperature range, the system can be employed both in a hot climate and in the Arctic.

Wellhead outlet

The cable is sealed in the wellhead equipment using a set of fittings (1) to pass through the pipe holder and wellhead adaptor with ¼" NPT thread using metal-to-metal sealing.

Metal-to-metal sealing of the cable and the metal pipe

Metal-to-metal fitting sealing
Wellhead sealing with a connection between downhole and surface cables through 60-mm and 30-mm tubing head adaptor threads

Cable protector

Downhole On-Tubing Cable Protector (DTCP) fastens, holds and protects downhole cables during tripping operations.

Each tubing collar has one Cable Protector installed on it. Various types of protectors and cable bands include stamped or cast steel versions with fast connectors.


Cable band

Downhole cable

Downhole Cable feeds power supply voltage and transfers data from a downhole PDMS tool to Surface Recorder.

Data transfer principle 

Encapsulated polymer-coated cable TEC 316L – with a metal tube and metal-to-metal sealing at the connection between the cable and measurement modules and in Wellhead Outlet – is used for voltage supply and data transfer from the measurement modules of PDMS to Surface Recorder

Encapsulated cable TEC 316L

  • Copper conductor; 
  • Fluoroplastic insulation; 
  • Cable armour: Stainless steel tube. Tube OD: 6.35 mm. Wall thickness: 0.75 mm; 
  • Polypropylene sheath with a square cross-section of 11х11 mm or a round cross-section of 11 mm.

TEC downhole cable

Measurement Module

Measurement Module consists of a mandrel containing tools with high-precision quartz pressure and temperature sensors without active electronic components as a system comprising only a quartz crystal in bellows and a connection cable.

Pressure Sensor

A pipe connector installed for branching, bending and pipe diameter changes

Upper range limit, MPa                      

60 / 130

Resolution, kPa


Error, kPa

0.1% of URL

Temperature sensor

A pipe connector installed for branching, bending and pipe diameter changes.

Upper range limit, °C                       

+ 90, + 150

Resolution, °C


Error, °C

± 0.2


The mandrel shall have no welded joints and comply with or exceed
tubing specifications.

The mandrel interior shall completely contain a measurement module.

Sensors shall be immovably fixed within the mandrel to prevent loss of seal in the connection of the cable with the sensor, in particular due to vibrations during well operation.

Successful implementation cases

Our implementations of Permanent Downhole
Monitoring Systems

Case Study 1

Installation even a single PDMS unit has provided a real-time Pressure and Temperature measurements of two reservoirs isolated by a packer.
Since first deployment of the PDMS system in 2016, not a single failure of the downhole measuring sensor has been revealed, even for fields with hydrogen sulfide content.
The figure shows that the pressures in the two reservoirs are different, which indicates that the packer is tight.