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   /  GKS MWD systems with hydraulic (positive mud pulse) communication channel

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GKS downhole MWD systems with positive mud pulse communication channel is designed for realtime trajectory control while directional and horizontal oil and gas wells drilling by means of continuous deflector angle measurement, azimuth, zenith and the natural gamma radiation of the formation.

GKS telemetry (MWD) systems allows to measure following parameters during drilling:

  • Zenith angle
  • Azimuth angle
  • Benthousing position
  • Formations gamma ray
  • Downhole temperature
  • Generator rpm
  • Vibration
  • Total intensity of geomagnetic field
  • Aggregate vector of the Earth's gravitational field

Permneftemashremont JSC produces GKS MWD systems with positive mud pulse communication channel of the following dimension types:

203, 178, 108 mm.

Features

GKS telemetry (MWD) systems have the following features: 

  • Allows to drill with constantly drill string rotation,
  • Are batteryless, so they are powered by downhole generator, driven by the mud flow,
  • The generator does not have any face seals, so there is no lubricant consumption during operation, there is no need to control the level and add lubricant at the wellsite,
  • Do not have the operational constraints related to the depth of wells and geological conditions.

Operation principle

  • GCS telemetry system consists of a downhole tool, which is mounted in the bottom hole assembly above the hydraulic downhole motor, and the surface equipment,
  • The downhole tool consists of a pulser, downhole measuring unit and a generator. During drilling downhole tool makes navigation and geophysical parameters measurements, then using the pulser this data converts to pressure pulses that spread in mud trunk inside the drill string. These manifold pressure sensor reads these pulses.
  • Surface equipment consists of a pressure sensor, a receiving (interface) device, a computer station, a load cell, a depth sensor and a driller's monitor. At the surface the manifold pressure sensor receives the signal and sends it to a receiving device, where amplification, decoding and filtering takes place. The decoded data is fed to the operator's computer where it could be stored in memory in any convenient format.
  • The software package, which is used for downhole tool indications processing, performs the data exchange, editing, snapping the measurement data to the depth and visualization on the computer monitor in digital and graphical forms.

 

Operational conditions of the GKS MWD system downhole tool:

Operating conditions

GKS-203

GKS-178

GKS-108

The connecting threads of the downhole tool

lower NMDC

З-152 (6 5/8 Reg)

З-133 (NC-50)

З-86 (NC-31)

upper NMDC

З-171 (6 5/8 FH)

Vertical depth of the borehole

with no restrictions

Operating/maximum axial load

400/2000 кН

300/1000 кН

120/200 кН

Operating/maximum torque on the body parts

30/45 kN*m

25/35 kN*m

12/18 kN*m

Max rotor/top drive RPM (drilling with rotation)

60 rpm

60 rpm

60 rpm

Mud flow rate

475…951 gpm

380...586 gpm

110…222 gpm

Mud minimum density

900 kg/m3 (7.51 ppg)

900 kg/m3 (7.51 ppg)

900 kg/m3 (7.51 ppg)

Mud sand content

not more than 2%

not more than 2%

not more than 2%

Operating temperature range

-10...+85°C (+125°C)

-10...+85°C (+125°C)

-10...+85°C (+125°C)

Maximum pressure

90 MPa

90 MPa

90 MPa

Pressure drop per pulse

0,3-2 MPa

0,3-2 MPa

0,3-2 MPa

The level of mechanical stress

 

MS3-1 group by GOST 26116-84

MS3-1 group by GOST 26116-84

MS3-1 group by GOST 26116-84

Maximum intensity of the borehole curvature

without rotation while drilling

5°/10 m

6°/10 m

8°/10 m

drilling with rotation

2,5°/10 m

3°/10 m

4°/10 m

Specifications of measured peremeters of GKS telemetry systems:

Measured parameters

GKS-203

GKS-178

GKS-108

Azimuth measuring range

0...360°

0...360°

0...360°

Zenith angle measuring range

0...180°

0...180°

0...180°

Benthousing angle measuring range

0...360°

0...360°

0...360°

The level of natural gamma radiation

0...250 µR/h

0...250 µR/h

0...250 µR/h

Temperature

0...125°

0...125°

0...125°

Vibration

0...500 m/s2

0...500 m/s2

0...500 m/s2

Permissible limits of basic absolute error during measurement

azimuth

± 2°

± 2°

± 2°

zenith angle

± 20’

± 20’

± 20’

benthousing angle

± 2°

± 2°

± 2°

gamma-ray

± 10%

± 10%

± 10%

temperature

± 2°

± 2°

± 2°

vibration

± 10%

± 10%

± 10%

Transmission frequency, Hz

0,5; 0,8 Hz

0,5; 0,8 Hz

0,5; 0,8 Hz

Period of data updating at a transmission frequency of 0.8 Hz

15,0 sec

15,0 sec

15,0 sec

Dispensing metering time at the transmission frequency of 0.8 Hz

156 sec

156 sec

156 sec

 

Reliability characteristics of GKS MWD systems basic components and parts:

Unit

Guaranteed overhaul period, h.

Specified life, h.

Generator

500

2000

Downhole measuring unit

500

no limits (verification, calibration -once in 6 months)

Pulser

500

2000

Body parts

no limits
(Inspection - every 500 hours)

2000
(in the absence of defects)