Mud Flow Sensor

What is Mud Flow Sensor

Three different types of flow sensor are available to monitor drilling fluid flow at all times; Instantaneous indication of mud flow rate changes, Essential measurements for maximising rig safety and Immediate warning of kicks or mud losses.

MUD FLOW PADDLE

The Mud Flow Paddle measures relative flow rate in the mud return flow line, from 0-100% of full flow. When connected to the Advanced Logging System, the sensor provides a continuous chart of relative flow. Alarms can be set for flow above and below pre-selected limits.

See Also: Mud Resistivity Sensor

Operating Principle

The flowmeter consists of a sealed potentiometer attached to a metal arm with an adjustable paddle-shaped blade, free to move through an arc of 90 degrees. The mud stream pushes the arm, which actuates the potentiometer.

Installation

The sensor is installed in a horizontal (or gently sloping) section of the flow line, with the concave side of the paddle facing upstream. For installation on closed flow lines, a rectangular opening of 2 3/4” x 9 ½” must be cut to accept the paddle. A steel base flange (supplied) is then welded around the pre-cut opening, and the sensor housing is bolted to the flange. For opentrough flow lines, the base flange is unnecessary; the sensor housing should be bolted to fabricated supports that allow it to straddle the trough.

Mud Paddle.

Technical Specifications

Measurement range: 0-100 % of flow
Accuracy: 1 %
Sensitivity: 1 %
Response time: < 5 seconds
Working temperature range: -25 to 100 °C (-77 to 212 °F)
H x W x D: 240 x 270 x 300 mm (9.4” x 10.6” x 11.8”)
Weight: 11 kg (24 lbs)
Power supply: 2.5 mA

ELECTROMAGNETIC FLOWMETER (MAG 3100)

The MAG 3100 is a volumetric flowmeter that operates on the principle of magnetic induction. Versions are available for both standpipe (flow IN, 4” ID flanges) and return flow line (flow OUT, 8” ID flanges) mountings. Each sensor replaces a short section of the pipe on which it is mounted. The transmitter electronics package contains a barrier which ensures intrinsic safety for the electrical circuitry.

The sensors can be adjusted to measure several flow rate ranges, the maxima being 0-4000 l/min (1057 gal/min) for flow IN and 0 to 20,000 l/min (5283 gal/min) for flow OUT. Connection to the Advanced Logging System enables real-time monitoring and permanent recording of the flow parameters, as well as automated calculation of differential flow, essential for reliable detection of small-volume kicks or losses.

Operating Principle

Each sensor consists of a pair of circular electrodes flush with the inside of the pipe. When the sensor is energised, a magnetic field is set up at right angles to the pipe axis, creating a potential difference between the two electrodes that is proportional to the fluid flow rate. The electromagnetic flowmeter operates in waterbased muds, and in other mud compositions if the continuous phase is water.

Installation and Operation

Installation requires modification of the rig piping to accept the sensors. After cutting out a section of pipe at the appropriate location, a pair of flanges (supplied) are welded in place; the sensor is then bolted to the flanges.

For flow OUT, it is best to mount the sensor in a bypass circuit controlled by gate valves (supplied), to allow periodic cleanout of settled cuttings without shutting down the main flowline. Both sensors (flow IN and flow OUT) must be full of mud at all times during operation; thus they should not be mounted at a high point in the system.

Electromagnetic Flow Sensor OUT installed under the drill floor (left) and MAG 3100 control box situated in the Logging Unit (right).

Technical Specifications

CORIOLIS-EFFECT FLOWMETER (DS 600)

The DS 600 Coriolis-effect sensor accurately measures mass flow and density of a circulating fluid, gas or slurry, at low to moderate pressures. The sensor is normally installed on the outlet flow line and measures:

1. Mass Flow
2. Volumetric Flow
3. Density
4. Temperature

The complete system consists of the sensor and a signal transmitter which are connected to the Advanced Logging System for display and permanent storage of the data.

Coriolis-effect Flow Sensor in an installation frame.

Operating Principle

The sensor uses Coriolis-effect principles to measure the mass flow of a fluid. Fluid enters the sensor and passes through a pair of flow tubes, which are free to vibrate and twist under the influence of the fluid flow. Flow is measured by quantifying the amount of twist in the flow tubes, which is proportional to the mass flow rate of the fluid, according to Newton’s Second Law of Motion. The density of the fluid is obtained by measuring the resonant frequency of vibration of the flow tubes. The measured values are automatically compensated for temperature changes.

Installation

The sensor is normally installed on a bypass channel added to the return flow line. No straight run of pipe is required. The sensor employs magnetic fields in its operation, and therefore should be located at least 0.6 m (2 ft) from any magnetic source such as a large transformer or motor.

For liquid measurement applications: the sensor should be located so that it remains full of liquid. To prevent gas from accumulating in the sensor, it should not be located at a high point in the piping.

For gas applications: the sensor should be located so that it remains full of gas during operation. To prevent liquid accumulation, the sensor should not be located at a low point in the piping.

See Also: Mud Temperature Sensor

Technical Specifications

Maximum flow range: 0 - 680 400 kg/hr (0 - 25 000 lb/mn)
Minimum flow range: 0 - 34 020 kg/hr (0 - 1250 lb/mn)
Flow accuracy: +0.2% of flow rate, + zero stability
Flow repeatability: +0.05% of flow rate, + 1/2 of zero stability
Density accuracy: +0.0005 g/cc
Density repeatability: +0.001 g/cc
Zero stability: 66 kg/hr (2.5 lb/mn)
Working temperature range: -240 to 204 °C (-400 to 400 °F)
Pressure rating: 43 bar (625 psi)
Power supply: 230V, 50/60 Hz
Dimensions: (L x W x D) 211 cm x 109 cm x 42 cm (83.1’’ x 43.0” x 16.5”)
Weight (shipping): 635 kg (1400 lbs) including flanges
Certificate: Ex ib d IIB T3
UL approved: Class I, Div.1, Groups C,D; Class II, Div. 1, Groups E,F,G; Class I, Div. 2, Groups A,B,C,D.