Energy Efficiency in On shore Exploration- Oil Pumping Application

Beam pump Controller

Contents• Beam pump general

• Regeneration control

• ENA System

• Speed control for Beam Pumps and

related problems

• Speed control algorithm

• HMI and messaging

Beam pump – Lay-out

Plunger

Up Stroke

Down Stroke

Polished RodStuffing Box

Rod String

Beam

Alternative Position

Sensor Location

Position SensorMotor

Crank

Counter Balance Weights

Gearbox

Electrical Enclosure

Travelling Valve

Horse Head

Standing Valve

Reservoir

Sucker Rod Pump Assembly

Beam Pump Controller

Challenges• Regenerative energy during parts of the pumping

cycle

• Ever changing well conditions require complex speed regulation algorithm.

• Extreme climatic conditions.

• High starting torque, due to eccentric load

• Retro fit applications make extensive equipment modifications difficult and application specific

Beam Pump Issues/Problems

Changing Well conditions• Pumps are installed and geared up to

match the well conditions, ensuring 100% pump fill per stroke

• Well capcatity reduces over time resulting in incomplete filling.

• This results in ineficency and severe mechanical deteriation.

• Fluid Pound

•Gas Lock

ATV71 – ENA SYSTEM

Regeneration occurs during stroke direction transition

Zero torque limit

Regeneration• During direction transition the motor

will regenerate energy for a short period of time.

• In a Direct On Line system, this energy is fed back into the mains.

• Standard Drives, as standard, can not handle this energy and IGBT’s will be turned off to protect the drive. This will result in loss of control.

ATV71 ENA System

Regeneration: Common Solutions:1. Dynamic Brake Resistors

• Energy waste because the regenerative energy is transformed to heat

• Additional equipment

2. Active Front End

• No energy waste

• Expensive

Regeneration: ATV71 ENA feature.

• The pump speed is adjusted to absorb the regen energy as kinetic energy in the moving mechanism

• No additional equipment, no energy waste

• Economical

§ A special Algorythm for Oil pumps

§ Easy to adjust (3 parameters only)

§ No external or additional device to brake the counter weight

§ Energy saving

§ Preserve the mechanics of the system

§ Display with customer unit : hits / minute

§ No motor inductances : shot distance to the pump

ENA SystemENA System

Energy consumed in the network is reduced because of the ENA algorythm. This make a huge energy saving that can reach 50%.

Line current with a standard system Line current with Ena System

Decrease the network consumption Decrease the network consumption

Beam Pump Issues/Problems

Optimum Operation - 100% Pump fill – No Fluid Pound

Beam Pump Issues/Problems

Non Optimum Operation 50% pump Fill – Fluid Pound and Low Efficiency

Beam Pump Issues/Problems

100% pump fill

• Torque profile on the up stroke is the same for 100% and 50% pump fill (Energy required in both cases is N)

• Torque on the down stroke is different, because the travelling valve is closed as the plunger travells through gas. (Energy required for the 100% pump fill is N, Energy required for the 50% pump fill is N/2)

• The total energy required for one stroke is N+N=2N for 100% pump fill and N+N/2=1.5N for 50% pump fill

The total Energy consumed in one stroke is NOT proportional to pump fill level!

Over 30% Energy waste can occur!

Low Pump Fill - Energy Waste:

Beam Pump Issues/Problems

Gas Lock• Gas Lock results from very low pump fill.

• On the down stroke the standing valve is closed. The travelling valve also remains closed. The gas is compressed,.. On the way up, the gas expands and again both valves remain closed.

• The plunger travels up and down without pumping oil. The result is energy waste, production loss and mechanical wear as the plunger is now un-lubricated

ATV71 RodMax – Pump Fill Controller

Hig

h Pos

ition

Zero

Low Level 1

High Level

Low Level 2

+

-

0

--

Low

Posi

tion

Span

Rod Position Calculator

Motor Torque Prox Switch Motor Speed

Pump Energy Consumption

Pump Fill CalculatorSpan & Zero setup via RMO

Pump Fill Comparator

Speed Adjust Algorithm

Speed Reference

Adjust Rate/Stroke

Minimum Speed

Pump Fill Controller Block. Block Diagram:

ATV71 – messaging

Messaging. providing full system operation feedback

• Stroke Length Monitoring. Monitors belt slippage, switch failure. (the PFC is disabled and an alarm is generated)

•System status (starting, pumping, direction, short or long cycle, wait)

•Energy Meter displays the estimated KWh consumed by the drive.

•Minimum and maximum achieved pump fill level.

• Hours run counter for maintenance purposes.

•Balance display indicates the balance of the counter weights.

•Motor and Drive thermal state

•Crank position in degrees or %

•Pump Torque and Speed

•Real date and time

RodMax Optimiser

Start / stop plot

Display / hide up stroke

Dynamometer Display Used to calibrate the Pump Fill Controller.

Pump Information

ENA permit the utilization of standard 4 poles motors instead of highly isolated motors like Nema B that are more expensive.

4 Polos

1450 RPM

Use of standard motors Use of standard motors

§ Cost cutting : no motor inductances, no braking resistors

Advantages of ENA system with Advantages of ENA system with AltivarAltivar 71 71

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