15B Turbines

Sperry Drilling Services

2007.1

Why Do We Use Turbines ?

Directional Drilling

•

Typical applications - Straight (vertical) hole drilling - Features of drilling turbines

Turbines

•

Conditions of use - Borehole preparation - Rig preparation

•

Shortcomings

Sperry Drilling Services 2007

Efficiency of Turbines ΔP × Q The energy conversion : Ninput = 1714

Turbine Speeds - Examples Noutput = RPM× TQ 5252

Neyrfor – Weir Bent Housing Turbodrills

Efficiency of the conversion : η = Noutput ×100 % Ninput

Theoretical efficiency : 70% Actual ------------------ : 60% - approximately

3-3/8”

800

4-3/4” 6-5/8”

The actual efficiency takes into consideration all frictions, and depends on string RPM, mud flow, wear on the bearings, mud type.

Rotating Speed of Turbines

The rotating speed is directly proportional to the flow

9-1/2”

1800 1400

700 1000

400 300

700

Drive Torque of Turbines The drive torque is proportional to the mud flow squared, to the mud specific gravity and to the radius of the blading discs. TQ = f (K2 ; Q2 ; SG ; R)

n = f (K1; Q) This torque is directly proportional to the number of drive stages. Zero at runaway speed (off-bottom) and maximum when the turbodrill stalls For a given flow, the actual speed depends on the bit torque

Directional Drilling – Turbines

Page 1

Sperry Drilling Services

2007.1

The Delivered Power

Pressure Drop of Turbines

The power is proportional to the cube of the flow, and equal to the torque times the rotating speed.

The pressure drop is proportional to the square of the mud flow, the density of mud and number of drive stages.

P = f (K3 ; R ; Q3 ; SG)

Δp = f (Q2 ; SG ; n)

Turbine Operating Characteristics Turbine General Characteristic P,T, ,

p

Example : 9-1/2” Neyrfor - Weir Bent Housing Turbodrill

Pn

torque

Tn Δpn

S

0

max

P p psi T S n r ηmax …

Sr Speed (rpm)

Sn Power, hp Differential pressure, Efficiency Output torque, ft-lbs Output speed, rpm Nominal … Runaway … Maximum efficiency

Construction of a Turbine (1)

Directional Drilling – Turbines

p

Power output ------- : 520 hp Max. drilling tq.------ : 5,000 lb.ft Drilling speed ------- : 300 -700 rpm Nominal pressure -- : 2,130 psi Bent housing angle : ½ - ¾ - 1° Dogleg capability --- : 4°/100 ft with 3/4° bend

Construction of a Turbine (2)

Page 2

Sperry Drilling Services

2007.1

Construction of a Turbine (3)

Construction of a Turbine (4)

Turbine Disks (1)

Turbine Disks (2) Complete small turbine stage

stator disc

rotor disc

Turbine Disks (3)

Turbine Disks (4)

Complete turbine stage

Directional Drilling – Turbines

Page 3

Sperry Drilling Services

2007.1

Turbine Bearing

turbine axis

Turbine Bearing Parts spacer elastomer lining

fixed disk turbine housing

moving disk moving disk

rubber pad

fixed disk

Labyrinth Seal

Suppliers How does it work ?

Directional Drilling – Turbines

• Neyrfor-Weir • DRILEX (5; 7; 7-1/4”) • Various Russian manufacturers

Page 4