SUCKER ROD PUMP
1. INTRODUCTION 1.1 WHAT IS OIL WELL? An oil well is a general term for any boring through the earth's surface that is designed to find and acquire petroleum oil hydrocarbons. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.
1.2 SUCKER ROD PUMP The over ground drive for a reciprocating piston pump installed at a borehole (e.g. an oil well).A special steel pumping rod. Several rods screwed together make up the mechanical link from the beam pumping unit on the surface to the sucker rod pump at the bottom of a well. Sucker rods are threaded on each end and manufactured to dimension standards and metal specifications set by the petroleum industry. Lengths are 25 or 30 feet (7.6 or 9.1 meters); diameter varies from 1/2 to 1-1/8 inches (12 to 30 millimetres). there is also a continuous sucker rod (trade name: corod).A pump jack (also known as nodding donkey, pumping unit, horse head pump, beam pump, sucker rod pump (SRP), grasshopper pump, thirsty bird and jack pump) is the over ground drive for a reciprocating piston pump installed in an oil well. It is used to mechanically lift liquid out of the well if there is not enough bottom hole pressure for the liquid to flow all the way to the surface. The arrangement is commonly used for onshore wells producing relatively little oil. Pumpjacks are common in many oil-rich
areas,
dotting
the
countryside
and
occasionally
serving
as
local landmarks. Depending on the size of the pump, it generally produces 5 to 40 litres of liquid at each stroke. Often this is an emulsion of oil and water. The size of the pump is also determined by the depth and weight of the oil to be removed, with deeper extraction requiring more power to move the heavier lengths of sucker rods (see diagram at right). A pump jack converts the rotary mechanism of the motor to a vertical reciprocating motion to drive the pump shaft, and is exhibited in the characteristic nodding motion.
S.S.G.B.C.O.E&T
Page 1
SUCKER ROD PUMP The engineering term for this type of mechanism is a walking beam. It was often employed in stationary and marine steam engine designs in the 18th and 19th centuries.
2. LITERATURE SURVEY Gipson and Swaim did an excellent job of summarizing a sucker-rod lift-system design in The Beam Pump Design Chain with the API RP 11L approach. This recommended practice should be consulted for continued discussion of this equipment, along with a review of a sample problem and a recommended solution. In summary, use the design procedure presented in API RP 11L or a suitable wave equation. Several commercial wave-equation computer programs are available that many operators have successfully used.
2.1 BEAM-PUMPING SYSTEMS Beam pumping, or the sucker-rod lift method, is the oldest and most widely used type of artificial lift for most wells. A sucker-rod pumping system is made up of several components, some of which operate aboveground and other parts of which operate underground, down in the well. The surface-pumping unit, which drives the underground pump, consists of a prime mover (usually an electric motor) and, normally, a beam fixed to a pivotal post. The post is called a Sampson post, and the beam is normally called a walking beam. Figs. 2.1 and 2.2 present detailed schematics of a typical beam-pump installation. This system allows the beam to rock back and forth, moving the downhole components up and down in the process. The entire surface system is run by a prime mover, V-belt drives, and a gearbox with a crank mechanism on it. When this type of system is used, it is usually called a beam-pump installation. However, other types of surface-pumping units can be used, including hydraulically actuated units (with and without some type of counterbalancing system), or even tall-tower systems that use a chain or belt to allow long strokes and slow pumping speeds. The more-generic name of sucker-rod lift, or sucker-rod pumping, should be used to refer to all types of reciprocating rod-lift methods.
S.S.G.B.C.O.E&T
Page 2
SUCKER ROD PUMP
3. THEORY 3.1 PARAMETER FOR SELECTING THE SUCKER-ROD PUMPING METHOD Many factors must be considered when determining the most appropriate lift system for a particular well. Artificial presents a discussion of the normally available artificial-lift techniques, their advantages and disadvantages, and the selection of a method for a well installation. Sucker-rod pumping systems should be considered for new, lower volume stripper wells, because they have proved to be cost effective over time. Operating personnel usually are familiar with these mechanically simple systems and can operate them efficiently. Inexperienced personnel also can operate rod pumps more effectively than other types of artificial lift. Most of these systems have a high salvage value. Because of its long history of successfully lifting well fluids, the sucker-rod lift method is normally considered the first choice for most onshore, and even some offshore, installations all over the world. This method is limited by:
Size of the casing, tubing, and downhole pump
Strength and size of the various rods
Speed with which they can be reciprocated
Under favourable conditions, approximately 150 BFPD can be lifted from greater than 14,000 ft, while more than 3,000
3.2 COMPONENTS OF SUCKER-ROD LIFT SYSTEM The major components of a sucker-rod lift system are discussed in separate articles:
Downhole sucker-rod pumps
S.S.G.B.C.O.E&T
Page 3
SUCKER ROD PUMP
Sucker rods
Miscellaneous downhole equipment
Sucker-rod pumping units
Prime movers
3.3 OPERATION OF THE PUMP A motor and gearbox supply power to turn the power shaft. There is a counterweight at the end of the crank. A pitman arm is attached to the crank and it moves upward when the crank moves counter clockwise. The Samson arms support the walking beam. The walking beam pivots and lowers or raises the plunger. The rod attaches the plunger to the horsehead. The horsehead (not rigidly attached) allows the joint (where rod is attached) to move in a vertical path instead of following an arc. Every time the plunger rises, oil is pumped out through a spout. The pump consist of a four bar linkage is comprised of the crank, the pitman arm, the walking beam, and the ground. Here the plunger is shown at its lowest position. The pitman arm and the crank are inline. The maximum pumping angle, denoted as theta in the calculations, is shown. L is the stroke length. After one stroke, the plunger moves upward by one stroke length and the walking beam pivots. The crank also rotates counter clockwise. At the end of the upstroke the pitman arm, the crank, and the walking beam are in-line. For name and location of parts, see Fig.3.1. 1
A motor supplies power to a gear box. A gearbox reduces the angular velocity and increases the torque relative to this input.
2
As shown in Fig.3.2, (the crank turns counter clockwise) and lifts the counterweight. Since the crank is connected to the walking beam via the pitman arm, the beam pivots and submerges the plunger. Figure B also shows the horsehead at its lowest position. This marks the end of the down stroke. Note that the crank and the pitman arm are in-line at this position.
S.S.G.B.C.O.E&T
Page 4
SUCKER ROD PUMP 3
The upstroke raises the horsehead and the plunger, along with the fluid being pumped. The upstroke begins at the point shown in Fig.3.2. At the end of the upstroke, all joints are in-line. This geometric constraint determines the length of the pitman arm.
4
Figures 3.3 show the plunger and ball valves in more detail. These valves are opened by fluid flow alone. On the upstroke, the riding valve is closed and the standing valve is open. Fluid above and within the plunger is lifted out of the casing while more fluid is pumped into the well. On the down stroke, the riding valve is opened and the standing valve is closed. Fluid flows into the plunger and no fluid is allowed to leave the well.
4. COMPONENTS AND DESCRIPTION 4.1 GEAR BOX ARRANGEMENT: The simple gear box arrangement is fixed to the frame stand. In front of the stand to reduce the speed of motor and increase the torque to driven shaft Most modern gearboxes are used to increase torque while reducing the speed of a prime mover output shaft (e.g. a motor crankshaft). This means that the output shaft of a gearbox rotates at a slower rate than the input shaft, and this reduction in speed produces a mechanical advantage, increasing torque. A gearbox can be set up to do the opposite and provide an increase in shaft speed with a reduction of torque. Some of the simplest gearboxes merely change the physical rotational direction of power transmission.
4.2 PULLEY BELT ARRANGEMENT: A belt is a loop of flexible material used to mechanically link two or more rotating shafts, most often parallel. Belts may be used as a source of motion, to transmit power efficiently, or to track relative movement. Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel. In a two pulley system, the belt can either drive the pulleys normally in one direction (the same if on parallel shafts), or the belt may be crossed, so that the direction of the driven shaft is reversed (the opposite direction to the driver if on parallel shafts). As a source of motion, a conveyor
S.S.G.B.C.O.E&T
Page 5
SUCKER ROD PUMP belt is one application where the belt is adapted to continuously carry a load between two points V belts (also style V-belts, vee belts, or, less commonly, wedge rope) solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life. They are generally endless, and their general cross-section shape is trapezoidal (hence the name "V"). The "V" shape of the belt tracks in a mating groove in the pulley (or sheave), with the result that the belt cannot slip off. The belt also tends to wedge into the groove as the load increases—the greater the load, the greater the wedging action— improving torque transmission and making the V-belt an effective solution, needing less width and tension than flat belts. V-belts trump flat belts with their small centre distances and high reduction ratios. The preferred centre distance is larger than the largest pulley diameter, but less than three times the sum of both pulleys. Optimal speed range is 1,000– 7,000 ft/min (300–2,130 m/min). V-belts need larger pulleys for their thicker crosssection than flat belts. For high-power requirements, two or more V-belts can be joined side-by-side in an arrangement called a multi-V, running on matching multi-groove sheaves. This is known as a multiple-V-belt drive (or sometimes a "classical V-belt drive"). V-belts may be homogeneously rubber or polymer throughout or there may be fibres embedded in the rubber or polymer for strength and reinforcement. The fibres may be of textile materials such as cotton, polyamide (such as Nylon) or polyester or, for greatest strength, of steel or aramid (such as Twaron or Kevlar). When an endless belt does not fit the need, jointed and link V-belts may be employed. Most models offer the same power and speed ratings as equivalently-sized endless belts and do not require special pulleys to operate. A link v-belt is a number of polyurethane/polyester composite links held together, either by themselves, such as Fenner Drives' Power Twist, or by metal studs, such as Gates' Nu-T-Link. These provide easy installation and superior environmental resistance compared to rubber belts and is length adjustable by disassembling and removing links when needed.
4.3 STAND:
S.S.G.B.C.O.E&T
Page 6
SUCKER ROD PUMP This is a supporting frame and made up of mild steel.
4.4 SINGLE PHASE INDUCTION MOTOR WITH PULLEY:This is used to drive the wheel by using two pulleys with belt drive mechanism.
4.4.1 SINGLE-PHASE THEORY Because it has but a single alternating current source, a single-phase motor can only produce an alternating field: one that pulls first in one direction, then in the opposite as the polarity of the field switches. A squirrel-cage rotor placed in this field would merely twitch, since there would be no moment upon it. If pushed in one direction, however, it would spin. The major distinction between the different types of single-phase AC motors is how they go about starting the rotor in a particular direction such that the alternating field will produce rotary motion in the desired direction. This is usually done by some device that introduces a phase-shifted magnetic field on one side of the rotor.
4.5 PULLEYS: There are two pulleys are used in our project. One is coupled with motor shaft and another one is coupled to the wheel. These two pulleys are connected by belt drive.
S.S.G.B.C.O.E&T
Page 7
SUCKER ROD PUMP
S.S.G.B.C.O.E&T
Page 8
SUCKER ROD PUMP
5 DOMINANT PHYSICS & DESIGN: Table 5.1: Variable Descriptions, Values and Units Variable
Description
Typical Value
Units
ϴ
Full Pump Angle
---
degrees
Fl
Total Force Pump must exert
---
lbs
Ff
Weight of Fluid
---
lbs
Fr
Weight of the Rods
---
lbs
Fc
Weight of counterweight
---
lbs
Fb
Buoyant force on rods
---
lbs
W
Rod weight per unit length
---
lbs/ft
Lr
Length of one rod
25 - 30§
ft
Nr
Number of Rods
---
---
Pi
Input Power
4000§§
psi
H
Depth of Well
10,000§§§
ft
ϼ
Fluid Density
---
lbm/in^3
G
Gravitational
Acceleration ~9.8
m/s^2
Constant L
Stroke Length
16 - 192§§§§
in
T
Required Pumping Torque
6,400 - 912,000§§§§§
in-lb
Vf
Fluid Volume per Stroke
---
ft^3
Ar
Rod Cross sectional area
---
psi
Sy
Yield Strength of Rod
---
psi
Ap
Plunger Cross Sectional Area
---
psi
To design a sucker rod pump, the depth of the well must first be determined. This value is then used to calculate the amount of fluid that can be pumped per stroke. This amount is the volume of fluid that fits in a cylinder of height L and cross sectional area Ap. Vf = Ap L
S.S.G.B.C.O.E&T
Page 9
SUCKER ROD PUMP This volume is then multiplied by the density of the fluid and by the g to find the weight of the column of fluid the pump must lift. Ff = Mfϼg The pump must also provide enough power to lift the sucker rods (see Figure A). Manufacturers specify typical values of weight per unit length, w, for the rods they make. This number is multiplied by the length of one rod, Lr, and by the number of rods, Nr. Fr = w Lr Nr Since the rods are submerged in fluid, a buoyant force is present. This force is found using Archimedes’ Principle. It states that the buoyant force a submerged object feels is equal to the weight of the fluid it displaces. Therefore, the volume of displaced fluid is equal to the submerged volume of the rods. The weight of this fluid is equal to this volume multiplied by the fluid’s density and g. To obtain the volume of the rods, we multiply their cross sectional area by their total length. Fb = Ar Nr Lr ϼ g Now the total load the pump must lift can be calculated. Fl = Ff + (Fr – Fb) Two things must be noted. First, the above analysis is very rough and does not include additional factors such as impulse forces. Also, the forces described above vary with time and this must be taken into account. The stroke length of the pump is the vertical distance the plunger travels in one stroke. This length depends on the amount of fluid being pumped. Once the stroke length is known, the geometry of the four bar linkage can be determined. To avoid excessive wear of the machinery, it is good engineering practice to reduce the number of cycles the pump completes per unit of time. In order to do this more fluid should be pumped per cycle. In order to increase the fluid displacement, the stroke length should be maximized. Typical values for stroke length vary from 16 to 192 inches. The stroke length can be used to calculate the torque required to pump the oil according to the following formula.
S.S.G.B.C.O.E&T
Page 10
SUCKER ROD PUMP T = C L Fl Here, C is a function of the geometry of the four bar linkage and the force the counterweight exerts on the crank. Typical values for torque range from 6,400 to 912,000 in-lb. On the upstroke, two forces help pump the oil from the well. The first is the "force" supplied from the torque produced by the motor and gearbox. The second force comes from the weight of the counterweight as it falls.
5.2 LIMITING PHYSICS: Care must be taken to choose a cross sectional area large enough so that the rods do not yield. This area can be found by dividing the total tensile load by the yield stress of the material. Ay = Fl / Sy The area of the rods must be greater than this area. This is a minimum. Fatigue affects (function of material and loading) will require a larger value.
5.3 EFFICIENCY: The efficiency of the sucker rod pump can be defined as the volume of oil it actually pumps divided by the volume it can theoretically pump. When the well is initially drilled, the oil contains a lot of gas. This gas displaces a small volume of oil at the beginning. This volume decreases eventually. The volumetric efficiency of this type of pump is rated at about 80%.
5.4 WHERE TO FIND SUCKER ROD PUMPS: Sucker rod pumps are used primarily to draw oil from underground reservoirs. The mechanisms it employs however are found in a wide variety of machines. The four bar linkage can be found on door dampers, on automobile engines, and on devices such as the lazy tong. The Sterling engines manufactured in 2.670 also use a linkage similar to the one used by the pump. S.S.G.B.C.O.E&T
Page 11
SUCKER ROD PUMP
5.5 Bearing design Bearing Type = Deep Groove Ball Bearing (1) d = 6 mm D = 20 mm B = 8 mm Basic load capacity, C C = 3924 N Limiting speed, n n = 20000 rpm Mass, m m = 0.020 Kg Designation - SKF 6001
(2) d = 17mm D = 35 mm B = 10 mm Basic load capacity, C C = 4562 N Limiting speed, n n = 20000 rpm Mass, m m = 0.040 Kg Designation - SKF 6003
S.S.G.B.C.O.E&T
Page 12
SUCKER ROD PUMP
5.6 Design of bearing housing Name of part – Bearing Housing Qty – 44 Material – Aluminum For small bearing Tolerances on inner race in mm −0.008 On mean diameter 120.000
Circularity -0.011 +0.003 Width
0.000 -0.120
Radial runout 0.010 Tolerances on outer race in mm 0.000 On mean diameter 28−0.011
Circularity +0.003 -0.014 Radial runout 0.020 For large bearing Tolerances on inner race in mm −0.008 On mean diameter 170.000
Circularity -0.011
S.S.G.B.C.O.E&T
Page 13
SUCKER ROD PUMP +0.003 Width
0.000 -0.120
Radial runout 0.010 Tolerances on outer race in mm 0.000
On mean diameter 35−0.013 Radial runout
0.025
5.7 Screw selection Screw type: Counter sunk screws (1) Size- M3
(2) Size- M6
d = 3 mm
d = 6 mm
l = 10 mm
l = 20 mm
(3) Size- M3
(4) Size- M3
d = 3 mm
d = 3 mm
l = 6 mm
l = 6 mm
(5) Size- M5 d = 5 mm l = 20 mm
5.8 Gear design Given Data:-
S.S.G.B.C.O.E&T
Zp = 15
;
dp = 30mm
; Page 14
Zg = 30 dg = 60mm
SUCKER ROD PUMP Ka = 1
;
Km = 1.6
np = 7.5 rpm
;
ng = 15 rpm
T = 367.875 N-m ;
σu = 56 N/mm²
Grade 12
;
Φ = 20°
b= 10 mm
;
Material – Acetal (Delrin)
Bending Stress σb = σu / 2.5 = 22.4 N/mm² Yp = 0.289 Yg = 0.358
(σb *Yp) = 6.4736 N/mm²
(σb *Yg) = 8.0192 N/mm²
As (σb *Yp) < (σb *Yg) pinion is weaker in bending hence it is necessary to design pinion for bending. Bending Strength: Fb = σb*m*b*Yp = 129.472 N Wear Strength: dp = m*Zp
S.S.G.B.C.O.E&T
Page 15
SUCKER ROD PUMP = 30mm
Q=
= 1.33
K = 1.05 N/mm²
Fw = dp*b*Q*K = 418.95 N As Fb
Effective Load: V=(
*dp*np) / (60*1000)
= 0.0117 m/s P = (2*
*n*T) / (60*1000)
= 577.85 KW
Ft = P/V = 49.38 N Kv = 3/ (3+V) = 0.996 S.S.G.B.C.O.E&T
Page 16
SUCKER ROD PUMP
Feff = (Ka*Km*Ft) / Kv = 79.31 N
Fb = Nf * Feff Nf = 1.59
Check for Design: ep = 79.84*10^-3 mm eg = 82.68*10^-3 mm e = ep+ eg = 165.52*10^-3 mm.
Buckingham’s Equation:
Fd =
Ft = 49.38 N. Ftmax = Ka*Km *Ft V = 0.0117 m/s C = K*e *[
S.S.G.B.C.O.E&T
]
Page 17
SUCKER ROD PUMP Fd = 2.1252 N
Feff = 81.10 N
Nf =
= 1.6
1.59
Therefore available Factor of safety is same as required. Therefore the gear pair is safe against bending failure.
6 LIST OF COMPONENTS S.S.G.B.C.O.E&T
Page 18
SUCKER ROD PUMP SL.
NAME OF THE PARTS
NO. 1 2 3 4 5 6 7
Frame Pendulam Pump Bearing Connecting lever Valve Frame Stand
M.S.(fitting) M.S.(fitting) M.S Steel M.S(cutting,welding) rubber,plastic 0.75 inch angle
1 1 1 2 1 2 1
Screw Shaft
M.S(Cutting,Welding M.S M.S
1 1
9 10
MATERIAL(Operation)
QUANTITY
7 COSTING 7.1 MATERIAL COST: SL.
NAME OF
NO.
THE PARTS
S.S.G.B.C.O.E&T
MATERIAL(Operation)
QUANTITY
APPROX AMOUNT(RS)/eac
Page 19
SUCKER ROD PUMP h 1 2 3 4 5
Frame Pendulam Pump Bearing Connecting
M.S.(fitting) M.S.(fitting) M.S Steel M.S(cutting,welding)
1 1 1 2 1
3200 1900 1750 250 950
6 7
lever Valve Frame Stand
rubber,plastic 0.75 inch angle
2 1
350 2550
9 10
Screw Shaft
M.S(Cutting,Welding M.S 1 M.S 1 TOTAL COST
250 650 = 11850
7.2 LABOUR COST LATHE, DRILLING, WELDING, GRINDING, POWER HACKSAW, GAS CUTTING: Cost = 2000/-
7.3 OVERHEAD CHARGES The overhead charges are arrived by “Manufacturing cost” Manufacturing Cost =
Overhead Charges
Material Cost + Labour cost
=
11850+2000
=
13850
=
20% of the manufacturing cost
=
2770
7.4 TOTAL COST Total cost
=
Material Cost + Labour cost + Overhead Charges
=
11850+2000 +2770
Total cost for this project
S.S.G.B.C.O.E&T
=16620
=16620
Page 20
SUCKER ROD PUMP
8 ADVANTAGES 8.1 Economical aspect: a) Least maintenance cost. b) No rent for electricity utilized c) No fuel required for operation S.S.G.B.C.O.E&T
Page 21
SUCKER ROD PUMP
8.2 Technical aspect: a) Noiseless operation b) No person required to operate the system c) Simple in construction, so easy to fabricate d) Pollution free e) Less chance of accidents
9. LIMITATIONS 9.1 Economical aspects a) High initial installation cost
10. CONCLUSION The fabrication of Sucker Rod Pump was successfully completed as per the specification. The trial performance of this device provides to be successful, with case of operation and safety, hence the results has given a clear indication of its commercial
S.S.G.B.C.O.E&T
Page 22
SUCKER ROD PUMP viability. The cost analysis has shown its economic feasibility and we are under the impression that it can be further reduced, when produced on a mass scale.
S.S.G.B.C.O.E&T
Page 23
