Mud Report 1

Dr. Catalin Teodoriu

Institut fr Erdl- und Erdgastechnik 1TBT I 2014

Vorlesung Tiefbohrtechnik 1

Introduction to Rotary-Drilling Technology (inc. Rig Count)

Drilling a Well, Drilling methods

Rock Mechanics I

Drilling Mud: Functions, Properties, Rheology

Rock Mechanics II, Well stability

Borehole hydraulics, Overbalance vs. Underbalance

Drilling bits, Selection criteria

Drilling optimisation concepts

Drill-string basics

Downhole motors I (Theory, Moineu Motoren)

Downhole motors II (Turbinen, Selection Criteria)

Special drilling systems (Drilling Hammer, Coring)

Formation pressure, Frac-gradienten

Measuring drilling parameters



Drilling Hydraulics Applications

Calculation of subsurface hydrostatic pressures that may tend to burst or collapse well tubulars or fracture exposed formations

Several aspects of blowout prevention

Displacement of cement slurries and resulting stresses in the casing string

Bit nozzle size selection for optimum hydraulics

Surge or swab pressures due to vertical pipe movement

Carrying capacity of drilling fluids



Pressure drop in a well

Pp=Psc + Pdp + Pdc + Pdt + Pb + Pdca + Pdpa >50%

Less than 50%

PP Pump pressure

PSC surface equipment

Pdp Drill pipe

Pdc Drill collar

Pb - Bit

Pdca Annulus in DC Range

Pdpa Annulus in DP range

DP DC



Wellbore hydraulics

HYDROSTATICS

HYDRODINAMCS



Buoyancy Force = weight of fluid displaced (Archimedes, 250 BC)

Figure 4 -9. Hydraulic forces acting on a foreign body



Effective (buoyed) Weight

s

fe 1WW

s

f

f

be

W-W

V-W

FWWWe = buoyed weight

W = weight in air

f= fluid density

s= steel density

Fb = buoyancy force

V = volume



Effective (buoyed) Weight

s

fe 1WW

Buoyancy Factor (BF)

Valid for a solid body or an open-ended pipe! (WHY?)

s

f1BF



Types of Flow: Laminar Flow

Flow pattern is linear (no radial flow)

Velocity at wall is ZERO

Produces minimal hole erosion



Types of Flow: Laminar Flow

Mud properties strongly affect pressure losses

Is preferred flow type for annulus (in vertical wells)

Laminar flow is sometimes referred to as sheet flow, or

layered flow:

* As the flow velocity increases, the flow type changes from laminar to

turbulent.



Types of Flow: Turbulent Flow

Flow pattern is random (flow in all directions)

Tends to produce hole erosion

Results in higher pressure losses (takes more energy)



Mud properties have little effect on pressure losses

Is the usual flow type inside the drill pipe and collars

Thin laminar boundary layer at the wall

High turbulent flow is found under the bit and

sometime in the annular area around drill collars and

stabilizers

Types of flow : Turbulent flow



Types of f low:Turbulent flow

Fig. 4-30. Laminar and turbulent flow patterns in a

circular pipe: (a) laminar flow, (b) transition between

laminar and turbulent flow and (c) turbulent flow



pf = 11.41 v 1.75

turbulent flow

pf = 9.11 v

laminar flow



Turbulent Flow - Newtonian Fluid

The onset of turbulence in pipe flow is characterized

by the dimensionless group known as the Reynolds

number

dvN

_

Re

dv928N

_

Re

In field units,



Turbulent Flow - Newtonian Fluid in SI units

We often assume that fluid flow is

turbulent if Nre > 2,100

cp. fluid, ofviscosity

in I.D., piped

ft/s velocity,fluid avg. v

lbm/gal density, fluid where

_

dvN

_

Re

Kg/m3

m/sec

m

Pa s



Turbulent Flow - Newtonian Fluid in field units

We often assume that fluid flow is

turbulent if Nre > 2,100

cp. fluid, ofviscosity

in I.D., piped

ft/s velocity,fluid avg. v

lbm/gal density, fluid where

_

dv928N

_

Re



Non-static Well Conditions

Physical Laws

Rheological Models

Equations of State

FLUID FLOW



Physical Laws

Conservation of mass

Conservation of energy

Conservation of momentum



Physical Laws

constant2211 qvAvA

konstanthgp2

v0

2

Conservation of mass

Conservation of energy



Law of Conservation of Energy (Brnoulli)

States that as a fluid flows from A to B:

QW

vvDDg

VpVpEE

2

1

2

212

112212

2

1

In the wellbore, in many cases Q = 0 (heat)

= constant{



Physical Laws

Stokes Law

18

dg)(v

2

mcs

sr vv

Cutting transport



Settling velocity, after Bourgoyne et al.



Slip Velocity, after Bourgoyne et al.

189.1f

sss

f

dv



Particle Slip Velocity - small particles

cp viscosity, fluid

in particle, of diameterd

lbm/gal fluid, ofdensity

lbm/gal particle, solid of density

ft/s velocity, slipv

s

f

s

s

2

sfss

d)(138v



Intermediate: 1/3af

2/3

fsss

_

)(

)(2.90dv

Fully Turbulent:f

fsss

_ )(d1.54v

Particle Slip Velocity other than laminar

Note: all equations are in field units



Rheological Models

Newtonian

Bingham Plastic

Power Law

API Power-Law



Typical Drilling Fluid Vs. Newtonian, Bingham and Power Law Fluids



Equations of State

Incompressible fluid

Slightly compressible fluid

Ideal gas

Real gas



Average Fluid Velocity (SI units)

Pipe Flow Annular Flow

WHERE

v = average velocity, m/s

q = flow rate, m3/s

d = internal diameter of pipe, m

d2 = internal diameter of outer pipe or borehole, m

d1 = external diameter of inner pipe, m

2

4d

qv

2

1

2

24

dd

qv



Average Fluid Velocity (field units)

Pipe Flow Annular Flow

WHERE

v = average velocity, ft/s

q = flow rate, gal/min

d = internal diameter of pipe, in.

d2 = internal diameter of outer pipe or borehole, in.

d1 = external diameter of inner pipe, in.

2448.2 d

qv

2

1

2

2448.2 dd

qv



Velocity Profiles (laminar flow)

(a) pipe flow and (b) annular flow



Representing the Circular Annulus as a Slot

)r(r W slot of Width

)r(r h slot ofHeight

rr Wh slot equivalent of Area

12

12

2

1

2

2

{ slot approximation is OK if (d1/d2 > 0.3 }

Equal

Area

and

Height

Simpler

Equations

-yet

accurate



Free body diagram for fluid element in a narrow slot



yWdL

dpp y WpF

ypWF

f22

1

Representing the Annulus as a Slot

F4 = y + yW L = +ddy

y W L

F3 = W L

Consider:

- pressure forces

- viscous forces




state,steady At

F = maSumming forces along flow:

F = 0

F1

F2 + F3 F4 = 0

0LWdy

d -LWyW

dL

dp-p -y pW f

,gSimplifyindp fdL

ddy

= 0




dy

dv

:integrate and variablesSeparate

Model, FluidNewtonian With

dL

dp

dy

d f=

dL

dpy 0

f Evaluate 0 at wall where y = 0

But, -dy

dv= So,




dyydL

dp-dv 0

f

00f

2

vy

dL

dp

2

yv

o

f

dL

dpy

dy

dv+=-

0 v0,y when 0 vSince 0




h-

dL

dp

2

h-0 h,y when 0 vSince 0f

2

dL

dp

2

h- f0

2f yhydL

dp

2

1v

Hence, substituting for v0 and 0 :




vWdyvdAq

The total flow rate:

h

0

2f dy yhydL

dp

2

Wq

dL

dp

12

Whq f

3

g,Integratin

12

2

1

2

2 rrh and )r(rWhBut

( )2f yhydL

dp

2

1v -=




2

12

2

1

2

2f )r)(rr(r

dL

dp

12q

)r(r

q

A

qv

2

1

2

2

velocity,averageBut

2

12

_

f

)r(r

v12

dL

dp

dL

dp

12

Whq f

3




2

12

_

f

)r(r

v12

dL

dp

In field units,

2

12

_

f

)d1000(d

v

dL

dp

psi/ft, cp., ft/sec, in



Hydraulics Optimization

The Art of Compromise

- Improve Annulus cutting transport versus Bit

flow regime (high velocity vs. Low pressure

drop)

Optimising Targets

- Maximizing Hydraulic Horsepower (HHP)

- Maximizing Impact Force (HIP)

- Maximizing Nozzle velocity (HNV)



Horsepower

Horsepower is defined as work per time

Hydraulic horsepower is calculated as follows:

PQ

Where:

Q = Flowrate in gallons/minute

P = bit pressure drop in psi

1714

PQ

Where:

Q = Flowrate in cubic meters/minute

P = bit pressure drop in Pa



Horsepower

Please derive this equation for: flowrate in L/min

and pressure in bar

?PQ



Input Horsepower Requirement

Input horsepower requirement is the

horsepower required to be used to develop the

desired output horsepower. Note that there is

always the efficiency that reduces the output/

- Function of Energy conversion efficiency- Energy conversion to energy source (Diesel Engines, Generators)

- Energy source to pump prime mover (Electric motor, Diesel Engine)

- Prime mover losses through coupling (transmission, gearbox, belt slip, friction, etc.)

- Pump efficiency



Setting Flow Rates

Q maximum

Q optimum

Q minimum



Q Minimum

Roller Cone Bits: Bottom Hole Cleaning (removing cuttings and transport them in annular section)

- Additionally: Bit cooling and cleaning

Fixed Cutter Bits: Cutter cooling and

cleaning (temperature sensible tools)

- Additionally: Hole cleaning (why?)

Delay time to get cuttings samples to surface which

reduce the ability to react.



Q Maximum

Hole erosion

- Turbulent Flow (very controversial today)

E.C.D. effects

- Fracture Gradient (max. Q > increase pressure loss)

- R.O.P. Reduction (Why?)

Pump capacity (limited power)

Surface volume handling and treating

capacity

Energy expenses and costs

Equipment wear



Setting QMinimum

Hole Cleaning:

- Rule of Thumb (v = 0.3 to 0.8 m/s)

- Observation (experience)

- Slip Velocity (Stokes or other)

Bit Cooling and Cleaning:

- Empirical Recommendations

- Observation



Setting QMaximum

Hole Erosion

- Turbulent Flow

- Strength of Formation Being Drilled

E.C.D. Effects- Mud Rheology

- Fracture Gradient

- R.O.P. Reduction

Pump Capacity

- Pressure Limits

- Flow Rate Limits

- Horsepower Limits

- Surface Equipment Pressure Limitations



Setting QMaximum

Surface Volume Handling and Treating Capacity- Solids Control Equipment Limits

- Gas Handling Limits

Energy Expenses and Costs

- High Horsepower Use Leads to Increased Fuel

Consumption

Equipment Wear

- High Pressure and Flow Rates Leads to Increased Wear

and Tear on Equipment



Bit Hydraulics Optimization Methods

Hydraulic effectiveness can be optimized two ways:

- Maximum hydraulic horsepower at the bit

- Maximum impact force at the bit

Maximum cleaning efficiency is limited by surface equipment limits and energy limits (i.e. pumps, lines).



vpb ppp

Pump pressure System losses

Hydraulic Horse Power at bit

vpbb ppqqpH

Flow rate

Pressure Loss at the Bit



bn

p2v

bdn

p2cv

cd = 0,95 - 0,98

Jet velocity at bit nozzle



Maximum Impact Force at the Bit

McLean performed experimental work that indicated that bit cleaning was maximized when the impact force was maximized at the bit. This was supported by studies performed by Eckel who found that maximum impact force lead to maximum rate of penetration.



Maximum Horsepower at the Bit

Bit horsepower is maximized when the bit pressure

loss is equal to:

0.57 x Psystem

Psystem is limited by equipment and power available.



Maximum Impact Force at the Bit

Kendall and Goins determined the impact force was maximized when bit pressure loss is equal to:

0.47 x Psystem

Psystem is limited by equipment and power available.



Maximum Horsepower at the Bit

Kendall and Goins derived a relationship for

maximizing horsepower at the bit. The derivation

of this relationship is left to the class participant.



Setting QOptimum

Cutting transport Pump limitation

Maximizing ROP



Example of Hydraulic calculationsKonzept vj max Hb max

HHP

Fj max

HIF

Pump pressure pp [MPa] 25,00 25,00 25,00

Flow rate qopt[L/min]

800 1019 1209

Bit pressure Drop pb [MPa] 18,66 15,69 11,33

System pressure loss pv [MPa] 6,34 9,31 13,67

Total input Power Hp [kW] 333 425 504

Bit (horse) power Hb [kW] 248,77 266,50 228,31

Impulse force Fj [N] 2675,88 3146,22 3312,30

Jet velocity vj [m/s] 171,13 156,91 133,33



Example of Hydraulic calculations

0

10

20

30

40

50

60

70

80

Bit

pre

ss

ure

dro

p

pre

ss

ure

lo

ss

[%p p

]

vj HHP HIF

optimization concept



Example of Hydraulic calculations

0

50

100

150

200

250

300

800 900 1000 1100 1200 1300

Pump rate[L/min]

Hb [

kW

]

vj [m

/s]

0

500

1000

1500

2000

2500

3000

3500

Fj [k

W]

vj

Fj

Hb



Pressure loss in surface equipment

86,1

z

qCp

C = Pressure loss coefficient

z = Unit coefficient

Pump Surface pipes Mud Hose Swivel Kelly



Alternative Hydraulic Designs

Vortex

Nozzles

Clean Sweep

Mudpick

Switchblade

Asymmetric

NozzlesAll pictures courtesy of Schlumberger


Institut fr Erdl- und Erdgastechnik 65TBT I 2014Viewing the Well as a Manometer

Mud Report 1

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Transcript of Mud Report 1