Introduction Of Well Problems

Introduction To

Oil and Gas Production Problems TM-4030

Choke

Natural Flow Production System

PWH

Flowline Vertical / tubing Flow Performances Tubing Inflow Performance Sand Face Formation

Casing

Packer

re

(Drainage Radius )

Production System of oil/gas well

Figure 2 : A typical Hydrocarbon Phase Diagram

Two Phase

∆P

∆T

Schematic Phase Diagram for an Undersaturated Oil

Pressure and Temperature Profile in Wellbore

Gas Cap Drive

Solution Gas Drive

Water Drive

Reservoir Drive Mechamisms

Gas

Schematic view of possible phase changes in tubing ( Flow Pattern )

PWH Mist Flow

Liquid

Annular Flow

Churn Flow

Pressure Profile Slug Flow

Bubble Flow

Fluid Characteristics

Tubing Flow Performances

Changes in pressures and temperatures

Inflow Performance

PWF

INFLOW PERFORMANCE PROBLEMS 1. Reservoir conditions 2. Types of fluid 3. Multiphase flow 4. Reservoir geometry (Thick, drainage) 5. Reservoir Configuration / shape 6. Fluid entry (Perforation) 7. Rock heterogeinety (porosity, Channeling) 8. Rock type (Carbonate, Clastics) 9. Layering 10. Reservoir size and patterns 11. Drive mechanism

12. Well orientation (Horizontal, Vertical, Incline) 13. Well spacing 14. Well completion

RESERVOIR CONDITIONS

1. Reservoir pressure ( high or Low Pressure ) 2. Reservoir Temperature ( high or low

Temperature)

Types of Fluid 1. Heavy Oil : high viscosity, high density, high Molecular weight density < 20 API, 2. Paraffinic oil : Viscosity increase as temperature decreases 3. Light Oil : low density and viscosity, High GOR, Properties changes very quickly with pressure. 4. Resinic Oil : light color, low – medium viscosity, sticky oil, oil wetting, not good for water flooding, Low RF 5. Black Oil : Constant composition, high molecular weight, dark color.

VERTICAL FLOW/ TUBING FLOW PERFORMANCE PROBLEMS

1. Well geometry (D, L) 2. Well Orientation (Off Shore)

3. Multiphase flow (Flow Pattern) 4. Pressure (Low) 5. Fluid type 6. Fluid characteristics 7. Pump / artificial lift methods 8. Deep sea operation (Low Temp) 9. Well completion 10. Temperature (Low Temp)

Gas

Schematic view of possible phase changes in tubing ( Flow Pattern )

PWH Mist Flow

Liquid

Annular Flow

Churn Flow

Pressure Profile Slug Flow

Bubble Flow

Fluid Characteristics

Tubing Flow Performances

Changes in pressures and temperatures

Inflow Performance

PWF

Production Offshore Problems Why this is a problem ?

Gas

Liquid Gas

Slug Flow Gas

At the same wellbore

Flow Rate

Liquid Gas

Pressure Loss Slug Flow

Gas

GAS

Mist

Depth

Tubing

Pada dasar sumur, tekanan relatif masih tinggi sehingga sebagian besar gas masih larut dalam fasa minyak. Pada posisi ini aliran masih satu fasa cair (single phase). Semakin keatas sumur, tekanan fluida semakin berkurang dan gas semakin banyak yang terbebaskan dari fasa minyak. Sehingga aliran Bubbly terbentuk dengan bertambahnya gas, kemudian semakin besar volume gas terbebaskan berturut turut terbentuk Aliran Slug, Aliran Churn dan terakhir adalah berupa aliran Annular.

PIPELINES FLOW PERFORMANCE PROBLEMS

1. Pipeline design ( diameter ) 2. Multiphase flow ( gas – water – oil ), (solid-Water-Oil)

3. Pressure ( high or low) 4. Gas condensate (change phase, change properties) 5. Fluid characteristics ( viscosity, density, sticky, Molecular Weight) 6. Transportation (multiphase flow, undulation, deposition) 7. Deep sea operation (low temp, high viscosity, multiphase) 8. Bottle necking (increase gradient pressure)

PIPELINES FLOW PERFORMANCE PROBLEMS

1. Gas condensate a. Liquid deposition, b. Phase changes, c. Properties changes. Droplets of Condensate

Back Pressure, Bottle Necking, Choking

Pipelines

Lower Pressure

OUTLET

INLET Condensate deposition

Flow Efficiency is decreasing

MULTIPHASE FLOW PROBLEM

Alaska Oil Pipeline

SCADA (kependekan dari Supervisory Control And Data Acquisition)

PIPELINES FLOW PERFORMANCE PROBLEMS

1. Gas condensate Gas Flow Rate

Tb q = 3.23 Pb Droplets of Condensate

~f

1   f

0.5

0.5

 P1  P2  2.5 . D     g .T .L.z  2

Friction Factor

2

Pipelines

OUTLET

INLET Condensate deposition

Flow Efficiency is decreasing

MULTIPHASE FLOW PROBLEM

[f]

Laminer

In This area, friction is not function of NRe

~f

PIPELINES FLOW PERFORMANCE PROBLEMS

1. Gas condensate Gas Flow Rate

 Tb q = 737 E   Pb Flow Eff.

Droplets of Condensate

1.02 

  

   0.961 T L z  g  P12

 P2

2

0.51

D 2.53

Panhandle B

Pipelines Choke OUTLET

INLET Condensate deposition

Flow Efficiency is decreasing, back pressure, Pressure drop increase, need pigging to clean MULTIPHASE FLOW PROBLEM

Fungsi Pigging • Membersihkan bagian dalam pipa dari: – Liquid yang tidak mengalir (sistem produksi gas) – Pasir/material kecil – Wax/Gas hidrate Pipelines

WAX

Pipeline leak

Panhandle-B Equation P1

Gas Pipelines

 Tb q = 737 E   Pb

1.02 

  

P2

   0.961 T L z  g  P12

 P2

2

0.51

No

Date

Gas Rate

P1

P2

1

2-1-2016

300 MM

450 psi

320 psi

2

2-2-2016

280 MM

460 psi

300 psi

D 2.53

PIPELINES FLOW PERFORMANCE PROBLEMS

1. Pipeline design ( diameter , thickness)

Large

Medium

Small

MULTIPHASE FLOW PROBLEMS

2. Multiphase flow ( gas – water – oil )

a. b. c. d. e. f.

Flow Pattern (vertical pipes, Horizontal pipes) Lifting, Pump Selection, Liquid loading. Phase Flow Prediction. Modeling. Emulsion Mixing Properties

MULTIPHASE FLOW PROBLEMS a. Liquid Loading terjadi pada tekanan rendah di Bottom hole ( pada sumur Gas)

b. Aliran laminer di pipa horizontal (pada Liquid Pipelines) c. Terjadi solid settling di pipa horizontal dan vertikal. d. Kehilangan panas lebih besar pada aliran yang laminer, e. Pump selection is important, f. Bottle neck problem in pipeline network at low pressure g. Fluid Surge and down / drop

Oil - Water Laminer Flow

INLET

Measurement Problem

Oil transmission Lines

OUTLET

qo

qo

t ( time )

t ( time ) NRE ≤ 2000 Aliran Laminer

Oil Phase Oil Density < Water Density

Dalam Pipa

Water Phase Flow Pattern

Oil Phase Water Phase

Decline

Water is faster than oil phase

Horizontal

Water velocity is equal to oil

Inclined pipe

Water is slower than oil phase

RADIAL FLOW GEOMETRY IN POROUS MEDIA Single layer in single well

1

2

k 

3

ln (re / rw ) ln (r1/rw ) ln (r2 /r1 ) ln (r3 /r2 )   k1 k2 k3

k 

k1h1  k 2 h 2  k 3h 3 h1  h 2  h 3

RADIAL FLOW GEOMETRY IN POROUS MEDIA

3

2

1 SKIN

Value Permeability Average

ln (re / rw ) k  ln (r1/rw ) ln (r2 /r1 ) ln (r3 /r2 )   k1 k2 k3

When k1 = 0, then

k 0

Productivity Index (PI) Well P2

P1

FORMATION L

q 

0.001127 k A (p1 - p 2 )  L

q 0.001127 k A   PI (p1 - p 2 )  L

P1

Adanga Gas yang keluar dari fasa minyak

P2

qL

Gas

Water

Oil-water-Gas

Vertical Fluid Transition in one Layer

Oil-Gas

Gas Zone GOC

Oil Zone

Oil – Water Transition Zone

h Producing WOC

Original WOC

Water Water

Pc (pressure) ~ h (height)

0

SWIR

SOR

SW

Fluid Flow Characteristic In Porous Media • • • •

Type of Fluids in the reservoir, Flow regimes, Reservoir Geometry, Number of Flowing Fluids in the reservoir

Type of Fluids In general, reservoir fluids are classified into three groups: 1. Incompressible Fluids ( (water ) 2. Slightly Compressible ( Oil ) 3. Compressible Fluids ( Gas )

The isothermal compressible coefficient (c) 1 V c V P



1   P

V = fluid volume

ρ = fluid density P = pressure c = isothermal compressible fluid, p-1

Incompressible Fluids An incompressible fluid is defined as the fluid whose volume or density does not change with pressure. This is

V  0 P

and

 P

 0

Incompressible fluids do not exist; however this behavior may be assumed in some cases to simplify the derivation and the final form of many flow equations.

V = fluid volume ρ = fluid density P = pressure

V  0 P

Incompressible

Volume

Slightly Compressible

1 V c V P

Compressible

Pressure Pressure – Volume Relationship

V  0 P

Incompressible

Volume

Slightly Compressible

Compressible

Pressure Pressure – Volume Relationship

Steady State Flow P t

 0

The flow regime is said to be a steady state flow if the pressure at every location in the reservoir remain constant. It does not change with time.

PseudoSteady-state Flow P  constant t

The flow regime is said to be a pseudo steady state flow if the pressure at every location in the reservoir remain constant. But, it slighly changes with time.

Persamaan Aliran Radial Steady State 7.08 k h ( Pe - Pw ) q   ln (re /rw ) P = tekanan, psia k = permeability, darcy

re = jari jari luar ( drainage radius)

re

rW

re

µ = Viscosity of fluid, cp h = Formation Thickness, ft

rW = jari jari sumur (Well radius)

PW

PW

Pe

Q=0 Pi

Pi

Radius / Distance Q = constant

Pi

t1

t2

t3

t4

t4

Pwf decreases as time increases Radius / Distance

Pi

Q=0 Pi

Pi

q

Pi

re

t1

t2

r1

r2

Pwf = constant

Pressure Distribution as function of time

t3 r3

t4 r4

Pi

re

Pressure Distribution as function of time

q Pi

Pi

Q (r)

q 0

re

re Pwf = constant

Pressure Distribution as function of time Pi

Pwf = constant

r re Pi

0 rW

Ln r

0.47 re

re

Well Damaged

FLOW Undamaged Reservoir Damaged

Semakin besar Skin Factor, maka Pwf nya semakin kecil dan laju alir nya semakin kecil juga.

PSKIN

{ R (radius)