Introduction to Gas Processing

Introduction to Production Technology

Presenter: Ta Quoc Dung

Introduction to Production Technology 2GEOPET

Chapter 1. Introduction

Chapter 2. Process Overview

Chapter 3. Performance of Flowing Well

Chapter 4. Artificial Lifts

Chapter 5. Enhanced Oil Recovery

Contents

Content


Learning Objectives

Having go through this course, students will be able to:

Describe the overview of Petroleum Production Technology

Describe the role of Production Engineer in a Petroleum

Operating Company.

Describe a production system and its facilities both onshore

and offshore.

Understand the concept of inflow performance, lift

performance and their integrated nature.

Understand the enhanced oil recovery process.

Learning Objectives


Chapter 1

Introduction


Content

1.1. Historical Background

1.2. Origin of Petroleum

1.3. Petroleum Production

1.4. Production Engineer

Chapter 1 - Content


Historical Background

Oil has been used for many thousand years.

Initially, oil was collected from seepage or tar ponds.

6000 BC, thick gummy asphalt was used to waterproof

boats and heat home.

3000 BC, Egyptians used asphalt in the construction of the

pyramids, to grease the axles of the Pharaoh’s chariots, as

an embalming agent for mummies and in medicine.

500 BC, Chinese were using natural gas to boil water.



Historical Background

1885, internal combustion engine was invented by Karl

Benz. Later, Gotlied Daimler improved on this invention.

1894, Rudolph Diesel created the engine bearing his name.

Since then, oil started to play a dominant role in the world.

Initially, gas was burned off or left in the ground. After

World War II, natural gas industry boom due to:Welding techniques

Pipe rolling

Metallurgical advances

=> Construction of reliable long distance pipelines



The First Oil Wells

“Colonel” Edwin Drake’s well at

Titusville, Pennsylvania, marked the

start of the oil industry in 1859



The First Oil Wells

First wells were shallow, less than 50 meters in depth.

However, they could give quite large production, e.g. 4000

barrels per day for a single well.

Oil was collected in wooden tank, called “barrel”. Many

different sized barrels in the background. Current standard,

one barrel is 159 liters.



The First Oil Wells

Philips well4000 bbl/d, Oct 1861Woodford well

1500 bbl/d, July 1862



The First Oil Wells

Well “jungle” at Spindletop, 1903



What is Petroleum?

Petra = Rock Oleum = Oil

Petroleum is a mixture of naturally occurring hydrocarbons which may exist in the solid, liquid, or gaseous states, depending upon the composition and conditions of pressure and temperature to which it is subjected.

Gaseous = natural gas

Liquid = condensate, crude oil

Solid = asphalt, tar, bitumen



Petroleum Components



Origin of Petroleum

Origin of petroleum

Organic

Inorganic

Primary Requirements for Petroleum Reservoir

formation:

Organic life

Water for transportation

Tectonic activities



Type of Hydrocarbon Produced

Oil produced is classified by shrinkage, density or GOR.

Normally, high value oil has high API density.


Other Uses of OilCrude Oil

Refinery

Solvent for paintInsecticidesMedicinesSynthetic FibersEnamelDetergentsWeed Killers & FertilizersPlasticsSynthetic RubberPhotographic FilmCandlesWaxed paperPolishOintments & CreamsRoofingProtective PaintsAsphalt

Bottled GasGasolineJet FuelFuel Oil (home heatingFuel Oil (factories)Diesel OilAnd others

PetrochemicalPlant

Petroleum Products



Petroleum from Beginning to the End

Exploration Evaluation Drilling

Completion Production Separation

Treatment Transport Refining

Treatment Transport End Users



Key Areas in Production Technology

Production technology is both a diverse and complex area.

It is, possible to identify several key subject areas:Well Productivity

Well Completion

Well Stimulation

Associated Production Problems

Remedial and Workover Techniques

Artificial Lift / Productivity Enhancement

Surface Processing

1.3. Production Technology


Production Technology Topics

WELLPERFORMANCE

WELLPERFORMANCE

PRODUCTIONENHANCEMENT/ARTIFICIAL LIFT

PRODUCTIONENHANCEMENT/ARTIFICIAL LIFT

PRODUCTIONPROBLEMS

PRODUCTIONPROBLEMS

WELL MONITORING,DIAGNOSIS

ANDWORKOVER

WELL MONITORING,DIAGNOSIS

ANDWORKOVER

STIMULATIONAND REMEDIAL

PROCESSES

STIMULATIONAND REMEDIAL

PROCESSES

SURFACEPROCESSINGSURFACE

PROCESSING

WELLCOMPLETION

WELLCOMPLETION

PRODUCTIONTECHNOLOGYPRODUCTIONTECHNOLOGY

1.3. Production Technology


Scope of Production Engineer

Production Engineer is responsible for the production system.

The production system describes the entire production

process and includes the following principal components:The Reservoir

The Wellbore

Production Conduit

Wellhead, Xmas Tree and Flow Lines

Treatment Facilities



Elements of A Production Technology System



Role of Production Engineer

Production Engineer performs tasks to achieve optimum

performance from the production system.

To achieve this the technologist must understand:Chemical and physical characteristics of the fluids.

System which will be utilised to control the efficient and safe

production/injection of fluids

The importance of the Production Chemistry and Flow Assurance input has only recently been widely

acknowledged.



Contribution to Oil Company Operations

Contributes substantially, in particular to economic

performance and cash flow.

The overall incentive will be to maximise profitability.

The objectives of an oil company operation could be

classified as:Maximising magnitude and accelerating cash flow.

Minimising cost/bbl, i.e. total cost minimisation may not be

recommended.




Cash flow

The overall objectives would ideally be to maximise both

cash flow and recoverable reserves. This would normally

require maintaining the well in an operational state to

achieve:Maximum production rates

Maximum economic longevity

Minimum down time




Costs

In this category there would be both fixed and direct costs.

On this basis the production technologist would seek to:Minimise capital costs

Minimise production costs

Minimise treatment costs

Minimise workover cost

Ensuring that the company’s operation are safe, efficient

and profitable.



Time Scale of Involvement

Specialist task teams to fields or groups of wells i.e. field

groups or asset teams.

Specialist groups or individual who provide specific

technical expertise.

This ensure that there is a forward looking and continuous

development perspective to field and well developments.

The production engineer is involved in the initial well design

and will have interest in the drilling operation from the time

that the reservoir is penetrated.




The inputs of production engineer will last throughout the

production life of the well, to its ultimate abandonment.

The production engineer will contribute to company

operations on a well from initial planning to abandonment.

The inputs in chronological order to the development and

the operation of the well are listed below.




Drilling

Casing string design.

Drilling fluid selection.

Completion

Design/installation of completion string.

Production

Monitoring well and completion performance.

Workover/re-completion

Diagnosis/recommendation/installation of new or improved production

systems.

Abandonment

Identify candidates and procedures.



Questions

1. Which company is producing oil the most in Vietnam?

What is its average day-rate?

2. Locate main oil and gas production fields in Vietnam?

3. Name some oil refinery projects in Vietnam?

Chapter 1 - Questions


Chapter 2

Process Overview


Content

2.1. Production SystemsOnshore

Offshore

2.2. Production FacilitiesWellhead

Manifold/Gathering

Separator

Gas Compressor

Pipeline

Metering, Storage and Export Facilities

2.3. Utility Systems

Chapter 2 - Content


Basic Process Scheme


Process Overview

2.1. Facilities

ProductionWellheads

Productionand TestManifolds

Gas Compressor Metering andStorage

Export

Production Separators

Drilling

InjectionWells

InjectionManifolds

Mud and Cementing

Utility Systems (selected)

Test Separator

Water injectionpump

Gas injectioncompressor

Oil Storage

Water Treatment

Power Generation

Instrument Air

Potable Water

FirefightingSystems

HVAC

1-Stage

2-StageCrudePump

OilMeter

PigLauncher

PigLauncher

GasPipeline

OilPipeline

TankerLoading

LP HP Gas Meter


Oil and Gas Production

Oil and gas is produced in almost every part of the world.

Production from 100 bbl/day to 4000 bbl/day per well.

Depth of production from 20 m to 3000 m, and more.

Current trend of petroleum production:Explore reservoirs at ultra high water depth.

Develop subsea production system.

2.1. Production System


Production System

1. Onshore well

2. Fixed, multi platform

3. Fixed, self-contained platform

4. Self-contained, concrete gravity platform

5. Floating, single point mooring

6. Storage/shuttle tanker

7. Floating, tension leg platform

8. Subsea manifolds



Onshore

Production from a few tens barrels a day upward.

Worldwide, there are several millions oil and gas

production wells.

Production system:

sucker rod pump

(donkey pump).



Onshore

Heavy crude, tar sands and oil shales

have become economically extractible.

Heavy crude may need heating and

diluent.

Tar sands have lost their volatile

compounds and are strip mined or

could be extracted with steam.

These unconventional of reserves may

contain more than double the

hydrocarbons found in conventional

reservoirs.



Offshore

Facilities selected depending on:Type of fluid: oil, gas or condensate.

Production rate.

Location of field and water depth.

2.1. Facilities


Offshore Production System


Type of Offshore Platform



Type of Offshore Platform (cont.)


Type of Offshore Platform (cont.)1353 ft(1991)

1754 ft(1998)

4674 ft(2004)

5610 ft(2004)

6300 ft(2003)

4429 ft(2005)

7570 ft(2004)


Shallow Water Complex

Water depth up to 100 m.

Several independent platforms with different parts of the

process and utilities linked with gangway bridges.

Individual platforms will be described as:Wellhead Platform

Riser Platform

Processing Platform

Accommodations

Platform and Power

Generation Platform



Integrated Steel Jacket Platform


Gravity Base

Water depth: 100 – 500 m.

Concrete fixed structures

placed on the bottom, typically

with oil storage cells.

Large desk receive all parts of

the process and utilities.



Compliant Tower

Water depth 500 – 1000m.

Much like fixed platforms, consist of narrow tower attached

to a foundation on the seafloor and extending up to the

platform.

Compliant tower is quite flexible.



Compliant Tower

Moving a compliant tower

to a field.



Rig-up

Fixed platforms are built in

onshore bases.

Then they are towed to the

field by tugboats.

Platforms positioned and

connected to seafloor.

2.1. Facilities


Floating Production

All topside system are located on a floating structure.

Floaters:FPSO - Floating Production, Storage and Offloading, 200-2000 m.

TLP – Tension Leg Platform, up to 2000 m.

SPAR – single tall floating cylinder hull, 300 – 3000 m.

Turrets are positioned by:POSMOR (position mooring): chain connections to anchors.

DYNPOS (dynamic positioning): thrusters and propellers.



FPSO


FPSO with Tanker


TLP



TLP with subsea wells



SPAR


SPAR anatomy

1. Monocolumn Hull

2. Tendon Porches

3. Tendons

4. Foundation

5. Deck

6. Hull to Deck Transition

7. Riser Porch

8. Riser/Umbilical Pull Tubes

9. Moonpool

10.Production Risers


Subsea Production System

Typically used at 7000 ft depth or more.

Drilling and completion are performed from a surface rig.

Wells located on the sea floor.

Petroleum is extracted at the seafloor, then “tied-back” to

an existing production system by subsea pipeline and riser.



Subsea FPSO Development




Host Platform connected to several Subsea Fields


Main Process Section

An oil and gas production system consist of the main

following sections:Wellhead

Manifold/Gathering

Separator

Gas compressor

Pipeline

Some optional facilities may be requiredHeat exchanger

Scrubber and Reboiler

2.2. Production Facilities


Wellhead

Located on top of the well, also called “The X-mas tree”.

Allow a number of operations relating to production and

workover. Workover refers to various technologies for

maintaining the well and improving production.

Control the flow of the well with a choke.

Two main type of wellheads:Dry completion: conventional wellheads.

Subsea completion: subsea wellheads.



WellheadC

ASI

NG

HEA

DTU

BIN

GH

EAD

X-M

AS

TREE



Wellhead (cont.)

A wellhead consists of three component:

Casing head: where casing are bolted or welded to casing hanger.

Tubing head: used to position the tubing correctly in the well.

X-mas treeMaster gate valve: high quality valve, not used to control flow.

Pressure gauge: may also fitted together with temperature gauge.

Wing valve: when shut in, tubing pressure can be read.

Swab valve: access to the well for wireline operations, etc…

Choke: made of high quality steel, used to control the flow.



Subsea Wellhead

Placed in subsea structure.

World deepest subsea production tree is 9000 ft of water.

Compact system, function similar to conventional wellhead.

Operated by ROV

(remote operated vehicle).



Subsea Wellhead (cont.)


History of Subsea Technology


ROV



Types of Choke

Principal surface system pressure loss occurred at choke.

Choke is designed to control the well flow rate and

pressure before fluid exposed to surface equipment.



Manifold/Gathering

Every individual well is brought in to the main production

facilities over a network of gathering pipelines and manifold

systems.

Manifolds allow to set up and control production of a “well

set” and utilize reservoir.

Manifolds can be placed on surface, on platform or on

seafloor, depending on the production system.



Manifolds

Subsea manifoldsManifolds



Separator

Production fluid of a well may consist of gas, oil, water,… and must be separated and processed.

Separator form the heart of the production process.

When fluid fed into a separators:Pressure is controlled and reduced in several stages

After a retention time, gas bubble out, water settle at the bottom and oil stay in the middle.

There are 2 types of separator:Gravity separators,

Centrifugal separators: in which the effect of gravity is enhanced by spinning the fluids at a high velocity.



Gravity Separators

Working on the density difference between the phases be separated.

Cylindrical vessel up to 5m in diameter and 20m long.

Either 2-phase or 3-phase.

Normally mounted in a series of 2, 3, or even 4 separators.


3-phase Horizontal Gravity Separator


3-phase Vertical Gravity Separator

Tend to be larger

than a horizontal

separator for the

same separation

capacity due to

smaller interface

areas.



Gas Compressor

Gas from a pure natural gas wellhead might have sufficient

pressure to feed directly into a pipeline transport system.

Gas from separators has generally lost so much pressure

that it must be recompressed to be transported.

Typical gas compressor is turbine compressor, which

contains a type of fan that compresses and pumps the

natural gas through the pipeline.



Gas Compressor (cont.)

Compressor power is often delivered by gas turbines,

diesel engines or electric motor, depending on location and

power required.

Types of compressor: Centrifugal compressor

Positive displacement reciprocating compressor.

Both compressor types are susceptible to damage by liquid

droplets, hence the presence of the liquid knockout vessels prior to each compressor.



Simplified Processing Oil Facilities Scheme



Pipeline

Pipeline exists everywhere in a production system.

Many types of pipe and flowline are used in transportation

of oil and gas, diameters vary from 6” to 48” and more.

Due to oil and gas properties and harsh environment,

production pipeline has special construction and design.



Layers of a Production Line

1. Carcass

2. Inner liner

3. Pressure armour

4. Tensile armour5. Outer sheath



Heat Exchanger

For a compressor operates in an efficient way, the

temperature of the gas should be low.

Heat should be conserved, e.g. by using cooling flood from

the gas train to reheat oil in the oil train.


Scrubber and Reboiler

Used to remove small fraction of liquid from the gas before it reaches the

compressor. Liquid droplets can erode the rotating blades if they enter the

compressor.


Metering

Several metering devices are used in every petroleum

production system to measure gas or oil properties as it

flows through the pipeline.

Metering stations allow operators to monitor and manage

the natural gas and oil flow without impeding its movement.

Typically, a metering installation consists of a number of

meter runs and associated prover loops so that the meter

accuracy can be tested and calibrated at regular intervals.

Oil metering Gas metering



Storage

Gas is usually not allowed to storage on platform.

Oil is often stored before loading on a vessel.

Offshore production facilities without a direct pipeline

connection rely on crude storage in the base or hull and

allow a shuttle tanker

to offload periodically.



A Base at Night


Export of Oil

The volume of oil being exported has to be measured to the

highest accuracy.

Pipeline requires regular cleaning to ensure its efficient

operation. A “pig” is usually used to remove settled sand,

wax deposit, stagnant water,…

Offshore, loading on tankers involve loading systems,

ranging from tanker jetties to sophisticated single point

mooring and loading systems that allow the tanker to dock

and load product even in bad weather.



Export - FPSO Offloading to a Tanker


Export of Gas

Gas has to pass several process and treatment before

exporting to customers, including:Separation

Compression

NGL stabilization

Dehydration

Acid gas treating

These processes may repeat to improve the purity of gas

and control gas properties.



Gas Field Facilities


Export - Gas Transportation


Export - Gas Transportation (cont.)


Produced Water TreatmentProduced water, after separation and treatment, is normally disposed of by injection into disposal wells, reinjection into the reservoir or pumping to open pits where it is allowed to evaporate or drain.

In offshore operations, there are other sources of water that require treatment before disposal:

Water used for washing / cleaning of equipment,

Sea spray and rain water,

Utility water previously used for heating and cooling duty,

Displacement water from crude oil storage systems and shuttle tankers.

At some offshore locations if the environmental regulations permit it, oil-free water may simply be pumped into the ocean.



Produced Water Treatment (cont.)

Primary separation may be enhanced by:1. Heating of the crude oil: to reduce viscosity.

2. Addition of demulsification chemicals: to alter the interfacial tension

between the oil droplets and the water.

3. Electrostatic separation: to further reduce the water content of

relatively dry oil. The water droplets suspended in the oil carry a small

electrical charge and by imposing the appropriate electrical field across

(part) of the settling region inside the separator, the settling rate of

water will increase. This method is not widely used but is occasionally

employed in conjunction with the more difficult to separate, typically

denser, crude oils.

After above methods, oil content in water is still about 500 – 2000 ppm.



Produced Water Treatment (cont.)

Further treatments are applied to reduce oil content down to 40 ppm average, which is required by legistration in many countries.

Many schemes have been developed to reduce this oil content:

1. (Corrugated) Plate Interceptors

2. Flocculation / Coagulation

3. Flotation

4. Hydrocyclones

5. Coalescer Units

6. Centrifuges



(Corrugated) Plate Interceptors

Reducing the distance required for a droplet to migrate before it comes

into contact with other oil droplets and coalesces.



Flocculation / Coagulation

Uses a chemical (such as Ferrous Sulphate) which forms a voluminous

precipitate in contact with water, artificially increasing suspended liquid

size and their ability to coalesce.



Dispered Gas Flotation

Gas injected into the water and dispersed by a rapidly rotating impeller,

rising gas bubbles attaching themselves to the oil droplets.



Dissolved Gas Flotation

Gas dissolved in the water under high pressure. When pressure is rapidly

reduced - by passage of the water through a throttling valve - gas comes

out of solution in the form of many small bubbles (champagne bottle

effect).



Hydrocyclones

Standard device for cleaning oily water,

developed in the early 1990s.

Using centrifugal force to increase the

effect of gravity separation.



Coalescer Units

Provide a (usually oleophilic) surface on which the small

droplets of oil can collect, grow and eventually break free

and be removed for subsequent separation.

Can produce the lowest oil concentrations (5 ppm oil in

water has been achieved in ideal circumstances).



Centrifuges

The principle of enhanced gravitational force employed by

Hydrocyclones can be further extended by use of

centrifuges where an external electric motor is used to spin

the fluid at high velocity together with a suitably designed

internals to promote oil/water separation.



Modern Scheme for Clean Produced Water


Utility Systems

Utility systems are systems that does not handle the hydrocarbon process

flow, but provides some utility to the main process safety or residents.

1. Control and Safety Systems

1. Process Control Systems

2. Emergency Shutdown and Process Shutdown

3. Control and Safety Configuration

4. Fire and Gas Detector System

5. Telemetry

6. Condition Monitoring and Maintenance Support

7. Production Information Management System (PIMS)

8. Training Simulator



Example of Process Control System



Utility Systems

2. Power Generation and Distribution

3. Flare and Atmospheric Ventilation

4. Instrument Air

5. HVAC (heat, ventilation, air conditioning system)

6. Water System

1. Portable water

2. Sea water

3. Ballast water

7. Chemical and Additives

8. Telecom



Questions

1. Which is more expensive, production onshore or offshore?

Why?

2. Why did the oil industry start drilling and production

offshore?

3. What are the main differences between oil production and

gas production?

Chapter 2 - Question


Chapter 3

Performance of Flowing Well


Content

3.1. Production Wells

3.2. Well Productivity

3.3. IPR and VLP

3.4. Skin Factor

3.5. Two Phase Flow in Tubing

Chapter 3 - Content


Production Wells

Production well is a

conduit between the

petroleum reservoir and

the surface.



Types of Production Wells

There are 3 main types of production wells:Oil well with associated gas

Natural gas wells: contain little or no oil

Condensate wells: contain natural gas and liquid condensate.

Condensate is a liquid hydrocarbon mixture that is often separated from the natural gas during the processing.

Lifting equipment and well treatment are not necessary in natural gas and condensate wells.

For oil wells, many types of artificial lifts may be installed, particularly when reservoir pressure declines during production.



Well Productivity

The productivity of the system is dependent on the

pressure loss which occurs in:The reservoir

The wellbore

The tubing string

The choke

The flow line

The separator

In natural flow conditions:

PR = ∆Psystem + Psep.



Well Productivity

For natural flow: PR = ∆ PRES + ∆ PTBG + PTH

Where: PTH = tubing head pressure

The pressure drop across the reservoir, the tubing and

choke are mostly rate dependant.

There could be limitations on the extent to which we can

optimise the dissipation of this energy. These are the

following:Limited Reservoir Pressure

Minimum Surface Pressure



Limited Reservoir Pressure

If the reservoir pressure is limited, it may not be feasible to

achieve economic production rate from the well.

In such cases it may be necessary to use gas or water

injection for pressure maintenance or possibly system re-

pressurisation.

Alternatively, the use of some artificial lift technique to

offset some of the vertical lift pressure requirements,

allowing greater drawdown.



Minimum Surface Pressure

On arrival at the surface, the fluids are fed to a pipeline

through a choke and into a processing system.

In many cases the mixture will be “flashed” through a series

of sequential separators.

It will be necessary to have a minimum surface pressure

which will be based upon the required operating pressure.

Separator pressure will depend upon the physical difficulty

in separating the phases and pressure requirement for fluid

flow.



IPR and VLP

Minimisation of energy loss between these various areas

has a major bearing on the cost effectiveness of a well,

recovery factor, and production costs.

The pressure drop which occurs across the reservoir, ∆Pres, is defined as the inflow performance relationship or IPR.

The pressure drop in lifting the fluids from the reservoir to

the surface, ∆PTBG, is known as the vertical lift performance or VLP, or the tubing performance relationship or TPR.

3.3. IPR and VLP


IPR and VLP (cont.)

Inflow Performance Relationship (IPR)Single phase

Two phase

Vertical Lift PerformanceSingle phase

Two phase

3.3. IPR and VLP


IPR and VLP (cont.)

3.3. IPR and VLP


Production Performance

Production performance involves matching up the following

three aspects:Inflow performance of formation fluid flow from formation to the

wellbore.

Vertical lift performance as the fluids flow up the tubing to surface.

Choke or bean performance as the fluids flow through the restriction

at surface.

3.3. IPR and VLP


Tubing Performance

The pressure loss in the tubing can be a significant

proportion of the total pressure loss. However its

calculation is complicated by the number of phases which

may be exist in the tubing.

It is possible to derive a mathematical expression which

describes fluid flow in a pipe by applying the principle of

conservation of energy.

The principle of the conservation of energy equates the

energy of fluid entering in and exiting from a control

volume.

3.3. IPR and VLP


Determining Bottom Hole Flowing Pressure

Use correlation

By metering or logging,

which is can not

operate regularly.

3.3. IPR and VLP


Fluid Flow Through Porous Media

The nature of the fluid flow

Time taken for the pressure change in the reservoir

Fluid migrate from one location to another

For any pressure changes in the reservoir, it might take

days, even years to manifest themselves in other parts of

the reservoir.

Therefore flow regime would not be steady state.

Darcy’s law could not be applied.

Time dependent variables should be examined.

3.3. IPR and VLP


Idealised Flow Pattern

They are:

Linear, Radial, Hemi-spherical and Spherical.

The most important cases are linear and radial models,

both used to describe the water encroachment from an

aquifer.

Radial model is used to describe the flow around the

wellbore.

3.3. IPR and VLP


Characterisation and Modelling of Flow Patterns

The actual flow patterns are usually complex, due to:

1. The shape of oil formations and aquifers are quite

irregular.

2. Permeability, porosity, saturation, etc are not

homogeneous.

3. Irregular well pattern through the payzone.

4. Difference in production rate from well to well.

5. Many wells do not fully penetrate the pay zone, or not fully

perforated.

3.3. IPR and VLP


Darcy’s Law

Henry Darcy(1803 – 1858)

P1 L P2

Q

A

Darcy’s law

µA

LPPKQ 21 −=

∆L∆P

µK

LPP

µK

AQU −=

−== 21

3.3. IPR and VLP


Darcy’s Law

DefinitionOne Darcy is defined as the permeability which will permit a fluid of

one centipoise viscosity to flow at a linear velocity of one centimeter

per second for a pressure gradient of one atmosphere per centimeter.

Assumptions for use of Darcy’s LawSteady flow

Laminar flow

Rock 100% saturated with one fluid

Fluid does not react with the rock

Rock is homogeneous and isotropic

Fluid is incompressible

3.3. IPR and VLP


Radial Flow for Incompressible Fluids

Reservoir is horizontal and of constant thickness h.

Constant rock properties φ and K.

Single phase flow.

Reservoir is circular of radius re.

Well is located at the center of the reservoir and is of radius rw.

Fluid is of constant viscosity µ.

The well is vertical and completed open hole.

3.3. IPR and VLP


Characteristics of the Flow Regimes

Steady-State: the pressure and the rate distribution in the

reservoir remain constant with time.

Unsteady-State (Transient): the pressure and/or the rate

vary with time.

Semi-Steady State (Pseudo Steady-State): is a special

case of unsteady state which resembles steady-state flow.

It is always necessary to recognise whether a well or a

reservoir is nearest to one of the above states, as the

working equations are generally different.

3.3. IPR and VLP


Radial Flow for Incompressible Fluids

Two cases are of primary interest:

Steady state: the reservoir conditions does not change with

time.Flow at r = re

Semi steady state or pseudo steady state: reservoir

conditions change with time, but dP/dr is fairly constant and

does not change with time.No flow occurs across the outer boundary.

Fluid production of fluids must be compensated for by the

expansion of residual fluids in the reservoir.

3.3. IPR and VLP


Coping with Complexities

There are essentially two possibilities:

1. The drainage area of the well, reservoir or aquifer is

modelled fairly closely by subdividing the formation into

small blocks. This results in a complex series of equations

which are solved by numerical or semi-numerical methods.

2. The drained area is represented by a single block in such

a way that the global features are preserved.

Inhomogeneities are averaged out or substituted by a

simple pattern. Here the equations of flow can be solved

analytically.

3.3. IPR and VLP


Skin Factor

khBq

PSs

SKIN

πµ

2

∆=

3.4. Skin factor


Skin Factor

The actual drawdown across the reservoir when a skin exists,

∆Pactual, can be related to the ideal drawdown predicted from

radial flow theory ∆Pideal and the skin pressure drop ∆PSKIN by:

[ ] [ ][ ]

SkhBqP

SkhBqP

PPP

PPPPP

PPP

sSKIN

sSKIN

actualwfidealwfSKIN

SKINidealwfeactualwfe

SKINidealwfactualwf

.2.141

.2

µπµ

=∆

=∆

−=∆

∆+−=−

∆+∆=∆

−−

−−

−−

In field units

3.4. Skin factor


Skin Factor

We can simply add the ∆PSKIN to the radial flow expression developed earlier e.g. for steady state flow of an

incompressible fluid, by adding in the skin pressure drop:

SkhTQP

Srr

khBqPP

sSKIN

w

esactualwfe

.1422

ln2.141

'

=∆

⎥⎦

⎤⎢⎣

⎡+⎟⎟⎠

⎞⎜⎜⎝

⎛=− −

µ

For compressible fluids

3.4. Skin factor


Flow Pattern

Flow in a tubing can be vertical, horizontal or inclined, depending on the direction of that tubing.

Flow in tubing can be:Single phase: simple

Multiphase: complicated, use experienced correlations.

Flow in tubing is affected by several factors:Pressure

Temperature

Viscosity

Roughness

…

3.5. Flow Pattern


Multiphase Flow Pattern

Multiphase flow up the tubing

3.5. Flow Pattern


Multiphase Flow Pattern

Horizontal Multiphase flow

3.5. Flow Pattern


Practical Application for Multiphase Flow

Multiphase flow correlations could be used for:Predict tubing head pressure at various rate

Predict flowing bottom hole pressure at various rate

Determine the PI of well

Select correct tubing sizes

Predict maximum flow rate

Predict when the well will die and hence time for artificial lift

Design artificial lift application.

The important variables are: tubing diameter, flow rate, gas

liquid ratio, viscosity, etc.

3.5. Flow Pattern


Chapter 4

Artificial Lifts


Content

4.1. Stages of Production

4.2. Artificial LiftsSucker Rod Pump

Hydraulic Jet Pumping

Electrical Submersible Pump

Hydraulic Piston Pumping

Progressive Cavity Pumping

Gas Lift

Plunger Lift

Chapter 4 - Content


Stages of Production

Production of a well can be divided into 3 stages:

Primary recovery: original reservoir drive mechanism

Secondary recovery: Reservoir pressure maintained by water, gas injection

Artificial lift

Enhanced recovery:Hydraulic fracturing

Matrix Acidization

Acid Fracturing

Frac Packing

4.1. Stages of Production


Artificial Lifts

Artificial lift is required when a well will no longer flow or

when the production rate is too low to be economic.

Over 90% production well is applying artificial lift.

Artificial lifts include:Submersible pump:

Gas lift

Plunger lift

4.2. Artificial Lifts


Artificial Lifts (cont.)

In details, artificial lifts include:Sucker Rod Pump

Gas Lift

Electrical Submersible Pump

Hydraulic Piston Pumping

Progressive Cavity Pumping

Plunger Lift

Hydraulic Jet Pumping




Each artificial lift system has a preferred operating and

economic envelope influenced by factors such as:

Fluid gravity

GOR

Production rate

Sand production

Development factors such as well type, location and

availability of power/gas.




4.2. Artificial Lift


Sucker Rod Pump – Surface Equipment



Sucker Rod Pump


Gas Lift

Gas lift methods include:Continuous Lift

Intermitten Lift


Gas Lift Valves

Two type of gas lift valveOrifice Valve

Dummy Valve


Gas Lift Valves (cont.)

Orifice valve

Dummy valve



Gaslift Valve Installation



Gaslift Valve Retrieval



ESP



Chapter 5

Enhanced Oil Recovery


Content

5.1. Type of Well Stimulation

5.2. Enhanced Oil recovery

Chapter 5 - Content


Well Stimulation

Why well stimulation is required?

Productivity of a well naturally arises fluids mobility and the

flow properties of the rock.

In some cases the degree of inter-connection of the pore

space may be very poor.

In such situations it may be beneficial to stimulate the

production capacity of the well.

5.1. Type of Enhanced Oil Recovery


Well Stimulation

What are the objectives in stimulation?

Stimulation techniques are intended to:Improve the degree of inter-connection between the pore space,

particularly for low permeability or vugular rocks

Remove or bypass impediments to flow, e.g. damage

Provide a large conductive hydraulic channel which will allow the

wellbore to communicate with a large area of the reservoir.



Well Stimulation

What are the techniques in stimulation?

In general, there are 4 principal techniques applied,

namely:Propped Hydraulic Fracturing

Matrix Acidisation

Acid Fracturing

Frac Packing



Enhanced Oil Recovery

Propped Hydraulic Fracturing

Whereby fluids are injected at a high rate and at a pressure

which exceeds the formation break down gradient of the

formation.

The rock will then fail mechanically producing a “crack”.

To prevent closure or healing of the fracture, it is propped

open by a granular material.

This techniques increases the effectiveness well bore

radius of the well.

5.2. Enhanced Oil Recovery


Propped Hydraulic Fracturing



Enhanced Oil Recovery (cont.)

Matrix Acidisation

This process is conducted at pressure below the formation

break down gradient.

It requires the injection of acid into the reservoir to either

dissolve the rock matrix and/or dissolve damage material

contaminants which has invaded the rock pore space.

The main objective of acidisation is to increase the

conductivity of the rock.




Acid Fracturing

Whereby acid injected at a pressure above the formation

break down gradient, creates a fracture.

The acid then etches flow channels on the surface of the

fracture which on closure will provide deep conductive flow

channels.




Frac Packing

Which is a shallow penetrating hydraulic fracture

propagated usually into a formation of moderate to high

permeability, and is subsequently propped open prior to

closure.

The process is used to reduce the near wellbore flow

induced stress, and in some cases can also limit/reduce

and production.



Review

Production Technology is a diverse and broad based

discipline, closely associated with the maintenance,

operation and management of wells.

It is critically important to the economic success of field

developments.

As a discipline it interfaces with drilling, geoscience,

reservoir engineers, as well as well intervention specialists.

It is a business driven responsibility but it based on an

integrated understanding of reservoir behavior and

engineering systems.

End of Lesson


Contents

Introduction1

Performance of Flowing Wells2

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Introduction to Gas Processing

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