Lecture%2013_Petroleum%20Production%20Engineering%202_Office%202007

Petroleum Production Engineering 2(PTE 431)

By SDr. Adel Salem

Asst. Prof. PE

Suez Canal UniversityFaculty of Petroleum and Mining Engineering

Petroleum Engineering DepartmentWinter Semester 2009/2010

OutlinesOutlinesPerformance of Productive Formations,M lti h Fl i V ti l d H i t l Pi liMultiphase Flow in Vertical and Horizontal Pipelines.Flowing Well Performance, (Vertical Lift Performance),Nodal AnalysisNodal Analysis,Bean Performance,Principle of Gas-Lift,Gas Lift DesignStimulation : 1. Hydraulic FracturingStimulation : 1. Hydraulic FracturingP i Pumping ….

Lecture 13: 2November 24, 2009 Dr. Adel Salem - PTE 431

Lecture 13Sti l ti Sti l ti Stimulation Stimulation 1 Hydraulic Fracturing1. Hydraulic Fracturing

November 19, 22, 2009November 19, 22, 2009


Quiz- After Lecture 12Quiz After Lecture 121. The following test was conducted on a solution gas drive

reservoir:reservoir:Given data:Av. Reservoir Pressure = 2000 psiPwf = 1500 psi at qo = 650 bpd

Using Vogel correlation find the following:g g g1. AOF2. The flow rate at Pwf = 500 psi

2. Gas lifting system is considered: (your answer may be not one choice)(your answer may be not one choice)

1. Primary Recovery 2. Secondary Recovery3. Enhanced Oil Recovery (EOR)4 Improved Oil Recovery (IOR)

Lecture 13: 4

4. Improved Oil Recovery (IOR)

November 24, 2009 Dr. Adel Salem - PTE 431

OutlineOutline

Stimulation Treatments

1.1. Hydraulic Fracturing: Hydro.Hydraulic Fracturing: Hydro. FracFrac..

22 Acid Treatments: Matrix AcidizingAcid Treatments: Matrix Acidizing2.2. Acid Treatments: Matrix AcidizingAcid Treatments: Matrix Acidizing


Stimulation: DefinitionStimulation: DefinitionStimulationStimulation: the action of attempting to improve and enhance a well’s performance by the application of horsepower using pumping equipment, placing sand in artificially created fractures in rock or using chemicals such as acid to dissolvefractures in rock or using chemicals such as acid to dissolve the soluble portion of the rock.

OR

Hydraulic fracturingHydraulic fracturing and Matrix stimulationMatrix stimulation treatments are used to restore or enhance well productivity and performed in all types of formations and reservoir environmentsall types of formations and reservoir environments.


StimulationStimulation

1. Hydraulic Fracturing1. Hydraulic Fracturing1. Hydraulic Fracturing1. Hydraulic Fracturing

Outline: Hydraulic Fracturing

IntroductionR k A d F t M h iRock And Fracture Mechanics

Fracturing Fluids And AdditivesFracturing Fluids And AdditivesPropping Agents And Fracture Conductivity

Fracture Treatment DesignAcid FracturingF t G t M d lFracture Geometry Models

Frac Job EvaluationFrac Job EvaluationComputer Designing ProgramsCase Study And Example


What Is Fracturing?What Is Fracturing?Hydraulic FracturingHydraulic Fracturing: an operation in which a specially blended liquids is pumped down a well and into ablended liquids is pumped down a well and into a formation under pressure high enough to cause the formation to open a crack, Forming passages through

hich oil can flo into the ellborewhich oil can flow into the wellbore.

Sand grains aluminum pellets glass beads or similarSand grains, aluminum pellets, glass beads, or similar material are carried in suspension into the fractures. When the pressure is released at the surface, the fractures partially close on the Proppants leaving channels for oilpartially close on the Proppants, leaving channels for oil to flow through to the well.


What Is Fracturing?What Is Fracturing?

Hydraulic fracturing is the process of using hydraulic pressure to create an artificial fracture in a reservoir,

The fracture grows in length, height and width byThe fracture grows in length, height and width by pumping a mixture of fluid and Proppant at high pressure,

The fractures generally travel a few hundred feetThe fractures generally travel a few hundred feet, although fracturing fluids have been known to travel 3000 ft away from the well.

Lecture 13: 10November 24, 2009 Dr. Adel Salem - PTE

431

Why Fracture?Why Fracture?Hydraulic fracture operations may be performed on a well for one (or more) of three reasons:

To bypass near-wellbore damage and return a well to its “natural” productivity

To extend a conductive path deep into a formation and thus increase productivity beyond the natural l llevel

To alter fluid flow in the formation.


Introduction: History of Hydraulic FracturingIntroduction: History of Hydraulic Fracturing40’s First treatment in 1947 in the Hugoton field in Kansas, USA using napalm and

crushed wall nut hulls,

Stanolind Oil and Gas Company (Pan American Petroleum Corp. >> Amoco >> BP) researched the breakdown process and developed the fracturing process “Hydrafrac”.

I 1949 th H d f fi t d il bl l i l t thIn 1949 the Hydrafrac process was first made available exclusively to the Halliburton Oil Well Cementing Company “Howco”. Not long after in 1953 the exclusive license agreement with the Halliburton Oil Well Cementing Company was terminated making the fracturing process available to other service companies.

Early 70’s Oil-based fluids with low Proppant concentrations

70’s Linear water based gels

80’s Linear water based gels in seventies followed by X-linked fluids in the eighties, allowing Proppant concentrations up to 20 lbs/gal,

90’s Massive fracs and Frac & Packs with Screen-out designs90 s Massive fracs and Frac & Packs with Screen-out designs

High capacity, sophisticated pumps and blenders, etc.

Industry-wide understanding of the principle

Computer aided design and executionComputer aided design and execution


World Wide ApplicationWorld Wide ApplicationWorld Wide ApplicationWorld Wide Application

Sh ll C dSh ll C d(Mearsk)(Mearsk)

Sh ll C dSh ll C d(Mearsk)(Mearsk)

PDOPDO

Shell CanadaShell Canada

Syria ShellSyria Shell

Thai ShellThai Shell

NAMNAMBEBBEB( )( )

Shell EgyptShell Egypt(Shell Oil)(Shell Oil)PDOPDO

Shell CanadaShell Canada

Syria ShellSyria Shell

Thai ShellThai Shell

NAMNAMBEBBEB( )( )

Shell EgyptShell Egypt(Shell Oil)(Shell Oil)

BSPBSPPDOPDO

SPDCSPDC

Thai ShellThai Shell(HOCOL)(HOCOL) BSPBSP

PDOPDO

SPDCSPDC

Thai ShellThai Shell(HOCOL)(HOCOL)

Shell ToddShell Todd

CAPSACAPSA

Shell ToddShell Todd

CAPSACAPSA

Shell ToddShell ToddShell ToddShell Todd


Present Fracture Stimulation Activities in ShellPresent Fracture Stimulation Activities in Shell

Application Examples

Germany Multi-frac horizontal wells - PIF of 5+South Texas low cost HPHT fracs

2001

South Texas low cost HPHT fracsPDO LNG fracs - PIF of 2.5PDO Athel fracs - PIF of 15+Egypt Obayed fracs - PIF of 3Egypt Obayed fracs - PIF of 3


Fracture Stimulation Integration of Multi-DisciplinesFracture Stimulation Integration of Multi Disciplines

Production EngineeringReservoir Engineering Well Design & CompletionRock MechanicsFluid MechanicsFl id Ch i t Fluid Chemistry Material BehaviourOperationsOperations


Naturally Fractured Rock Cores Naturally Fractured Rock Cores


Formation CharacteristicsFormation CharacteristicsRock mechanics play an important role in governing the geometry of propagating hydraulic fracturespropagating hydraulic fractures.

Some factors the affect the fracture propagation include:Variations in in situ stresses existing in different layers of rocksVariations in in-situ stresses existing in different layers of rocks,Relative bed thickness of formations in the vicinity of the fracture,Bonding between formations,

i i i i iVariations in mechanical rock properties,Fluid pressure gradients in the fracture, andVariations in pore pressure between zones.

Desired Fracture Characteristics:Maximum permeability (conductivity)Fracture penetrationProppant placementSettled fracture width


Rock Mechanics: Basic ConceptsRock Mechanics: Basic ConceptsSome of the most important aspects of rock mechanics as applied to the reservoir stimulation process:

1. Stresses

2. Strain


StressesStresses


StrainStrain


Stress-Strain CurveStress Strain Curve

During testing of a material During testing of a material sample, the stress–strain curve is a graphical representation of the relationship between stress relationship between stress, derived from measuring the load applied on the sample, and strain, derived from measuring derived from measuring the deformation of the sample, i.e. elongation, compression, or distortion.


Stress vs. StrainStress vs. Strain3. Stress/Strain Relationships

When submitting a rock sample to load, it will deform, the higher the stress level, the more strain the rock

ill iwill experience.

E is Young’s modulusE is Young’s modulus


Effective StressEffective Stress4. Pore Pressure and Effective

StStress

Pore fluids play an important p y prole because they support a portion of the total applied stress.

Effective stress :

Or

Where α between 1 and 0


Who Carries the Load?

Total Stress = Effective Stress + Total Stress = Effective Stress + αα **[Pore Pressure][Pore Pressure]

Force Pore FluidGrains Force Pore FluidGrains

α ∼ 0 7Biot’s constant α ∼ 0 7Biot’s constant α ∼ 0.7Biot s constant α ∼ 0.7Biot s constantNovember 24, 2009 Dr. Adel Salem - PTE 431

Failure CriteriaFailure Criteria

5. Failure Criteria

It is a relation between the principal eff. Stresses, representing a limit b d hi h i bili beyond which instability or failure occur.Th t l it i The most popular criteria include:


Rock Properties And Their MeasurementRock Properties And Their MeasurementUniaxialUniaxial and TriaxialTriaxial tests are considered the most

f l t t i th t d f h i l k useful tests in the study of mechanical rock properties. The difference between them resides in the presence or absence of confining pressure the presence or absence of confining pressure applied to the specimen. A typical triaxial testing system is shown schematically in the next Figure.y y g


ROCK PROPERTIES AND THEIR MEASUREMENTROCK PROPERTIES AND THEIR MEASUREMENT

6. Uniaxial & Triaxial Tests


7. Mohr Circle7. Mohr CircleThe Mohr circle contains all the information

t d t i th t t t t necessary to determine the stress state at any orientation in the rock sample.

Horizontal axis represents the effective normal normal stressstress the vertical one represents shear stressshear stressstressstress, the vertical one represents shear stressshear stress.

The intersection with the horizontal axis determine The intersection with the horizontal axis determine the min and max normal stressesmin and max normal stresses. The apex is the max max shear stressshear stress.shear stressshear stress.


Mohr-coulomb Criteria Mohr coulomb Criteria The point of intersection can be used to determine the be used to determine the angle θ between the normal to the failure plane and the di ti f direction of σ.


The Mohr DiagramThe Mohr DiagramThe relations between stress and rupture for many rocks may be determined graphically by Mohr’s stress circles. Consider g p y yan imaginary plane through a cylindrical rock specimen inside a triaxial compression chamber. The confining pressure σ3 is applied and the longitudinal load σ1 is increased until failure occurs Continued loading of the rock specimen will cause it to occurs. Continued loading of the rock specimen will cause it to deform via micro-cracks which, as more loading is applied, extend and ultimately join together to form a macro-weakness plane (shear plane) along which rupture will occur. At the peak p ( p ) g p pload, the stress conditions are: σ1 = F/A and σ3 = P, where F is the highest load supportable parallel to the cylindrical axis, and p is the pressure in the confining medium.

Failure or rupture is caused by a critical combination of both shear and normal stresses. This state can be represented by a point in the plane of τ vs σ known as Mohr’s diagrampoint in the plane of τ vs. σ, known as Mohr s diagram.


The Mohr DiagramThe Mohr DiagramSeveral triaxial tests at increasing confining pressures will lead to several Mohr’s circles; each pressures will lead to several Mohr’s circles; each test must be run until rupture occurs.

A line drawn tangent to the circles is known as “Mohr’s envelope.” Stresses that fall within the

l b l h f f l h envelope are below the point of failure, whereas outside the envelope the stresses will cause failure.failure.

The Angle that this envelope line makes with the g phorizontal axis of the diagram, is the angle of internal friction.


The Mohr DiagramThe Mohr DiagramThe angle that fractures theoretically should make with the ygreatest principal stress, σ1, is obtained from:


Stresses in a Reservoir RockStresses in a Reservoir Rock


Fracture PermeabilityFracture Permeability8. Frac Permeability

Primary k vs. Secondary k ,Orfracture kf:

Fracture Permeability:


Rock compressibility:Rock compressibility:9. 9. Rock compressibilityRock compressibility


In-situ StressesIn situ StressesThe in-situ stress, as it affects hydraulic fracturing, is the local stress in a given rock mass at depth stress in a given rock mass at depth.

The three principal stress components of the local state of stress, which are typically compressive, anisotropic and non-homogeneous, are the result of the weight of the overlying rock (overburden), burial history, pore pressure, temperature,

k ti di i t t i d i l tirock properties, diagenesis, tectonics and viscoelasticrelaxation.

In addition, drilling, production and fracturing can also alter some of these parameters, thereby changing the local stress field


Stresses in a Reservoir RockStresses in a Reservoir Rock


In-Situ stressesIn Situ stresses

The in-situ stresses control the fracture orientation (vertical The in situ stresses control the fracture orientation (vertical or horizontal and the azimuth of the fracture plane), vertical height growth and containment, surface treating pressures, Proppant crushing and embedment Proppant crushing and embedment.

Fractures are generally planar and oriented perpendicular to g y p p pthe minimum in-situ stress


10. Fracture Direction in Horizontal Wells10. Fracture Direction in Horizontal WellsFor horizontal wellsFor horizontal wells, if drilled perpendicularperpendicular to the minimum horizontal stress the created fracture will be minimum horizontal stress, the created fracture will be longitudinal.

If the horizontal well is drilled parallelparallel to the minimum horizontal stress, the created fractures are expected to be perpendicular to the horizontal well, and transverse be perpendicular to the horizontal well, and transverse fractures will be created.

h l ll d (h hl ) d d ll d ll d For horizontal wells and (highly) deviated wells drilled in an intermediate direction relative to the direction of the in-situ horizontal stresses, non-planar fracture geometry p g ymay be created near the wellbore.


Principle of least resistance

Least Principal StressLeast Principal Stress

Horizontal fracture Vertical fracture


Longitudinal Vertical Fracture - Horizontal wellLongitudinal Vertical Fracture Horizontal well

Can it be Can it be done?done?

σH,min

done?done?

σH,max

xf

σH,min

Lecture 13: 41

H,max


Transverse Vertical Fractures - Horizontal WellTransverse Vertical Fractures Horizontal Well

Radial Radial

σH,max

Hydraulic Fracture

σH,max

converging converging flow in flow in fracfrac

D

xff

Lecture 13: 42

σH,minNovember 24, 2009 Dr. Adel Salem - PTE 431

Lecture%2013_Petroleum%20Production%20Engineering%202_Office%202007

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