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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
Lecture 13: 3November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 5November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 6November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 8November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 9November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 11November 24, 2009 Dr. Adel Salem - PTE 431
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
November 24, 2009 Dr. Adel Salem - PTE 431
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
November 24, 2009 Dr. Adel Salem - PTE 431
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
November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 15November 24, 2009 Dr. Adel Salem - PTE 431
Naturally Fractured Rock Cores Naturally Fractured Rock Cores
Lecture 13: 16November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 17November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 18November 24, 2009 Dr. Adel Salem - PTE 431
StressesStresses
Lecture 13: 19November 24, 2009 Dr. Adel Salem - PTE 431
StrainStrain
Lecture 13: 20November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 21November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 22November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 23November 24, 2009 Dr. Adel Salem - PTE 431
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:
Lecture 13: 25November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 26November 24, 2009 Dr. Adel Salem - PTE 431
ROCK PROPERTIES AND THEIR MEASUREMENTROCK PROPERTIES AND THEIR MEASUREMENT
6. Uniaxial & Triaxial Tests
Lecture 13: 27November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 28November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 29November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 30November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 31November 24, 2009 Dr. Adel Salem - PTE 431
The Mohr DiagramThe Mohr DiagramThe angle that fractures theoretically should make with the ygreatest principal stress, σ1, is obtained from:
Lecture 13: 32November 24, 2009 Dr. Adel Salem - PTE 431
Stresses in a Reservoir RockStresses in a Reservoir Rock
Lecture 13: 33November 24, 2009 Dr. Adel Salem - PTE 431
Fracture PermeabilityFracture Permeability8. Frac Permeability
Primary k vs. Secondary k ,Orfracture kf:
Fracture Permeability:
Lecture 13: 34November 24, 2009 Dr. Adel Salem - PTE 431
Rock compressibility:Rock compressibility:9. 9. Rock compressibilityRock compressibility
Lecture 13: 35November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 36November 24, 2009 Dr. Adel Salem - PTE 431
Stresses in a Reservoir RockStresses in a Reservoir Rock
Lecture 13: 37November 24, 2009 Dr. Adel Salem - PTE 431
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
Lecture 13: 38November 24, 2009 Dr. Adel Salem - PTE 431
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.
Lecture 13: 39November 24, 2009 Dr. Adel Salem - PTE 431
Principle of least resistance
Least Principal StressLeast Principal Stress
Horizontal fracture Vertical fracture
November 24, 2009 Dr. Adel Salem - PTE 431
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
November 24, 2009 Dr. Adel Salem - PTE 431
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 13: 43November 24, 2009 Dr. Adel Salem - PTE 431