Petroleum Production Engineering - Lecture 2 - Production From Undersaturated Oil Reservoirs - Final
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BEng (Hons) Petroleum Engineering Course: Petroleum Production Engineering (ENG 691) Instructor Dr. Tarek Darwich 1
description
Petroleum Production Engineering
Transcript of Petroleum Production Engineering - Lecture 2 - Production From Undersaturated Oil Reservoirs - Final
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BEng (Hons) Petroleum Engineering
Course:
Petroleum Production Engineering (ENG 691)
Instructor
Dr. Tarek Darwich1
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Petroleum Production Engineering
Weekly Petroleum Production News:
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Petroleum Production Engineering
Course Outlines:
What is Petroleum Production Engineering?
The Inflow Performance Relationship (IPR)
The Outflow Performance
Well Deliverability & Production Forecast
Well Completion & Artificial Lift Systems
Well Stimulation
Surface Production Separation & Treatment of produced Fluids.
Main Reference Book:
Economides, M.J., Hill, A.D., Ehlig-Economides, C. and Zhu, D., Petroleum Production System, 2nd ed., Prentice Hall, 20123
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Chapter 2 Production from Under-saturated Oil ReservoirsProduction from Under-saturated Reservoirs
Under-saturated OilReservoirs: Reservoir pressure is abovethe bubble point pressure.
No free gas exists till thereservoir pressure dropsbelow the bubble pointpressure.
The reservoir drive energyis provided by the bulkexpansion of the reservoirrock and fluids (oil andwater).
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Chapter 2 Production from Under-saturated Oil ReservoirsProduction from Under-saturated Reservoirs
Main Flow Geometries
Linear Flow.
Radial Flow
Spherical Flow
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Chapter 2 Production from Under-saturated Oil ReservoirsIntroduction
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
Steady-State:
means all parameters including flow rate and all pressures, areinvariant with time.
For a vertical well draining a region with radius re, this requiresthat the pressure at the well boundary, pe, and the bottomholeflowing pressure, pwf, are constant with time.
pe can remain constant only in the presence of pressuremaintenance either by natural water influx from an aquifer or byinjection.
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
- The near-wellbore region is extremely important in well production because that is where much of the pressure drop occurs.
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
The Skin Concept:
In many producing wellsthe value of the formationpermeability close to thewellbore is different from itsvalue further back in thereservoir.
Reasons:
Invasion of the poresby mud filtrate.
Mechanical disturbanceof the sand grains.
resistance to flowcreated by gravel pack.
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
The Skin Concept:
Skin, s, results in an additional steady-state pressure dropgiven by:
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Chapter 2 Production from Under-saturated Oil ReservoirsSteady-State Well Performance
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Chapter 2 Production from Under-saturated Oil ReservoirsTransient Flow
Transient Flow:
If you picked a piece of rock and threw it in a calm water in asmall lake, a radial system of waves will radiate towards you fromthe point of entry of the rock.
Before the waves reach the banks of the lake, pressuredistributions (pressure transients) are changing rapidly and notconstant.
The above analogy to hydrocarbon reservoirs.. If fluidproduction at a constant rate q is initiated at the well bore,pressure transients will radiate from the well and travel towards theouter boundaries.
The rate of travel of the pressure transient is independent of theproduction rate at the well but is proportional to a property of thereservoir termed formation diffusivity.
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Chapter 2 Production from Under-saturated Oil ReservoirsTransient Flow
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Chapter 2 Production from Under-saturated Oil ReservoirsTransient Flow Equations
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Chapter 2 Production from Under-saturated Oil ReservoirsPseudosteady-State Flow
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s
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Chapter 2 Production from Under-saturated Oil ReservoirsPseudo-steady State Flow Equations
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Average reservoir pressure
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Chapter 2 Production from Under-saturated Oil ReservoirsTransition to Pseudo-steady from Infinite
Acting Behaviour
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Dimensionless Time(depends on the drainage shape
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Chapter 2 Production from Under-saturated Oil ReservoirsWells Draining Irregular Shapes
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Dietz Shape factor
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Chapter 2 Production from Under-saturated Oil ReservoirsWells Draining Irregular Shapes
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Chapter 2 Production from Under-saturated Oil ReservoirsInflow Performance Relationship (IPR)
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The IPR is a relationship between the well production rate (q)and the driving force in the reservoir
The driving force in the reservoir is the difference between theinitial outer boundary (pe) or average reservoir pressure (pr)andthe bottom hole flowing pressure (Pwf)
What a well can produce is a combination of what the reservoircan deliver and what the imposed wellbore hydraulics allow.
Productivity Index = J = q/(Pr-Pwf)
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Chapter 2 Production from Under-saturated Oil ReservoirsEffect of the presence of Water
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The permeability k in all the previous equations should bereplaced by the effective permeability of the oil ko.
Effective Permeability (ko) =
Absolute Permeability (k)* relativePermeability (kr)
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Chapter 2 Production from Under-saturated Oil ReservoirsEffect of the presence of Water
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