WELL PERFORMANCE ANALYSISWELL PERFORMANCE ANALYSIS

P.O.G.CP.O.G.CSubject of ConferenceSubject of Conference

In The Name of God

OutlinesOutlines

IntroductionIntroduction Inflow performance relationship (IPR)Inflow performance relationship (IPR) Tubing performance relationship (TPR)Tubing performance relationship (TPR) Wellhead performance relationship (WPR)Wellhead performance relationship (WPR)

Goals of Well Analysis Determination of the flowrateDetermination of the flowrate

To determine under what flow conditions well will cease to To determine under what flow conditions well will cease to produce. produce.

To select the most economical time for the installation of artificial To select the most economical time for the installation of artificial lift lift

ToTo optimize the well conditions and system geometryoptimize the well conditions and system geometry

To analyze each component in the well systemTo analyze each component in the well system

5

porous media

vertical well

surface facility Separator

Stock tank

Sales Gas

production system

Inflow performance relationship (IPR) is defined as the relation Inflow performance relationship (IPR) is defined as the relation between the surface flowrate (q) and bottomhole flowing pressure between the surface flowrate (q) and bottomhole flowing pressure (P(Pwfwf). ).

Inflow Performance Relationship (IPR)

IPR curves are used to analyze the deliverability of wells by IPR curves are used to analyze the deliverability of wells by estimating the production rate for a given bottomhole flowing estimating the production rate for a given bottomhole flowing pressure and vice versa and also reflect the ability of the reservoir to pressure and vice versa and also reflect the ability of the reservoir to deliver fluid to the wellbore. deliver fluid to the wellbore.

IPR Curve

11 ( (Straight line (Constant PI)Straight line (Constant PI)

22 ( (A curve which shows that the PI is decreasing with rateA curve which shows that the PI is decreasing with rate

33 ( (A combination of 1 and 2A combination of 1 and 2..

Constant PIConstant PI

)( wfro PPJq • Production rate is proportional to the pressure drawdown

• Occurs for single phase liquid flow

IPR Equation for Multiphase FlowIPR Equation for Multiphase Flow

Vogel’s EquationVogel’s Equation

Fetkovich’s Equation Fetkovich’s Equation

Klins and Majcher EquationKlins and Majcher Equation

Pudjo Sukarno’s EquationPudjo Sukarno’s Equation

Fetkovich’sFetkovich’s EquationEquation

nwfro PPCq )( 22

Using data from multirate tests on 40 different oil wells in six fields, Using data from multirate tests on 40 different oil wells in six fields, Fetkovich showed that the following approach was suitable for predicting Fetkovich showed that the following approach was suitable for predicting performance:performance:

where 0.5 ≤ n ≤ 1.0where 0.5 ≤ n ≤ 1.0

n

r

wf

o

o

P

P

q

q])(1[

)(2

max

This can be expressed in a form similar to Vogel’s IPRThis can be expressed in a form similar to Vogel’s IPR..

))PP

rr22 – P

– P

wf

wf22

( (ps

iaps

ia

Flowrate ( q ) STB/dFlowrate ( q ) STB/d LogLog

LogLog

11//nn

IPR Curve for Multiphase FlowIPR Curve for Multiphase Flow

Effective Parameters on Inflow PerformanceEffective Parameters on Inflow Performance

Dow point and bubble point pressureDow point and bubble point pressure

Reservoir pressure depletionReservoir pressure depletion

Skin effectSkin effect

Tubing Performance Relationship (TPR or VFP)Tubing Performance Relationship (TPR or VFP)

Tubing performance may be defined as the behavior of a well in giving up the reservoir fluids to the surface .

Flowing bottomhole pressure (tubing intake pressure) for each production rate equals total pressure drop through the tubing and any

bottomhole restriction and wellhead pressure.

Pwh

Q

Pw

f

relation between the surface flowrate (q) and relation between the surface flowrate (q) and tubing intake ressure(Pwf).(Pwf).

Pressure Drop In the Vertical WellPressure Drop In the Vertical Well

Hydrostatic pressure dropHydrostatic pressure drop

Friction pressure dropFriction pressure drop

Vertical Two-Phase Flow PatternVertical Two-Phase Flow Pattern

Bubble flow (A)Bubble flow (A)

Slug flow (B)Slug flow (B)

Transition flow (C)Transition flow (C)

Annular-mist flow (D)Annular-mist flow (D)

Flow Regimes

Change in phase behavior in the production tubing

Natural flowNatural flow Accrue when the wellbore flowing pressure and tubing intake pressure

(at perforation depth) are equal, TPR and IPR curves intersect together. The intersection of TPR and IPR curves called natural flow

point.

Variables that Effects on Natural FlowVariables that Effects on Natural Flow

Wellhead pressureWellhead pressure

Gas/liquid ratio Gas/liquid ratio

Tubing sizeTubing size

Static pressure &…Static pressure &…

Effect of Wellhead PressureEffect of Wellhead Pressure

Effect of Gas/Liquid RatioEffect of Gas/Liquid Ratio

Effect of Tubing DiameterEffect of Tubing Diameter

Effect of the SkinEffect of the Skin

BHSP

59005500500045004100

Wellhead PerformanceWellhead Performance By using of the wellhead performance can show in which range of flowrate By using of the wellhead performance can show in which range of flowrate

in the well column, the hydrostatic pressure drop is more than friction in the well column, the hydrostatic pressure drop is more than friction pressure drop. pressure drop.

26

porous media

Separator

Stock tank

Sales Gas

production system

vert

ical w

ell

IPR & TPR & WPRIPR & TPR & WPR

PPwhwh

TPRTPR

WPRWPR

RateRate

Pre

ssu

reP

ress

ure

IPRIPR

Choke PerformanceChoke Performance The main function of a choke is to dissipate large amounts of potential The main function of a choke is to dissipate large amounts of potential

energy (i.e., pressure losses) over a very short distanceenergy (i.e., pressure losses) over a very short distance . .

Two types of two-phase flow can exist in a chokeTwo types of two-phase flow can exist in a choke: :

Critical flowCritical flow

Subcritical flow Subcritical flow

PP1 1 = Wellhead ( upstream) pressure= Wellhead ( upstream) pressure

PP2 2 == downstream pressuredownstream pressure

P2/P1 ≤ %50 = RC

P2/P1 > %50 = RC

CPR and WPRCPR and WPR

The intersection of the WPR and choke performance curve defines the The intersection of the WPR and choke performance curve defines the rate of natural flow for the given choke size. rate of natural flow for the given choke size.

Gilbert and RosGilbert and Ros

CBL dGLRAqDP )(1

RecommendRecommend

Basic requirement for well performance Basic requirement for well performance analysis is the ability to determine , so it is analysis is the ability to determine , so it is required to determine BHP using surface datarequired to determine BHP using surface data

Determine the best correlation to predict the Determine the best correlation to predict the fluid behavior in well column same as fluid behavior in well column same as culender smite or duckler &…culender smite or duckler &…

Examine the quality of separator tests using Examine the quality of separator tests using daly reports of SPGC daly reports of SPGC

Thanks for your Thanks for your attentionattention