PERFORM - Evaluating Pressures in Completions - En

7/31/2019 PERFORM - Evaluating Pressures in Completions - En

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EvaluatingPressures inCompletions fromPressures at theWellhead

Unleash Your Asset Potential

Alfonso R. Reyes,IHS Energy TechnicalPrepared for ATCE 2012San Antonio, TexasOctober 2012


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Copyright 2011 IHS Inc. All Rights Reserved.

Introduction

2

CaseWe want to complete a gas well with a

gravel pack.

The goal for this study is finding the

proper tubing size and the optimum

number of shots per foot for thecompletion.

Additionally, we would like to develop a

method to evaluate the pressure drop in

the gravel pack from pressures measured

at the surface.

Activities1. Find the tubing size

2. Create scenarios for different

number of shots per foot

3. Design a plot that will allow to

correlate the pressure drop at thegravel pack with pressures at the

wellhead


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Well Data

3

Completion Data

Completion Type Gravel PackPerforation Interval 30 ft

Perforation Density 2 SPF

Perforation Diameter 0.750 in

Perforation Length x in

Avg Reservoir Perm x md

Perm Ratio - Kc/Kf x

Gravel Pack Length 10.000 in

Gravel Pack Perm 2400.000 md

Fluid Data

Oil Gravity 50 API

SG Gas 0.65

Watercut 0 %

SG Water 1.070

Condensate Yield 0.0005 bbl/MMcf

Reservoir Data

Reservoir Pressure 4000 psi

Reservoir Temperature 240 FAvg Resv Permeability 100.0 md

Reservoir Thickness 30 ft

Perforation Interval 30 ft

Reservoir Skin 6.000

Wellbore Radius 5 in

Reservoir Radius 450 ft

Shape Factor 0.564

Reservoir Area 640 Acres

Setup

Well Fluid Type GasFlow Direction Production

Location Onshore

Analysis Type System

Node Position Bottomhole

Wellbore Data

Wellhead Pressure 1200 psig

Wellhead Temperature 40 F

Top of Perforations 10500 ft

Flow Type @ Surface Tubular

Type MD

(ft)

OD

(in)

ID

(in)

Casing 11000 8.625 7.625

Tubing 10000 4.500 4.000


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2

Starting PERFORM

4

1 2

1 Open an existant case Create a new case

OR


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Workflow in PERFORM

5

Setup

Reservoir Data

Completion Data Wellbore DataTemperature Gradient

Fluid Data

IPR / Inflow Correlations

Wellbore / VLP / Outflow CorrelationsTemperature Correlations


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Correlation for the Inflow Curve

6

Jones et al (1976)


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Inflow Curve Correlation: Jones et al (1976)

7

Inflow CorrelationJones et al (1976)For high flow rates the Darcy

equation does not provide for

energy losses due to turbulent flow,

especially gas, through theperforations in the completion.

In the Jones, Blunt y Gaze equation,

developed in 1976, the effects due

to turbulent flow are finally taken in

consideration. This effect is

considerable in the neighborhood of

the wellbore where the permeability

decreases.


8/27Copyright 2011 IHS Inc. All Rights Reserved.

Inflow Correlation: Jones et al (1976)

8

a b

Turbulent flow Laminar flow

whereIs the turbulence coefficient or inertial

coeficient (1/ft)



Inflow Curve: Jones et al (1976)

9

a b

turbulent flow Laminar flow

Reservoir Temperature,

R

Specific Gravity of

gas

Drainage area

factor

Skin factor

Prforated Interval, ft

Well

radius, ft

Viscosity of

gas, cp

Formation

Thickness, ft

Effective

Permeability, md

Turbulence Coeficient,

1/ft

Flowing Pressure, psi

Average Formation

Pressure, psi

Gas Flow Rate,

SCF/D

Compressibility

Coefficient



Scenarios for optimum tubing size

10

We create three scenariosin the parametric study

1

2-7/82

3-1/23

4-1/2



Plot for optimum tubing size

11

2-7/8

3-1/2

4-1/2

Scenarios 1 2 3



Project File No.1

12

Gaswell.pf7 Press double-click on the icon on

the left to open the file in PERFORM

Copyright 2011IHS Inc. AllRights Reserved.

Plot for optimum tubing size

11

2-7/8

3-1/2

4-1/2

Scenarios 1 2 3



Analysis of the Perforation Density

13

Next StepGravel PackAfter we have found the optimum

tubing size, 4-1/2, we will proceed to

resolve the optimization of the gravelpack at different perforation

densities.

ActivitiesCreate scenariosUse the following number of shots

per foot (SPF) to create five

scenarios:2, 4, 8, 12 y 16.



Scenarios for the perforation densities

14

We create five scenarios inthe parametric study section

1

2SPF

2

4SPF

3

8SPF

4

12SPF

5

16SPF

SPF: shots per foot



Scenarios at different perforations in the

gravel pack

15

Base Case Case 2 Case 3 Case 4 Case 5 units



Inflow plot at different perforation densities

16

Flow Rate, K SCF/D

BottomholePressure,psig



Differential Pressures at the gravel pack

17

161284 SPF2

Our solution pressure will be the lower in the gravel

pack or the pressure closer to 300 psi

Flow Rate, K SCF/D

PressureDrop,psi



Project File No. 2

18

GasWell_Jones_45+SPF.pf7 Press double-click on the icon on

the left to execute the project file

directly in PERFORM

Copyright 2011IHS Inc. All RightsReserved.

Diferential Pressure at the gravel pack

17

161284 SPF2

Our solution pressure will be the lower in thegravel pack or the pr essure closer to 300 psi

Flow Rate, K SCF/D

PressureDrop,psi



Pressure Analysis at the wellhead

19

Next StepWellhead Pressure

Once the optimum perforation

density has been determined to be 16

SPF (shots per foot), we proceed toanalyze the behavior of the outflow

curve at different wellhead pressures

(Pwh).

The objective is investigating: (i) what

happens with our bottomholepressure or Pwfas we vary Pwh, and (ii)

what is the pressure loss in the gravel

pack at different Pwh

ActivitiesCreate scenarios for PwhWe will use the following wellhead

pressure values:

800, 1000, 1200, 1400 y 1600 psi,to create our five scenarios.



Scenarios for Wellhead Pressures

20

Base Case Case 2 Case 3 Case 4 Case 5 units



Plot for Pwh scenarios

21

What happen with Pwf at

different values of Pwh?

Flow Rate, K SCF/D


PARAMETRIC STUDY



If we select SPF=16

22

4 SPF

8

12

16

P

If we observe the pressure at the wellhead

Pwh and the flow at the surface, we could

visualize indirectly the pressure drop in the

gravel pack downhole

Flow Rate, K SCF/D

PressureDrop,psig

PARAMETRIC STUDY



Project File No. 3

23

GasWell_Jones_45+SPF+Pwh.pf7 Press double-click on the icon on

the left to execute the project file in

PERFORM

Copyright 2011 IHS Inc. AllRights Reserved.

If we select SPF=16

22

4 SPF

8

12

16

P

If we observe the pressure at the wellhead

Pwh and the flow at the surface, we could

visualize indirectly the pressure drop in thegravel pack downhole

Flow Rate, K SCF/D

PressureDrop,psig

PARAMETRIC STUDY



Effect of a partial perforation of the interval

24

Using the same methodology we

could analyze the effect on the wellproduction if the formation interval

(h) is partially perforated (hp)

hp

30.00

22.50

15.00

7.50

3.00

Flow Rate, K SCF/D




Project File No. 4

25

GasWell_Jones_45+SPF16_hp(var)_h30.pf7

Press double-click to open the

project file directly in PERFORM

Copyright 2011IHS Inc. AllRights Reserved.

Effect of a partial perforation of the interval

24

Using the same methodology we

could analyze the effect on the well

production if the formation interval(h) is partially perforated (hp)

hp

30.00

22.50

15.00

7.50

3.00

Flow Rate, K SCF/D




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References


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PERFORM - Evaluating Pressures in Completions - En

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