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Wellbore Implosion: Case Study of Perforation Enhancement

MENAPS 16-24

AUTHORS: Mahmood Kalbani, Hassan al Saadi ,Muhammad Mirza, Medco Energi and Shafie Jumaat, Schlumberger

NOV 14TH, 2016

MUSCAT, OMAN

Agenda

• Field Background

• Perforation Damage

• Dynamic underbalance technique

• Wells candidates

• Pre-job simulation

• Operation

• Wells performance

AGENDA

1

Field Background

• Field on land in Oman with more than 250 producers and injectors

• Sandstone 1500m deep at 50mD and 20% porosity.

• 4.5” or 7” cemented casing.

• Water injection started in January-2013 but some wells with low injectivity.

• Perforating system including reactive liner charges and propellant tried but result was not satisfactory.

• This case study is about dynamic underbalance post perforating (DUB-PP)

INTRODUCTION

2

Perforation Damage

• Perforation damage:

• Plugged tunnels

• Low permeability crushed zone around the tunnel

from SPE-143997Conventional Perforating Dynamic Underbalance Perforating

3

Why Dynamic Underbalance ?

Dynamic underbalance aka Wellbore Implosion

Magnitude and sharp pressure drop is key to break (fail) the crushed zone, leading to cleaner perforations.

Design guns to achieve dynamic wellbore implosion pressure event.

(from SPE 143997)

Conventional Underbalance Dynamic Underbalance

4

Dynamic Underbalance (DUB)andDynamic Underbalance Post Perforating (DUB-PP)

Conventional DUB gun

DUB-PP gun

Special punchersDeep-penetrating

shaped charges

• DUB-PP evolved from conventional DUB.

• Both create “implosion” in wellbore.

• DUB-PP used anytime after the actual perforations established

• DUB-PP required for lower pressure environment.

5

Well Candidates

• Start operation with Well-B and C, followed by Well-A later.

• Reperforation not planned for Well-B and Well-C.

6

Well Casing Size Perforation History

Well A 7-in.Previously perforated w ith 4.5-in. 5-

spf guns

Well B 7-in.

Previously perforated w ith 4.5-in. 5-

spf reactive liner charges follow ed by

3.375-in. propellant system

Well C 4.5-in.

Previously perforated w ith 2.875-in, 5-



Perforating Plan

Reperforate existing

interval w ith 4.5-in, 5-

spf guns

Not applied

Not applied

DUB-PP Plan

4.5-in. DUB-PP guns

4.5-in. DUB-PP guns

2.875-in. DUB-PP

guns

Well-B and Well-C Operations

7

Pre-Job Simulation

• DUB-PP gun designed based on simulation.

• Reservoir pressure expected to be about 900-psi

Well B prejob DUB-PP dynamic underbalance

simulation output.Well C prejob DUB-PP dynamic underbalance

simulation output.

8

Operations

• Stop well injection 2-days before the actual operation.

• Run pressure survey to confirm wellbore pressure stability.

• Re-run the pre-job simulation based on new pressures.

• Run DUB-PP guns together with fast-recording-pressure-gauge to record DUB event.

2106

2106.5

2107

2107.5

2108

0 200 400 600 800 1000

Well B Wellbore Pressure Record on 30-Oct-2013

2057.5

2057.6

2057.7

2057.8

2057.9

2058

2058.1

2058.2

2058.3

2058.4

2058.5

0 500 1000

Well C Wellbore Pressure Record on 15-Nov-2013

Time (seconds)Time (seconds)

Pressure (psi)

Pressure (psi)

9

Pre-Job Simulation – Based on Actual Well Pressure

Actual GaugeSimulation


10

Operations – Post Job

• DUB achieved.

• Gauge data compares well to simulation



11

Post Job Well Performance

Date Events on Well-BReservoir Pressure

(psi)

Injection Pressure

(psi)

Injection Rate

(litres/minute)

Injectivity

(Litres per day/psi)

Jan-13 Perforating us ing Reactive Liner fol lowed with propel lant 900

Feb-13 Wel l testing us ing dedicated wel l test unit 900 1150 2.2 1.4

Nov-13 Wel lbore Implos ion us ing DUB-PP system 2112

Jan-14 Wel l testing us ing dedicated wel l test unit 2112 1250 53 64.4

Not Tested

Not Tested

Date Events on Well-CReservoir Pressure

(psi)

Injection Pressure

(psi)

Injection Rate

(litres/minute)

Injectivity

(Litres per day/psi)

Dec-12 Perforating us ing Reactive Liner fol lowed with propel lant 900

Jan-13 Wel l testing us ing dedicated wel l test unit 900 1250 1.9 1.1

Nov-13 Wel lbore Implos ion us ing DUB-PP system 2075

Jan-14 Wel l testing us ing dedicated wel l test unit 2075 1250 53 62.5

Not Tested

Not Tested

12

Well-AOperations

13

Well Casing Size Perforation History Perforating Plan DUB-PP Plan

Well A 7-in.Previously perforated w ith 4.5-in. 5-

spf guns

Reperforate existing

interval w ith 4.5-in, 5-

spf guns

4.5-in. DUB-PP guns

Well B 7-in.

Previously perforated w ith 4.5-in. 5-



Not applied 4.5-in. DUB-PP guns

Well C 4.5-in.

Previously perforated w ith 2.875-in, 5-



Not applied2.875-in. DUB-PP

guns

Well-A Plan

• To reperforate followed by DUB-PP

• Job sequence similar to previous two wells

Well A historical injection performance prior to the reperforation and DUB-PP job.

14

Well-A Post Job Analysis

• DUB achieved but well injectivity did not improve.

• Neither reperforation nor DUB-PP effective.


15

Conclusion

• Wellbore implosion using the DUB-PP technique successfully improved injectivity of two water injector wells in the low to medium reservoir pressure range.

• Standard perforating or DUB-PP could not overcome well with suspected water-rock compatibility problem.

16

Wellbore Implosion: Case Study of Perforation Enhancement

QUESTIONS? THANK YOU!

MENAPS 16-24

MUSCAT, OMAN

17

Documents

Wellbore Implosion: Case Study of Perforation Enhancementperforators.org/wp...2016_24-Wellbore-Implosion.pdfWellbore Implosion: Case Study of Perforation Enhancement MENAPS 16-24 AUTHORS: