BUKU PETUNJUK PRAKTIS

“DSF REMEDIAL CEMENTING”

Heavy Oil Wellwork 2005

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Daftar Isi Buku: • Daftar Isi ………………………………………... 1 • Cementing Job Ground Rules…………………… 2 • Cementing Decision Flow Process ……………... 3 • CBL Guideline ………………………………….. 4 • Cara Membaca VDL ……………………………. 5 • Cara QC CBL …………………………………. 6 • CAST-V / USIT Guideline …………………….. 7 • Menentukan Squeeze Interval ………………….. 9 • Menetukan Slurry Design ……………………… 10 • Menentukan Jumlah saxs Cement …………… 11 • Contoh Cara Menentukan Slurry Design dan Jumlah Cement ……………………………….12 • Cementing Technique …………………………. 13 • Contoh Pumping Chart ……………………...… 14 • Procedure Persiapan Sebelum Squeeze job …… 15 • Bullhead Cementing Procedure ………………. 16 • Contoh Perhitungan Bullhead Cementing …… 18 • Equalize Cementing Procedure ……………….. 19 • Contoh Perhitungan Equalize Cementing ……. 22 • Contoh Cementing Report ……………………. 23 • Contoh Cementing Score Card……………..…. 24 • 2005 HOWW Cementing Team...…………..…. 25

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Cementing Job Ground Rules

• WW Reps mempunyai accountability terhadap Cementing Jobs

• Cementing Focus Team akan membantu WW Reps untuk menentukan squeeze interval, slurry design, placement technique, perhitungan and onsite support jika diperlukan

• WW Reps and Cementer harus mempunyai Design dan Perhitungan Cementing yang sama dan benar

• WW Reps harus witness Cementing job (Injectivity test, Pumping water head, Pumping Cement Slurry, Water displacement and Hesitation)

• WW Reps mengisi form Cementing Score Card dan menyerahkan ke Cementing Team

• Cementing team akan mengumpulkan dan mengevaluasi Cementing Score Card untuk meningkatkan kualitas cementing Job

Com

piled by Iwan W

ijanarko 2005 3

Squeeze Cementing Decision Flow Process

WWReps

Pre- job meeting

Serco repsCementing Team

Squeeze Job I

Success?

Continue next program

Evaluate and Re -design

Next Squeeze job(s )

Success?

Continue next program

TL Operation RMT/PMT

Plan

ning

Exec

utio

n

Discuss the plan forward

Re-squeeze?

N

Y

N

Y

Y

•Other alternatives •Continue next program•Pack well off

N

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Tabel CBL Guideline

Class "H" cement † POZ Mix ‡

Csg. Size

Csg. Wt. TT Expected

Compressive Strength 3000 psi

Compressive Strength 1500 psi

(in) (ppf)

Transit Time

( µ sec) Free Pipe 100% Good Bond 100%

Good Bond

Amplitude Cement Cut Off cement Cut Off mV (mv) (60%) (mv) (60%)

Interval req'd for Isolation

(ft)

3 - 1/2 9.3 239 92 N/A < 1.0 N/A N/A 5 4 - 1/2 9.5 254 81 0.2 2.3 N/A N/A 5

11.6 0.6 4.6 13.5 1.0 7.0

5 15.0 239 77 0.9 5.7 2.3 10.1 5 18.0 236 2.4 10.4 4.6 16.5 21.0 234 3.8 14.7 7.3 21.0

5 1/2 15.5 248 71 0.7 4.7 1.6 8.2 7.5 17.0 247 1.0 6.1 2.4 10.3 20.0 245 2.2 9.4 4.1 14.9 23.0 243 3.4 13.2 6.1 18.5

7 23.0 272 61 1.0 5.6 2.4 9.3 10 26.0 270 1.8 7.8 3.4 12.1 29.0 269 2.5 9.4 4.5 14.6 32.0 267 3.3 11.8 6.1 17.1 35.0 266 3.9 13.1 6.9 18.1 38.0 264 4.9 15.2 9.0 20.7 40.0 263 6.1 17.1 10.2 22.4

9 5/8 40.0 313 52 1.7 6.7 3.2 10.6 15 43.5 312 2.5 8.7 4.1 12.6 47.0 311 2.7 9.1 4.7 13.7 53.5 308 3.7 11.8 6.6 16.4

10 3/4 40.5 334 50 1.1 5.0 2.4 8.4 18 45.5 333 1.7 6.5 3.2 9.7 48.0 331 2.3 8.0 3.8 11.2 51.0 330 2.5 8.5 4.2 12.0 54.0 329 2.6 8 .9 4.6 12.8 55.0 329 2.8 9.2 4.9 13.4

† Bond Cut Off for Class ‘H’ Cement must be used as the Bond Cut Off guidel ine for

Old Wells and Wells where the cement has been in place more than 24 hours (for Primary or Remedial Cementing, the Compressive Strength is estimated to have reached 3000 psi). ‡ Bond Cut Off for POZ Mix Cement can be used only as the guideline for w ells where the cement has been in place for less than 24 hours (after Primary or Remedial Cementing, Compressive Strength is estimated to have reached only 1500 psi).

Used for Old Cement

Used for New Cement < 24 hrs

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Cara membaca VDL Cement Bond yang bagus selain dari Amplitude, juga ditentukan dari bacaan VDL. VDL digunakan untuk menentukan apakah ada cement bond dari casing ke cement dan cement ke formasi.

• Casing to Cement Bond: èBacaan VDL di sebelah kiri agak kabur (Putih untuk HLS log dan abu-abu untuk Schlumberger log)

• Cement to Formation Bond: èBacaan VDL di sebelah kanan tidak lurus, biasanya mengikuti pola Gamma Ray.

Amplitude: Lihat tabel di atas untuk menentukan cut off good bonding

Good Bond Casing-Cement: Kabur/ Putih

Good Bond Cement-Formation: Polanya tidak Lurus mengikuti pola Gamma Ray

Gamma Ray Amplitude (mV) VDL

Good Bonding

Bad Bonding

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Bagaimana QC CBL? • Pastikan CBL tersebut ON-DEPTH dengan meng-

korelasikan pada Mark Log / CBL sebelumnya • Pastikan bacaan Free Pipe Amplitude sesuai

dengan Estimate Free Pipe Amplitude (Lihat Tabel) • Pastikan bacaan Transit Time sesuai dengan

Estimate Transit Time (Lihat Tabel) • Bacaan Amplitude harus sama antara Main Log

dengan Repeat Section

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CAST-V / USIT Cast-V atau USIT adalah ultrasonic log yang bisa menggambarkan acoustic impedance Z (~ compressive strength) material yang ada di belakang casing dan ditampilkan dalam 360 degree image sehingga bisa diketahui jika ada chanelling di belakang casing. Ultrasonic log ini di run jika hasil CBL tidak memenuhi cut-off good bonding yang kemungkinan disebabkan karena adanya Micro Annulus. CAST-V-Halliburton Skala Z plot berdasarkan warna:

• 1st block (red): 0 to 0.34 MRayls (indication of gas) • 2nd block (light blue): 0.34 to 1.03 MRayls (indication of

fresh water) • 3rd block (medium blue): 1.03 to 2.06 MRayls (indication

of water and/or drilling mud) • 4th block (light yellow): 2.06 to 2.41 MRayls (indication of

foamed cement, contaminated cement or heavy mud) • 5th block (light brown): 2.41 to 3.44 MRayls (indication of

cement, depends on density and compressive strength developed)

• 6th block (dark brown): 3.44 to 4.47 MRayls (indication of cement, depends on density and compressive strength developed)

• 7th block (black): 4.47 to 5.50 MRayls or higher (indication of high strength cement)

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USIT-Schlumberger Skala Z plot berdasarkan warna:

Material Z (Mrayls) Gas (red) < 0.30

Liquid (blue) 0.3 – 2.6 Cement (brown to black) >2.6

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Bagaimana Menentukan Squeeze Interval?

• Tentukan Zone Interest berdasarkan Program – 240 to Surface – Rindu to 240 – Rindu to Surface – PK zone to Rindu

• Tentukan Posisi Masing-masing Top dan Bottom Sand 240, Rindu dan Pertama

• Tentukan Posisi Shale yang menjadi target squeeze • Bandingkan dengan posisi Bad Bonding hasil CBL. • Interval Squeeze paling ideal adalah pada Bad

Bonding di daerah Shale dan berjarak minimum 10ft dari interval sand

Top 240

Btm 240

Top Rindu

Btm Rindu

Top Pertama

=Focus area of Squeeze Interval

•240 to Surface = A •Rindu to 240 = B •Pertama- Rindu = C •Rindu to Surface = A & B •Pertama to Surface= A & B & C

A

B

C

240 Sand

Rindu Sand

Pertama Sand

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Menentukan Slurry Design Dasar menentukan Cement Slurry Design:

1. Circulating Temperature 2. Injectivity Pressure

Standard Cement Slurry Design yang bisa dipilih:

• Slurry working temperature o 90 F o 105 F o 125 F

• Cement Slurry Type

o Lead Cement Slurry o Tail Cement Slurry

Pemilihan Cement Slurry Design berdasarkan Injectivity: Type Injectivity Pressure

(@0.6 bpm)Slurry Design

Loose Injection Profile <50 Psi Lead slurry atau Lead + sedikit Tail Slurry

Moderate Injection Profile 50 -200 Psi Lead + Tail Slurry

Tight Injection Profile >200 Psi Tail Slurry

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Menentukan Jumlah saxs cement: Jumlah cement yang akan digunakan berdasarkan panjang squeeze interval dan injectivity pressure. Berdasarkan job-job sebelumnya yang hasilnya bagus, table berikut ini dapat digunakan sebagai referensi untuk menentukan jumlah cement berdasarkan injectivity-nya: Tabel Cara menentukan Jumlah Cement yang dibutuhkan Injectivity Pressure (Psi) Min Cement (sxs) Max Cement (sxs)

0-50 200 30050-100 150 200100-150 125 150150-200 100 125200-250 75 100

>250 50 75

Note: Guideline diatas untuk pekerjaan squeeze IB dan Squeeze casing leak. Sedangkan untuk perkerjaan Squeeze off interval yang intervalnya panjang, jumlah cementnya dilebihkan.

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Contoh Cara Menentukan Slurry Design dan Jumlah Cement 1. Pekerjaan squeeze IB

Hasil Injectivity: 125 Psi @ 0.6 bpm Circulating temperature: 95 deg F Maka:

• Jumlah cement: 125-150 sxs (lihat tabel di atas) • Design Slurry

o Temperatur design: 90 F (standard) o Jenis Slurry : 50% Lead + 50% Tail

2. Pekerjaan squeeze off interval (panjang interval 20’)

Hasil Injectivity: 40 Psi @ 0.6 bpm Circulating temperature: 110 deg F Maka:

• Design Slurry o Temperatur design: 105 F (standard) o Jenis Slurry : 75% Lead + 25% Tail

• Jumlah cement: 250 sxs (lihat tabel di atas) Untuk interval yang lebih panjang, sebaiknya jumlah cement ditambah.

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CEMENTING TECHNIQUE Remedial Technique di Duri ada 2 macam:

• Bullhead Technique (tubing di atas) è Paling sering di pakai untuk kondisi normal

• Equalize Technique (tubing dibawah) Diaplikasikan untuk kondisi: o Well sand problem yang berpotensi menutup

squeeze interval dan menghalangi cement o Jika ada beberapa squeeze interval yang letaknya

berjauhan dan akan di squeeze sekaligus o Untuk squeeze / shut off interval yang kondisi

wellnya Loss Circulation atau Low pressure

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Contoh Pumping Chart Pumping Cement Slurry – Water Displacement

Hesitation

A

B C

D Pressure

Time

A-C: Pumping cement slurry A-B: Pressure turun karena air di wellbore digantikan cement yang densitynya lebih besar B-C: Pressure kembali naik karena cement slurry mulai masuk formasi (blocking effect)

C-D: Water Displacement

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PROCEDURE Procedure Persiapan Sebelum Squeeze job

1. Pressure test Casing sampai400 psiuntuk wellbaru atau 200 Psi untuk well lama. Pressure test BOP untuk memastikan BOP dalam keadaan bagus

2. Diusahakan well bore dalam kondisi full dengan 2% KCl water.

3. Buka annulus valve antara surface casing dan production casing Gali sekeliling WH untuk memastikan FM seal tidak bocor

4. Pasang pressure gauge 0 - 1000 psi pada BOP connection valve.

5. Run CBL, record max. temperature, perforate squeeze interval. Lakukan injectivity test menggunakan rig pump. (Lihat procedur menentukan squeeze interval).

6. Set OE tubing +/- 10 feet dibawah squeeze interval. 7. Rig up cementing unit & pressure test surface line,

manifold sampai dengan 2000 psi sebelum mulai job. 8. Reverse out, ambil BHCT dan lakukan injectivity test

w/0.6 BPM, dengan 2 % KCl water. 9. Lakukan pre-job meeting untuk membicarakan

kondisi downhole (tight, moderate, or loose injection type), volume cement slurry yang akan di pompa, minimum pumping rate dari cement slurry, maximum pressure, pumping procedure, dan menentukan langkah-langkah yang harus diambil jika terjadi sesuatu.

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Bullhead Procedure 1. Raise-up OE tubing ke 70 feet di bawah rotary table

atau seperlunya. 2. Buka BOP dan tutup annulus, fill up well dengan 2%

KCl water, tutup BOP. 3. Pompa 2% KCl water sebelum mixing cement slurry. 4. Mix dan pompa cement slurry berdasarkan injectivity

test 5. Displace lewat tubing dan annulus dengan 0.6 bpm

water secara bergantian. 6. Hesitate lewat tubing dengan 0.2-0.3 bpm water untuk

mendapatkan maximum pressure ~ 300 Psi. Estimate top cement slurry 50 ft dari top squeeze interval. Tutup OE tubing valve.

7. Hold pressure & WOC minimum 4 jam, RDMO cementing unit.

Langkah Perhitungan:

1. Tentukan est TOC ~ 50 ft diatas top perforasi 2. Hitung Vol line dan Vol OE tubing 3. Tentukan perkiraan Hesitate Volume ~ 3 bbls 4. Tentukan Total Displacement

=Vol Line + Vol OE tubing + Vol (est TOC – OE tbg) – Vol Hesitate o Displacement I (Tubing) = Vol Line + Vol OE tubing o Dispalcement II (Annulus) = 1-2 bbls o Dispalacemet III (Tubing) = Total Displ – Displ II – Displ III

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B

Pump Cement Slurry Displace Tubing =Vol line (A) + Vol OE Tubing (B)

Est TOC

A

C

D

E

Displace annulus =Volume C

Displace tubing =Volume D

Hesitate =Volume E

Total Volume Displacement + Hesitate= Vol Line + Vol OE Tubing + Vol Casing antara Ujung OE tubing ke Est TOC )= A + B + (C + D + E)

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Contoh Perhitungan

Displacement Volume Bullhead Squeeze

Example:Casing size = 10-3/4”, Capacity = 0.0981 bbl/ft, PBTD @ 420 ftInterval will be shut off = 400’ - 410’Tubing size = 3-1/2”, Capacity = 0.0087 bbl/ft, Set @ 70 ft

Calculation:

Tubing volume (B) = 70 ft x 0.0087 bbl/ft = 0.6 bbls

Proposed top of cement slurry left inside casing at 340 ft, thenDisplacement volume = {(340 - 70) ft x 0.0981 bbl/ft} + 0.6 bbl –Hestitation vol= 26.4 bbl + 0.6 bbl – 3 Bbls = 24.0 bbl

Assume line volume = 0.5 bbl

Total displacement volume = 24.5 bbl420’

400’-410’

70’

340’

Cement

Water

Hesitation volume (E) = 3 bbls

(0.5+0.6) Bbls from tubing5 BBbls from annulus19 Bbls from tubing

Hesitation = 3 bbls

Displacement(B +C)

Hesitation(E)

Line (A)

OE tubing (B)

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Equalize Technique Procedure

1. Set OE 5 ft dibawah bottom perforasi 2. Buka BOP dan tutup annulus, fill up well dengan 2%

KCl water, tutup BOP. 3. Pompa 2% KCl water sebelum mixing cement slurry. 4. Pompa Cement Slurry 5. Choke Annulus, Equalize cement slurry sesuai

kebutuhan. 6. Displace pump truck line dan OE tubing dengan air

0.6 BPM. 7. Raise-up OE tbg +/- 100 ft diatas squeeze interval,

reverse out the slurry 8. Raise-up OE tbg ke ~ 70 ft. Fill up dan tutup BOP 9. Hesitate lewat tubing dengan 0.2-0.3 bpm water

untuk mendapatkan maximum pressure ~ 300 Psi. Estimate top cement slurry 50 ft dari top squeeze interval. Tutup OE tubing valve.

10. Hold pressure & WOC minimum 4 jam, RDMO cementing unit.

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Langkah Perhitungan Equalize Technique:

1. Tentukan est final TOC ~ 50 ft di atas top perforasi 2. Tentukan est top slurry setelah equalize ~ 100 di atas

top perforasi (TOC1) 3. Hitung volume yang akan di equalized =

Vol Annular (TOC1-Top perf) + Vol Metal Displacement tubing (TOC1-OE tbg) – (Vol line + Vol Tubing displacement to TOC1)

4. Hitung Volume cement slurry yang akan dipompa sebelum equalize = Total Slurry – Equalized Volume

5. Tentukan perkiraan Hesitate Volume ~ 3 bbls 6. Tentukan Total Casing Displacement

= Vol (est TOC – Est TOC1) – Vol Hesitate

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•Set OE tubing 10 ft below bottom interval•Pump Cement Slurry=Total Slurry – Volume

equalized

•Choke Annulus.•Equalize cement = A + B - C=Vol Annular (TOC1-Top perf) + Vol Metal Displacement tubing (TOC1-OE tbg) – Vol Line and Tubing Displacement to TOC1

D

E

Displace tubing to TOC1 (C)

•Raise up tubing to TOC1•Reverse out

•Raise up OE to 60 ft•Displace (D + E)•Hesitate (F)

Equalize Cementing

Choke

F

Note:TOC1 = ~ 100 ft above top interval

OE

TOC1

A+B-C

Water

Cement

C

C

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Volume to be equalized = A + B - C= annulus volume (Top Intv – TOC1) + Metal Displc tbg (OE-TOC1)

- Line and Tbg volume to TOC1= [(0.0862 bbls/ft) x ( 400-250) ft ] + [0.00321 bbls/ft x(415-250)ft]

- [0.6 + 0.0087 (250)]

=(12.9 + 0.53 - 2.8)bbls = 10.6 bbls

Displace Vol Tubing toTOC1 == vol line + vol inside tbg 250 ft = 0.6 + 0.0087 (250) = 2.8 bbls• Continue with raise up OE to 250’• Reverse out • Raise up OE to 70’• Displacement =Vol casing (340’-250’) – Vol Hesitation• Hesitation = ~ 3 bbls

CALCULATIONS Equalize/ Braden head SqueezeCasing size = 10-3/4”, Capacity = 0.0981 bbl/ft, PBTD @ 420 ftInterval will be shut off = 400’ - 410’Tubing size = 3-1/2”, Capacity = 0.0087 bbl/ft, OE Set @ 415 ftAnnulus 10-3/4” – 3-1/2” = 0.0862 bbls/ftMetal Displacement 3-1/2” tubing: 0.00321 bbls/ft

Calculation:

Expected top of cement slurry (TOC1) is ~ 250 ft

Estimate Final TOC 340 ftPump Slurry = Total volume – Volume to be equalized

420’

OE 415’

TOC1=250’

Displacement

Hesitation

420’

415’

340’

250’

70’

A+B-C

Cement

Water

C

400’-410’

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LAMPIRAN 1 Contoh Report yang harus di isi setiap Cementing Job COMP-001 REV.5. June-03 (NI)

WELL INFO

Grid No : 6R20A i.e 6N83A Well Type :

Area : 6 Comp. Type : I.e CHGP, OHGP, SS, PSD etc

Well ID : D-2716 i.e D-1933 Casing Size : Inch

Program No : IBBPRO0620050002 Rig / CTU : SPA # 03 i.e BN-11 or CTU H-1

Job Type : IB i.e SQ/IB/CL/IS Job Sequence : SQZ 1 i.e 1, 2 or 3 and next

Job Date : i.e 07-JAN-2003

Injectivity Test : 0.6 BPM 170 Psi BHCT 130 Deg F

Target Interval 1: Upper : 250 f t 1: Lower 252 ft2: Upper : ft 2: Lower ft

3: Upper : ft 3: Lower ft

4: Upper : ft 4: Lower ft

5: Upper : ft 5: Lower ft

Total GP sand : Sxs (Sqz Pack Job)

Temp Slurry design : 125 Deg F Total Cement Usage : 125 Sxs

Cement Type : "G" CMT ("G", "MMC") LCM Used : NO USAGE

Lead : 14 Bbls Fluid Loss 256 cc/30min Density 15.8 ppg Thickening Time 1:55 (hh:mm)

Tail : 21 Bbls Fluid Loss 144 cc/30min Density 15.8 ppg Thickening Time 2:20 (hh:mm)

Service Comp : DOWELL Cementer Name BIDNER SIANTURI Total Cost 4209.8 US$

Placement Technique OE set @ FTBraden Head (Equalize) Bullhead (Cement Retainer) TOC @ FT (estimate)

X Bullhead (OE Tubing) NA TOC @ FT (actual)

Krypton Result Good Bad NA

Result for SQ/IB/CL/IS Good Bad Leak NA For IB Only MV ft

WW Representatives : RAFLIATA # 15893 i.e ERS Hesitation

Compresive strength 500 psi : 5 hrs Initial Press 133 Psi

WOC : 5 hrs Final Press 400 Psi

Test Target Interval : 400 Psi Hesitate Total 2.5 BBls

Sueeze Result : CIF 29.5 BBls

LEAK : BPM , PSI CIP 14:15 HRS

24-Apr-05

70

195

Pressure

REMEDIAL CEMENTING REPORT

OHGP

10-3/4"

INJECTOR PRODUCER OTHER

24

LAMPIRAN 2 Contoh Score Card yang harus di isi setiap Cementing Job REMEDIAL CEMENTING SCORE CARD

WELL: 6R-20A # 2716 WW REPS: RAFLIATA # 15893DATE: 24-04-2005 SERCO : DOWELL

ACTIVITY Start-Time Compl-Time Remark

Call Cementing Unit 16:30 22:00Cementing Unit Rig-Up 3:30 4:00Injectivity test 4:30 5:00Discuss Slurry design and Placement technique

Yes

Yes

Yes

Mixing slurry8:00 10:00

Pumping slurry __35_____ bbls Pumping Rate: 0.8 BPM Pumping pressure: IP 170 , FP: 133

Displacement __9.7_____bbls Pumping Rate : 0.8 BPM Pumping pressure: IP: 146 FP: 110

Hesitate __3_____ bbls 1. Voulme : …0.5………… bbls Pumping pressure: IP 92 PSI….….. FP: …114…PSI….. W/O 10 MNTS

2. Voulme : …0.5………… bbls Pumping pressure: IP …92 PSI….….. FP: …119 PSI……….. W/O 30 MNTS

3. Voulme : …0.5………… bbls Pumping pressure: IP 87 PSI…….….. FP: 133 PSI………….. W/O 30 MNTS

4. Voulme : …0.5………… bbls Pumping pressure: IP 92 PSI….….. FP: …179 PSI……….. W/O 30 MNTS

5. Voulme : …0.5………… bbls Pumping pressure: IP …130 PSI….….. FP: 400 PSI………….. HOLD PRESS

6. Voulme : …………… bbls Pumping pressure: IP …….….. FP: ………….. 7. Voulme : …………… bbls Pumping pressure: IP …….….. FP: ………….. 8. Voulme : …………… bbls Pumping pressure: IP …….….. FP: …………..

WOC FOR 5 HRS 14:15 HRS 0.80208DOCPressure test with ____ Psi ____ minutes

Call CBLCBL Truck Rig-UpRun CBL (after squeeze)

Date : 24April 2005

0;6 BPM 170 Psi. Temp 130o FWW Reps Calculation and Procedure

WW Reps Calculation and Procedure

Same Calculation and Procedure between WW Reps and Cementer

Date : 23 April 2005Date : 24 April 2005