Memahami Konsep Well Integrity dalam Operasi Migas

Definisi Well Integrity

Well Integrity adalah kemampuan sumur untuk menahan dan mengontrol fluida formasi secara aman sepanjang lifecycle sumur, dari drilling hingga abandonment.

Menurut NORSOK D-010, well integrity didefinisikan sebagai:

"Application of technical, operational and organizational solutions to reduce risk of uncontrolled release of formation fluids throughout the life cycle of a well."

Mengapa Well Integrity Penting?

1. Keselamatan

Well integrity yang buruk dapat menyebabkan:

Blowout (uncontrolled flow)
Gas migration ke lingkungan
Casing failure yang membahayakan personel
Environmental damage

2. Aspek Ekonomi

Kegagalan well integrity berdampak pada:

Production loss akibat shut-in
Workover cost yang tinggi
Reputational damage
Regulatory penalties

3. Regulasi

Berbagai regulasi internasional mewajibkan:

API RP 90: Annular Casing Pressure Management
NORSOK D-010: Well Integrity in Drilling and Well Operations
ISO 16530: Well Integrity Standards

Komponen Well Integrity

Barrier System

Konsep barrier adalah fondasi well integrity. Setiap sumur harus memiliki minimum dua independent barriers untuk mencegah uncontrolled flow.

Primary Barrier

Barrier pertama yang mencegah flow dari formasi:

Drilling Phase:
- Mud column (hydrostatic pressure)
- BOP (Blowout Preventer)
Production Phase:
- Tubing dengan packer
- Wellhead dengan valves
- Subsurface Safety Valve (SSSV)

Secondary Barrier

Backup jika primary barrier gagal:

Drilling Phase:
- Casing dengan cement
- BOP system
Production Phase:
- Casing dengan cement
- Annulus monitoring system
- Surface safety systems

Well Integrity Management System (WIMS)

1. Design Phase

Pertimbangan kunci dalam design:

Load cases: Internal pressure, external pressure, thermal, bending
Material selection: Sesuai dengan environment (H2S, CO2, temperature)
Barrier philosophy: Redundancy dan independence
Monitoring capability: Pressure, temperature, annulus

2. Construction Phase

Eksekusi yang memastikan integrity:

Casing running: Proper centralization, no damage
Cementing: Good bond, no channels, adequate TOC
Pressure testing: Casing test, BOP test, wellhead test
Quality control: Documentation, verification

3. Operation Phase

Monitoring dan maintenance:

Annulus pressure monitoring: Deteksi leak atau gas migration
Production surveillance: Rate, pressure, temperature trends
Integrity testing: Periodic pressure test, leak test
Inspection: Visual, NDT (Non-Destructive Testing)

Annular Pressure Management

Sustained Casing Pressure (SCP)

SCP adalah pressure di annulus yang:

Tidak turun setelah bled off
Rebuild setelah beberapa waktu
Indikasi ada leak di barrier

Penyebab SCP

Cement failure:
- Micro-annulus
- Channeling
- Poor bond
Casing failure:
- Corrosion
- Mechanical damage
- Connection leak
Tubing/packer failure:
- Leak di tubing
- Packer seal failure

Best Practices

1. Proactive Monitoring

Implement real-time monitoring untuk annulus pressure
Set up alarm thresholds untuk early warning
Regular data review dan trend analysis

2. Competency Management

Ensure trained personnel untuk well operations
Regular training dan competency assessment
Clear roles and responsibilities

3. Documentation

Maintain well integrity database
Document semua integrity tests dan inspections
Keep as-built drawings dan well schematics

Well integrity adalah aspek fundamental dalam operasi migas yang tidak boleh dikompromikan. Memahami konsep well integrity akan membantu membuat design decisions yang lebih baik, mengidentifikasi potential risks lebih awal, dan berkontribusi pada safe operations.