The Hydrocarbon Highway – Chapter 9

Chapter 9 – Mature Fields explains how oil and gas fields progress from peak production to
decline and describes the technologies used to sustain output and recover additional reserves.
As global production shifts toward older assets, mature field management has become central to the
petroleum industry.
This chapter introduces Improved Oil Recovery (IOR) and Enhanced Oil Recovery (EOR) techniques,
showing how operators extend reservoir life, optimise well performance, and access previously unrecoverable hydrocarbons.

Overview

• Defines mature fields and the decline in natural reservoir drive mechanisms.
• Introduces artificial lift, secondary recovery and tertiary recovery approaches.
• Explains how waterflooding, gas injection, and polymer flooding improve field performance.
• Discusses the role of reservoir monitoring, 4D seismic and production data analytics.
• Highlights engineering challenges including scaling, souring, corrosion and water disposal.

Key Topics and Concepts

• Reservoir Drive Mechanisms – Gas drive, water drive and gravity drainage as primary production forces.
• Artificial Lift – Rod pumps, ESPs and gas-lift systems used to boost declining reservoir pressure.
• Secondary Recovery (IOR) – Water and gas injection systems used to increase reservoir pressure and sweep hydrocarbons.
• Tertiary Recovery (EOR) – Steam, CO₂ flooding, chemical floods and microbial processes to mobilise trapped oil.
• 4D Seismic Monitoring – Time-lapse imaging to identify bypassed oil zones and optimise injection strategies.
• Flow Assurance – Preventing scale, wax formation and hydrate build-up in wells and pipelines.
• Subsurface Water Management – Produced-water handling, reinjection systems and disposal strategies.

Case Studies and Field Applications

• Brazilian Offshore (Petrobras) – Water reinjection and scale inhibitor programs extending field life in the Campos Basin.
• North Sea (Brent & Troll) – Use of multilateral drilling and reservoir imaging in thin oil zones.
• Trinidad & Tobago (BP Columbus Basin) – 4D seismic enabling bypassed pay identification and optimized well placement.
• Oman – Economic oil production maintained even at >90% water cut through large-scale IOR programs.

Scientific and Operational Methods

• Reservoir characterisation based on porosity, permeability, saturation and fluid properties.
• Reservoir simulation and production history matching for predictive planning.
• 4D seismic interpretation to monitor fluid movement and injection front behaviour.
• Remote subsea intervention for horizontal and deepwater well maintenance.
• Polymer and microbial applications to modify permeability and improve production sweep.

Summary

Mature fields demonstrate that significant hydrocarbon volumes remain even after natural reservoir
pressure declines. Through IOR, EOR and advanced reservoir monitoring, energy companies can increase
recovery factors and extend the commercial life of assets.
These methods are essential as global production increasingly depends on older fields rather than new megafield discoveries.

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