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Industry Glossary Term

Mud Logging

A well-site service that monitors drilling fluid returns to detect hydrocarbons and analyse formation data in real time. Subcontractors provide specialised technicians and instrumentation units for this work. It is commonly scoped as a standalone package within a drilling contract.

Related Terms

Subsea Production System

Industry

A network of underwater equipment — including wellheads, manifolds, flowlines, and control systems — installed on the seabed to extract and transport oil or gas to a surface facility, representing a specialised scope of subsea installation, inspection, and maintenance work that subcontractors must hold specific certifications and equipment to perform. For field service companies, contracts in this space typically involve saturation diving support, remotely operated vehicle (ROV) operations, or subsea engineering services under strict offshore safety and quality regimes.

Gyroscopic Guidance

Industry

A downhole navigation system that uses gyroscopes to track drill bit position and direction without magnetic interference. Subcontractors use it in areas where magnetic tools fail, such as near casing or in high-latitude regions. Accurate wellbore placement reduces costly corrections and keeps projects on schedule.

Crude Oil Stock Build

Industry

A rise in stored crude oil inventories, signalling weak demand or oversupply. This often triggers operators to slow production, which can delay or reduce field service work orders. Subcontractors should monitor stock build trends as an early indicator of project slowdowns.

AFE (Authorization for Expenditure)

Industry

A budgeting document used in oil and gas projects that outlines expected costs and seeks approval before work begins. Subcontractors often work under AFEs issued by operators.

Jackup

Industry

A mobile offshore drilling rig with retractable legs that jack down to the seabed, elevating the platform above water. Subcontractors mobilising to a jackup must account for offshore certification, marine logistics, and platform-specific access requirements.

GWD (Getting Work Done)

Industry

A safety and compliance management system used by some operators to pre-qualify and manage contractors working on their sites.

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