Appraisal Drilling

Any post-completion operation performed on a producing well to restore or improve output. Subcontractors are often mobilised for wireline, coiled tubing, or pump work during these campaigns. Scope can change quickly, so confirm work orders before committing crew and equipment.

An older well built to outdated standards that may require specialised remediation, abandonment, or workover services. Subcontractors should expect non-standard equipment configurations and additional compliance requirements. Scope creep and unforeseen costs are common on legacy well projects.

A well evaluation process where multiple reservoir intervals are tested separately in a single wellbore operation. Subcontractors must coordinate pressure testing, fluid sampling, and equipment rigging across several zones. Scope changes between zones can affect crew hours, tool rentals, and invoicing significantly.

The phase where completed systems and equipment are tested, verified, and handed over to the client as fully operational. For subcontractors, it often means intensive punch-list work, inspections, and sign-offs before demobilisation. Scope creep is common during this phase, so track all additional hours carefully.

A well used to pump fluids — such as water, CO2, or chemicals — into a subsurface formation for disposal or enhanced recovery. Subcontractors are commonly hired for drilling, wellbore servicing, and chemical injection work on these sites. Scope can include pump maintenance, pressure testing, and regulatory compliance support.

The process of converting natural gas into liquid form (LNG) by cooling it to extreme temperatures for storage and transport. Subcontractors supporting liquefaction facilities must meet strict safety and technical certifications. Work scopes often include maintenance, insulation, and cryogenic system servicing.

What Is an AFE in Oil and Gas and How Does It Affect Subcontractor Payments?

An AFE (Authorization for Expenditure) controls every dollar spent on an oilfield project. Learn how it affects your billing, change orders, and cash flow as a subcontractor.