Sequencing (construction)

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.

A formal notice from an operator or prime contractor inviting subcontractors to express interest in an upcoming project or contract. It typically outlines scope, required certifications, and submission deadlines. Responding early can improve your chances of being shortlisted for the work.

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

Drilling rigs specifically configured to drill natural gas wells, requiring crews and equipment rated for high-pressure gas formations. For subcontractors, gas rigs often demand specialised certifications and H2S training. Work volumes typically follow natural gas commodity prices and seasonal heating demand.

The maximum depth reached by a drilling rig during well construction, measured from the surface to the bottom of the wellbore. For subcontractors, TD determines project scope, equipment requirements, and billing milestones as it marks the completion of the drilling phase.

A piece of solids-control equipment that separates reusable drilling fluid from cuttings on the rig site. Subcontractors operating or maintaining this unit help reduce fluid disposal costs and waste volumes. It is commonly found in directional drilling and HDD (Horizontal Directional Drilling) scopes.

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.