BHA (Bottom Hole Assembly)

A well drilled in an unproven area to determine whether hydrocarbons are present, typically representing higher-risk, shorter-duration work for subcontractors with less certainty of follow-on contracts compared to development drilling programmes. Field service companies should account for the speculative nature of these projects when negotiating mobilisation costs and contract terms.

The straight-line vertical distance from surface to a specific point in a wellbore, regardless of how the well is drilled — subcontractors working on directional or horizontal wells need to reference TVD (not measured depth) when scoping equipment reach, calculating hydrostatic pressures, or verifying work zone depths on service orders.

The upstream segment of the oil and gas industry covering the search for and extraction of hydrocarbons, representing the primary client base that hires field service subcontractors for drilling, completions, well servicing, and site construction work. Understanding whether a client operates in E&P helps subcontractors anticipate project cycles, budget timing, and the boom-and-bust demand patterns that directly affect contract volumes and payment schedules.

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

A project delivery model where one main contractor handles all phases from design to completion, typically creating multiple subcontracting opportunities for field service companies across different project phases. For subcontractors, EPC projects often mean working under a prime contractor who coordinates all trades and manages the overall timeline and specifications.

A company hired by a general contractor or directly by an operator to perform a specific portion of work. Subcontractors often specialize in particular services or trades.