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IWCF Level 4 Drilling study materials
IWCF Level 4 Drilling study resources

IWCF Level 4 Drilling: Drilling Well Control

IWCF Level 4 Drilling · Work through your exam, one topic at a time.

All guide sections

Drilling Well Control

Drilling Well Control

This section covers supervisor-level well control: recognising an influx, shutting in correctly, and planning and monitoring a kill. The exam tests pressure relationships and calculations, so each answer should trace to a formula and a measured value.

Core rules and concepts

  • Kick indicators include a flow check with pumps off, pit gain, increased return flow and changing pump pressure; confirm before shutting in.
  • Both shut-in methods end with the BOP closed and the choke controlling pressure. Record SIDPP, SICP, pit gain and slow circulating rate (SCR) at the same pump rate.
  • SIDPP reflects formation pressure; SICP also includes the influx. Kill mud weight uses SIDPP only: KMW = MW + SIDPP/(0.052 × TVD).
  • Initial circulating pressure (ICP) = SCR + SIDPP; final circulating pressure (FCP) = SCR × KMW/OMW.
  • MAASP = (maximum allowable shoe strength in ppg equivalent − current MW) × 0.052 × shoe TVD; recalculate after every mud weight change.
  • Kick tolerance is the largest influx that can be circulated without exceeding shoe strength; it falls as mud weight drops or TVD rises.
  • Wait and Weight weights up before circulating; Driller's Method circulates the influx on the original weight first. Both hold casing pressure on the choke.

Worked example

TVD 10,000 ft, MW 12.0 ppg, SIDPP 520 psi, SICP 780 psi, SCR 350 psi at 30 spm, shoe at 8,000 ft TVD with 15.0 ppg equivalent strength. KMW = 12.0 + 520/(0.052 × 10,000) = 13.0 ppg. ICP = 350 + 520 = 870 psi; FCP = 350 × 13.0/12.0 ≈ 379 psi. MAASP = (15.0 − 12.0) × 0.052 × 8,000 = 1,248 psi. Reasoning: SIDPP sets kill weight because the influx does not affect it; SICP is higher because it includes the influx's hydrostatic component.

Traps that cost marks

  • Using measured depth instead of TVD in pressure calculations.
  • Using SICP to calculate kill mud weight, which overweights the mud.
  • Quoting ICP without the SCR measured at the kill rate.
  • Drilling ahead after a mud weight change without recalculating MAASP.
  • Ignoring choke line friction in deep water, underbalancing bottom-hole pressure.
  • Circulating gas without controlled expansion; bleed casing pressure as gas expands.