On both Company and Contractor-owned drilling and workover rigs (regardless of the type of contract) it is the responsibility of the Company representative to ensure that drilling operations are conducted in a manner to provide for complete well control.

The responsibilities of the Company representative in no way reduce those of the Contractor with regard to well control.

Offshore Installation Manager; OIM

The OIM as the asset holder is ultimately responsible for the safety of personnel and installation. The OIM must be kept fully aware of any pressure development downhole. The OIM will co-ordinate any further action, such as limitations on concurrent operations, mustering of personnel at life boat stations, emergency production shutdown, etc., as a result of a well control situation.

Drilling Supervisor(s)

It is the responsibility of the Senior Drilling Supervisor and Drilling Supervisor to:

• acquaint himself with the locality in which he is drilling;
• include a full knowledge of H2S procedures in areas where a possibility of H2S occurrance exists and to verify that all contractors on site are suitably equipped and trained.
• be acquainted with the contingency plans relating to fire, blowout, pollution and spillage on or around the location;
• Keep the OIM fully informed on any well control situation, and continuously discuss upcoming operations with regards to well control and concurrent operations philosophies.
• Ensure that all well operations are conducted with full primary well control, and that necessary kill mud and mud weight building material are onboard at all time.
• Ensure that company policies and instructions are correctly transmitted to the contractors, and that they are fully understood and implemented.
• Be familiar with the platform and locality in which drilling takes place.
• Maintain a system of well control data sheets to be ready for immediate use if required.
• Ensure that consistent units (SI or field units) are used throughout the operations, and that the units are consistent with the drilling programme.
• Review in detail the drilling and test programmes and advise his immediate supervisor onshore of any aspects which might cause well control problems.
• Be acquainted with the contingency plans relating to fire, blowout, pollution and spillage on and from the platform.
• Report the results of tests and drills carried out for well control purposes.

Rig Drilling Engineer

The Rig Drilling Engineer works with the Company Drilling Supervisor(s) to ensure that all well operations are conducted by the contractors in accordance with company policies and instructions. Specific responsibilities with regard to well control are to:

• Monitor, in conjunction with the mud logging and MWD contractors, for indications of abnormal pressure zones or lost circulation zones.
• Calculate the mud weights required to control the well, and supervise operations regarding kill mud preparation etc.
• Monitor and record details of events.
• Supervise formation strength tests

Drilling Contractor

The Drilling Contractor has the primary responsibility for the implementation of the company policies and procedures on well control from the instructions given by the Senior Drilling Supervisor. These responsibilities are not diminished in any way by the responsibilities of the Senior Drilling Supervisor. The Drilling Contractor has the responsibility to:

• Ensure that all contractor personnel are fully conversant with the Company policies and procedures.
• Ensure that early signs of over pressure are detected and recognised.
• Ensure tests and drills are carried out as required and their results reported to Senior Drilling    Supervisor, and recorded on the IADC report.

As such, the contractor's Senior Drilling Representative (Drilling Section Leader) on the drilling unit assumes overall responsibility to implement these policies.

Data Logger and MWD/ LWD Engineer

It is important that the Data Logger and the MWD/ LWD Engineer are able to immediately recognise the early indications of potential over pressures, from the data being gathered, and immediately inform the Driller and the Senior Drilling Supervisor.

The Data Logger has the prime responsibility to ensure the following monitoring systems are both fully operational and well maintained:

• Gas detection (including hydrogen sulphide - H2S).
• Drilling fluid data: Density, temperature, flow rates (both in and out of the well ), resistivity, and surface volumes (i.e.: pit volume totaliser - PVT).
• Drilling parameters: Hook load, weight-on-bit, rotary torque, pump-rate, standpipe (& casing)   pressure, and penetration rates.

The MWD/LWD Engineer (if MWD/LWD is used for the purpose of well control) shall also monitor the resistivity and gamma ray readings  being continuously gathered downhole.

Mud Engineer

The Mud Engineer is responsible for measuring mud parameters. It is important that he should be able to recognise changes in the mud parameters that may indicate potential over pressures, and immediately inform the Driller and the Senior Drilling Supervisor.

He shall keep the Driller informed of any mud transfers, treatment, or any other act that will change the mud parameters or volume of the active mud system.

He is also responsible for planning the maintenance of adequate chemical stocks required for well control purposes.