As we discussed in section 2, all emergencies will result from one or more of the fallowing:
operational problems natural causes third party action
In this section, we discuss the action that must be taken to deal with these problems. Clearly each well or drilling programme must be dealt with individually, however, the following provides a guide for input into Emergency Contingency Manuals.
6.1 Operational problems
Most well control problems will be solved by the rig supervisory staff. However, sometimes matters do get out of control and a blowout follows. The effects of a blowout vary greatly and the Contingency Plan must consider each well's situation with respect to its potential flow and its environment. The factors to be considered in each case are:
Of these 1. and 2. are the cheapest options. However, since their chances of success can vary, it is expedient to start a relief well immediately after a blowout to ensure that if options 3. and 4. are required there is minimal delay in achieving these.
On land relief wells, the killing pump station will be located at the relief well site, consequently any site should be large enough to contain this and a vast amount of drilling fluid storage capacity.
Regaining control of well All initial procedures taking place on site to regain control must be automatic and be laid down clearly in the Emergency Contingency Manual. They should be implemented whilst simultaneous support is being arranged. These actions will typically include:
Shut down ancillary machinery Shut down process equipment Isolate and depressurise process system Reduce/remove flammable materials
Isolate and protect non-affected areas and equipment
Control access to site
Deploy fire control teams
Deploy rescue teams
Prepare to abandon rig/area
Prepare to move a floating drilling unit off location Abandon installation
In establishing their anti-pollution plans, operators should study their operating methods and conduct surveys of the regions to identify vulnerable areas and areas of ecological importance. Any risk areas highlighted by the surveys form the basis for contingency planning. Emphasis should be placed upon the requirement to provide protection and containment. Subsequent collection and removal measures are largely remedial, totally dependent on the particular situation and may involve third parties.
In the event of an incident, steps must be taken immediately to assess the situation, eliminate the sources and contain the pollutant. The appropriate local authorities should be consulted when deciding upon removal and clean-up methods, as their approval may be needed.
Prevention Working practices should be such as to minimise the likelihood of accidental release. Drip trays and closed drain systems should be designed to contain likely spillages prior to detection and treatment. In areas of ecological sensitivity, protective booms and skimmers must be available.
Collection and containment The plans used for this must be realistic for the prevailing wind and wave conditions that could be expected in the areas. The effective methods to be used are very dependent on the wind and waves and include barriers, booms or chemicals offshore and physical damming onshore.
Removal The removal method selected is also dependent on the local conditions and the spill to be removed. The use of absorbent materials, skimming and pumping methods, chemical removal or even burning (if permitted) should be considered.
Dispersal Dispersants are now widely used in the removal of oil spills offshore and can be effectively applied in rough seas. None of the above-mentioned removal methods, with the exception of burning (which has to be done very quickly after the spill has occurred) is effective in rough seas, so in most heavy weather offshore locations, dispersal will probably be the best method to apply to the spill.
In developing contingency plans for accidental releases of hazardous materials, operators must evaluate the potential hazards associated with such products. They should identify vulnerable areas and determine the measures necessary to effect rapid containment and reduce the exposure risk to life and property.
Should an incident occur, prompt action must be taken to stem the flow at source, thereby preventing further spread of the substance. Particular attention must be paid to the prevailing wind strength and direction and the effect this may have on the spread of dangerous liquids or gases.
As an aid to determining different response levels to a particular situation, various operating conditions can be considered. Certain conditions represent situations of minor or moderate concern, whilst others may involve considerable loss of control, possibly with the release of lethal concentrations of gas. This condition, mainly applicable to blowout situations, might require ignition. This will, undoubtedly complicate subsequent control operations, but if lives are at risk, the decision should not be delayed.
For wells containing H2S, drills must be carried out on a regular basis on the installation to ensure that crews are familiar with H3S procedures. If a blowout occurs, consideration must be given to igniting all produced gas as quickly as possible. This matter must be covered in the Emergency Contingency Manual and not just left until the situation arises.
When H3S or SO, (which is created after igniting H,S) is released in an uncontrolled manner, it can affect areas much larger than the immediate installation. Prevailing winds can carry the gas to population centres and the possibility of this must be analysed and planned for in the Emergency Contingency Manual.
In the event of a major fire or explosion, the Emergency Contingency Manager will be confronted with a very confused situation. Reports will be coming in from several sources and in practice they will often contradict each other. Consequently, the Emergency Contingency Manual must provide guidelines for the Site Supervisor to send a clear and concise appraisal of the situation. The initial situation appraisal must determine the following:
In most cases, work at the scene of a fatality may not be resumed except with permission of the appropriate national authorities; unless, in the opinion of the Site Supervisor^ to fail to do so might endanger the lives of others.
The Emergency Contingency Manual should lay down the correct formula to be employed when informing the relatives of a casualty.
Was this article helpful?
What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.