Deepwater Drilling Emergency Response Plans

Blowout Contingency Planning

Well control events associated with deepwater drilling, production and workover activities present unique technical and logistical challenges to the operator and service company personnel. The consequences which result from a sustained blowout in a deepwater environment will be far-reaching and could, conceivably, have a lasting impact on public perception. History has shown that environmental groups and regulatory agencies are quick to make critical evaluations of the industry's commitment and capability to mitigate the damage associated with catastrophic events.

See also: Introduction Drill Emergency Response Deepwater Well

Therefore, the identification of potential hazards and the development of a systematic response have rightfully become an essential element in sound business practice. The methodology associated with this hazard identification and response strategy formulation is often referred to as the
Blowout Contingency Plan (BCP).

The following topics will be discussed in this section:

• Organizational aspects of the BCP
• Well specific BCP topics

Organizational Aspects of the Blowout Contingency Plan (BCP)

An effective, coordinated response to any emergency requires a pre-determined organizational structure. This is especially true with regard to deepwater blowouts since the technical and logistical aspects are among the most complex in the industry.

The key to a sound, effective BCP is to designate and properly organize a team of individuals with the right combination of technical and operational capabilities. There have been many instances where blowout response and intervention were impeded due to a lack of leadership and adequate organization. These difficulties have manifested themselves even though the group responding to the incident had a vast amount of technical and operational experience. There is no single organizational scheme that is appropriate for all operators. Each company must make an evaluation
of their level of experience, internal resources, corporate organization and operating philosophy in order to determine the best approach to managing a major deepwater blowout.

An evaluation of each district or business unit's (BU) ability to adequately manage a crisis is inherent in this process. This means looking closely at the resources and capabilities of each BU.

• Can the BU provide sufficient personnel to manage the crisis and carry on with other business functions?
• How will the BU handle the large capital outlays that are often required?
• Does a particular BU have personnel with the experience and operational/technical background to make the decisions and implement the solution?

These BU-specific evaluations often result in a scheme for specific corporate support of the BUs during a crisis. The extent and nature of this corporate support will be dependent upon the organizational framework and operating philosophy of the operator. A decision tree approach to such an evaluation is illustrated in Figure below.

Corporate strategy decision tree for blowout recovery management.

Experience has shown that the BCP is most effective when it is linked to an overall plan to respond to emergencies of all types (i.e., oil spills, natural disasters, business interruption, terrorism, civil unrest, etc.). There are many reasons for developing the BCP as a subset of a more comprehensive crisis management plan. These include:

• Standardized format for the initial response to all emergencies
• Decrease duplication of effort (many crises require similar support from Public Relations, Legal and Finance organizations)
• Coordination of simultaneous emergency response and intervention operations (i.e., blowout intervention and spill response).

The group of personnel charged with the management of the blowout recovery is referred to by many names. Examples include Emergency Response Team (ERT), Emergency Task Force (ETF), and Blowout Task Force (BTF), to name a few. The name designated within a given operator's organization should be chosen to be consistent with other names specified in other emergency response plans. For the purposes of this document, this group of people will be referred to as the Blowout Task Force (BTF).

The Blowout Task Force (BTF)

The blowout task force (BTF) must be well organized and adequately staffed with operator and service company personnel who are capable of performing the following tasks:

• Analyzing the technical, operational and safety-related aspects of the situation
• Making proper, informed decisions and formulating precise plans
• Implementing the intervention plans in the best possible manner
• Formulating alternative (contingency) plans based on experience and available information
• Handling the ancillary aspects of the crisis (public relations, legal, financial, liaison, etc.)

Blowouts do not always have a straightforward solution. There are many instances where precise plans can not be formulated until certain information is obtained. Thus, it is important that the BTF be capable of formulating feasible strategies based on experience and judgment. When adequate information is obtained, then the most viable solution can be implemented without delay.

Adequate experience allows the BTF to constantly monitor the intervention and identify possible problems.  Alternative plans can be developed in case the situation changes and can be implemented with minimum delay. The organizational structure of the BTF for a major deepwater blowout should provide for the management of direct intervention activities and simultaneous relief well operations (in addition to the other non-operational duties).

If direct intervention is not feasible, the BTF complexity can be reduced accordingly. The BTF organization will vary from one operator to the next and, in some cases, from one BU to another within a particular company. The figure below illustrates a generalized organizational scheme for a
BTF designed to manage a deepwater blowout.

Generalized organizational scheme for a deepwater Blowout Task Force (BTF).

Well Specific Blowout Contigency Plans (BCPs)

The preceding sections discuss the organization of personnel and other resources designed to properly manage a major deepwater blowout. Critical operations such as drilling, production and workover activities in deepwater often justify the development of well specific BCPs.

The well specific BCP is, in effect, an addendum to the overall, general BCP. It should be developed in such a way that it provides a ready information source to the blowout task force (BTF). While a great deal of the necessary information is contained in the drilling program and other documents, the well specific BCP is designed to provide a concise reference that can be quickly accessed during a crisis.

The information that is typically contained in the well specific BCP is broadly separated into two categories:

• Well and reservoir information
• Available resources

Supporting documents should be clearly identified and referenced.

Well Information

The most helpful information during a blowout is that which allows the BTF to evaluate and implement the possible control solutions. This includes the information that is required to analyze options for surface intervention and relief well design/implementation. Examples of well information useful for evaluating and implementing possible control solutions include:

Information needed to develop well control solutions, Continued on next table below.

Well information useful for evaluating and implementing possible control situations.

Available Resources

The well specific BCP allows for a more precise determination of the equipment and personnel resources that will be utilized in case of a blowout. Certain individuals within the business unit (BU) organization and participating service companies can be chosen for specific functions on the BTF. Equal importance should be placed on evaluating the equipment/services resources within the region and planning for rapid mobilization.

The equipment and services likely to be required in the event of a major deepwater blowout will not vary significantly from one well to the next. However, the availability and logistical aspects of mobilizing the necessary equipment could be vastly different.

The well specific BCP development process should include a detailed evaluation of the locally available equipment and services. Those services which are not specified in the drilling program or that might need to be supplemented by additional contractors should receive particular attention.

Agreements should be negotiated for the provision of all equipment and services for which no standing contract is in place. The selection of such equipment and services may require a thorough evaluation in order to determine which is most suitable in terms of location, capabilities, price and other factors. A general list of equipment and services that should be considered includes:

• Well control, well control engineering and relief well engineering services
• Relief well drilling rig (and supplemental riser/BOP equipment)
• Wellhead equipment (relief well)
• Ranging services (relief well)
• Specialized well control equipment (surface and subsea)
• Casing & cementing equipment
• ROV equipment
• Firefighting equipment (pumps, vessels, etc.)
• Seismic services
• Anchor handling vessels
• High pressure & low pressure pumping
• Additional fluid & storage

Sources of Flow and Source Control

It is highly probable that any subsea blowout will be flowing from either a production wellhead or a BOP. It is difficult to imagine that a riser system will remain intact or that a drilling rig associated with a riser system could remain on location in the event of a major flow. Formation fluids may be exiting in a well defined path such as a circular cross-section.

In the event of well-defined flow, ROV cameras can provide pictures which can be compared to known dimensions on the BOP stack to get a better idea of cross sectional area. High speed photographs can be used to estimate velocity by using bubbles or other discontinuities in the flow and measuring distance traveled between successive pictures.

However, it may be that flow will be from multiple sources on a BOP such as side outlets, bonnet seals, and other hardware that may have suffered damage. In a case like this, the wellhead may be partially or totally obscured so that inspection by ROV will not yield any method of gauging flow. In this case, experience may be the best source for an estimate of flow rate.

Deepwater wells may commonly be capable of production rates on the order of 30,000 BOPD or 60 MMSCF/d of gas. Absolute open flow potentials would of course be greater. Production capacity of this magnitude for a land well blowout would often result in collapse and bridging of the well. However, in a deepwater blowout scenario the seawater column backpressure at the wellhead may well have the same effect as using a choke to limit production rate and prevent the collapse of the well.

See also: Vertical Intervention Technique to Handle Subsea Blowouts Drilling

The result of seawater backpressure could be a sustained flow for which the only control method would be a relief well. One positive in this situation would the assistance in killing the flow that the backpressure would provide. In exploratory drilling there may not be reservoir information to assist in determining what well flow capability might be, so that visual inspection via ROV of the actual flow itself may yield the best source of information. If the well head is obscured it may be possible to get a visual inspection of plume development.

By measuring upward migration of the lighter formation fluids within the seawater and estimating or gauging the plume diameter, it is possible to calculate a volumetric flow. The gas/liquid ratio would have to be estimated and corrected for pressure imposed by the sea depth in order to get the estimated gas rate as well as the formation liquid rate.

In the event of a seafloor broach such that formation fluid is exiting some distance from the wellhead, it will probably be difficult or impossible to gauge flow as this will be obscured from mud and bottom fines which are stirred up by the flow. However, this event may allow re-entry of the wellhead area itself so that investigation can take place from inside the flowing wellbore to determine the amount and source of damage.