RIASSUNTO
Relief well planning can be a critical safety measure, ensuring readiness and rapid response in the event of a catastrophic blowout that threatens human life and the environment. Recent regulatory requirements in the oil industry have spurred a demand for extensive relief well planning for shelf and deepwater wells around the world. This paper discusses well planning, trajectory design, and drilling as it applies specifically to relief wells.
A relief well is drilled adjacent to an existing well that has suffered an uncontrolled release of pressurized hydrocarbons. From an operational standpoint, a relief well is drilled only if surface intervention or capping attempts are taking too long or have failed to cap the blowout. The goal of the relief well is to divert the pressurized hydrocarbons up a new wellbore in a controlled manner or to kill/cap the downhole blowout with heavy mud/cement. For either of these remedies to succeed, precise interception of the existing wellbore becomes a key component in relief well design. This, in turn, makes the entire relief well planning component a very crucial and challenging aspect of the well design.
This paper focuses on five phases of relief well planning:
1. Surface location selection, including shallow hazard assessment, metocean considerations and rig logistics.
2. Selection of drilling, evaluation, ranging and interception tools.
3. Directional trajectory design utilizing a bottom-up approach.
4. Project execution (drilling operations).
5. Intercepting the well considering cased hole, openhole or the reservoir section of the blowout well.
The United States Bureau of Safety and Environmental Enforcement (BSEE) provided detailed policies and procedures for relief well planning. It is now a mandatory requirement in the Gulf of Mexico to submit plans for two relief wells along with their drilling programs for drilling permit approvals. The regulations ensure safe planning and execution in response to a hazardous situation, and they are in the process of being adopted by worldwide government agencies.