Decommissioning is a process to remove something from active status. In the oil and gas industry, it removes a platform from an active state. In other words, it involves blocking the hole in the surface and remove off the equipment used in offshore oil production. Decommissioning is tremendously complex and expensive. Moreover, it is essential to ensure that a company has the right personnel in operation (guarantying a complete and safety capital project, cost-effective, and appropriate with the environment).
The process of decommissioning
- Project Management, Engineering, and Planning
- Permitting and Regulatory Compliance
- Platform Preparation
- Well Plugging and Abandonment
- Conductor Removal
- Mobilization and Demobilization of Derrick Barges
- Platform Removal
- Pipeline and Power Cable Decommissioning
- Materials Disposal
- Site Clearance
Project Management, Engineering, and Planning/Permitting and Regulatory Compliance
The first stage starts three years before the decommissioning running date. That helps to review the engineering analysis, operational planning, contract obligations, and contracting people. Usually, stage one and two are running at the same time. However, can take up to three years to have an offshore rig decommissioning permit.
On this step, it includes clean all tools used and residual hydrocarbons, and disconnect all equipment. This third stage contains two-part: planning well plugging (collecting date, first inspection, and selecting abandoning method); and the submittal of an application for Boemre(Bureau Of Ocean Energy Management, Regulation, And Enforcement) approval.
Well Plugging and Abandonment/Conductor Removal
Well abandonment part includes well entry operations, filling the well with fluid, remove downhole equipment, cleaning out wellbore, placement of a surface plug, etc. Indeed, it is considered one of the most expensive parts of decommissioning. According to BOEMRE, there are three ways to conduct removal: severing ( use of explosive, mechanical or abrasive cutting). Pulling-sectioning (use the casing jacks to raise the conductors that are unscrewed or cut into 40 ft-long segments). And, offloading (using a rental crane to not only lay down each conductor casing segment in a platform staging area, but also to unload sections to a boat, and offload it at a port. Then transport the conductor to an onshore disposal site). As an operator, you select one.
Mobilization and Demobilization of Derrick Barges, Platform Removal, Pipeline and Power Cable Decommissioning, Materials Disposal, and Site Clearance
According to BOEMRE, it is mandatory to move at least 15 ft below the mudline. In fact, pipeline and power cable may be neutralized in place if they do not interfere with navigation or commercial fishing operations; or pose an environmental hazard. BOEMRE rules demand to pull off the pipeline, and power during the technical and environmental review during the permitting process. Finally, Platform materials can be reused, refurbished, and recycle. In short, to obtain and maintain a proper site clearance, it is essential to have this procedure: pre-decommissioning survey, post-commissioning survey, ROVs and divers target, and test trawling.