Pre-formed Apertures in Casing for Plug and Abandon Operations
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Solution Overview
Problem
Current methods for plugging hydrocarbon wells for abandonment, such as 'perf, wash and cement' (PWC), are costly and resource-intensive due to the need for perforating the casing and using specialized equipment, which can result in irregular perforations and reduced predictability of the wash and cement process.
Innovation Solution
Incorporating pre-formed apertures in the casing during initial well installation, which remain closed for the life of the well, allowing for their selective opening during the abandonment process to facilitate the delivery of cement and wash fluid, thereby creating a reliable and efficient cement plug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If casing is perforated using explosive charges to create apertures, then apertures are formed in the casing, but the apertures have irregular size and burrs around the edges which reduce predictability of the wash and cement process
Solution Approach 1:
The patent applies preliminary action by pre-forming regular apertures in the casing during the initial casing installation process, before the well enters production. These apertures are manufactured with precise dimensions and smooth edges using conventional machining techniques, eliminating the need for later explosive perforation and ensuring predictable wash and cement operations when the apertures are eventually opened.
2Ease of manufacture
If a specialized perf gun with explosive charges is used to perforate the casing, then apertures are created, but the cost of equipment and time increases
Solution Approach 1:
The patent eliminates the need for time-consuming explosive perforation operations by pre-forming apertures during casing installation. This preliminary action shifts the aperture creation to the initial well construction phase, freeing up drilling rigs and specialized perforation equipment for other operations and reducing overall project timelines.
Solution Approach 2:
The patent extracts the aperture formation function from the well abandonment process and relocates it to the initial casing installation process. This separation eliminates the need for specialized perf guns and explosive charges during abandonment, reducing equipment costs and operational complexity.
3Reliability
If pre-formed apertures with closure members are installed in the casing, then the wash and cement process becomes more reliable and predictable, but the initial equipment cost increases
Solution Approach 1:
The patent applies preliminary action by installing closure members on the pre-formed apertures during the initial casing installation. These closure members remain in place during well production and are only opened during the abandonment process, ensuring that the apertures remain sealed and reliable until needed while simplifying the abandonment operation.
Data Source
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AI summary
The invention relates to the use of a casing or liner (3) with pre-formed, selectively openable apertures (5), in plug and abandon operations at the end of life of a hydrocarbon well. The casing or liner (3) is installed at the start of the well's life and the apertures (5) are provided over a length of the casing/liner above the reservoir where a permanent plug would normally be formed when the well is abandoned at the end of its life. Associated with the apertures are sliding sleeve closure members (6) which are designed to remain operational over the 20-30 year lifetime of the well.