Subsea Fluid Injection Assembly for Acid Stimulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for acid stimulation in subsea hydrocarbon wells require complex and costly equipment, such as jack-up rigs and workover risers, and lack direct connection solutions for large diameter ball delivery, making them inefficient and costly for high-rate acid injection.
Innovation Solution
A pressurized fluid injection assembly with a fail-safe close valve and flexible hose system that allows direct connection from a stimulation vessel to a subsea Xmas tree, enabling high-rate acid injection without the need for a jack-up rig or workover riser, and accommodating large diameter balls for effective stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a jack-up rig and workover riser are used for acid stimulation, then fluid injection capability is achieved, but operational cost and equipment complexity increase significantly
Solution Approach 1:
The invention extracts and eliminates the unnecessary jack-up rig and workover riser from the acid stimulation system, retaining only the essential components (subsea tree, hose, and injection assembly) needed for fluid delivery. This simplifies the overall system while maintaining the core function of high-rate acid injection.
Solution Approach 2:
The subsea tree is designed to perform multiple functions: it serves as both the production control device and the injection point for acid stimulation. The injection assembly integrates with the existing subsea tree infrastructure, allowing the same equipment to handle both production and stimulation operations without requiring separate specialized equipment.
2Reliability
If a jack-up rig and workover riser are used for acid stimulation, then fluid injection capability is achieved, but operational cost increases
Solution Approach 1:
The invention removes the expensive jack-up rig from the operational sequence, using only a standard vessel with a hose reel. This extraction of unnecessary equipment directly reduces daily operational costs while maintaining the ability to deliver acid at required rates and pressures.
Solution Approach 2:
The system uses a flexible hose that can be deployed and retrieved as needed, rather than maintaining a permanent, expensive workover riser infrastructure. The hose is a lower-cost, temporary solution that can be replaced or repositioned as required by different well locations.
3Reliability
If a conventional system is used, then fluid injection is possible, but large diameter balls cannot be delivered for effective stimulation
Solution Approach 1:
The flexible hose with sufficient internal diameter and smooth interior surface allows large diameter balls to pass through freely. The flexible nature of the hose accommodates the balls during deployment and retrieval, enabling the system to handle both fluid injection and ball delivery functions that rigid systems cannot accommodate.
4Device complexity
If a direct hose connection from vessel to subsea tree is made, then equipment complexity and cost are reduced, but connection reliability must be maintained
Solution Approach 1:
The injection assembly is pre-installed on the subsea tree before acid stimulation operations begin. This preliminary installation ensures that all connections, seals, and control mechanisms are in place and tested before the high-pressure acid injection begins, maintaining reliability while simplifying the overall operational sequence.
Solution Approach 2:
The injection assembly acts as an intermediary device between the hose and the subsea tree production bore. It provides a standardized interface that ensures reliable connection and controlled fluid delivery, mediating between the flexible hose system and the rigid subsea tree infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and cost-effective high-rate acid injection directly to subsea wells, reducing operational costs and complexity by eliminating the need for jack-up rigs and workover risers, while ensuring safe and controlled fluid delivery.
Implementation Method 1
A pressurized fluid injection assembly with a fail-safe close valve and flexible hose system that allows direct connection from a stimulation vessel to a subsea Xmas tree
Implementation Method 2
A pressurized fluid injection assembly with a fail-safe close valve and flexible hose system that allows direct connection from a stimulation vessel to a subsea Xmas tree
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to the introduction of pressurized fluid, e.g. acid, into a subsea well directly from a vessel (33). A fluid injection assembly (20) is fitted to the top of a subsea Xmas tree (3), the assembly (20) including fail safe closed valve (21) which is controlled via a hydraulic line (31) from the vessel. The hose and assembly and valve are designed with an internal bore allowing a large diameter ball to be dropped (required for acid stimulation). The subsea control module (8) on the Xmas tree is controlled from the producing platform.