Dual-Barrier Well Control Using Scale and Hydrostatic Head
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Solution Overview
Problem
Existing methods for controlling well pressure in longstanding hydrocarbon wells, especially subsea wells, are ineffective due to poor quality or deformation of production tubing, leading to uncertainty in seal formation and increased intervention costs, and subsequent interventions may not be possible without deploying a rig.
Innovation Solution
A method involving the addition of a scaling solution to form scale in reservoir pores or channels, combined with a hydrostatic head to create a dual barrier, allowing for well control and intervention without the need for a rig, by deploying a fluid to extend at least 50 m and forming a hydrostatic head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plug barrier is set in the well using drilling rig or wireline intervention tools, then well pressure control is achieved, but the cost increases and the operation may not be effective due to poor quality or deformation of production tubing in longstanding wells
Solution Approach 1:
The solution divides the well control function into two separate barriers: (1) a scaling solution injected into the reservoir to block pores and channels, and (2) a hydrostatic head created by deploying fluid into the well. This segmentation allows each barrier to address specific aspects of well control independently, improving reliability while avoiding the need for expensive rig-based plug installation
Solution Approach 2:
The invention replaces the mechanical plug installation system (drilling rig or wireline tools) with a chemical and hydrostatic system. The scaling solution chemically precipitates scale in the reservoir pores, and the hydrostatic head uses fluid weight to balance well pressure, eliminating the need for mechanical intervention equipment and reducing costs
2Reliability
If a plug barrier is set in the well, then well pressure control is achieved, but subsequent intervention in the well becomes inaccessible
Solution Approach 1:
The hydrostatic head fluid acts as an intermediary medium that transmits pressure control while allowing equipment to pass through. Unlike a solid plug that completely blocks the well, the fluid column maintains pressure control (through its weight) while permitting wireline or coiled tubing equipment to penetrate through and perform subsequent interventions
Solution Approach 2:
The solution changes the state of the well control barrier from a solid, impermeable plug to a fluid column with specific hydrostatic pressure properties. This parameter change allows the barrier to maintain pressure control while remaining penetrable by intervention equipment, thus preserving adaptability for future operations
3Reliability
If a rig is deployed to set a plug barrier, then well control is achieved, but the economics of intervention are compromised due to high cost
Solution Approach 1:
The invention uses relatively inexpensive, consumable materials (scaling solution chemicals and hydrostatic head fluid) instead of expensive, heavy equipment like drilling rigs. The scaling solution is injected and remains in the reservoir, and the hydrostatic head is maintained by fluid deployment, both being much more economical than rig-based plug installation while achieving equivalent well control
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
The method provides two independent barriers to prevent hydrocarbon leakage, enabling safe removal of topside apparatus and allowing various well interventions, such as replacing equipment or perforating new zones, while reducing intervention costs and risks.
Implementation Method 1
adding a scaling solution into a reservoir via the well which forms scale in pores or channels of the reservoir in order to inhibit fluid flow
Implementation Method 2
deploying a fluid into the well to create a hydrostatic head extending for at least 50 m
Data Source
AI summary
A method of controlling a well comprising adding a scaling solution into a reservoir via the well which forms scale in pores or channels of the reservoir in order to inhibit fluid flow; then, deploying a fluid into the well to create a hydrostatic head extending for at least 50 m. In this way two independent barriers are provided to control the well. Intervention work may then be done on the well, involving removing the wellhead. Equipment can be deployed through the hydrostatic head without the requirement to set a plug.