Jetting Cement Plug Tool for Low-Mixing Well Placement
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Solution Overview
Problem
Existing methods for setting cement plugs in wells face challenges in high angle scenarios, particularly in open or cased holes, where cement mixing with drilling fluid leads to insufficient strength, impermeability, or voids due to inadequate control of the U-tube effect and flow resistance.
Innovation Solution
A jetting tool with a narrow diameter and expandable energy-enhancing region is used, combined with a spring-loaded float valve, to deliver cement while rotating and withdrawing, minimizing mixing and ensuring effective displacement of existing fluid, and featuring a tapered end to reduce disturbance during withdrawal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cement is delivered down the drill pipe using conventional gravity-based methods, then the cement forms concentric columns in the drill string and annulus, but the cement mixes with drilling fluid due to the U-tube effect, leading to insufficient strength and impermeability
Solution Approach 1:
The patent applies dynamics by rotating the drill string during cement delivery. This rotation creates centrifugal force that counteracts the U-tube effect, preventing cement from floating up the annulus and mixing with drilling fluid. The dynamic motion transforms the static gravity-based cementing process into an active controlled process that maintains cement column stability.
Solution Approach 2:
The patent uses hydraulic principles by controlling cement flow through the drill string and annulus using fluid pressure. The cement is pumped under pressure down the drill string, and the flow dynamics are managed to ensure proper displacement of drilling fluid without excessive mixing, leveraging fluid mechanics to achieve clean cement placement.
2Ease of operation
If the drill string is withdrawn after cement delivery, then the cement plug is set in place, but the tapered end design causes disturbance to the cement column during withdrawal
Solution Approach 1:
The patent inverts the conventional approach by using a tapered end on the drill string that is wider at the bottom and narrower at the top. This inverted taper prevents the drill string from disrupting the cement column during withdrawal, as the geometry allows smooth passage without creating eddies or mixing zones that would compromise cement integrity.
3Adaptability or versatility
If a spring-loaded float valve is used to control cement flow, then cement flow from drill string to annulus is controlled, but the valve complexity increases the device structure
Solution Approach 1:
The spring-loaded float valve is designed to operate automatically based on cement pressure and flow conditions. The float rises and falls with cement level, automatically opening or closing the valve without external control signals. This self-regulating mechanism provides adaptive flow control while minimizing the need for complex external control systems.
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 enhances cement placement by controlling the U-tube effect, reducing mixing, and maintaining plug integrity, resulting in stronger and more impermeable cement plugs with minimal voids or channels.
Implementation Method 1
The gravitational and buoyancy forces acting on the cement and tending to cause it to form concentric columns of equal height in drill string and annulus (an effect referred to as U-tube effect)
Implementation Method 2
The gravitational and buoyancy forces acting on the cement and tending to cause it to form concentric columns of equal height
Implementation Method 3
The gravitational and buoyancy forces acting on the cement and tending to cause it to form concentric columns of equal height
Data Source
AI summary
A cementing tool (1) and method for setting a cement plug where Instead of the conventional “balanced plug”, the technique involves pumping cement whilst pulling and rotating the tool. The cementing tool (1) includes nozzles (9) for jetting cement which are located in a relatively narrow region (8) of the tool and a larger diameter choke region (5) proximal of the nozzles (9). The end of the tool (11) is closed off and tapered. The tool is passed down the well to a location where it is desired to set a plug, then cement is injected whilst rotating and withdrawing the tool. The jets of cement help displace existing fluid in the well thereby reducing mixing of the existing fluid with the cement, The choke region (5) increases the flow energy, whilst the tapered end (11) helps prevent disruption to the cement as the tool is withdrawn. The choke region (5) may be expandable to allow the tool to pass through a cased part of the well and then set a plug in an under-reamed open hole part of the well.