Single-Trip Packer Plug Removal with Reverse Circulation Milling
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Solution Overview
Problem
Deep well completion activities face challenges in efficiently removing compacted debris above packer plugs without the need for multiple trips, as existing tools risk shear failure and are inefficient in handling hard formations, leading to increased costs and operational complexities.
Innovation Solution
A combination tool with a milling shoe and grapple assembly that uses reverse circulation to mill debris and capture cuttings, allowing the grapple to advance and engage the packer plug upon weight indication, overcoming shear forces and enabling single-trip removal of the packer plug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grapple is advanced into the packer bore to retrieve the tool after milling, then the tool can be brought up to the surface, but the grapple may experience shear failure when torque is transmitted through the tab while partially engaged with the packer bore
Solution Approach 1:
The grapple is divided into multiple fingers that can independently engage with the packer bore. Each finger is a separate element that can be gripped by the tab, distributing the torque load across multiple engagement points rather than relying on a single continuous grapple structure. This segmentation prevents shear failure by localizing stress at discrete finger-root connections rather than creating a weak point in a continuous structure.
Solution Approach 2:
The grapple fingers extend radially outward from the central tab in a dimension perpendicular to the axial direction of force application. This radial arrangement allows the fingers to engage the packer bore circumferentially, creating a distributed grip that resists both axial pull-out forces and rotational torque forces simultaneously, rather than relying solely on axial engagement.
2Reliability
If multiple trips are made to remove debris and then retrieve the packer plug, then each operation can be performed optimally, but operational costs and time increase significantly
Solution Approach 1:
The tool combines the milling function and grapple retrieval function into a single integrated assembly that can be deployed in one trip. The milling shoe and grapple fingers are part of the same tool string, allowing debris to be milled and removed while the grapple remains positioned to engage the packer plug immediately afterward, eliminating the need to retrieve and re-deploy a separate grapple tool.
Solution Approach 2:
The tool assembly performs multiple functions: it mills compacted debris through rotation, removes cuttings via reverse circulation, and retrieves the packer plug using the grapple fingers. This multi-functional capability allows a single tool to complete what previously required multiple specialized tools and multiple trips, reducing both time and operational complexity.
3Ease of manufacture
If conventional circulation methods are used to remove debris, then the process is simple, but hard compacted debris cannot be sufficiently dislodged from deep wells
Solution Approach 1:
The milling shoe rotates at high speed to mechanically grind and fragment the hard compacted debris into smaller particles. This rotational mechanical action breaks up the compacted material barrier that conventional fluid circulation cannot dislodge, converting the debris into removable cuttings that can be carried away by the reverse circulation system.
Solution Approach 2:
The tool uses a reverse circulation hydraulic system where fluid is pumped down the annulus and returns up through the mill body, creating a strong upward flow that carries milled cuttings to the surface. This hydraulic reverse circulation provides the necessary lifting force to remove debris from deep wells more effectively than conventional downward circulation.
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 milling and removal of compacted debris with the packer plug in a single trip, reducing operational costs and avoiding shear failures, by utilizing reverse circulation and weight-activated mechanisms to securely engage and retrieve the packer plug.
Implementation Method 1
reverse circulation takes the cuttings up through a mandrel to a debris removal tool
Implementation Method 2
Weight is then set down to overcome a resisting force of a breakable member such as a shear pin or a spring or both
Data Source
AI summary
A combination tool is delivered to compacted debris above a packer whose plug is to be removed. The shoe or mill is on the lower end of an outer bushing and the grapple or overshot is held within the bushing but away from the shoe so that the shoe can advance into the debris as reverse circulation takes the cuttings up through a mandrel to a debris removal tool. When the shoe lands on the packer the surface personnel can see it on the weight indicator. Weight is then set down to overcome a resisting force of a breakable member such as a shear pin or a spring or both so that the grapple advances to engage the packer plug. Advancing the mandrel relative to the bushing with the shoe at its lower end also releases a torque lug that previously allowed tandem rotation of the mandrel with the bushing.