Well Flushing Tool for Cleaning Concentric Pipe Bodies
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Solution Overview
Problem
Existing methods for well plugging with two concentric pipe bodies are inefficient in cleaning residues and maintaining hydraulic isolation, as they struggle with removing casting material and achieving satisfactory pressure integrity between the pipes.
Innovation Solution
A method involving a perforation tool and a flushing tool attached to a string, which forms perforations and pumps a flushing fluid and fluidized plugging material through the innermost pipe body to clean and plug both the pipe bodies and annuli, using abrasive media and high-velocity flushing fluids to effectively remove residues and ensure hydraulic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If section milling is used to remove casing and establish a barrier in a well, then hydraulic isolation can be achieved, but the operation becomes very time-consuming and costly
Solution Approach 1:
The invention extracts and removes the problematic section of casing or pipe body using a milling tool that is lowered into the well and rotated to mill away the material. This allows the barrier to be established by removing the problematic section rather than by complex surface operations, significantly reducing operation time while maintaining hydraulic isolation reliability
Solution Approach 2:
The invention uses hydraulic flushing systems to clean the wellbore after milling operations. High-pressure flushing fluid is pumped down the drill string and annulus to remove metal chips and casting material, enabling the operation to be completed efficiently without requiring extensive surface installation time for chip separation
2Ease of manufacture
If surface installations are used for separating metal chips from drilling mud, then cleaning can be achieved, but the operation requires large costs and complex equipment
Solution Approach 1:
The invention implements self-service cleaning by using the drill string itself as the flushing conduit. The drill string is used to pump flushing fluid down to the wellbore and back up, eliminating the need for separate surface chip separation installations. The system cleans itself using its own structure, significantly reducing equipment complexity and costs
Solution Approach 2:
The drill string serves multiple functions: it acts as both the milling tool carrier and the flushing fluid conduit. The same drill string that brings the milling tool down the well is also used to pump cleaning fluid, combining multiple functions into a single piece of equipment and eliminating the need for dedicated surface separation installations
3Ease of operation
If conventional washing methods are used in wells with two concentric pipe bodies, then cleaning can be attempted, but pressure drop occurs in the annuli between pipe bodies and cleaning becomes unsatisfactory
Solution Approach 1:
The invention segments the flushing system into multiple independent flow paths: one path through the inner pipe body and another path through the annulus between pipe bodies. By using separate flushing nozzles positioned at different locations, the system can independently control and optimize flow in each annular space, avoiding pressure drop issues that occur when trying to flush multiple annuli simultaneously through a single path
Solution Approach 2:
The invention introduces radial dimension to the flushing system by positioning nozzles at different radial locations and orientations. Instead of relying solely on axial flow, the system uses radially directed nozzles that can target specific annular spaces, creating three-dimensional flushing coverage that overcomes the limitations of conventional single-direction washing methods
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 enables thorough cleaning and plugging of well sections with two concentric pipe bodies, improving hydraulic isolation and reducing operational costs by efficiently removing casting material and maintaining effective pressure integrity.
Implementation Method 1
pumping a flushing fluid down the string, out through at least one outlet of the flushing tool, into the innermost pipe body and further out into the annulus/annuli between the pipe bodies
Implementation Method 2
using abrasive media and high-velocity flushing fluids to effectively remove residues
Implementation Method 3
forming perforations in the pipe bodies along the longitudinal section by means of the perforation tool
Implementation Method 4
pumping a fluidized plugging material down the string and into the innermost pipe body at the longitudinal section
Data Source
AI summary
A method is for the combined perforation, cleaning, and the subsequent plugging of a longitudinal section of a well. The well is provided with two pipe bodies placed substantially concentrically. The method includes lowering a perforation tool into the innermost pipe body to the longitudinal section, forming perforations in both pipe bodies along the longitudinal section with the perforation tool, cleaning the longitudinal section with a flushing tool which is attached to a lower portion of a string allowing through-flow, pumping a fluidized plugging material down the string and into the innermost pipe body at the longitudinal section, and placing the fluidized plugging material in the innermost pipe body, and thereby also into the entire cross section of the well via the perforations within the longitudinal section. A flushing tool is for cleaning the longitudinal section of the well.