Differential Pressure Sliding Sleeve Asymmetric Inner Cylinder
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Solution Overview
Problem
Existing differential-pressure sliding sleeves for oil and gas well fracturing have low success rates, require high opening pressures, and are prone to clogging, making them difficult to open and posing construction risks.
Innovation Solution
A differential-pressure sliding sleeve with a simple structure, featuring an outer cylinder, an inner cylinder, and a carrier ring made of dissolvable material, which allows the sleeve to be opened with a relatively small pressure lower than the full wellbore testing pressure, ensuring stable and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening pressure of the differential-pressure sliding sleeve is increased to ensure reliable opening, then the success rate of opening improves, but the construction risk increases and the pressure range for operation decreases
Solution Approach 1:
The patent changes the pressure parameter by designing the inner cylinder with an asymmetric structure where the upper end surface area is greater than the lower end surface area. This geometric parameter change creates a pressure difference that generates downward force at lower operating pressures, resolving the contradiction between reliability and construction risk.
Solution Approach 2:
The sliding sleeve is segmented into an inner cylinder and an outer cylinder with distinct functional surfaces. The inner cylinder's upper end surface serves as the primary pressure reception surface, while the lower end surface has reduced area, creating segmented pressure zones that enable reliable opening at lower pressures.
2Reliability
If the opening pressure is set above the full wellbore testing pressure, then the sliding sleeve can be opened reliably, but the pressure range for operation becomes very small
Solution Approach 1:
By changing the geometric parameters of the inner cylinder (making the upper end surface area greater than the lower end surface area), the patent enables the sliding sleeve to open at pressures below the full wellbore testing pressure, thereby expanding the operational pressure range while maintaining reliability.
3Duration of action of moving object
If a time-delayed structure with small fluid inlet is used, then the differential-pressure sliding sleeve can be opened at controlled times, but the structure is prone to clogging and difficult to open
Solution Approach 1:
The patent extracts the time-delay function from the fluid inlet structure and implements it through the dissolvable carrier ring instead. This removes the small fluid inlet that was prone to clogging, making the device easier to open while retaining time-delay capability through the carrier ring's dissolution timing.
Solution Approach 2:
The dissolvable carrier ring acts as an intermediary mechanism that replaces the small fluid inlet for time-delay control. It mediates between the need for time-delayed opening and the desire to avoid clogging by providing a dissolution-based timing mechanism rather than a small opening-based mechanism.
4Device complexity
If the inner cylinder has equal area upper and lower end surfaces, then the structure is simpler, but the working fluid cannot generate sufficient pressure difference to open the sleeve at low pressure
Solution Approach 1:
The patent applies asymmetry by designing the inner cylinder with an upper end surface area that is greater than the lower end surface area. This asymmetric geometry creates the necessary pressure difference for low-pressure opening while maintaining relative structural simplicity, resolving the contradiction between simplicity and opening performance.
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 proposed solution enables the differential-pressure sliding sleeve to be opened reliably and efficiently at a lower pressure, reducing construction costs and risks, while improving the effectiveness and efficiency of oil and gas well fracturing operations.
Implementation Method 1
an area of the axial upper end surface of the inner cylinder is configured to be greater than that of an axial lower end surface thereof, so that the working fluid generates a pressure difference between the axial upper and lower end surfaces of the inner cylinder to provide a downward pressure for the inner cylinder
Implementation Method 2
a carrier ring arranged in the inner cavity of the outer cylinder and between the lower joint and the inner cylinder, the carrier ring being dissolvable under an action of working fluid
Data Source
AI summary
A differential-pressure sliding sleeve has an outer cylinder with a flow guiding hole being provided in a wall of the outer cylinder, an inner cylinder arranged in an inner cavity of the outer cylinder, an upper joint extending into the outer cylinder and fixedly connected to an upper end of the outer cylinder, a lower joint extending into the outer cylinder and fixedly connected to a lower end of the outer cylinder, and a dissolvable carrier ring arranged between the lower joint and the inner cylinder. An area of the axial upper end surface of the inner cylinder is greater than that of an axial lower end surface thereof, so that the working fluid generates a pressure difference to provide downward pressure for the inner cylinder, which moves downward under the pressure after the carrier ring is dissolved to open the flow guiding hole.