Reverse Cementing Density Sensor Valve System
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Solution Overview
Problem
Conventional cementing methods in oil and gas wells require high pressures, making them unsuitable for wells with softer formations or those prone to fracture, and lack effective means to detect cement fill completion in reverse cementing operations.
Innovation Solution
A density sensor-based system is deployed in the casing string to detect the presence of cement, triggering a valve to close and prevent further cement flow, indicated by a pressure spike, ensuring the annulus is fully filled and allowing the cement to set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cementing method is used to fill the annulus, then the cement can be forced into the annulus, but high pressure is required which may fracture softer formations
Solution Approach 1:
The patent inverts the conventional cementing approach by pumping cement from the annulus into the casing string instead of from the casing into the annulus. This reverse direction allows cement to be placed at lower pressures since the cement is pumped against the hydrostatic head of the drilling fluid rather than having to force it up the entire annulus length, thereby resolving the contradiction between reliable cement placement and excessive pumping pressure that could fracture formations
2Stress or pressure
If reverse cementing is used to reduce pressure, then lower pumping pressure is required, but there is no effective means to detect when the annulus is fully filled
Solution Approach 1:
The patent implements a feedback mechanism using a density sensor positioned in the casing string that continuously monitors the density of fluid entering the casing. When the density indicates cement has reached the sensor location, this triggers a signal to close a valve and stop pumping. This feedback system resolves the contradiction by providing real-time detection of cement fill status, eliminating the information loss problem while maintaining the low-pressure advantage of reverse cementing
3Stress or pressure
If reverse cementing is used, then cement flows up the inside of the casing string, but there is risk of cement entering the far end of the casing
Solution Approach 1:
The patent introduces a density sensor as an intermediary monitoring device and a controllable valve as an intermediary control mechanism. The density sensor detects the approaching cement front, and the valve acts as a barrier to prevent cement from entering the far end of the casing string. This intermediary system resolves the contradiction by allowing low-pressure reverse cementing while actively preventing the harmful effect of cement intrusion into the casing
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
This method allows for safe and efficient cement placement at lower pressures, preventing cement from flowing into the casing string and ensuring a hard, impermeable cement mass forms, supporting and bonding the casing string to the wellbore.
Implementation Method 1
A density sensor-based system is deployed in the casing string to detect the presence of cement
Implementation Method 2
triggering a valve to close and prevent further cement flow, indicated by a pressure spike
Implementation Method 3
the cement will begin to flow up the inside of the casing string unless pumping is stopped
Data Source
AI summary
A material detection and sealing device includes a body comprising a bottom end and a top end, and configured to fit within a casing string. The device includes a valve located within the body configured to open and close an orifice formed through the body. The device also includes a density meter located on or within the body configured to continuously sense the density of a neighboring fluid. The valve is configured to close upon the density meter sensing a certain density condition.