Flow Control Devices for SAGD Liquid Level Management
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Solution Overview
Problem
In Steam-Assisted Gravity Drainage (SAGD) processes, controlling the inflow distribution of oil and water over the horizontal length of a producer well and preventing breakthrough of gases into the well are challenging due to reservoir geology and wellbore hydraulics, leading to inefficient bitumen recovery and well damage.
Innovation Solution
A method to predict and characterize the vertical position of the liquid level in the producer well, using parameters like injection pressure, temperature, and permeability to design wellbore tubulars and flow control equipment, which influences pressure profiles and liquid levels, ensuring uniform reservoir depletion and steam chamber growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam is injected into the injector wellbore to reduce bitumen viscosity, then bitumen becomes flowable and can be produced, but gas breakthrough into the producer well occurs causing well damage
Solution Approach 1:
The patent applies preliminary action by pre-positioning the liquid level above the producer wellbore before steam injection begins. This pre-established liquid barrier prevents gas breakthrough into the wellbore during subsequent steam injection and production operations, resolving the contradiction between achieving bitumen production and maintaining well integrity
Solution Approach 2:
The patent uses liquid as an intermediary barrier between the steam chamber and the producer wellbore. This liquid layer acts as a mediator that blocks gas from reaching the wellbore while allowing controlled inflow of oil and water, thus protecting the well while maintaining productivity
2Reliability
If the liquid level is positioned above the producer wellbore to prevent gas breakthrough, then well integrity is protected, but steam chamber growth is restricted
Solution Approach 1:
The patent applies dynamics by allowing the liquid level to be dynamic rather than fixed. The liquid level can rise and fall in response to steam chamber growth and production rates, providing a flexible barrier that adapts to changing conditions. This enables the system to maintain well integrity while allowing steam chamber expansion through natural level fluctuations
Solution Approach 2:
The patent employs self-service by utilizing the natural density difference between steam and liquid to automatically maintain the liquid level barrier. The system self-regulates the liquid level position through natural convection and density-driven flow, eliminating the need for external control mechanisms while maintaining both well integrity and steam chamber growth
3Manufacturing precision
If wellbore tubulars and flow control equipment are designed to influence pressure profiles, then liquid level control is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the physical parameters of the wellbore environment, specifically pressure and temperature profiles, through the selection and placement of flow control equipment. By changing these parameters, the liquid level is controlled without requiring complex mechanical structures, thus achieving precise control while minimizing device complexity
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 approach enhances production rates by promoting uniform steam chamber growth, reducing pressure losses, and preventing steam breakthrough, thereby improving the efficiency and economics of SAGD operations.
Implementation Method 1
Steam is injected from the injector wellbore into the hydrocarbon-bearing formation... The steam permeates the formation within a region of the formation adjacent to the injector well; this steam-permeated region is referred to as a steam chamber. As steam is continuously injected into the formation, it migrates to the edges of the steam chamber and condenses at the interface between the steam chamber and the adjacent region of the bitumen-bearing formation. As the steam condenses, it transfers energy to the bitumen, increasing its temperature and thus decreasing its viscosity
Implementation Method 2
As the steam condenses, it transfers energy to the bitumen, increasing its temperature and thus decreasing its viscosity
Implementation Method 3
the mobile bitumen and condensed water flow down the edges of the steam chamber, accumulating as a 'liquid inventory' in a lower region of the steam chamber and flowing into the producer wellbore
Data Source
AI summary
In a method for controlling interface level between a liquid inventory and an overlying steam chamber in a subterranean petroleum-bearing formation, an inflow relationship is developed to predict the vertical position in a gravity field of the interface between the two fluids (liquid and steam) with a density contrast relative to a horizontal producer well. The inflow relationship is applied to producer well completions by designing the completion to raise or lower sand face pressures according to mobility variations over the horizontal length of the well. This pressure distribution will affect liquid levels according to the inflow relationship. The completion can include tubing-conveyed or liner-conveyed flow control devices to create flow network that provides a customized sand face pressure distribution. Axial flow relationships between adjacent locations along the producer well may be modeled in order to develop an axial flow network to facilitate estimation of liquid levels at selected locations.