Fishbone Well Configuration for Steam-Drive Oil Recovery
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Solution Overview
Problem
Current steam-based oil recovery methods, such as SAGD, are inefficient in thin or low permeability reservoirs, requiring large amounts of water and energy, and are limited in their ability to access immobile bitumen, leading to suboptimal oil recovery and high production costs.
Innovation Solution
The use of fishbone well configurations with open-hole laterals connects adjacent horizontal wells near the base of the pay zone, allowing for steam injection and production, which accelerates heat transfer and mobilizes bitumen, enabling steam drive processes in previously unsuitable reservoirs by reducing the need for vertical injector wells and optimizing well placement and spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional SAGD methods are used, then oil recovery is achieved in thick high permeability reservoirs, but water consumption and energy requirements become excessively high
Solution Approach 1:
The patent divides the reservoir into multiple stacked pay zones and targets them with individually positioned horizontal wells. Each well is placed to optimize steam injection and oil drainage from specific zones, allowing selective recovery without the excessive water consumption of conventional SAGD that treats the entire thick formation uniformly.
Solution Approach 2:
The patent transitions from vertical well configurations to horizontal wells positioned at various depths within the pay zone. This dimensional change allows steam to be injected laterally through the formation, improving heat distribution efficiency and reducing the total steam and water required compared to vertical SAGD methods.
2Productivity
If conventional SAGD methods are used, then oil recovery is achieved, but the cost of production becomes high due to water conversion to steam
Solution Approach 1:
By segmenting the reservoir into discrete pay zones and targeting them with specifically positioned horizontal wells, the patent reduces the total volume of formation that requires steam heating. This segmentation lowers the energy input needed to heat and mobilize bitumen compared to conventional SAGD that must heat entire thick formations.
Solution Approach 2:
The patent changes the spatial parameters of well placement and orientation, positioning horizontal wells at optimal depths and intervals within the pay zone. This parameter optimization improves the efficiency of steam injection and heat transfer, reducing the total energy required for bitumen mobilization and production.
3Adaptability or versatility
If conventional SAGD methods are used, then oil recovery is achieved in thick reservoirs, but thin or low permeability reservoirs remain inaccessible
Solution Approach 1:
The patent applies local quality by positioning horizontal wells with specific orientations and intervals tailored to the characteristics of each pay zone. In thin or low permeability zones, wells are placed closer together or oriented to maximize contact with the formation, allowing effective steam injection and bitumen mobilization in reservoirs that would be inaccessible to conventional SAGD.
Solution Approach 2:
The patent employs dynamic well placement strategies where horizontal wells are positioned at various depths and orientations within the pay zone based on reservoir characteristics. This dynamic approach allows the system to adapt to different reservoir types, including thin and low permeability formations, by optimizing well configuration for each specific geological setting.
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 oil recovery by reducing the steam-to-oil ratio, conserving water and energy, and allowing access to thinner pay zones, thereby lowering production costs and environmental impact while improving recovery efficiency.
Implementation Method 1
At the interface between the steam chamber and cold oil, steam condenses and heat is transferred to the surrounding oil
Implementation Method 2
heat is transferred to the surrounding oil
Implementation Method 3
heated oil becomes mobile and drains, together with the condensed water from the steam, into the production well due to gravity segregation within steam chamber
Data Source
AI summary
The present disclosure relates to a particularly effective well configuration that can be used for steam-drive based oil recovery methods. Fishbone multilateral wells are combined with steam drive, effectively allowing drive processes to be used where previously the reservoir lacked sufficient injectivity to allow steam drive or cyclic steam based methods.