Steam Drive and Gas Injection for Late-Life SAGD Efficiency
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Solution Overview
Problem
Existing steam-assisted gravity drainage (SAGD) methods for heavy oil production are inefficient, energy-intensive, and costly, with high steam-to-oil ratios (SOR) and low recovery factors, especially in the late life cycle of wells, necessitating improvements to reduce steam usage and enhance production efficiency.
Innovation Solution
A method called steam drive and gas (SDG) is implemented, involving steam injection followed by steam and non-condensable gas (NCG) co-injection in every other injector, with shut-in injectors converted to infill producers, maintaining bottom hole pressure and optimizing steam and NCG usage to stabilize SOR and maintain oil production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam injection is continued in traditional SAGD method, then oil production is maintained, but steam-to-oil ratio increases and energy efficiency deteriorates in late well life
Solution Approach 1:
The injection array is segmented by shutting in every other injector, creating alternating active and inactive injection zones. This segmentation allows the active injectors to maintain pressure and drive oil toward producers more efficiently, reducing the total steam required while maintaining production levels.
Solution Approach 2:
The method implements periodic alternating injection patterns where every other injector is cycled between active and inactive states. This periodic action creates pressure differentials that enhance oil displacement efficiency and reduces the cumulative steam-to-oil ratio compared to continuous uniform injection.
2Productivity
If steam injection is increased to maintain oil production, then productivity is maintained, but energy consumption and cost increase
Solution Approach 1:
Inactive injectors are taken out of the steam injection system, removing them from the energy consumption loop. These shut-in injectors still contribute to production as additional producers, reducing the energy required per barrel of oil produced while maintaining overall productivity.
Solution Approach 2:
The system changes operational parameters by alternating injector status between active and inactive states. This parameter change optimizes the steam distribution pattern, reducing total steam consumption while maintaining oil production through enhanced pressure differentials and improved sweep efficiency.
3Area of stationary object
If every injector remains active, then steam chamber coverage is maximized, but steam usage and operational cost increase
Solution Approach 1:
The active steam injectors self-adjust to provide adequate steam chamber coverage by operating at optimized injection rates. The alternating pattern allows each active injector to serve a larger effective area, maintaining sufficient thermal coverage while reducing total steam consumption through the contribution of shut-in injectors as producers.
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 SDG method significantly reduces the steam-to-oil ratio by 40-50% and maintains or improves oil production, minimizing energy consumption and surface footprint while enhancing recovery efficiency.
Implementation Method 1
heating the oil with steam
Implementation Method 2
The initial viscosity of the oil at reservoir temperature is often greater than five million centipoise (cP) and because of its thickness cannot be pumped. Thus, it must be either mined from the surface or treated in situ to make it pumpable.
Implementation Method 3
the heated oil and any condensed water are produced by gravity drainage to the lower horizontal well
Implementation Method 4
a non-condensable gas (NCG), which helps to maintain pressure
Implementation Method 5
It also provides some insulating effect, reducing heat loss to the overburden
Data Source
AI summary
A method for producing heavy oil while reducing steam usage, the method including producing oil by SAGD or a SAGD variant in an array of wellpairs until an SOR increases, then shutting in every other injector and injecting steam plus noncondensable gas (NCG) in the remaining injectors and producing oil from all producers.