SAGD Start-Up Time Reduction via Preheating and Steam Squeeze
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Solution Overview
Problem
The steam-assisted gravity drainage (SAGD) process for recovering viscous hydrocarbons is hindered by a lengthy start-up phase, typically taking three months or more to establish efficient communication between injection and production wells, which can be inefficient and costly due to the need for independent well operations and heated fluid circulation.
Innovation Solution
A method that reduces the start-up time by introducing a preheating stage followed by a steam squeeze stage, where heat is introduced between the injection and production wells, and steam is injected into the formation at a rate greater than what can be reproduced, promoting convective heating and reducing steam circulation, allowing for faster establishment of communication between the wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent well operations with heated fluid circulation are used during start-up, then the wells can be operated independently to establish communication, but the start-up time increases to three months or more
Solution Approach 1:
The patent applies preliminary action by injecting steam into the formation before initiating full SAGD production. This pre-steam injection phase heats the formation and establishes initial communication between wells, reducing the subsequent start-up time while maintaining operational reliability. The steam injection creates initial pressure gradients and thermal conditions that facilitate faster hydrocarbon mobilization.
Solution Approach 2:
The patent changes operational parameters by transitioning from independent well operations with heated fluid circulation to a coordinated steam injection approach. By modifying the injection strategy to use steam at specific rates and pressures, and by adjusting production rates to match steam chamber growth, the system achieves faster establishment of communication while maintaining well operation reliability.
2Loss of time
If steam is injected at high rates to accelerate steam chamber growth, then the start-up time is reduced, but steam may short-circuit between injection and production wells
Solution Approach 1:
The patent applies feedback by continuously monitoring production rates and adjusting steam injection rates accordingly. Production rates are used as feedback signals to modulate steam injection, ensuring that steam chamber growth remains controlled and prevents short-circuiting. This closed-loop control allows high steam injection rates to be used safely while maintaining reliable steam circulation control.
Solution Approach 2:
The patent implements dynamics by making steam injection rates variable rather than constant. Injection rates are dynamically adjusted based on steam chamber growth stage, formation properties, and production response. This dynamic approach allows aggressive injection during early stages when beneficial, while preventing short-circuiting as the steam chamber develops and connects injection and production zones.
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 can reduce the start-up time by 20% to 70% and maintain the quality and quantity of hydrocarbon production, eliminating the need for foam creation and heated fluid injection, thus lowering operational costs and maintenance requirements.
Implementation Method 1
heating the hydrocarbon formation around each well by thermal conduction
Implementation Method 2
promoting convective heating
Implementation Method 3
where the steam condenses and heats a layer of viscous hydrocarbons by thermal conduction
Implementation Method 4
where the steam condenses and heats a layer of viscous hydrocarbons by thermal conduction
Implementation Method 5
The mobilized hydrocarbons (and aqueous condensate) drain under the effects of gravity towards the bottom of the steam chamber
Data Source
AI summary
The present embodiment is a method for decreasing the time required for a start-up phase in a steam assisted gravity drainage production. The present method begins by forming a steam assisted gravity drainage production well pair within a formation comprising an injection well and a production well, beginning a preheating stop by introducing heat between the injection well and the production well, beginning a steam squeeze stage by injection steam into the formation and beginning the steam assisted gravity drainage production.