Interval Plugging for In Situ Combustion Front Stability
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Solution Overview
Problem
In situ combustion for oil recovery often experiences instability and premature extinguishing of the combustion front, leading to inefficient oil recovery due to short circuiting of oxidants and increased sand production, which complicates the process and reduces oil handling efficiency.
Innovation Solution
The method involves controlling the inflow of products into a production well by using a device to create obstructions at specific intervals, such as cement plugs, to prevent short circuiting and maintain a stable combustion front, allowing for targeted management of oxidant breakthrough and ensuring the combustion front sweeps across the entire reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxidant is injected into the reservoir to propagate combustion front, then oil recovery is enhanced, but combustion front stability deteriorates due to premature extinguishing
Solution Approach 1:
The production well is divided into multiple intervals with selective completion. The wellbore is segmented into upper and lower portions, where the upper portion is completed to allow oxidant inflow while the lower portion is sealed with a packer. This segmentation prevents short-circuiting of oxidant through the production well and ensures stable combustion front propagation.
Solution Approach 2:
A packer is introduced as an intermediary element in the production well to control fluid flow. The packer acts as a mediator that selectively allows oxidant inflow in the upper portion while blocking flow in the lower portion, preventing premature oxidant consumption and maintaining combustion front stability.
2Productivity
If production well is open to product inflow throughout, then oil recovery is maximized, but short circuiting of oxidants increases
Solution Approach 1:
Different portions of the production well are given different flow characteristics. The upper portion is completed with flow permits to allow oxidant inflow for combustion support, while the lower portion is sealed with a packer to prevent oxidant short-circuiting. This local differentiation optimizes both oil recovery and oxidant utilization.
3Productivity
If combustion front propagates through entire reservoir, then oil recovery improves, but sand production increases
Solution Approach 1:
The production well is segmented into completed and sealed portions. By sealing the lower portion with a packer, the system prevents uncontrolled sand inflow through the wellbore while maintaining controlled oxidant flow in the upper portion for sustained combustion front propagation.
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 stabilizes the combustion front, enhancing oil recovery by preventing short circuiting and reducing sand production, thereby improving the efficiency of oil handling and recovery processes.
Implementation Method 1
an oxidant injected into the reservoir reacts with some of the oil to propagate a combustion front through the reservoir. This process heats the oil ahead of the combustion front
Implementation Method 2
operating a device disposed within the production well to create an obstruction to the inflow at the first portion while leaving a second portion of the production well open to the inflow of the products
Data Source
AI summary
Methods and apparatus relate to controlling location of inflow into a production well during in situ combustion. The production well includes intervals closable to the inflow at identified times. Once a combustion front from the in situ combustion passes one of the intervals, a blockage conveyed from surface into the production well forms a barrier to the inflow at the interval that has been passed by the combustion front. An example of the blockage includes a cement plug delivered through coiled tubing into the production well, which may include production tubing that defines the intervals based on at least two consecutive alternating lengths of solid wall sections and slotted or perforated sections of the production tubing.