Encapsulated Polymer Flooding for Shear Degradation Reduction
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Solution Overview
Problem
Conventional polymer flooding methods face issues such as large shear degradation losses and low-efficiency circulation due to high shear rates and reservoir heterogeneity, leading to reduced oil recovery rates in oilfields.
Innovation Solution
An encapsulated polymer flooding method where polymers are encapsulated in a shell layer, providing shear resistance and controlled release, allowing for targeted profile control and enhanced viscosification deep within the reservoir, reducing shear degradation and improving circulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polymer flooding is used, then oil recovery enhancement is achieved, but large shear degradation losses occur due to high shear rate and reservoir heterogeneity
Solution Approach 1:
The polymer is segmented into capsule structures with internal polymer cores and external shell layers. This segmentation protects the polymer from shear degradation while maintaining its viscosity-enhancing functionality. The capsule structure divides the polymer into discrete units that can withstand high shear rates without degrading.
Solution Approach 2:
The capsule shell layer acts as a flexible protective film that surrounds the polymer core. This shell structure provides mechanical protection against shear forces while allowing the polymer to function when released. The shell's flexibility enables it to deform and migrate through reservoir heterogeneities without breaking.
2Stability of the object's composition
If conventional polymer flooding is used, then some profile control effect is achieved, but serious low-efficiency circulation occurs due to channeling from high-permeability layers
Solution Approach 1:
The capsule structure provides different functional qualities at different locations: the shell layer provides mechanical strength and migration capability in high-permeability channels, while the internal polymer core provides viscosity enhancement in target zones. This local differentiation enables the polymer to navigate through heterogeneities and achieve profile control without causing low-efficiency circulation.
Solution Approach 2:
The capsule structure is dynamic, transitioning from an intact state during migration to a released state during polymer flooding. The capsules migrate through the reservoir maintaining their structure, then release the polymer under formation conditions (temperature, salinity, shear stress). This dynamic behavior enables the polymer to overcome channeling issues and achieve effective profile control.
3Length of stationary object
If polymer is injected directly, then viscosity enhancement is achieved, but the polymer cannot reach deep reservoir parts effectively due to near-wellbore heterogeneity
Solution Approach 1:
The polymer is pre-encapsulated in capsule structures before injection, preparing it for long-distance migration through heterogeneous near-wellbore zones. The capsule structure is designed in advance to withstand shear forces and deformations during migration, enabling the polymer to reach deep reservoir parts before release.
Solution Approach 2:
The capsule shell acts as an intermediary between the polymer core and the reservoir environment during migration. It protects the polymer from degradation while migrating through near-wellbore heterogeneities, then facilitates polymer release under formation conditions. This intermediary structure enables the polymer to overcome the barrier of near-wellbore heterogeneity and reach target zones effectively.
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 method effectively reduces shear degradation, enhances oil recovery by targeted polymer release, and improves the overall flooding effect, particularly in medium- and low-permeability reservoirs, thereby increasing the oil recovery rate.
Implementation Method 1
the capsule wraps a polymer to bind a molecular chain as if the molecular chain wears a 'straitjacket ', the viscosity is not released, and the shear resistance is strong
Implementation Method 2
the capsule is a particle, which can temporarily block, deform, and migrate in the rock to achieve a strong near-wellbore profile control and displacement effect
Implementation Method 3
When the polymer capsule migrates to a deep part of a reservoir, a shell layer of the capsule is gradually broken under the action of formation conditions (temperature, salinity, and the like) and releases the internal encapsulated polymer
Implementation Method 4
electrostatic shielding mechanism of salinity: a capsule shell, that is, molecules of a shell layer, have electrostatic interactions, and salt ions can destroy the shell layer and shield the electrostatic interactions, making the structure of the shell layer unstable, shrink, and deform
Implementation Method 5
the molecular chain of the polymer is stretched to realize sustained release and viscosification of the displacing fluid
Data Source
AI summary
An encapsulated polymer flooding method and system for enhancing oil recovery includes: (1) determining reservoir parameters, a well deployment, and a development dynamic state of a target oil reservoir; (2) determining a near-wellbore targeted profile control area and a far-wellbore targeted viscosification area; (3) designing and synthesizing an encapsulated polymer according to conditions of the target oil reservoir; (4) evaluating and determining whether the anti-shearing performance, the sustained release and viscosification performance, the injection performance, and the profile control performance of the encapsulated polymer meet expected performance requirements based on laboratory tests; (5) formulating an injection scheme for an encapsulated polymer flooding field; and (6) monitoring the development dynamic state of the oil reservoir; according to the present disclosure, the polymer is wrapped with a shell layer, which greatly reduces the shear degradation during injection of the polymer and effectively reduces the cost.