Starch Microspheres for Oil-Gas Plugging
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Solution Overview
Problem
Existing starch-containing microspheres for oil-gas reservoir protection have limitations, including poor plugging effectiveness in various geological structures due to monodisperse or polydisperse particle size distributions that do not meet broad-spectrum requirements, and existing methods fail to achieve uniform particle size distribution and high microsphere content.
Innovation Solution
The development of starch-containing microspheres with uniformly distributed polydispersity, achieved through a method involving the addition of starch, a solubilizer, a cross-linking agent, a zwitterionic surfactant, and inorganic salt, with epoxy chloropropane, to create microspheres with a specific particle size distribution and improved properties such as salt resistance and temperature resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If monodisperse or polydisperse starch-containing microspheres are used as temporary plugging agents, then the preparation method is simple, but the plugging effectiveness is poor in various geological structures due to non-uniform particle size distribution
Solution Approach 1:
The patent changes the particle size distribution parameter from monodisperse or conventional polydisperse distributions to a specifically controlled uniformly distributed polydisperse distribution. This is achieved by adjusting preparation parameters including using a zwitterionic surfactant and inorganic salt cross-linking system, controlling the particle size concentrated distribution interval, and ensuring uniform distribution across the distribution interval, thereby achieving broad-spectrum plugging effectiveness in various geological structures
Solution Approach 2:
The patent creates a composite microsphere system by combining starch with zwitterionic surfactant and inorganic salt cross-linking agents. This composite structure provides both the biodegradability and plugging capability of starch microspheres and the enhanced uniformity and stability provided by the zwitterionic surfactant-inorganic salt system, resulting in microspheres with uniformly distributed polydispersity that work effectively across different geological conditions
2Ease of manufacture
If existing starch-containing microsphere methods are used, then the manufacturing process is straightforward, but the microsphere content and uniform particle size distribution cannot be achieved simultaneously
Solution Approach 1:
The patent introduces a zwitterionic surfactant as an intermediary substance during the cross-linking process. This surfactant acts as a mediator between the starch and inorganic salt cross-linking agent, enabling controlled and uniform microsphere formation. The zwitterionic surfactant facilitates uniform particle size distribution while maintaining a relatively simple manufacturing process, achieving both ease of manufacture and manufacturing precision
3Ease of operation
If conventional temporary plugging agents are used, then the application process is simple, but the filtration loss reduction capability is insufficient across different geological structures
Solution Approach 1:
The patent optimizes the particle size distribution parameters of the temporary plugging agent to achieve uniformly distributed polydispersity within a concentrated distribution interval. This parameter optimization enables the microspheres to effectively plug pore throats across various geological structures, significantly reducing filtration loss while maintaining simple application procedures through conventional drilling fluid incorporation
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 starch-containing microspheres exhibit excellent plugging capability, forming compact mud cakes and reducing filtration loss across different geological structures, meeting industrial requirements with their uniform particle size distribution and high microsphere content, and enhancing wellbore stabilization.
Implementation Method 1
adding a cross-linking agent under a cross-linking reaction condition to react
Implementation Method 2
adding a zwitterionic surfactant into the feed liquid
Implementation Method 3
adding an solution of inorganic salt and a second cross-linking agent into the feed liquid to react
Data Source
AI summary
A preparation method of the starch-containing microsphere includes the steps of first reacting starch with a low concentration of epichlorohydrin, and then reacting the resultant product with a surfactant, followed by final crosslinking to give microspheres. The starch-containing microspheres thus prepared are polydisperse starch-containing microspheres with a uniform particle size distribution, with the particle size being in a range of 0.1-500 μm.