Sequenced Block Polymers for Oil Well Fluid Loss Control
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Solution Overview
Problem
Existing fluid loss control agents in oil extraction are not fully effective, especially in the presence of additives like dispersing agents or set retarders, and fail to adequately control fluid loss and rheology in subterranean formations, leading to issues such as rapid cement setting and well integrity damage.
Innovation Solution
The use of specific block polymers comprising a short block irreversibly adsorbed onto particles and a long, soluble block, which forms a polymer layer around particles to reduce filtration cake permeability and control fluid loss, while allowing adjustment of rheological properties and compatibility with various additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluid loss control agents are used, then some fluid loss control is achieved, but they are not fully effective in the presence of additives like dispersing agents or set retarders, and fail to adequately control fluid loss and rheology
Solution Approach 1:
The polymer is divided into two distinct blocks: a first block (A) with weight-average molecular weight typically less than 30,000 g/mol that adsorbs onto particles, and a second block (B) with weight-average molecular weight greater than 10,000 g/mol that remains soluble in the fluid. This segmentation allows each block to perform its specific function independently, resolving the contradiction between effective fluid loss control and compatibility with additives.
Solution Approach 2:
Different parts of the polymer molecule have different properties: the first block is designed to interact with particles through adsorption, while the second block maintains solubility and provides rheological control. This local differentiation of properties enables the polymer to simultaneously achieve strong particle attachment and maintain fluid compatibility with various additives.
2Loss of substance
If fluid loss control agents are used to prevent liquid penetration into rock, then fluid loss is reduced, but the liquid concentration increases leading to increased viscosity affecting fluid mobility
Solution Approach 1:
The polymer composition is specifically designed to change the rheological parameters of the fluid in a controlled manner. The soluble second block provides viscosity modification that prevents excessive thickening while maintaining adequate fluid mobility, thus resolving the contradiction between reducing fluid loss and preserving fluid mobility.
3Duration of action of stationary object
If dispersing agents or set retarders are added to cement grouts, then cement setting is controlled, but the effectiveness of fluid loss control agents deteriorates
Solution Approach 1:
The segmented polymer structure isolates the particle-adsorbing function in the first block from the fluid-interacting second block. This segmentation protects the fluid loss control mechanism from interference by dispersing agents or set retarders, allowing all additives to coexist without compromising each other's effectiveness.
Solution Approach 2:
The polymer acts as an intermediary between particles and the fluid medium, with the first block anchoring to particles and the second block interacting with the fluid and additives. This intermediary role allows the polymer to maintain fluid loss control effectiveness even in the presence of other additives like dispersing agents or set retarders.
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 block polymer system effectively reduces fluid loss and maintains particle suspension, allowing for the use of challenging additives, thereby enhancing the stability and integrity of oil extraction wells by controlling fluid loss and rheology.
Implementation Method 1
a first block (A), also known as 'short block' hereinafter, with a weight-average molecular weight typically of less than 30 000 g/mol, which is adsorbed, preferably irreversibly, on at least a portion of the particles (p)
Implementation Method 2
the block polymer system effectively reduces fluid loss and maintains particle suspension, allowing for the use of challenging additives, thereby enhancing the stability and integrity of oil extraction wells by controlling fluid loss and rheology
Data Source
AI summary
The present invention relates to the use of a sequenced polymer as an agent for monitoring the filtrate and the rheology of a fluid injected under pressure into an oil rock, wherein the fluid comprises solid particles and/or is brought into contact with solid particles within the oil rock after being injected, the polymer comprising: a first block which is adsorbed onto at least some of the particles; and a second block having a composition other than that of the first block and a mean molecular weight of more than 10,000 g/mol, for example more than 100,000 g/mol, and which is soluble in the fluid.