Block Copolymers for Fluid Loss Control in Cementing
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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, which can inhibit their performance, leading to issues such as rapid cement setting and weakened well integrity.
Innovation Solution
Development of specific block copolymers synthesized through controlled radical polymerization, comprising a short block for anchoring to particles and a long block for viscosity increase, which forms a polymer layer to prevent fluid loss in subterranean formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluid loss control agents are used, then fluid loss can be limited to some extent, but their effectiveness deteriorates in the presence of dispersing agents or set retarders
Solution Approach 1:
The polymer is divided into two distinct blocks: a first block (A) with 1 to 100 monomer units that provides anchoring functionality, and a second block (B) with 10 to 10,000 monomer units that provides fluid loss control. This segmentation allows each block to perform its specific function independently, with block A ensuring compatibility and anchoring while block B provides effective fluid loss control even in the presence of additives like dispersing agents or set retarders.
2Reliability
If fluid loss control agents are used to prevent liquid penetration into rock, then well integrity is maintained, but the fluid viscosity increases affecting mobility
Solution Approach 1:
The polymer layer formed by the block copolymer provides localized viscosity increase and fluid loss control at the rock-fluid interface, while the bulk fluid maintains its mobility. The first block anchors to the rock surface creating a localized protective layer, while the second block extends into the fluid phase providing controlled viscosity enhancement only where needed, preserving overall fluid mobility.
3Reliability
If cement grout is injected to cement the annulus, then well stability is ensured, but fluid loss can cause excessively rapid setting
Solution Approach 1:
The block copolymer acts as an intermediary between the cement grout and the rock formation. The first block anchors to the rock surface while the second block interacts with the cement grout, creating a controlled interface that prevents uncontrolled fluid loss into the rock. This intermediary layer regulates the interaction between cement and rock, preventing excessively rapid setting while ensuring proper cementation for well stability.
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 copolymers effectively control fluid loss by forming a stable polymer layer around particles, preventing fluid penetration into the rock and maintaining well integrity even in the presence of harmful additives.
Implementation Method 1
the first block (A), known as 'short block', 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 following controlled radical polymerization stages: (E1) the following are brought into contact, typically in an aqueous medium: ethylenically unsaturated monomers mA, which are identical or different, chosen for the construction of the block (A); a source of free radicals which is suitable for the polymerization of said monomers
Data Source
AI summary
The invention relates to a method for preparing a sequenced copolymer comprising a first block (A) connected to a second block (B), said method comprising the following steps of monitored radical polymerisation: (E1) bringing into contact, typically in an aqueous medium: unsaturated ethylene monomers mA, selected in order to constitute the block (A); a source of free radicals; and an agent for monitoring the radical polymerisation; and then (E2) bringing into contact: the polymer obtained from step (E1); unsaturated ethylene monomers mB; a source of free radicals; and a polymer P0 which is not ethylenically unsaturated and supports labile hydrogens.