Expandable Graphite Plugging for Ultra-Deep Reservoirs
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Solution Overview
Problem
Conventional plugging agents are ineffective in ultra-deep oil reservoirs due to high temperatures, high salinity, and high pressures, leading to instability and limited application in profile control and water shutoff.
Innovation Solution
A multi-component composite intercalated low-temperature expandable graphite system is developed, comprising an inorganic acid, an organic acid, and an intercalation reinforcing agent with an alkali metal halide and cationic surfactant, which allows for expansion at 130° C. to 200° C. and resistance to high salinity, enabling effective profile control and water shutoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plugging agents (polymer particle gel, inorganic particles, foam) are used in ultra-deep oil reservoirs, then profile control and water shutoff are attempted, but the agents are poor in stability and easy to degrade under ultra-high temperature (≥150°C), ultra-high salinity (≥200,000 mg/L), and ultra-high pressure (≥50 MPa) conditions
Solution Approach 1:
The patent employs a composite plugging agent system combining expandable graphite particles with polymer binders and crosslinking agents. This composite structure provides thermal stability through the graphite's inherent high-temperature resistance while the polymer matrix provides binding and controlled release properties, enabling the system to maintain stability under ultra-high temperature and salinity conditions where conventional single-material agents fail
Solution Approach 2:
The patent modifies the physical and chemical parameters of the plugging agent by controlling the expansion temperature of graphite particles through chemical treatment and selecting specific polymer compositions that remain stable at ultra-high temperatures. The system is designed to expand at controlled temperatures and maintain structural integrity under extreme pressure and salinity, fundamentally changing the operational parameter range of conventional plugging agents
2Strength
If inorganic particles are used for profile control, then plugging capability is improved, but transport depth is limited due to difficulty in transporting deeply into the reservoir
Solution Approach 1:
The patent uses expandable graphite particles that remain in a compact, low-volume state during transport but expand in situ when exposed to reservoir conditions. This dynamic transformation allows the particles to be easily pumped to great depths without requiring high transport pressure, then provide strong plugging capability after expansion, effectively decoupling transport ease from plugging strength
Solution Approach 2:
The expandable graphite particles are nested within a polymer binder matrix that protects them during transport and facilitates their movement through the reservoir. The polymer coating acts as a protective layer that prevents particle aggregation and damage during pumping, while allowing the particles to reach deep reservoir zones before releasing their plugging function
3Device complexity
If foam is used for profile control, then construction complexity is reduced, but validity period is short and cannot meet long-term requirements
Solution Approach 1:
The patent incorporates pre-expanded or pre-activated graphite particles that are prepared in advance to expand at specific temperature thresholds. These particles are mixed with thermally stable polymers designed to maintain their structure and provide long-term plugging. The preliminary preparation of the graphite expansion state and polymer composition ensures that once deployed, the system maintains its plugging function for extended periods without requiring complex construction procedures
Solution Approach 2:
The patent replaces expensive, complex foam systems with a simpler, more durable graphite-polymer composite that, while requiring less complex construction, provides extended service life. The use of stable polymer matrices and inert graphite particles creates a plugging system that does not degrade quickly like foam, eliminating the need for frequent re-treatment while maintaining operational simplicity
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 system provides long-term stability, high expansion times, strong plugging properties, and good scouring resistance, suitable for ultra-deep oil reservoirs with temperatures of 130° C. to 200° C. and salinity of 100,000 mg/l to 300,000 mg/l, enhancing profile control and water shutoff efficiency.
Implementation Method 1
allows for expansion at 130° C. to 200° C.
Implementation Method 2
Composition for multi-component composite intercalation
Data Source
AI summary
The present disclosure relates to the field of oilfield chemistry, in particular to a composition for multi-component composite intercalation, a method of preparing a graphite system and a method of profile control and water shutoff.