Expandable Polymeric Microparticles for Diverting Injected Fluids in Reservoirs
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Solution Overview
Problem
In hydrocarbon recovery, thief zones with high permeability divert injected fluids away from lower permeability zones, leading to inefficient hydrocarbon sweep and high costs due to fluid cycling, with existing methods failing to effectively isolate or divert fluids in reservoirs with fractures or rubble zones, resulting in poor recovery rates and costly well modifications.
Innovation Solution
Development of highly cross-linked expandable polymeric microparticles with hydrolytically labile silyl ether or silyl ester crosslinkers that can propagate through the reservoir rock, expanding to impede fluid flow and divert injected fluids into less swept zones upon reaching specific temperature and pH conditions, allowing for improved hydrocarbon recovery without the need for specialized fluids or high salinity carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical seals or cement plugs are used to block thief zones, then fluid diversion is achieved in isolated zones, but the method fails when communication exists between layers outside the reach of cement such as fractures or rubble zones
Solution Approach 1:
The invention uses chemical gels that change their flow properties in response to environmental parameters (temperature, pH, ionic strength) to adapt to different reservoir conditions including fractures and rubble zones. The gel composition and crosslinking mechanisms are adjusted to ensure effective diversion across diverse geological structures.
Solution Approach 2:
The invention employs composite gel formulations combining multiple polymers and crosslinking agents to create a material that can simultaneously address mechanical plugging needs and adapt to complex fracture networks. The composite structure provides both structural integrity for blocking and flexibility for navigating irregular pore spaces.
2Reliability
If chemical gels are applied to seal off swept zones, then fluid diversion is achieved, but the treatment can bypass the gel and re-enter the thief zone having contacted only a small proportion of remaining hydrocarbon
Solution Approach 1:
The invention uses dynamically responsive gels that can change their permeability and flow resistance properties during the injection and production process. The gel structure evolves over time, initially allowing some flow then progressively increasing resistance to prevent bypass while maintaining connection to unswept zones.
Solution Approach 2:
The gel system incorporates feedback mechanisms where the gel's physical and chemical properties respond to the presence of hydrocarbon, water, and temperature gradients. This self-adjusting behavior ensures the gel maintains optimal diversion performance based on real-time reservoir conditions.
3Productivity
If the well is converted to a fluid injector to increase field injection rate, then overall recovery may be improved, but the injected fluid will mostly enter the thief zone and cause similar problems in nearby wells
Solution Approach 1:
The invention applies gel treatments to injection wells in advance of converting them to producers or increasing injection rates. This preliminary conformance control ensures that when injection rates are increased, the gel already in place prevents preferential flow into thief zones, directing fluids into unswept areas.
Solution Approach 2:
The gel acts as an intermediary material between the injected fluid and the thief zone, intercepting the fluid flow and redirecting it into lower permeability zones. This mediator prevents direct communication between the injection well and thief zones, enabling increased injection rates without repeating the bypass problem.
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 polymeric microparticles efficiently propagate and expand within the reservoir, effectively diverting injected fluids into under-swept zones, enhancing hydrocarbon recovery rates and reducing operational costs by blocking preferential flow paths and improving fluid distribution within the reservoir.
Implementation Method 1
the microparticle properties, such as particle size distribution and density, of the constrained microparticle are designed to allow efficient propagation through the pore structure of hydrocarbon reservoir matrix rock, such as sandstone. On heating to reservoir temperature and/or at a predetermined pH, the reversible (labile) internal cross links start to break allowing the particle to expand by absorbing the injection fluid (normally water).
Implementation Method 2
On heating to reservoir temperature and/or at a predetermined pH, the reversible (labile) internal cross links start to break allowing the particle to expand by absorbing the injection fluid
Implementation Method 3
the microparticle conformation is constrained by hydrolytically labile silyl ether or silyl ester crosslinkers. On heating to reservoir temperature and/or at a predetermined pH, the reversible (labile) internal cross links start to break
Data Source
AI summary
The present disclosure is directed to compositions and methods that may be used for enhanced oil recovery, for modifying the permeability of subterranean formations and for increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations. The compositions may include, for example, expandable cross linked polymeric microparticles having an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns and a cross linking agent content of from about 100 to about 200,000 ppm of hydrolytically labile silyl ester or silyl ether crosslinkers and from 0 to about 300 ppm of non-labile crosslinkers.