Fracture Blocking with Disposable Pack-off Particles
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Solution Overview
Problem
Fractured oil-gas reservoirs face high water content and reduced oil production due to strong flow conductivity of fractures, leading to low recovery efficiency, with existing blocking methods like gel blocking being ineffective and short-lived under harsh underground conditions.
Innovation Solution
A method involving the injection of blocker particles into the wellbore and fractures until stratum crack/fracture extension pressure is reached, followed by production, to effectively block fractures and reduce water production, using spherical particles made of polyethylene or similar materials with a concentration of 1-20% in a filling liquid, ensuring long-lasting blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gel blocking method is used to block fractures, then water production is reduced initially, but the blocking effect is short-lived and ineffective under harsh underground conditions
Solution Approach 1:
The patent uses blocker particles that are simple, robust, and can be easily replaced or supplemented. These particles are designed to be cost-effective and functional rather than durable, allowing for repeated injection treatments. The particles serve their blocking purpose and can be replenished without requiring long-term stability under harsh conditions.
Solution Approach 2:
The patent changes the physical parameters of the blocking medium by using solid particles with specific size ranges (0.1-5mm) and density characteristics instead of gel-based materials. This parameter change allows the blocking medium to maintain effectiveness under high temperature and pressure conditions where gels would degrade.
2Productivity
If fractures are left unblocked, then oil production maintains initial flow rate, but water content reaches more than 90% and recovery efficiency is very low
Solution Approach 1:
The patent applies blocking particles selectively to fracture zones rather than treating the entire reservoir uniformly. The particles are injected to specifically target and block water-flowing fractures while leaving oil-bearing matrix regions unaffected, creating local quality differences in permeability throughout the reservoir.
Solution Approach 2:
The patent segments the flow paths by blocking specific fracture channels with particles of different sizes. This segmentation divides the continuous water flow paths into blocked and unblocked sections, forcing water to take longer, less efficient paths through the matrix while maintaining oil production from unaffected zones.
3Reliability
If blocker particles are injected to block fractures, then water production is reduced and oil recovery is improved, but injection pressure must reach stratum crack/fracture extension pressure
Solution Approach 1:
The patent performs preliminary fracturing or uses existing fracture openings to create pathways for particle injection. By preparing the fracture network in advance through controlled fracturing or utilizing naturally open fractures, the injection pressure requirement is reduced while still achieving effective particle placement in the target zones.
Solution Approach 2:
The patent uses a carrier fluid or slurry as an intermediary medium to transport blocker particles into the fracture system. This intermediary allows particles to be injected at lower pressures by suspending them in a fluid that can flow through existing channels, with the particles then depositing in the fracture zones once the fluid pressure is reduced.
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 method significantly reduces water production and improves oil recovery by effectively blocking fractures, maintaining a high input-output ratio and lasting blockage, even in unopened and narrowly opened fractures, thereby enhancing the pressure gradient and utilization of the matrix oil-gas.
Implementation Method 1
injecting a filling liquid carrying blocker particles into a wellbore and a fracture via a wellhead
Implementation Method 2
blocker particles to reduce water and increase oil production... effectively blocking fractures
Data Source
AI summary
A method for filling an oil and gas well of a fractured oil and gas reservoir with pack-off particles to reduce water and increase oil production comprises the following steps: (1) injecting a filling liquid carrying pack-off particles into a wellbore and a fracture via a wellhead, until a stratum crack/fracture extension pressure is reached or exceeded, or until an injection amount per unit injection pressure is close to zero, or until a preset filling amount of pack-off particles is reached; (2) launching production.