Polymer Elastic Granules for Fracture Plugging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing water-based drilling fluids for fractured reservoirs face challenges in achieving effective temporary plugging and easy flowback, as they often require accurate fracture width assessment and can block oil and gas flow, necessitating plug removal, which complicates reservoir protection and productivity.
Innovation Solution
A water-based drilling fluid comprising bentonite, a tackifier, a filtrate reducer, an anti-collapse agent, a reservoir protectant composition with polymer elastic granules and synthetic fibers or film formers, which provides high plugging efficiency, unidirectional plugging, and temperature resistance up to 200°C, allowing for easy plug removal and maintaining reservoir permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid granule materials (e.g., calcium carbonate) are used for temporary plugging, then plugging effect is achieved, but plug removal is required after drilling which complicates the process
Solution Approach 1:
The patent changes the physical and chemical parameters of the granule materials by using polymer elastic granules with specific elasticity modulus, density, and size ranges (0.06-0.2 mm) that enable automatic removal after drilling. The granules are designed to deform and pass through the wellbore without manual intervention, transforming the rigid granule concept into a flexible, self-removing system.
Solution Approach 2:
The patent introduces dynamic characteristics to the plugging materials through polymer elastic granules that can deform under stress and flow back through the wellbore after drilling. The granules exhibit dynamic behavior by transitioning from a plugging state during drilling to a flowable state during removal, eliminating the need for separate plug removal operations.
2Object-affected harmful factors
If protective materials enter into fractures to generate plugging effect, then reservoir protection is achieved, but oil and gas flow is blocked requiring plug removal
Solution Approach 1:
The patent applies local quality by creating a selective plugging effect where the polymer elastic granules plug only the larger fracture channels that allow drilling fluid intrusion, while leaving smaller pathways open for oil and gas flow. The granules are sized to selectively block harmful flow paths without completely sealing the reservoir, achieving differential plugging based on local fracture characteristics.
3Object-affected harmful factors
If shielded temporary plugging mechanism is used, then drilling fluid intrusion is prevented, but accurate fracture width assessment is required which is difficult due to reservoir heterogeneity
Solution Approach 1:
The patent achieves universality by designing polymer elastic granules with a size range (0.06-0.2 mm) that can effectively plug fractures of varying widths without requiring precise measurement. The elastic nature and size distribution of the granules allow them to adapt to different fracture geometries, making the system universally applicable across heterogeneous reservoirs with unknown fracture characteristics.
4Reliability
If rigid granule materials are used for plugging, then temporary plugging effect is achieved, but plugging success ratio is low when fracture characteristics are unknown
Solution Approach 1:
The patent changes the mechanical parameters of the plugging materials from rigid to elastic by using polymer granules with specific elasticity modulus and deformability characteristics. This parameter change enables the granules to adapt to unknown fracture geometries and achieve reliable plugging without requiring precise manufacturing tolerances or prior knowledge of fracture dimensions.
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 fluid achieves a high success ratio for temporary plugging, maintains reservoir protection without requiring plug removal, and is suitable for deep and ultra-deep wells with improved lubrication properties, ensuring effective reservoir protection and oil well productivity.
Implementation Method 1
the polymer elastic granule deforms and plugs the reservoir fracture when a pressure difference is applied
Implementation Method 2
the polymer elastic granule flows back through the wellbore, removing the plug automatically when the pressure difference is removed
Implementation Method 3
The fluid achieves a high success ratio for temporary plugging, maintains reservoir protection without requiring plug removal, and is suitable for deep and ultra-deep wells with improved lubrication properties
Data Source
AI summary
The present invention relates to the technical field of petroleum drilling, and discloses a water-based drilling fluid for protecting fractured reservoirs and preparation method and use thereof. The drilling fluid includes: bentonite, a tackifier, a diluent, a filtrate reducer, an anti-collapse agent, a reservoir protectant composition, a lubricant, and water, wherein, the reservoir protectant composition comprises at least one of a polymer elastic granule, a synthetic fiber and a film former; the polymer elastic granule comprises an intermediate product, an alkali, a salt, and water in specific contents; the intermediate product is prepared from raw materials including acrylamide, a cationic monomer, a cross-linker, an initiator, a toughener, and water in specific contents. The drilling fluid provided in the present invention has a temperature-resistant property up to 200° C. or above, achieves a high temporary plugging success ratio, has a unidirectional plugging characteristic, and attains an outstanding reservoir protection effect.