Gel Plugging Slurry for Well Drilling Fracture Sealing
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Solution Overview
Problem
Conventional bridge plugging methods have a low success ratio due to formation fluids in lost circulation zones, and existing gel plugging methods suffer from poor plugging efficiency and material waste due to low solid particle concentration and narrow particle size distribution, as well as inadequate resistance to high pressure differences.
Innovation Solution
A gel plugging slurry comprising water, special gel, bridging material, linking material, and packing material, with specific weight ratios, that forms stable structures at fractures, allowing for improved plugging efficiency and wider fracture width coverage, and a slug plugging method involving packers to ensure accurate delivery and pressure balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the plugging slurry is held in still state for gelatinization at the lost circulation zone for a long time, then the gelatinization is more complete, but the plugging slurry is mixed with formation fluids and thinned, flowing into deep portions and resulting in plugging failure
Solution Approach 1:
The gel plugging slurry is prepared with pre-selected solid particles (0.5-5mm diameter) and special gel components before injection. The slurry is designed to achieve sufficient gelatinization and plugging effect within a shorter holding time (0.5-2 hours) at the lost circulation zone, preventing thinning and deep flow while ensuring complete gel formation for reliable plugging.
2Ease of operation
If the concentration of solid particles in the plugging slurry is low, then the slurry is easier to inject, but the plugging effect is poor and general applicability is reduced
Solution Approach 1:
The plugging slurry uses solid particles with optimized diameter (0.5-5mm) and concentration parameters. This parameter range ensures the slurry maintains adequate flowability for injection while providing sufficient solid particle concentration to achieve effective plugging across a wide span of fracture widths, improving both injection ease and plugging reliability.
3Ease of manufacture
If the actuation pressure of the special gel is low, then the gel slugs are easier to form, but the pressure drop gradient is not enough to resist high leaking pressure difference
Solution Approach 1:
The plugging slurry combines special gel with solid particles (0.5-5mm diameter) to form a composite plugging system. The special gel provides ease of slug formation and adaptability, while the solid particles enhance the pressure resistance capability. This composite structure enables the plugging material to resist high leaking pressure differences while maintaining ease of formation.
4Reliability
If bridge plugging materials are added to the gel plugging slurry, then the plugging effect is enhanced, but the high cohesive force after swelling makes it difficult to add materials
Solution Approach 1:
The gel plugging slurry is prepared with all necessary components (special gel, solid particles, and other additives) thoroughly mixed and uniformly distributed before injection. This preliminary mixing ensures that despite the high cohesive force that develops after swelling, the materials are already in their final positions and configurations, eliminating the need for additional material addition at the wellsite and simplifying the overall process.
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 gel plugging slurry achieves quicker gelatinization, effective plugging across a wide range of fracture widths, and improved plugging efficiency with reduced material waste and enhanced resistance to pressure differences, leading to higher success ratios and better applicability.
Implementation Method 1
holding the non-cross-linked special gel plugging slurry in still state for 4-8 h
Implementation Method 2
the special gel is a water-soluble polymer and has a good shear-thinning property
Data Source
AI summary
A gel plugging slurry for well drilling, comprising water, special gel, bridging material, linking material, and packing material, wherein based on 100 parts by weight of the water, the amount of the special gel is 1-15 parts by weight, the amount of the bridging material is 8-20 parts by weight, the amount of the linking material is 20-40 parts by weight, and the amount of the packing material is 25-45 parts by weight. The gel slug plugging method including simple operation and low requirement for ambient environment; besides, the bridging material, linking material and packing material in the gel plugging slurry form stable structures in the gel, and thereby the gel plugging effect can be improved effectively.