Pressure-Bearing Plugging Agent for Strata Crack Sealing

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Solution Overview

Problem

Conventional plugging agents fail to effectively address the low pressure-bearing capacity of strata due to the formation of secondary cracks and subsequent leakage, as they primarily form a filling layer at the surface of cracks, which is prone to breakdown under increasing pressure differences.

Innovation Solution

A pressure-bearing plugging agent comprising a water-absorbing swellable core coated with a paraffin layer and a cemented rigid particle layer, which disintegrates to allow water absorption and swelling, filling the crack interior and maintaining structural integrity under stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bridging plugging materials are compounded into a plugging slurry and squeezed into leakage sites, then a filling plugging layer is formed at the shallow part and surface of the crack, but the filling plugging layer is prone to fall off or break down under increasing pressure difference, causing leakage to reappear

Engineering Contradiction:

Improveplugging effectVSAvoidpressure-bearing capacity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The plugging agent is divided into multiple functional layers: a water-absorbing core for volume expansion, a paraffin coating layer for controlled disintegration, and a rigid particle coating layer for structural strength. This segmentation allows each layer to perform its specific function optimally.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The plugging agent undergoes parameter changes through water absorption by the core material, causing volume expansion from the core outward. This dynamic parameter change enables the agent to adapt to crack width variations and maintain effective plugging under different pressure conditions.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the filling plugging layer is formed to separate the interior space of the crack from the wellbore, then the leakage is eliminated initially, but the pressure difference between wellbore and crack interior increases, causing the filling plugging layer to break down

Engineering Contradiction:

Improveplugging durabilityVSAvoidpressure difference

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The plugging agent transitions from a compact state to an expanded state through water absorption. This dynamic transformation allows the agent to adapt to increasing pressure differences by expanding and distributing stress over a larger volume, preventing breakdown.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The plugging agent combines multiple materials with different properties: water-absorbing polymer for expansion, paraffin for controlled disintegration, and rigid particles for structural support. This composite structure provides both flexibility for pressure accommodation and strength for durability.

Inventive Principle:

Principle #40Composite materials

3Volume of stationary object

If the water-absorbing swellable material is used as the core, then the crack interior space can be filled through swelling, but the structural integrity may be compromised without proper coating layers

Engineering Contradiction:

Improvefilling volumeVSAvoidstructural integrity

Core Design Contradiction:

Volume of stationary objectVSStrength

Solution Approach 1:

The water-absorbing core is nested within the paraffin coating layer, which is in turn nested within the rigid particle coating layer. This nested structure allows the core to expand and fill the crack while the outer layers maintain structural integrity and protect the core.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The paraffin coating layer acts as a flexible shell that can accommodate the volume expansion of the water-absorbing core while maintaining containment. This flexible shell allows the core to swell to fill the crack space without compromising the overall structural integrity.

Inventive Principle:

Principle #30Flexible shells and thin films

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 agent effectively bridges and fills cracks, enhancing the stratum's pressure-bearing capacity by absorbing water and swelling to fill internal spaces, preventing secondary crack formation and maintaining structural strength.

Implementation Method 1

the core is made of a water-absorbing swellable material... the core may absorb water and swell, such that the interior space of the crack is effectively and completely filled

Methodology Applied

Scientific EffectWater absorption and swelling: Absorption (physical)

Implementation Method 2

when the pressure-bearing plugging agent enters the interior part the crack, a paraffin layer inside the pressure-bearing plugging agent melts due to a high temperature of the stratum crack

Methodology Applied

Scientific EffectDisintegration:

Implementation Method 3

the second coating layer is obtained by cementing the rigid particles with an adhesive

Methodology Applied

Scientific EffectCementing: Adhesive

Data Source

PatentUS11453814B2Pressure-bearing plugging agent and preparation method and use thereof

Publication Date: 2022.09.27 SOUTHWEST PETROLEUM UNIV

AI summary

The present disclosure a pressure-bearing plugging agent, comprises a core, a first coating layer and a second coating layer which are sequentially coated on an outer surface of the core, wherein the core is made of a water-absorbing swellable material, the first coating layer is a paraffin layer, and the second coating layer is obtained by cementing the rigid particles with an adhesive.