Friction-Triggered Explosive Pellet for Fracture Characterization

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Solution Overview

Problem

Conventional hydraulic fracture monitoring methods face challenges in accurately detecting acoustic energy from fractures due to minor energy generation or interference from adjacent rock, and explosive pellets designed to detonate at temperatures less than or equal to 100° C pose safety risks during transportation and storage in warmer climates.

Innovation Solution

Development of explosive pellets with a casing containing ignition, detonation, and explosive materials, where friction-generated heat from non-explosive materials or temperature exposure triggers detonation, and a fluid composition with metallic powder, water, and a gelling agent initiates an exothermic reaction to detonate pellets within fractures, generating detectable seismic signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If explosive pellets are designed to detonate at temperatures less than or equal to 100° C., then the pellets can be used to characterize fractures in shallow reservoirs, but the transportation and storage of the pellets becomes dangerous in warmer climates

Engineering Contradiction:

Improvedetonation reliabilityVSAvoidsafety risk during transportation and storage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter of the explosive pellet by incorporating a temperature-sensitive component that remains stable at ambient temperatures but triggers detonation when exposed to reservoir temperatures. This allows the pellet to be safe during transportation and storage while ensuring reliable detonation in the target environment.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a temperature-sensitive intermediary substance within the explosive pellet that acts as a trigger mechanism. This intermediary remains inert during handling but activates the detonation sequence when exposed to the thermal conditions of the reservoir, thereby resolving the contradiction between safety during transport and reliability during use.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If conventional explosive pellets are used for fracture characterization, then acoustic energy can be generated, but the acoustic energy is too minor to detect or is generated by adjacent rock rather than the fracture

Engineering Contradiction:

Improveacoustic energy detection accuracyVSAvoidinsufficient or misattributed acoustic signal

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent segments the explosive pellet into distinct functional components: a temperature-sensitive trigger section, a detonation material section, and an explosive material section. This segmentation ensures that the acoustic energy is generated precisely at the fracture location by the explosive material, rather than by adjacent rock, thereby improving measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces conventional mechanical initiation methods with a temperature-based chemical initiation system. The temperature-sensitive component triggers a chemical reaction that generates controlled acoustic energy, providing a more reliable and location-specific signal for fracture characterization compared to mechanical methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enhances the accuracy of fracture characterization by ensuring detonation at various temperatures and pressures, providing reliable seismic signals for mapping hydraulic fractures while ensuring safety during transportation and storage.

Implementation Method 1

Movement of the nonexplosive material can generate a predetermined amount of energy in the form of friction-generated heat sufficient to detonate the explosive material

Methodology Applied

Scientific EffectFriction-generated heat: Friction

Implementation Method 2

The detonation material can detonate the explosive material when the pellet is exposed to a predetermined temperature

Methodology Applied

Scientific EffectTemperature-triggered detonation: Detonation

Implementation Method 3

An exothermic reaction of the fluid can be initiated. The fluid can include about 5 vol % to about 50 vol % of a metallic powder, about 50 vol % to about 95 vol % water, and about 0.1 vol % to about 3 vol % of a gelling agent

Methodology Applied

Scientific EffectExothermic reaction: Exothermic Reaction

Data Source

PatentUS9334719B2Explosive pellet

Publication Date: 2016.05.10 SCHLUMBERGER TECH CORP

AI summary

An explosive pellet for characterizing a fracture in a subterranean formation is provided. The pellet can include a casing having a detonation material and an explosive material disposed within the casing. The pellet can also include a nonexplosive material moveably disposed within the casing. Movement of the nonexplosive material can generate a predetermined amount of energy in the form of friction-generated heat sufficient to detonate the explosive material.