Coated Tracers for Acid Stimulation Monitoring
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Solution Overview
Problem
Current methods are inadequate for assessing the zonal distribution and effectiveness of acid stimulation in hydrocarbon wells, particularly in deepwater assets and horizontal completions, as they lack effective tools to monitor acid placement and diversion across the pay zone.
Innovation Solution
Deployment of coated tracers at pre-determined downhole locations, which remain inert until activated by acid stimulation, allowing for the measurement of tracer concentrations in produced fluids to identify zones receiving adequate or inadequate acid stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole temperature sensing (DTS) is used to monitor acid stimulation effectiveness, then zonal distribution of acid injection can be assessed, but the method is infeasible and infrequently conducted in deepwater assets and horizontal completions
Solution Approach 1:
The patent introduces coated tracers as intermediary elements that interact with acid stimulation fluids. These tracers are deployed in the wellbore and coated with materials that dissolve or change properties when exposed to acid, allowing remote sensing of acid distribution without requiring direct downhole temperature sensing equipment. The tracers serve as a mediator between the acid stimulation process and the monitoring system.
Solution Approach 2:
The patent replaces the mechanical/physical downhole temperature sensing system with a chemical sensing approach. Instead of using DTS equipment that requires physical installation in the wellbore, the system uses coated tracers that respond chemically to acid stimulation. The measurement is performed remotely on produced fluids, eliminating the need for complex downhole mechanical sensing systems.
2Measurement precision
If dissolvable chemical tracers are used to assess zonal contribution to production, then relative contributions of different zones can be measured, but the method is only suitable for early-life production due to rapid dissolution and installation requirements
Solution Approach 1:
The patent modifies the dissolution rate parameter of the tracer coating by selecting materials with specific solubility characteristics. The coating is designed to dissolve or change properties at a controlled rate that matches the production timeline. This allows the tracer to remain intact during early production phases and only dissolve when acid stimulation occurs, extending its effective service life beyond the limitations of conventional dissolvable tracers.
Solution Approach 2:
The patent uses composite tracer structures combining tracer cores with protective coatings. The composite material consists of a tracer component (for detection) and a coating component (for protection and controlled release). This composite structure allows the tracer to maintain its integrity during storage and initial production, then selectively release when exposed to acid stimulation, extending its operational duration.
3Measurement precision
If coated tracers are placed at pre-determined downhole locations, then acid stimulation effectiveness can be monitored, but the tracers must remain inert until activated by acid stimulation
Solution Approach 1:
The patent selects coating materials with specific pH-dependent solubility parameters. The coating remains insoluble and inert in neutral or alkaline produced fluids during normal production, then changes solubility parameters when exposed to acidic stimulation fluids. This parameter change allows the coating to transition from a protective inert state to an active dissolving state that releases the tracer signal only when acid stimulation occurs.
Solution Approach 2:
The patent applies different properties to different parts of the tracer system. The tracer core provides the detection signal, while the coating provides localized protection and controlled release functionality. The coating's chemical properties are specifically tailored to respond to acid stimulation locally at the tracer location, maintaining overall system reliability while enabling precise measurement of acid distribution.
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
Enables accurate assessment of acid stimulation effectiveness by determining which zones received acid, thereby optimizing remedial stimulation operations and improving well productivity.
Implementation Method 1
the coating is soluble in the acid stimulation fluid used to stimulate the well
Implementation Method 2
The amount of the tracer in a produced fluid from the hydrocarbon well is measured
Data Source
AI summary
The present application pertains to a method of tracing acid stimulation treatment in a hydrocarbon well using one or more coated tracers. The method comprises placing the one or more coated tracers at pre-determined downhole locations in the hydrocarbon well. The well is then acid stimulated and the amount of the tracer in a produced fluid from the hydrocarbon well is measured. The one or more coated tracers each comprise a tracer and a coating which are described herein.