Wellbore Annular Cementing Evaluation Using Transient Thermal Response
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Solution Overview
Problem
Poor zonal isolation in wellbores due to inadequate cementing practices leads to undesirable fluid mixing, which is difficult to detect using existing sonic and acoustic methods, especially when the density of the annular material is similar to the surrounding fluid, limiting the effectiveness of these techniques.
Innovation Solution
Employing a fiber optic cable to collect transient thermal response data by creating a temperature gradient in the wellbore, which allows for the identification of poorly cemented zones by comparing measured temperature data over time to predicted thermal responses based on mathematical models of conduction and convection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sonic and acoustic methods are used to detect annular material, then detection capability is provided, but detection reliability deteriorates when annular material density is similar to surrounding fluid density
Solution Approach 1:
The patent replaces sonic and acoustic detection methods with a thermal detection system. A heater element applies thermal energy to the wellbore wall, and temperature sensors measure the thermal response. This substitution of mechanical wave-based detection with thermal field-based detection resolves the limitation of density-dependent acoustic detection, providing reliable annular material identification regardless of density similarities between cement and formation fluids.
Solution Approach 2:
The patent changes the detection parameter from acoustic properties (which are density-dependent) to thermal properties (specifically thermal conductivity and heat capacity). By measuring temperature transient response to controlled heating, the system identifies annular material based on its thermal characteristics rather than acoustic impedance, thereby maintaining detection reliability across varying density conditions.
2Measurement precision
If thermal gradients are created in the wellbore to enable thermal response measurement, then detection accuracy improves, but energy consumption increases
Solution Approach 1:
The patent applies partial heating rather than heating the entire wellbore volume. The heater element is positioned at a specific location and applies thermal energy locally to create a controlled temperature gradient in the annular space. This partial action approach achieves sufficient thermal contrast for accurate material identification while minimizing overall energy consumption compared to bulk heating methods.
Solution Approach 2:
The thermal detection process employs periodic heating cycles where the heater element is activated for controlled time intervals and then deactivated. This periodic action allows the system to accumulate thermal response data during heating phases and perform measurements during cooling phases, improving detection accuracy through repeated observations while managing energy consumption through duty-cycled operation rather than continuous heating.
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
This method provides reliable and interpretable data for identifying poorly cemented regions, enabling targeted remediation such as squeeze cementing, and is cost-effective and logistically simple, regardless of the relative density of the annular material.
Implementation Method 1
A fluid may be circulated through the wellbore in sufficient quantity, at a sufficient temperature, and for a sufficient amount of time to provide for a sufficient temperature gradient in the wellbore in a radial and/or axial direction
Implementation Method 2
The transient thermal response can occur as a result of conduction and convection processes that occur within the wellbore
Implementation Method 3
The transient thermal response can occur as a result of conduction and convection processes that occur within the wellbore
Data Source
AI summary
A method for identifying zones in an annulus with poor cementing that may include deploying a fiber optic cable within the wellbore, creating a temperature gradient in the wellbore, and collecting temperature data over a period of time as the wellbore returns to a thermal equilibrium. The method may also include comparing the temperature data collected by the fiber optic cable at one or more locations to predicted temperature data over the period of time at the one or more locations to identify locations where the measured temperature data deviates from the predicted temperature data for identifying locations or zones of the annulus that have poor cementing.