Cement Annulus Permeability Measurement Tool
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Solution Overview
Problem
Current methods for in situ testing of cement annulus permeability in oil wells lack the ability to effectively measure fluid dynamic properties, which are crucial for ensuring the integrity and isolation of the cement sheath, particularly in formations intended for carbon dioxide sequestration, as they do not adequately assess permeability and leakage potential.
Innovation Solution
A wellbore tool with a pressure probe is used to measure the change in pressure over time within the cement annulus, allowing for the determination of fluid dynamic properties such as permeability, by drilling through the casing and setting the probe in hydraulic contact with the cement annulus, and using mathematical models to correct for boundary conditions and flow dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic measurements are used to evaluate cement integrity, then mechanical properties such as bond quality and strength can be determined, but fluid dynamic properties such as permeability cannot be measured
Solution Approach 1:
The evaluation tool is designed to perform multiple measurement functions: acoustic measurements for mechanical properties and pressure measurements for fluid dynamic properties. This multi-functional approach allows a single tool to assess both bond quality and permeability, resolving the contradiction between measurement precision for specific properties and measurement versatility across different property types
Solution Approach 2:
A pressure probe is introduced as an intermediary component that enables direct pressure measurements within the cement annulus. This probe serves as a mediator between the evaluation tool and the cement material, allowing measurement of pressure changes that indicate permeability without interfering with acoustic measurements
2Reliability
If the cement annulus is evaluated using non-invasive acoustic methods, then the cement integrity can be assessed without drilling, but fluid dynamic characteristics remain undetected
Solution Approach 1:
The evaluation process is segmented into two distinct measurement modes: acoustic evaluation for mechanical integrity and pressure probe measurement for fluid dynamics. Each segment targets specific properties, allowing comprehensive assessment without compromising reliability of either measurement type while preventing loss of fluid dynamic information
Solution Approach 2:
The tool performs acoustic measurements first to assess cement integrity before deploying the pressure probe. This preliminary action ensures that the structural integrity is evaluated first, then fluid dynamic properties are measured in the same location, preventing loss of information by systematically collecting both types of data
3Measurement precision
If pressure probe measurements are conducted by drilling through the casing, then fluid dynamic properties can be measured, but the complexity of the testing procedure increases
Solution Approach 1:
The drilling operation and pressure measurement functions are merged into a single integrated tool. The same device that drills through the casing also houses the pressure probe and measurement electronics, reducing overall system complexity despite the invasive nature of the measurement
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 enables accurate measurement of cement annulus permeability, facilitating the identification of suitable zones for carbon dioxide sequestration by ensuring low permeability and preventing undesirable leakage, thereby enhancing well integrity and storage efficiency.
Implementation Method 1
measuring the change of pressure in the probe over time, where the change in pressure over time is a function of among other things, the initial probe pressure, the formation pressure, and the fluid dynamic property of the cement
Implementation Method 2
The appropriate cement formulation helps to achieve a durable zonal isolation, which in turn ensures a stable and productive well without requiring costly repair
Data Source
AI summary
The permeability of the cement annulus surrounding a casing is measured by locating a tool inside the casing, placing a probe of the tool in hydraulic contact with the cement annulus, measuring the change of pressure in the probe over time, where the change in pressure over time is a function of among other things, the initial probe pressure, the formation pressure, and the permeability, and using the measured change over time to determine an estimated permeability. By drilling into the cement and making additional measurements of the change of pressure in the probe over time, a radial profile of the cement permeability can be generated.