Zonal Injection Profiling Using Hybrid Warmback Analysis
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Solution Overview
Problem
Current methods for injection profiling in multi-layer hydrocarbon reservoirs, such as Conventional Warmback Analysis, often produce inaccurate results in mature reservoirs due to the assumption that the Geothermal Temperature Profile remains valid over the reservoir's life, which is not the case as thermal properties change with prolonged injection, leading to incorrect zonal flow rate estimates.
Innovation Solution
The method involves using the Long-Term Shut-In Temperature Profile as the Reference Temperature Profile and applying a Hybrid Warmback Analysis that includes a pre-processing step to transform temperature profiles, mirroring cooldown zones to equivalent warmback processes, enabling accurate injection profiling in mature and sub-cooled reservoirs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Conventional Warmback Analysis uses Geothermal Temperature Profile as reference, then the method is simple to implement, but the measurement precision deteriorates in mature reservoirs due to thermal property changes
Solution Approach 1:
The patent changes the reference temperature profile parameter from the static Geothermal Temperature Profile to the dynamic Long-Term Shut-In Temperature Profile that evolves with reservoir thermal conditions. This parameter change allows the analysis to adapt to thermal property changes in mature reservoirs, resolving the contradiction between implementation simplicity and measurement precision.
Solution Approach 2:
The patent performs preliminary long-term shut-in of the injection well before conducting Warmback_analysis to establish an accurate reference temperature profile that reflects the actual thermal state of the reservoir. This preliminary action ensures the reference profile accounts for thermal property changes, improving measurement precision without significantly complicating the overall process.
2Measurement precision
If the reference temperature profile is updated to account for thermal changes, then the measurement precision improves, but the device complexity increases due to additional monitoring requirements
Solution Approach 1:
The patent makes the temperature monitoring system multi-functional by using the same distributed temperature sensing infrastructure for both real-time injection monitoring and for establishing the reference Long-Term Shut-In Temperature Profile. This universal approach improves measurement precision without proportionally increasing device complexity, as the same hardware serves multiple purposes.
3Measurement precision
If long-term shut-in is performed to establish accurate reference profile, then the measurement precision improves, but the productivity decreases due to well downtime
Solution Approach 1:
The patent applies partial action by performing the long-term shut-in only once or periodically to establish the reference temperature profile, rather than requiring continuous shut-ins. This partial approach achieves sufficient measurement precision while minimizing productivity loss, as the reference profile can then be used for multiple subsequent injection profiling operations without additional shut-ins.
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 approach provides more accurate zonal flow rate profiling by accounting for changes in thermal properties, improving the reliability of injection profiling in mature reservoirs and addressing inaccuracies in Conventional Warmback Analysis methods.
Implementation Method 1
The injected fluid temperature profile is strictly lower than or equal to the Long-Term Shut-In Temperature Profile
Implementation Method 2
injection of a cooler fluid into the wellbore... heat exchange between the injected fluid and the surrounding rock
Implementation Method 3
the wellbore fluid does not warm back all the way to the Geothermal Temperature Profile even after extended shut-ins... thermal relaxation to the Long-Term Shut-In Temperature Profile
Data Source
AI summary
Herein disclosed are methods and systems related to processes for injection wells generally utilized in the oil and gas industry. More particularly, disclosed herein are methods and systems related to improving the accuracy of profiling and determining individual cumulative fluid injection profiles for an injection period for multiple zones of an injection well in reservoir systems utilizing conventional warmback models. The methods herein allow for proper modeling and allocation of all injection zones, including zones experiencing a cooldown phenomena during shut-in by transforming the cooldown zonal temperature profiles into temperature profiles which can be utilized in a conventional warmback analysis. These methods are particularly useful in mature reservoir systems where the background reference temperature profile is no longer governed by the geothermal reference temperature profile.