Transient-Pressure Testing for Water Injection Well Reservoir Damage
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Solution Overview
Problem
Transient-pressure tests for water injection wells are distorted by induced fractures, making it difficult to determine reservoir characteristics and remediate shallow damages, especially when their location and severity are unknown, leading to inefficient well operation and potential formation damage.
Innovation Solution
A method for transient-pressure testing that involves determining a test injection rate below the formation fracture pressure, conducting injection and fall-off tests, and analyzing well test data to identify the location and severity of shallow damages, thereby mitigating the effects of fracture storage and selecting appropriate remediation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection pressure is increased to overcome formation plugging, then injection rate can be maintained, but formation fractures are induced which cause additional reservoir damage
Solution Approach 1:
The patent applies preliminary action by conducting a transient-pressure test before actual water injection operations to detect formation plugging and shallow damages in advance. The test identifies reservoir conditions and potential issues, allowing operators to adjust injection parameters before committing to high-rate injection that could cause fracturing. This preliminary diagnostic step prevents formation damage by enabling proactive management of injection rates based on actual formation conditions.
2Loss of time
If transient-pressure tests are conducted at high injection rates, then test duration can be reduced, but induced fractures distort test data making reservoir characterization inaccurate
Solution Approach 1:
The patent applies parameter changes by systematically varying injection rates during the transient-pressure test to identify the optimal rate that avoids fracture induction while maintaining adequate test signal. The method involves conducting tests at multiple injection rates and analyzing the pressure transient data to determine the rate at which reservoir-dominated flow occurs without fracture storage effects. This parameter optimization ensures accurate reservoir characterization within acceptable timeframes.
3Productivity
If water injection is used to maintain reservoir pressure, then hydrocarbon production is stimulated, but fine-suspended solids in injected water block formation flow paths causing formation plugging
Solution Approach 1:
The patent applies preliminary action by using transient-pressure tests to detect formation plugging caused by suspended solids before it severely impacts injection performance. The test identifies the extent and location of plugging, allowing operators to implement remediation measures such as injection rate adjustments, chemical treatments, or well stimulation before the formation damage becomes irreversible. This early detection protects long-term productivity despite the presence of solids in injected water.
Data Source
AI summary
Provided in some embodiments are systems and methods for transient-pressure test of an oil reservoir water injection well system. Embodiments provide for determining a fracturing injection rate for the well, setting a test injection rate preferably below the fracturing injection rate, conducting a stabilized injection of water into a wellbore of the well at the test injection rate for a prescribed period, and conducting a fall-off test including shutting-in the well for a prescribed fall-off period, and acquiring test data indicative of fluid pressure in the wellbore of the well during the injection and the fall-off periods. Embodiments also provide for generating a model prediction, comparing the model to the test data to determine whether it is a match for the well, and associating the parameter values with the well, including the severity and the location of the shallow damage, if the reservoir model is a match.