Virtual Metering for Multi-Zonal Injection Wells
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Solution Overview
Problem
Conventional methods for monitoring and controlling fluid injection into underground reservoirs, particularly in injection wells with multiple zones or branches, face challenges such as inaccurate flow metering, meter failures, and the lack of subsurface measurement capabilities, which affect the reliability of injection operations and oil/gas production processes.
Innovation Solution
A method that involves monitoring fluid flow and pressure in a collective header conduit assembly, performing dynamically disturbed injection well tests, and using well variable monitoring equipment to derive injection estimation models for each well, allowing for real-time estimation and reconciliation of injection rates, even in the absence of shared well testing facilities, and adjusting inflow control valves to optimize injection into individual zones or branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional flow meters are used for monitoring injection flows, then injection rates can be measured, but the meters are susceptible to drift in accuracy or complete failure
Solution Approach 1:
The patent creates a virtual copy of the flow metering function using computer algorithms that process pressure and flow data from multiple sources to generate virtual flow rate estimates, providing a backup measurement system that does not suffer from the same failure modes as physical flow meters
Solution Approach 2:
The system uses pressure sensors and flow data that serve multiple purposes: they monitor well conditions, detect anomalies, and provide input for both actual and virtual flow metering, making the measurement system more robust and less dependent on any single component
2Measurement precision
If subsurface flow meters are installed in injection wells with multiple zones or branches, then injection flows into individual zones can be measured, but the device complexity and cost increase significantly
Solution Approach 1:
The patent introduces an intermediary computational system that processes readily available pressure and flow data through algorithms to derive zonal injection rates, eliminating the need for complex subsurface flow meters while achieving the same measurement objective
Solution Approach 2:
The patent replaces mechanical subsurface flow meters with a computer-based algorithmic system that calculates zonal injection rates from pressure differential measurements and total flow data, significantly reducing device complexity while maintaining measurement capability
3Reliability
If multiple flow meters are installed at each injection well to monitor individual zones, then accurate zonal monitoring is achieved, but the system becomes vulnerable to multiple points of failure
Solution Approach 1:
The patent combines multiple measurement inputs (pressure sensors, total flow meters) into a unified virtual metering system that processes data centrally, reducing the number of individual flow meters needed while improving overall system reliability through redundancy and cross-validation
Data Source
AI summary
A method for virtually metering flow rates in a cluster of injection wells comprises: closing each well in and performing a dynamically disturbed injection test (DDIT) on it, during which the injection rate to the well is varied while the flow rate in the header conduit assembly (HCA) and one or more injection well variables of the test well and the other wells are monitored, and the other wells are controlled so that their tubing head pressures or flow meter readings remain constant; for each tested well deriving a model providing a correlation between variations of the fluid flowrate attributable to the test well and variations of the well variables monitored during each DDIT; injecting fluid into each well while monitoring a flow pattern in the HCA and one or more well variables; calculating an estimated injection rate at each well basis on flow pattern, well variables and the model.