SAGD Liquid Level Control via Periodic Shut-in Measurements
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Solution Overview
Problem
Current methods for monitoring and controlling liquid levels in petroleum extraction processes, such as SAGD, face challenges in accurately determining local liquid levels due to variations in temperature and pressure, leading to inefficiencies and potential steam coning issues.
Innovation Solution
The method involves measuring local shut-in and operating temperatures and pressures in multiple inflow zones of production and injection wellbores, calculating local subcool values and profile values, and adjusting flow rates and wellbore configurations based on these measurements to maintain optimal liquid levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional liquid level monitoring methods are used in SAGD processes, then the system is simpler to operate, but the measurement precision of local liquid levels deteriorates due to temperature and pressure variations
Solution Approach 1:
The patent divides the production wellbore into multiple discrete measurement zones along its length. Temperature and pressure sensors are distributed at different locations (heel, middle, toe sections) to capture local conditions. This segmentation allows independent measurement of liquid levels in different zones, accounting for local temperature and pressure variations that affect accuracy.
Solution Approach 2:
The patent introduces temperature and pressure as intermediary parameters to indirectly determine liquid levels. Instead of directly measuring liquid level, the system measures temperature and pressure at multiple zones, then uses these intermediary measurements to calculate liquid levels by accounting for the effects of temperature and pressure variations on the measurement accuracy.
2Measurement precision
If periodic shut-ins are implemented for dynamic liquid level monitoring, then the measurement precision improves, but the productivity decreases due to production interruptions
Solution Approach 1:
The patent implements periodic shut-ins at predetermined intervals to perform dynamic liquid level monitoring. During these brief shutdown periods, the system captures temperature and pressure data to determine liquid levels. This periodic action allows the system to maintain high measurement precision while minimizing the impact on overall productivity, as the shut-ins are brief and scheduled rather than continuous.
Solution Approach 2:
The system performs liquid level measurements during shut-in periods before resuming production. By completing the measurement process during the brief shutdown window, the system obtains accurate liquid level data without requiring extended production interruptions. The preliminary measurement is completed quickly, allowing production to resume immediately afterward.
3Measurement precision
If multiple sensors are deployed in each inflow zone, then the measurement precision of temperature and pressure improves, but the device complexity increases
Solution Approach 1:
The patent segments the wellbore into multiple inflow zones and deploys temperature and pressure sensors at representative locations within each zone (heel, middle, toe). This segmentation approach allows the system to capture temperature and pressure variations across different zones without requiring excessive sensors, balancing measurement precision with manageable system complexity.
Solution Approach 2:
The patent applies local quality by positioning sensors at specific strategic locations within each inflow zone rather than uniformly distributing them. Temperature and pressure measurements are taken at representative points (heel, middle, toe) that capture the local conditions of each zone, providing sufficient measurement precision while minimizing the total number of sensors required.
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 allows for more accurate and dynamic control of liquid levels, improving production efficiency, reducing steam coning, and extending the lifespan of equipment by enabling real-time adjustments to maintain optimal operating conditions.
Implementation Method 1
measuring, using at least one first temperature sensor positioned in the production wellbore segment, a local shut-in temperature for each of a plurality of inflow zones
Implementation Method 2
measuring, using at least one first pressure sensor positioned in the production wellbore segment, a local shut-in pressure for each of the plurality of inflow zones
Implementation Method 3
gravity drainage refers to a recovery process in which gravity is the primary force used to recover heavy oil and bitumen from a reservoir
Implementation Method 4
high pressure steam is injected into the upper wellbore (also referred to as the injector) to heat the oil in the surrounding formation, thereby reducing its viscosity
Data Source
AI summary
Methods and systems for determining a liquid level in a formation between a horizontal segment of an injection wellbore and a horizontal segment of a production wellbore are disclosed. Under shut-in conditions, local temperatures and pressures are determined for each of a plurality of inflow zones along the production wellbore segment. Local profile values are determined based on local shut-in subcool values and local shut-in liquid levels. After flow has resumed, a local liquid level is determined based on the local operating subcool value and the local profile value for that inflow zone. The local profile values may be updated during subsequent shut-ins.