How SAGD Subcool is Affected by Fluid Dynamics

Recovery of heavy oil in steam-assisted gravity drainage (SAGD) is highly dependent on the temperature and viscosity of the fluids involved. It is well established that when the heated steam is passed down the injection well, the elevated temperature alters the viscosity of the oil. This change affects the flow of the oil to the producer well. This is the primary fluid dynamic principle that correlates the velocity, pressure, temperature, and density of the fluid with the productivity from the well. 

However, there is one important aspect to note in the fluid dynamics in the subsurface—the subcool. It is important to maintain SAGD subcool control in the oil reservoir to ensure safe and consistent production. The right component and equipment prevent temperature loss between the different zones of the wellbore to ensure there is no product loss in the process. Let's discuss this in further detail.

SAGD Subcool Control

Subcool, in SAGD, is the difference between the temperature of the saturated steam at the injection well to the temperature at the production well. That means the subcool is low if the temperature at the injector is not far off from that at the producer well. The lower subcool (i.e., the low-temperature difference) means that the high temperature of the steam is not lost and the oil viscosity is reduced for a higher recovery rate. 

However, it is essential to ensure subcool isn’t too low, resulting in temperatures that exceed the saturation point and overheating production. At too high a temperature, the high-velocity steam can carry the fine particle along with it, damaging the production well. Ensuring subcool control in accordance with the fluid dynamics is important to ensure efficient production. 

Several aspects of the SAGD process make it difficult to achieve subcool control. Some of them include:

• Well trajectory: Depending on the path and distance of the well trajectory, field temperature, and quality of the component used, heat may be lost to the surrounding between upper and lower sections of the wellbore.
• Reservoir performance: Depending on the oil and sand content, some reservoirs may require a higher subcool and others may require a lower.  

Multiple studies have suggested how liquid level can increase the temperature difference (subcool) between the injector and producer. Only by maintaining the SAGD subcool, is it possible to maintain the liquid level above the producing well for steady production. Steady steam injection and steam trap system help to maintain ideal liquid level without any heat loss on the way for consistent and efficient production. One way to do so is with the use of high-quality components.

How Quality Component Ensures SAGD Subcool Control

What do quality components mean for SAGD projects? Primarily, they are the system and equipment that are strong enough to withstand corrosive and abrasive environments and high pressure and temperature conditions as is the nature of the project. Additionally, they must be well constructed to prevent heat loss to the surrounding environment. Heat loss can be counterproductive in SAGD projects as more steam is consumed to counter the temperature loss leading to a very high steam to oil ratio. This factor can be especially critical in weather conditions like Alberta. 

The possible solutions can look like this:

• Steam or glycol tracing to maintain the process temperature throughout and prevent condensate build-up 
• Winterizing the piping system and equipment 
• Steam trap installation to prevent any condensate pooling
• Equipment housing to prevent temperature loss to the environment

Edmonton Valve & Fitting Can Help Identify Your Operational Challenges

For high-quality components to maintain SAGD subcool, seek consultation from the Field Advisors at Edmonton Valve & Fitting. They will work to identify possible issues and make repair and prevention plans for your SAGD project. We have years of experience troubleshooting possible leaks, and performing steam system audits to identify heat loss in the system. The evaluation is a step forward in making a proactive plan to enhance productivity. 

We also provide mission-critical components to prevent energy loss, leaks, and failure. Our valves and fittings are high-quality and designed to handle high-temperature, high-pressure, and abrasive conditions. When equipped with Grafoil packing, our single block and bleed and double block and bleed valves can handle the high temperature and pressure of your steam system. Similarly, our ZSML carbon steel fittings are designed to suit your high-pressure application as well as the high temperature of the superheated steam. Our components and fittings are made of materials such as Hastelloy C, titanium, and super duplex stainless steel that not only shows the compatibility of working with steam but also a wide range of other chemicals. The control systems can regulate the steam injection rate to maintain the liquid level and its temperature. By making sure the high temperature of the steam is not lost between the injection and production well, our high-quality components assist in maintaining efficient subcool control. 

Maintain efficiency and productivity within your SAGD projects by relying on solutions from Edmonton Valve & Fitting.