Top Flow Assurance Challenges for SAGD Operations—And How to Prevent Them

The term “flow assurance” has expanded from its original use to describe flow problems in offshore oil and gas operations to encompass maintaining flow from one point to another for any type of oil and gas operation—for example, steam-assisted gravity drainage (SAGD) wells.

SAGD operations use flow assurance analysis to understand the composition and characteristics of the production fluid—a mixture of bitumen and water—and how it flows from the well to the surface to a processing plant. However, as SAGD wells age, the fluid characteristics of the production fluid change. It’s important to understand these changes to know how to adjust processes over the lifetime of the well. 

Using good sampling practices with a well-designed system is the best way to ensure a thorough, up-to-date understanding of fluid characterization—which allows you to identify potential problems early in efforts to prevent them. In this post, we will look at some common flow assurance challenges in SAGD operations and how good sampling practices can work to prevent them.

Common Flow Assurance Challenges in SAGD Operations

SAGD operations rely on boilers to produce steam and pumps to move the product from place to place. Both pumps and boilers are critical failure points that can shut down operations if major problems occur.

Pumps

Plugged Seal: The high viscosity, solids-containing crude oil in SAGD wells makes plugs a common problem. Plugged seals can prevent the flush system from adequately flushing and lubricating the mechanical seal, which can ultimately lead to damage or failure. 

Process Fluid Mixing with Buffer or Barrier Fluid: If high-viscosity process fluid leaks into the buffer/barrier fluid, it is very likely to plug the seal. This can overheat the mechanical seal, leading to leaking or failure. It is important to select a buffer/barrier fluid that resists the diffusion of process fluid.

Mechanical Seal Heat Checking: Heat checking in rotating equipment is a significant risk in SAGD operations because of the high temperatures and high-viscosity fluids. Heat checking happens when flow problems lead to insufficient seal lubrication or cooling.

Boilers

Scale and Corrosion: Clean water is essential to efficient and reliable boiler operation. Higher-quality steam leads to a higher recovery factor and lower steam-oil ratio (SOR). About 90% of SAGD water is treated and reused in the boiler, so it is necessary to sample and test the treated water regularly. Improperly treated water can leave scale or corrosion on boiler tubes, which can increase operating temperatures, decrease efficiency, and eventually cause failure.

Accurate Sampling Prevents Flow Assurance Problems Before They Occur

Understanding the composition of the process fluid is critical to ensure flow and maintain efficient and reliable SAGD operations. A simple and effective way to do this is with periodic grab sampling. Grab samples, along with proper instrumentation, provide insight into produced fluid’s viscosity, temperature, pressure, and water-to-oil ratio and how they change and affect flow over time. This allows you to be proactive with adjustments to the process to keep the system optimized.

Samples must be as representative of the process fluid as possible, so they must be fully mixed and cannot be contaminated during or after sampling. Ensure your samples are clean and representative by following these guidelines. 

Use the Right Container: After collecting a sample, it is important to use a container that can maintain the sample at process conditions. Gases and volatile liquids require pressurized sample cylinders to prevent evaporation and fractionation. Bottles are an option only if the sample is an unpressurized, non-volatile, non-toxic liquid.

Avoid Contamination: Purge the line and container before sampling. Collect the sample with a smooth bore, not a corrugated hose. Analyze the sample as soon as possible to minimize the risk of contamination.

Avoid Phase Changes: Evaporation or condensation in the sampling line will alter the composition of the sample. Avoid phase changes by maintaining adequate pressure and temperature during collection. Use the P-T diagram of the fluid to understand the pressure and temperature needed to prevent phase changes, and never sample a fluid close to its phase change point.

Sample from the Right Location: Draw the sample from the middle third of the process line. The faster-moving fluid in the centre of the line is better mixed, while the slower-moving fluid near the wall is generally less representative of the process. Don’t sample from the bottom of the line where solids can collect.

Avoid Dead Legs: Dead legs are spaces in the system with no flow—like tees, pressure gauges, and temperature indicators—where solids and old fluid accumulate. Avoid drawing samples downstream of dead legs, and try to install these components downstream of the sampling station so they won’t affect sample integrity.

Look to Local Fluid Handling Experts for Grab Sampling Support

Edmonton Valve & Fitting is experienced with SAGD applications in Alberta and understands the flow assurance challenges of heavy crude oil. Our Field Advisors can perform a fluid systems evaluation to determine the best sampling system solution for your SAGD operations. Whether you need to repair or replace your current grab sampling system or you need a new one, our Field Advisors can help you understand your options.

Field Advisors at Edmonton Valve & Fitting can provide an onsite evaluation of your process to determine the best grab sampling solution. Our Field Advisors have ample experience with sampling systems for a wide range of SAGD applications and can make suggestions for improving SAGD efficiency.

About Tristian McCallion, Custom Solutions Manager, Edmonton Valve

Edmonton Valve has relied on McCallion for 26 years. His current title is Custom Solutions Manager. Earlier, he supervised our sales team. Before that, he managed sales throughout Edmonton and northeastern Alberta. For 12 years he also worked with Swagelok Energy Advisors across North America, training customers on steam fundamentals (TAP), testing steam traps, and conducting steam system audits.