Flow assurance fluid characterization is the concept of ensuring fluid flows effectively and efficiently from point A to point B. Originally, flow assurance was a term used to describe the analysis and evaluation of problems resulting from solids forming in pipelines for offshore oil and gas operations. However, flow assurance can pertain to all associated risks with maintaining flow from one point to another for any oil and gas operation.

Steam-assisted gravity drainage (SAGD) utilizes flow assurance analyses during initial drilling of horizontal wells to gain an understanding of what the production well is producing and how the produced fluid (bitumen and water) is flowing from production well to the surface and finally to a processing plant where the bitumen and water are separated. However, like any other oil field, produced fluids from SAGD wells change as the wells age. Flow assurance fluid characterization can help SAGD operators understand the impact of aging wells on the produced fluid, as this affects flow to processing plants as well as the water and bitumen separation process. Below, we will discuss the impact of aging SAGD wells, the importance of flow assurance analyses, and how grab sampling can aid in such analyses.

Flow Assurance Fluid Characterization in SAGD

As SAGD wells age, there are bound to be changes in the produced fluid. It is important to characterize these changes to understand how processes need to adjust over the lifetime of the wells to accommodate. Let’s take a look into aging well characteristics, the importance of flow assurance evaluation for aging SAGD wells, and some methods for maintaining efficient flow and SAGD operations to minimize downtime.

How SAGD Wells Age

After years of bitumen production at SAGD wells, the produced fluid will likely experience a change in the water-to-oil ratio. As the bitumen resource is non-renewable, over years of extraction, the bitumen under the earth’s surface begins to deplete, increasing the size of the cavity. As bitumen depletes and cavity size increases, more steam and heat are required to reduce the viscosity of the bitumen to be able to pump it to the surface. Thus, over time, SAGD wells are likely to produce larger amounts of water and less oil, changing the flow characteristics of the system.

Importance of Flow Assurance for Aging SAGD Wells

As the produced fluid’s water-to-oil ratio changes over time, it is important to quantify such changes, as they are likely to impact the flow properties of the system that may require adjustments to line sizes or pumping requirements. Changes in water-to-oil ratio may require updates to current processes occurring in SAGD operations. After the bitumen and water mixture leaves the production well, it is pumped to the surface to be routed to a processing plant. In the processing plant, this mixture is sent to a settling tank to separate the water from the bitumen. The time required to settle water to the bottom of a settling tank is likely to increase with higher water-to-oil ratios. 

If oil is not properly dewatered, this can result in water being passed into the oil lines or pipeline. If temperatures in these pipes are high, water can boil in the pipe, causing increased pressure and thus creating instantaneous backpressure. As the water expands, the flow of oil stops, increasing the oil pressure and forming a slug. As this slug moves through the system, the large mass and high velocity result in a large momentum which may cause damage to supports if the slug collides with an elbow in the piping.

Grab Sampling for Flow Assurance Fluid Characterization

Water-to-oil ratios will inevitably increase as SAGD wells age. It is important to fully understand flow properties and characteristics to make changes to SAGD processes accordingly and prevent unnecessary downtime. A simple and effective method for flow assurance fluid characterization is periodic grab sampling of produced fluid. Grab samples, along with proper instrumentation, provide insight into produced fluid properties, such as viscosity, temperature, pressure, and water-to-oil ratio. Taking regular samples of produced fluid from SAGD wells provides a deeper understanding of how the wells are aging and how the flow through the system is changing. This allows for operators to be proactive regarding necessary changes to SAGD processes that may be required as the properties of the produced fluid change.

Seek Local Fluid Systems Experts

Characterization of produced fluids from aging SAGD wells can provide insight into how the wells are changing over time and how to accommodate such changes. If you are looking to improve SAGD reliability through increased flow assurance fluid characterization, 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 SAGD applications and can make suggestions for improving SAGD efficiency.