Rethinking sand management for optimized production

The incredible thing about gathering large amounts of data is that—when visualized correctly—you can see things from new and different viewpoints. By managing the sand value chain, we see how sand impacts production.  

We are all familiar with the conventional methods for increasing production, but there is less recognition of the significant benefits in the transportation of sand out of oil and gas wells. This article explores how operators can move from traditional, reflexive actions for handling sand to a more proactive, long-term approach. 

PROACTIVE SAND MANAGEMENT IN BROWNFIELDS 

The consequence of having sand in your hydrocarbon production is easily described, using a beach analogy. Everyone can appreciate the view of a sandy beach and relate to the feeling of walking barefoot in the sand down to the water. Similarly, one can relate to the feeling of leaving the beach with wet feet and slipping into a pair of shoes or sandals, and the discomfort that ensues.  

Translating this to oil and gas operations, where you have both intricate measuring mechanics as well as high pressures and flow, one can understand the negative consequences and sub-optimal results that sand can have. Sand production occurs when loose formation sands or fines are mobilized, along with hydrocarbons during production, posing challenges to well integrity and productivity. 

When sand levels are too high, the immediate reflex is often to choke back production or shut-in the well to prevent consecutive problems in the processing facility. There are other solutions, but choosing the best one is not straightforward. All decisions have consequences, and depending on the state of the asset, decisions have different outcomes.  

As stated by Gordon Fryers in his article “Restore and reoptimize aging assets—Today’s new ROI” (World Oil, November 2022), mature fields present great opportunities, if managed and optimized correctly. Sand typically does not create big issues for greenfields but is common for brownfield assets. Reports from operators estimate that more than 50% of brownfield assets in sandstone reservoirs experience production challenges, due to sand, Fig. 1. Brownfields are where we have identified the best ROI for proactive sand management. 

Fig 1. A research report by consulting firm Arkwright Research shows the extent of sand producing wells worldwide. Image: Arkwright Research.

CHALLENGING CONVENTIONAL SOLUTIONS TO OPTIMIZE SANDY WELL PRODUCTION   

Choking back oil and gas production gives engineers time to breathe and look for viable solutions to manage the sand. Typically, engineers have a set of actions to choose from when the sand and fines are produced. 

Produce to separator. The first action is to continue production at the same rate as before, provided you have a separator fitted with jetting systems. However, as the sand builds up in the separator, the settling volume of the separator is reduced, lowering the separation efficiency.  

In the long run, this can affect the whole asset, as the overall production quality is lowered. During annual turnarounds, one of the tasks is to ensure the separator is performing optimally.  

If it is full of sand, manual labor armed with shovels must empty the separator. This is a job performed in a hazardous environment requiring confined space entry and full cover PPE (Automation and Closed-Loop Systems Reduce HSE Risks, JPT, August 2022). In effect, this is solving a problem, rather than finding a long-term solution. 

Recomplete the well. Recompletion implies that defective downhole sand screens are re-installed. This can be done when the downhole sand control fails, e.g. caused by sand following the water phase and eroding the sand screens.  

Recompletions are costly, planning-intensive and high-risk operations, but they can be a good and viable solution for greenfields with long, remaining field lives. Justifying a recompletion for a brownfield—trying to squeeze out the last reservoir margins during tail end production—is another story.  

Before investing heavily in terms of economics and man hours, one should evaluate other options. One pertinent question is how a screen restricting sand, but also hydrocarbons, is the best solution for optimizing production.  

Shut-in or choke the well back. This may seem like the best and least risky option. But, in our experience, it is the opposite, and can also be very decisive. Choking back enables production to continue, but at a lower rate. When the wells produce an acceptable sand rate (ASR) to the topside, it can be kept at that level.  

However, not producing all the sand to the surface means that some is left in the reservoir and, typically, in the wellbore. If it is not lifted to the surface, sand will build up in the wellbore or pipeline and slowly reduce the flow, ultimately leading to the well completely shutting down.  

This results in planned shutdowns and high-intensity intervention activities, such as coiled tubing, to clean out the well. If production continues at a choked-back rate, it is likely that the same will happen again. 

TAKING THE OPPOSITE APPROACH 

New challenges call for new solutions. The oil and gas industry is known for finding new, ingenious ways to enhance production.  This is certainly true for brownfield assets. New methods and processes have enabled a field like Norway’s Gullfaks A to be extended by an additional 20 years from the original, 30-year life span.  

For installations such as Gullfaks with large untapped resources, huge investments can be made. But this is not always the case for brownfields. Small independent companies buy late-life assets and rely on innovative solutions that can boost production with minimal capital expenditure. 

Since operators often misinterpret sand production as a sign of declining well performance, they mistakenly assume that the accumulation of sand behind screens signifies impending failure. However, we have observed that this sand accumulation serves only as a temporary hindrance, creating localized barriers that ultimately contribute to improved reservoir management. 

We recommend the opposite approach to sand management. 

As sand migrates through the formation, it accumulates and blocks pore spaces, effectively reducing the flow of fluids through the reservoir (this process is described in detail in “Sand Production Management for Unconsolidated Sandstone Reservoirs,” Zhou and Sun, Wiley Blackwell, 2016).       

While this may lead to a temporary decrease in production rates, it also creates opportunities for reservoir stimulation and optimization. By strategically managing sand production, operators can manipulate reservoir dynamics to optimize recovery and long-term productivity. 

By actively transporting sand out of the well, we can prevent sand accumulation and maintain or even enhance reservoir permeability over time. This proactive approach ensures that the reservoir remains productive and efficient, ultimately optimizing reservoir management.  

Zhou and Sun found that “integrated sand production management can reduce cost of operation and increase well production rate.” They also found the creation of wormholes in the formation, due to the influence of pressure and sand erosion to increase production, as also researched by M. B. Geilikman, M. B., Dusseault, and F. A. L. Dullien, “Dynamics of wormholes and enhancement of fluid production,” Technical Report Part I, Waterloo Sand Production Project Report, 1988. 

We have proprietary data indicating that transporting sand out of the reservoir serves to naturally clean and rejuvenate the formation. As sand is removed from the wellbore, it carries with it any accumulated debris or fines, effectively purging the reservoir of unwanted materials. This cleansing action improves reservoir performance and helps maintain the integrity of the formation over time. 

OPTIMIZING PRODUCTION USING THE WORLD’S LARGEST SAND MANAGEMENT DATABASE 

FourPhase has gathered data from more than 150,000 operational hours of sand management in our database, Fig. 2. Our experienced operators can analyze trends in our data and compare these with ongoing operations, Fig. 3. Finding trends and patterns is crucial for designing the production optimization for our customers.  

Fig. 2. The FourPhase database contains sand management data from more than 150.000 hrs of operation.

Fig. 3. Remote monitoring (one-way communication) of sand removal systems from FourPhase operations room.

This has led to several significant improvements covering the whole range of sand management; from closing and starting up sandy wells to minimizing slugs and enabling higher continuous production over time. By storing all data and making it available to everyone in our organization, the whole team can contribute their knowledge of how to ensure stable production. 

FourPhase has solved the challenge of continuously achieving high separation efficiency without non-productive time to empty tanks or replacing failing parts. With a third-party certification from DNV approving our separation efficiency at 99.8% on particle size 20 -10 000µm, we are confident in our separation abilities.  

With an operational uptime above 99.44% across 150,000 hrs, we primarily look to help customers that have challenging wells but also need stable production for their sandy producers. 

Topside sand management is one solution to maximize tail-end production, and we adapt our services to the customer’s business models. At FourPhase, we have employed an all-service solution called “Sand Management as a Service” (SMaaS). This model puts any operational risk on us as a supplier to deliver the sand-free flow, as agreed with our customers.  

CONCLUSION 

Our observations indicate that sand production plays a crucial role in reservoir management, particularly when viewed through the lens of top-side sand management. By recognizing the positive aspects of sand transportation, operators can implement strategies to optimize production and maximize recovery. Thus, both small, independent operators and majors can ultimately ensure the long-term viability of their assets. 

CASE STUDIES 

Enabling production from a shut-in well with a compact optimized solution 

Challenge. A leading U.S. operator faced a significant challenge, with excessive sand accumulation across multiple wells situated on one of its offshore platforms, earning the moniker, “The Devil's Well,” due to the severity of the issue, Fig. 4.  

Fig. 4. A DualFlow desander installed on an offshore installation in the Gulf of Mexico.

The existing equipment for sand and water management onboard proved inadequate, leading to a detrimental buildup of sand within the production separator. Consequently, the water treatment facility struggled to operate effectively.  

Compliance with stringent environmental regulations in the Gulf of Mexico mandated proper processing of produced water prior to reinjection, compelling the operator to shut down the high-producing well until the issue was resolved. 

Solution. To address the challenge, FourPhase implemented a cutting-edge DualFlow production enhancement unit, strategically designed to tackle sand production. This innovative solution facilitated continuous sand transportation out of the wellbore, effectively maintaining a sand-free environment.  

Consequently, the need for frequent interventions, due to sand buildup, was eliminated, allowing for optimal production rates to be sustained. 

Results. The outcomes were remarkable. Not only was the well swiftly restored to operational status, but production levels soared by an impressive 10%, attributed to the streamlined sand management process. This translated to a substantial increase of 6,000 bpd, achieved over a remarkable 167-day period without any downtime. As a result, the operator reaped an additional profit of $30 million.   

Beyond bolstering production figures, the successful sand management initiative also yielded secondary benefits. The enhanced quality of produced water minimized pollution within process equipment, thereby reducing wear and tear on critical components, such as production chokes and downstream processing facilities. Moreover, the need for costly cleanout operations, such as Coiled Tubing Clean Out (CTCO), was entirely averted. 

The installation delivered by FourPhase addressed the challenges posed by the wells with increased efficiency and sand separation, underscoring the necessity of active sand management to improve productivity. 

Optimizing a dry gas well using active topside sand control 

Challenge. One oil and gas major in the Caribbean had a small brownfield asset (30+ years old), with a shut-in well, due to sand production. Without the capacity to manage sand slugs from the dry gas well, it couldn’t be produced without topside sand control.  

When unmanaged, the sand slugs disrupt the production on the whole asset, making it necessary to choke or close the well.  With limited available real estate and crane capacity on the offshore platform, a compact desander was required. 

Solution. A standard rental solution was chosen for the asset to keep operational and economic flexibility. Utilizing simulations and experience from the FourPhase sand management database, CFD and 3D planning tools, there was great confidence in the effectiveness of the chosen solution. Keeping CAPEX at a minimum and production at a maximum is key for optimizing brownfields.  

A compact DualFlow desander was mobilized to solve the challenge, Fig. 5. With a small footprint of 6.6 ft x 6.6 ft and weight below 20,000 lbs, the desander could be installed, using the available platform crane. The rental solution ensured quick turnaround and installation, which in turn enabled faster Production Flow Recovery (PFR™). 

Fig. 5. The DualFlow desander is our cornerstone technology for successful sand removal.

Results. The shut-in dry gas well was started and currently produces around 13 MMcfd, resulting in considerable, additional daily revenue. In addition, the risk associated with sand slugs in the process system is minimized, which results in continuous steady revenue. 

To date, the dry gas well has produced close to 2,000 lbs (1,000 kg) of sand during less than a month of operation. By installing the desander, the operator has become increasingly confident.  

As FourPhase gathers experience data on erosion, speed and flow, the goal is to further increase the production rates by another 40% while ensuring sand free flow. 

About the Authors

Olof Nilsson

FourPhase

Olof Nilsson has experience in various engineering and project management roles in the oil and gas industry. He has managed various innovation projects in subsea and topside oil and gas. At FourPhase, a leading company in top-side sand removal technology, he is a marketing manager with responsibilities in marketing, IP management, and sales.