I asked AI to tell me about sand control in oil wells. While I don’t trust AI with certain questions, especially for seeking an opinion, I had no argument about its accuracy with this straightforward “what is” question:
What is sand control in oil and gas wells. Sand control refers to the techniques used to prevent sand and other solid particles from entering the wellbore during oil and gas production. It's a critical part of well completion because uncontrolled sand production can lead to:
Erosion of equipment (both downhole and surface)
Plugging of the wellbore
Reduced production rates
Costly maintenance and downtime.
Sand enters the wellbore due to:
Mechanical failure of the rock near the wellbore
High fluid drag forces pulling loose particles into the flow
Unconsolidated or weak formations that can't hold together under pressure.
Sand control methods fall into two main categories:
1. Passive methods. These aim to minimize sand production without physical barriers:
Oriented or selective perforation
Production rate management
Sand management strategies.
2. Active methods. These involve physical or chemical barriers to block sand:
Gravel pack: Sized gravel placed around a screen to filter sand
Frac pack: Combines hydraulic fracturing with gravel packing
Sand screens: Devices like slotted liners, wire-wrapped screens, or premium mesh screens
Expandable screens: Screens that expand to fit the wellbore for better contact
Chemical consolidation: Injecting chemicals to bind sand grains together.
It’s a very complete answer, but I wish to focus on just two aspects of this very broad topic. First, under passive methods – production rate management, and second, under active methods – chemical consolidation. I have always been skeptical of both. With production rate management, it seems that a time eventually comes when sand production is no longer preventable, or simply that production rate and drawdown are not managed carefully enough, and sanding ensues, despite the best intentions.
With chemical consolidation methods, which have been around a long time, the primary issue has always been that the better the method is in consolidating formation sand grains and fines, the worse it is in reducing near-wellbore formation permeability. So, the mitigation of sand production is at the expense of well productivity. The prevailing opinion of chemical sand consolidation treatments has been that they do not work. In fact, they do work, but too well, with permeability typically reduced too much.
Passive method–new wells. For new well completions in poorly consolidated sandstones, gravel packs and frac packs, combined with sand screens, are the most typical means of controlling sand production. Such completions are designed to withstand greater and increasing drawdown, by providing a multi-layer, sand filtration system, in effect, to prevent solids from entering the wellbore. However, while sand is blocked from entering the wellbore, eventually sand and fines plugging can occur in gravel or proppant packs, and in screens, thereby reducing productivity or requiring increased drawdowns to maintain desired productivity. Higher drawdowns increase stress on the completion, which can ultimately risk completion failure, in an extreme case.
An alternative method, which could be considered, is the use of Autonomous Inflow Control Valve (AICV) technology. AICVs are used in oil and gas wells to automatically regulate fluid inflow for the purpose of optimizing production. AICVs can shut off unwanted water at locations in which water breakthrough occurs. Unwanted water production is typically the culprit in inducing or exacerbating sand production. AICVs are also used to modulate drawdown and can be coupled with sand screens in higher-risk situations, such as in deepwater developments, or standalone in lower-risk cases in which drawdown management is deemed realistic in the absence of a gravel pack, for example.
The Norwegian company, InflowControl, is one which has developed AICV technology that can be applied in sand control completions, either alone or in combination with screen technologies to prevent or at least reduce sand particle plugging that can occur in screens over time. Without flow control devices such as AICVs, very high localized inflow rates, especially water, can cause formation particle migration into screens, leading to plugging, and eventually develop what are known as “hotspots” and subsequent screen failure. AICVs autonomously restrict water production, reducing the likelihood of damaging sand production.
Active method–mature wells. For older wells that may or may not have original sand control completions in place, the only options for controlling sand production may be chemical consolidation methods. As mentioned, the deserved reputation of such methods is that the better the chemical treatment is in consolidating sand, the worse it is in reducing formation permeability and production rate.
Traditional treatments have been with resins, which can be very effective in consolidating formation sand and increasing resistance to solids movement during flow, including at higher drawdowns. But such resin treatments can drastically reduce permeability. So, they have been more or less limited to last resort, desperation cases.
However, it seems there are some potential breakthroughs with chemical sand consolidation or rock strengthening treatments that can eliminate or reduce sand production, at least for a time that enables extended, economic oil or gas production. Companies, such as ChampionX and the French Poweltec propose unique solutions that may balance increased consolidation while maintaining permeability at an acceptable level. ChampionX has developed a chemistry that binds to sand surfaces upon contact with connate water, effectively “crosslinking” sand grains. The mechanism therefore requires minimal dosage, which enables permeability retention.
Poweltec has developed a small microgel, previously developed as a relative permeability modifier (RPM) treatment for water control, but also has been found to be applicable in near-wellbore sand consolidation. The idea of using RPM chemistry to control sand production makes logical sense. If effective, the RPM will resist water flow relative to hydrocarbon flow, and in sufficient concentration, a RPM can “hold” sand particles together, at least to an extent that enables non-sand producing drawdown and rates.
Other chemical sand consolidation formulations that are non-damaging to formation permeability are under investigation in academia and with certain chemical suppliers. Examples include nano-enhanced silica and alumina-reinforced polymers or resins. Such solutions, experimental at this point, contain silica and alumina nanoparticles that “reinforce” the polymer or resin to create a greater rock strengthening treatment solution containing lower active ingredient concentration, such that near-wellbore formation compressive strength is increased effectively while minimizing permeability reduction.
Alternative sand control methods—for new wells, with AICVs, and older wells, with “non-damaging” chemical consolidation methods—are gaining greater attention these days, and they merit investigation by interested readers. New chemical consolidation methods, which still must be proven on a greater scale in the field, should not be written off, based on past impressions of the traditional resin treatments. WO
LKALFAYAN@OUTLOOK.COM. / Leonard Kalfayan has 44 years of oil, gas and geothermal experience. He has worked for Hess, BJ Services, Unocal, and as a consultant. He is an SPE Distinguished Lecturer and Distinguished Member. He has authored numerous publications, including 3 books, and also holds 13 U.S. patents.