As the name implies, a sand screen has one primary function – keep out (screen out) sand during the collection of products located deep underground.

Suppose you fail to install a sand screen in the bore you are using for excavation; the sand will enter the bore and decrease the production.

Worse off, large sand particles can even render the drill unworkable.

As such, the sand screen helps prevent the above occurrences. Other essential functions of a sand screen include:

• Protection of surface equipment such as pumps and piping from damage
• Reduction of the maintenance costs associated with clean up and sand disposal
• Minimize any machinery malfunction that can result from sand plugging

A Sand Screen In Use

Since oil, water, and gas reservoirs are located deep in the ground, they are highly likely to be collected together with sand particles.

If large sand particles collect in the well stream, they will;

• Hinder production
• Affect the flowlines
• Interfere with the surface working equipment

Consequently, a sand screen will help keep out large sand particles and only permit fine sand particles to pass through. As a result, the collection process will proceed smoothly.

Screen bonding is manufacturing a (sand screen) through sintering – the fusion of particles together into one solid mass using both heat and pressure, minus melting the materials.

The major type of screen bonding is diffusion bonding.

In this process, a multi-layer woven wire material is squeezed and sintered together using a vacuum heater.

Screen bonding has the below advantages;

• Produces superb quality sand screens
• Manufactures robust sand screens
• The screens are light and easy to handle
• The resulting sand screens have good thermal, mechanical, and pressure ratings

Diffusion Bonded Sand Screen

The selection of the right sand screen is vital in ensuring that your sand screen will be productive and function efficiently upon installation.

Making the proper selection will depend on a range of factors, including;

Reservoir Sand Properties

Here, you will consider the particle size distribution (PSD), particle size, and particle size uniformity of the reservoir.

The above properties are essential when designing or choosing the right sand screen for your well.

Hole Of The Screen (Micron Rating)

The hole size of the sand screen will dictate the size of sand particles blocked or permitted into the bore.

You should select a sand screen with the correct hole size to balance the production and sand collection.

If the screens have huge holes, a large quantity of sand will enter the bore leading to sand plugging.

On the other hand, if the holes are too small, they will reduce the production level.

Material And Design

The other important factors to consider are the material and design of the sand screen.

The material should have high tensile strength and preferably be expandable.

Ideally, the sand screen should be designed and manufactured using the screen bonding technique in the case of premium screens.

The industry standard practice for testing the efficiency of a sand screen is conducting a laboratory sand-retention test on the screen.

The other option is to carry out screen plugging.

Notably, the laboratory sand retention test aims at determining the functional screen opening size.

Also, sand retention testing has no universal standards that dictate the performance of the test and the result interpretation.

The lack of measurements to elaborately quantify screen plugging makes it a less popular option for testing screen efficiency.

Usually, the experimental procedure of testing sand screen efficiency using a laboratory sand retention test involves:

1. Setting up the sand retention test apparatus, which comprises;
   • Two injection systems (one with clean fluid/water and the other with sand slurry
   • A sand retention cell test
   • Collection and separation system (for the fluid and sand)
2. You will then fill the hydraulic tubes and all sand retention cells with clean fluid or water.
3. Using the triplex pump, pump the clean fluid at an approximate flow rate of 400mL/min
4. As the mixer cell oscillates at 2 Hz, introduce the sand slurry at a slower flow rate of 5mL/min
5. You should collect all the fluid and the sand passing through the screen
6. Continue to do the injections at a constant rate as you empty the collection container once per litre
7. You will only stop the injection once you reach the sand pack’s height (about 10 – 20mm) or if you reach the send retention cell’s maximum pressure capacity.

From this simple test, you should be able to attain;

• The solid volume fraction, i.e. solid size that passes through the screen.
• Liquid flow velocity – the speed at which the fluid flows through the screen.

Sand screens have a simple structure and few components.

However, some sand screens may have additional features depending on the degree of sophistication.

The main parts of a simple sand screen are;

• Base pipe
• Pipe-screen weld
• An optional perforated shroud
• Control layer
• Drainage layer

The last three layers above (optional perforated shroud, control layer, and drainage layer) form the three-layer laminate.

This is where the actual separation of sand occurs.

More complex sand screens (like the pre-packed wire wrapped scren) may feature additional components.

These may include gravel packs, a perforated base pipe, outer and inner screens, and a support rib.

Parts Of A Sand Screen

Sand screens have a wide range of applications. However, the applications are mostly limited to those involving deep drilling operations.

The typical usage of sand screens are in applications such as;

• Pump strainer screens
• Sand-Gas separators
• Industrial filters
• Screens for both domestic and industrial wells
• Frack and gravel packaging
• Oil and gas wells

A Sand Screen In Use In Gas Production

No one material fits all when it comes to the manufacture of sand screens.

You can determine the ideal material for a sand screen after a thorough geological analysis.

It is worth noting that different wellbores have varying chemical compositions.

Hence, the material used for the sand screen should be able to work efficiently in the specific wellbore.

Also, the type and design of the sand screen determine the choice of material.

Remember, some materials are more machinable than the other options.

Mostly, stainless steel (specifically SS 304 and SS 316) are the most preferred materials.

This can be attributed to the versatility and high performance of these stainless steel classes.

However, there are also other standard material options;

• Stainless steel 904
• Nickel alloys 825, 625, and C276
• High Carbon steel
• Low Carbon Steel (ST37-2)
• Titanium
• Nickel-copper alloys (Monel)
• Inconel

Inconel Sand Screen

You can say a sand screen is efficient if it serves its purpose to the latter. Meaning it keeps out the large sand particles.

Several factors affect the efficiency of the sand screen. They include;

Particle Size

If the particle sizes are smaller than the aperture on the sand screen, the higher the probability of them passing through.

If the particles pass through, then the screen is not efficient.

On the other hand, particle sizes almost similar to the aperture size will reduce the probability of them passing through the screen.

However, they may get stuck on the apertures leading to screen plugging.

Screen plugging lowers the flow rate, making the sand screen inefficient.

Particle Shape

Typically, spherical particles tend to pass through openings easily.

However, particles with irregular shapes have a lesser probability of passing through the screen.

However, the irregular shape particles may obstruct other particles from passing through the screen, making them inefficient.

Vibration

The vibration rate on the sand screen should be enough to prevent plugging and blinding of the sand screen.

However, the vibration should not be intense to the extent of causing the sand materials to penetrate.

Screen Angle

The angle of inclination of the sand screen will also dictate how efficient the sand screen is. An accurate inclination will reduce the probability of particles passing through the sand screen.

Feeding Rate

This is the speed at which the slurry is fed to the sand screen. An extremely high or low feeding rate will negatively affect the efficiency of the sand screen.

Micron Rating (Hole Size)

Ultimately, the micron rating of a sand screen will affect its efficiency.

A tiny opening will lead to partial or total plugging, resulting in screen erosion rendering the sand screen useless.

Conversely, a huge opening will permit sand to pass through the screen. This will not only cause screen erosion but may also cause loss of the well due to excessive sand harvest.

Moisture

The material’s moisture content greatly dictates impacts the screening efficiency of the sand screen.

For example, clay and other sticky materials will tend to stick on the screen’s surface – blinding the screen.

A blinded sand screen is inefficient as it impacts the flow rate and, in turn, the production rate.

Analysis of sand particles is crucial when selecting the perfect sand screen for your well.

At the bore of sand particle analysis is the measurement of the sand particle’s size.

Usually, particle sizing defines the size of a spherical three-dimensional particle.

However, most sand particles are not spherical but instead have irregular shapes.

As such, measurement procedures for sand particles measure one characteristic of the sand grain and capitalize on it to determine the grain size.

Below are the two standard methods employed in measuring the size of the sand grains;

Dry Sieving

Dry sieving is an old sand particle measuring technique previously employed in the oil industry.

It is ideal for coarse sand with minimal fine particles.

Below is how this simple procedure is carried out using a mechanical sieve shaker;

1. First, you create a stack of sieves, arranging them in descending aperture size.
2. You then place the sand sample on the top screen.
3. Next, you place the stack of sieves on a mechanical shaker.
4. Finally, you will weigh the content of each sieve

The mechanical sieve shaker is time-consuming, dusty, and operator-dependent (since you will have to brush the blinded finer sieves manually).

Alternatively, instead of using a mechanical shaker, you can use a sonic sifter.

This equipment forcefully lifts and drops the sand particles in a column of oscillating air (set at a frequency of thousands of cycles per minute).

The high frequency of the oscillating air aids in preventing the sieves from blinding off. It also creates better dispersion.

Notably, the sonic sifter can better handle finer particles compared to the mechanical sieve shaker.

Laser Particle Sizing Analysis (LPSA)

Laser particle sizing is the most modern sand particle measurement method rapidly replacing the traditional dry sieving.

Popularly termed laser light scattering.

It operates on the principle that particle size determines the intensity pattern by which particles scatter light in various directions.

Technically, the angle of scattering is inversely proportional to particle size.

Conversely, the diffracted beam’s intensity at any given angle measures the number of particles with a given cross-sectional area in the beam’s path.

The general procedure for conducting an LPSA is as below;

1. Before sample introduction, the instrument measures the background. Usually, the sample size is around 1 gram. However, the sample amount might change depending on the number of particles.
2. Next, the sample is added to the water reservoir. For better sample dispersion, you can use ultrasonic agitation either before or during the sample measurement.
3. You will know if the sample added is enough if the instrument indicates obscuration.
4. Subsequently, the sample is pumped around the instrument and measurements recorded after every second for a definite measurement time (mostly 1 minute).
5. To get the final measurement, you will average the individual measurements.
6. Finally, you can either re-measure the sample or prepare the instrument for another sample.

Note: Typically, measurement using LPSA takes no more than 5 minutes.

Various Sieve Sizes For Sieving

The most common sand screen cleaning procedures involve:

1. The introduction of a cleanup fluid via a wellbore and into the portion of the underground formation
2. Application of pressure pulse to the cleanup fluid
3. Introduction of a consolidating agent via the wellbore and into the portion of the underground formation penetrated by the wellbore.

Typically, all sand screen cleaning procedures are done by dissolving scales, fines, and sands from plugged/blinded screens.

Generally, the lifespan of a sand screen is directly determined by the application of the specific sand screen.

Other factors that affect the lifespan of a sand screen include;

• Frequency of use of the sand screen
• Maintenance carried out on the sand screen
• The material used to manufacture the screen

Some sand screens can last long, such as the gravel packed screes – which can last up to 4 years or even the entire life of the wellbore.

For other sand screens like wire wrapped screens, pre-packed screens, and slotted liners; you may need to make replacements after every two years

Before sizing and designing a sand screen, the first and most important step is conducting a thorough sand analysis.

This will help determine the particle size, distribution, uniformity, and consolidation.

Once you have attained the specific characteristics of the subject sand, you can move on to the design stage. During the design, you will take into account:

• Size of the openings (micron rating) – not too small or too large.
• Material type – should be a strong material for durability.
• The size and the flow rate of the well
• Screen porosity – the number of openings on the screen
• Sizing – The screen should have an adequate size
• Sand screen control type
• Screen inflow performance – dependent on the screen’s permeability
• Plugging tendency – the design should take incorporate features to reduce the probability of plugging.

The price of a sand screen will depend on the screen’s type, size and design.

In terms of type;

• Slotted liners are relatively cheap, attracting a price of about $300
• Wire wrapped screens have a cost of about $800
• Pre-packed screens having a price tag of approximately $1200
• And the most expensive being gravel packed screens with a price ranging around $8000

For material and design, the price is higher depending on the degree of specification of either.

There are several sand screens at your disposal.

All these are dependent on your intended application. Below are the major types of sand screens available in the market.

Slotted Liner Sand Screen

Slotted liner sand screens are mainly used in low productivity wells and long horizontal completions.

It comprises slots and a base pipe. These sand screens are either manufactured using laser machines or slotting machines.

Slotted Liner Sand Screen

The diameter of the base pipe for the slotted liner sand screens ranges from 1.5 to 18 inches.

For the slot size, we can customize both the length and the width.

However, the width size range for the keystone or straight slots is limited to a minimum of 0.012 inches to a maximum of 0.25 inches.

The straight slot has lateral/straight sides and equal width through the entire casing’s wall.

On the other hand, keystone slots have a reversed ‘V” shape, having a wider spacing on the casing’s wall interior and a narrower spacing on the casing wall’s surface.

Advantages

• Help with bore stability
• Fairly cheap
• Easy installation
• Ideal for well-sorted sands

Disadvantages

• Prone to erosion
• Low inflow area
• Easy plugging
• Low rotational strength

Expandable Sand Screen (ESS)

Typically, an ESS consists of four overlapping rectangular metal sheets weave filters fixed to a slotted expandable base pipe and enveloped inside a protective metal casing.

Notably, these types of sand screens will help in sand control and offer support to your well. The expansion capability also helps reduce stress-induced damage.

Advantages

• Easy installation
• Increased internal diameter due to expansion
• Low plugging and hot spot probability

Disadvantages

• You cannot use fluid control devices
• Prone to collapse (Low collapse rating)
• Stimulation is separate

Expandable Slotted Sandscreens

Wire Wrap Screen

The formation of a wire wrap screen entails wrapping a profiled wire and welding it in place on a perforated liner.

Usually, a small enough space is left between each wire warp to retain the stationed behind the screen and at the same time minimize any production restrictions.

Advantages

• Cheapest
• Simple design
• Least prone to plugging
• It can be made entirely from stainless steel

Disadvantages

• Low erosion resistance
• Need of accuracy for wire spacing to reduce chances of plugging and production of sand
• Not ideal for horizontal or high angle installation
• Easily damaged in continuous operations

Wire Wrapped Sand Screen

Pre-packed Screen

The typical use of pre-packed sand screens is an alternative to the gravel pack sand screens. Their construction involves the addition of a resin-coated layer and consolidated gravel inside a metal casing.

Notably, you can use the pre-packed screens as standalone screens minus the gravel pack in horizontal cased holes or open holes well.

Advantages

• Fairly cheap
• Moderately erosion resistant
• Can be used in both the vertical and horizontal parts of the well

Disadvantages

• Easily plugged
• Easily damaged in continuous operations

Pre Packed Screen

Premium Sand Screen

A premium sand screen simply performs a similar role as all the other sand screens – preventing impurities from exiting the reservoir or well.

Commonly, woven metal mesh sand screens are referred to as premium sand screens.

The first stage for the formation of a premium sand screen is diffusion bonding of the screen.

Notably, the significant components of each screen is a filtration layer and a mesh layer.

After diffusion bonding, the screen is shaped into a tube. The single tubes can then be welded depending on the length required. Finally, every single tube is fitted with a cap.

Gravel Pack Screen

Simply put, a gravel pack is a downhole filter that prevents the harvesting of unwanted sand from the reservoir or well.

A gravel pack screen thus is equipment designed to support and reserve the sand placed during gravel pack operations.

It can either be an open hole grave pack or a cased hole gravel pack

Advantages

• Ideal for deep water reservoirs
• Moderately reliable

Disadvantages

• High installation cost
• Difficult to design
• Less inflow area
• The screen is closely located to the formation wall

Typically, to use a sand screen, you will only need to line the diameter of the wellbore with it.

Consequently, the product (primarily natural gas and water) passing through it are filtered, and sand is kept out of the borehole.

As a result, sand is refrained from entering the drills where it can slow down production or even entirely damage the drilling equipment.

Knowing the features of a product will ease your purchase of that specific product. The same applies to the sand screens.

We have highlighted some key beneficial features of sand screens to guide you.

• Large open area – for improved flow rate
• Precise and uniformly placed slots
• Option for customization
• Easy installation
• Reusable
• Strong casing/shroud
• Versatility in terms of pressure and temperature
• Lightweight
• High tensile and mechanical strength
• Economical – with regard to pricing
• Minimized pressure drop design

Importantly, the sand screening techniques are not similar to the types of sand screens. The techniques are the various methods used for sand controls in wells and reservoirs.

The standard techniques used include:

• Miantenance and Workover – It is a passive approach where the sand harvest is not controlled, but is only dealt with later if the need arises.
• Rate Restriction – Here, the well’s flow rate is restricted to a level that prohibits or minimizes sand production.
• Selective Completion Practice – This involves carrying out production in parts of the well having the most cemented sand that will not disintegrate during the drilling. The major draw back of this method is that it leaves most of the well underutilized.
• Plastic Resin Consolidation – As the name suggests, plastic resins (in liquid form) that can bind the sand particles is introduced into the well and consolidates the sand particles together. Commonly, the plastic resins used are furans, epoxies and phenolics.
• Resin-Coated Gravel – It involves pre-packing the well with gravel then introducing resins to harden the plastic. The consolidated plastic-sand mixture is then drilled out, leaving behind the resin-coated sand.
• Stand-alone Slotted Liners – This mainly involves the use of the slotted liners minus the gravel pack as filters. The slotted liners are placed in intervals in the wellbore for efficient sand control. However, using the slotted liners is not ideal since there is a high probability of screen plugging.
• Gravel Packing – It involves placing a slotted liner in the wellbore then surrounding it with gravel. The gravel prevents sand formation while the slotted liner retains the gravel.

The sizes and the dimensions of the sand screens will vary depending on the type of sand screens. Below are the size and dimension estimates for the common types of sand screens.

• Metal Mesh Screens – Size ranges from 4 inches to 8 inches with a minimum bend angle of 45^o and a maximum bend angle of 120^o.
• Wire Wrap Screens – Have a size range of 3 inches to 7 inches with a minimum bend angle of 43^o and a maximum bend angle of 120^o.
• Expandable Sand Screens – Mostly are in a size range of 4 inch to inch

The above dimensions are for the base pipe. The Outer Diameter (OD) is a couple of inches larger than the base pipe dimensions.

Note: The mesh and hole size dimensions are subject to customization; hence they vary.

The benefits of sand screens include;

• They are a cheap and efficient option for sand control
• It is easy to install most types of sand screens
• Some sand screens have both horizontal and vertical applications
• Sand screens require minimal maintenance depending on the type.
• Generally, sand screens have high temperature and pressure tolerance.

The typical limitations of the sand screen are;

• Some types of sand screens are prone to plugging
• Other sand screen types might have high installation costs
• Designing and manufacturing specific sand screens, such as wire wrap screens, need a high level of accuracy.
• Lastly, there are some sand screens prone to erosion.

Having a regular well bore inspection is vital to maintaining your sand screen. It will help you to detect and address any screen erosion timely.

Additionally, you can install an Intelligent Well System (IWS).

It is to help you carry out multi-rate testing on various zones to detect any variation in completion pressure.

This way, you will know if your screens are still effective.

Lastly, you should regularly carry out sand screening.

You can do this through patching, chemical sand screening or gravel patch through-tubing.

I know you may be interested in:

• Sand Control Screen
• DSM Screen
• Intake Screen
• Gravel Pack Screen

For all your sand screen, FilSon offers perfect solution for your – talk to us now.