Downhole Vortex Desander Alternatives | Schlumberger

Downhole Sand Control Screens for Artificial Lift

Field-proven alternative to downhole desanders when using gas lift, rod lift pumps, or ESP pumps

PumpGuard intake sand control screen and valve assembly outperforms downhole vortex desanders

Extend ESP run life
Reduce ESP shutdowns due to solids
Increase ESP restart success
The unique 3D pore structure has high resistance to plugging.

How does the PumpGuard assembly improve sand separation compared with a downhole desander?

By using MeshRite stainless steel wool screens. MeshRite screens incorporate a unique patented 3D pore structure with resilient high flow capacity and almost no resistance to flow in the near-wellbore area or across the screen. The MeshRite screen has 40% open flow area—whereas other screens typically have a maximum of 30%—and greater than 3,000-D air permeability.

The unique 3D pore structure has high resistance to plugging. MeshRite screens have angular pores ranging in size from 15 to 600 um, which retain harmful solids and minimize the risk of erosion. As sand is stopped at or near the screen surface, open space surrounds these particles, and the retained permeability of the screen itself remains high.

Screens with 40% open flow area and high resistance to plugging
Integrated cup packer that prevents fluid annular bypass
Pressure-activated intake valve that allows radial flow through screens and opens once screens bridge off
Extended ESP Runlife
Shell Extends ESP Run Life by 35% While Reducing Solids-Related Shutdowns and Improving Restarts, Texas
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Internal diagram of the Pumpguard system.
The red pathway indicates blocked fluid flow through the MeshRite screen. The induced pressure drop causes the intake valve to open and redirect fluid flow, bypassing the screen filter.

What happens if the MeshRite screen bridges off below the cup packer?

During the initial production, the  intake valve connected to the bottom of screen is closed, allowing radial flow of fluid into the MeshRite screen. Over time, formation particles fill the annular space between the outer surface of the PumpGuard assembly screen and the production casing. As the annular space fills with sand and the particles consolidate, it creates pressure drop across the sand pack. When the pressure drop across the sand pack reaches the preset value, the intake valve opens and allows flow directly through the pump intake bypassing the screen. Only at this stage will sand begin to cause wear on the pump, extending the life of the pump by the total operating time during which the intake valve remained closed.

The intake valve is adjustable, providing you with control of opening differential pressure. The intake valve can be set at the end of the screen, or multiple valves can be configured between screen joints to maximize rod lift or ESP pump lifetime. ESP pumps paired with a Phoenix artificial lift downhole monitoring systems and a remote surveillance service can monitor intake pressure changes to identify intake valve opening events. This allows you to

  • schedule workovers to avoid deferred production
  • reduce destroyed inventory costs for rented pumps
  • decrease pump and motor testing costs for rented pumps
  • in some cases, rerun the same ESP string with new screens
  • keep the downhole sand management problem downhole.

Why can’t a downhole vortex desander consistently separate solids downhole from an unconventional well with a wide particle size distribution?

Downhole desanders are simple and inexpensive but ineffective at removing a wide distribution of solids from unconventional wells alone. Downhole desanders depend on the same cyclonic separation principles of hydrocyclone technology to convert the incoming liquid velocity into rotary motion for separating heavy and light components. The induced centrifugal action within the desander sub to remove sand, scale, and iron sulfide from the produced fluid depends on fluid velocity to generate the force necessary to consistently separate the solids. The efficiency of separation is also largely dependent on the fluid viscosity with higher separation efficiency when the viscosity of the sand carrier fluid is lower but drastically reduces as viscosity increases. All wells, especially horizontal unconventional wells, have intermittent flow with slugs of oil, water, and gas. As a result of the intermittent flow entering the desander sub, the velocity and viscosity of the fluid changes, and the desander will intermittently separate solids. The separation efficiency of so-called “swirl tubes as a downhole desander device” has been studied and documented in "Experimental Analysis of Swirl Tubes as Downhole Desander Device" by Martins, Rosa, and Robson (2005), which we recommend for further reading.

What production problems are the solids bypassing the downhole desander likely causing?

The solids that bypass the downhole desander travel up thousands of feet through the production tubing, causing the following problems:

  • extended duration of frac flowback services because solids content from your measured basic sediment and water (BS&W) remains too high to pass through the multiphase flowmeter, the wellhead production facility equipment, or both
  • erosion of your ESP pump internals, specifically the pump stages, which reduces available lift and flow rate, causing production loss
  • possibility of renting or buying surface wellhead desanders and contracting staff to operate the desanders and dump, transport, and dispose of the produced solids
  • sand fallback causing hard restarts, reduced ESP pump run life, or worse yet, the need for a sand plugging intervention to reinitiate production due to a multijoint sand bridge.

What is sand fallback, and what causes it?

Sand fallback happens during temporary suspension of flow. For example, sand fallback occurs during an ESP pump shutdown due to gas slugging, inconsistent power, power surges, or shutdowns triggered by ESP drive automated algorithms or remote surveillance operators in efforts to preserve the pump. Sand fallback is also responsible for broken shafts on rod lift pumps.

What factors affect how long MeshRite screens can protect my pump from solids?

The amount of time the pump life is extended depends on the length of the screens deployed, the amount of solids produced, and the duration of time MeshRite screens can prevent these solids from flowing directly into the pump. These factors will be influenced by

  • size of the annular space between the production casing and the outer diameter of the MeshRite screen
  • size of the rathole beneath the perforation zone in the case of vertical wells
  • particle-size distribution and fluid velocity
  • frac hits
  • proportion of sand or fluid produced into the wellbore and the rate at which that sand reaches the screen
  • amount of fines and particle-size distribution of sand reaching the screen.
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