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Separator Jetting – Slurry Dewatering and Disposal (post B-FSM-130)

Note: The subject of dewatering and disposal of produced solids will be covered in great detail in a future training module. Jetting systems are covered in Facilities Sand Management training Module M7, while Solids Dewatering, Transport, and Disposal are covered in Module M9. Below is an abridged version of the information specific to jetting system design. Further information can be obtained in whitepaper reference listed at the end of this blog post.

The purpose of Dewatering is to remove the free liquids associated with a slurry.

  • The goal is to achieve >90% volume reduction
  • The produced liquids are returned to process, instead of disposal

Keep system compact and simple – one or two step process

  • Single 6” urethane hydrocyclone at 15 psid for bulk dewatering
  • Filter-bag or filter-bin for final dewatering

Use filter-bag for open system and filter-bin for closed system

Next week I will start the discussion flowsheet design for jetting systems.

References:

  1. Rawlins, C.H., “Design of a Cyclonic Solids Jetting Device and Slurry Transport System for Production Systems”, paper 166118, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, LA, 30 September – 2 October, 2013. https://doi.org/10.2118/166118-MS
  2. Rawlins, C.H., “What to do with Produced Solids after Separation: Dewatering, Transport, and Disposal”, eProcess whitepaper, 26 June 2020. https://eprocess-tech.com/wp-content/uploads/2020/08/DTD_20_06Jun26-Whitepaper.pdf

Separator Jetting – Discharge Piping Design (B-FSM-129)

Pre-requisites for this post:

Flow Boundary Conditions

All information below is based on calculations in posts listed above

Cyclonic jetting cluster basis

  • Four heads, each at 7.5 m³/hr, produced sand in 10% salinity water

Upper boundary – erosion velocity

  • API RP 14E: 3.7 m/s (12.2 ft/s)
  • McLaury-Shirazi (SPE 56812): >30 m/s (>100 ft/s)
  • 1” pipe for single unit, 2” for four units

Lower boundary – horizontal and vertical transport velocity

  • Durand-Wasp: VMT-H = 0.65 m/s (2.1 ft/s)
  • 2X Stokes Settling @ VMT-H = 1440 µm

Boundary Conditions: 0.65-3.7 m/s (2.1-12.2 ft/s)

Pipe use: 1-2 hours per day

Slurry outlet/header piping = 2” CS/DSS pipe sufficient for duty

Mechanical Design

ASME 31.11 for slurry piping transport systems

  • Horizontal runs sloped (1:100)
  • Elbows at long radius or 5R/10R
  • >10D between elbows
  • Eccentric reducers

Full port valves of gate or rotating disc

Sample ports on vertical upflow only

Operation

NEVER introduce slurry into empty piping or process equipment

  • Pre-fill with (moving) water
  • Post-flush all piping

Next week I will start the discussion slurry dewatering and disposal for jetting systems.

References:

  1. Rawlins, C.H., “Design of a Cyclonic Solids Jetting Device and Slurry Transport System for Production Systems”, paper 166118, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, LA, 30 September – 2 October, 2013. https://doi.org/10.2118/166118-MS

Separator Jetting – Discharge Slurry Profiles (B-FSM-128)

Both spray and cyclonic jetting result in discharge of concentrated slurry from the cleaned vessels. Their profiles are similar and knowledge of the concentration is required to design the subsequent piping and dewatering systems.

The discharge profile from a cyclonic jetting system is shown as the header graphic, while that of the traditional jetting (from Priestman paper) is shown below.

Both systems start with high solids. The cyclonic jetting slurry is lower at 36 vol.% (60 wt.%) while the spray jet is at 70 vol.%. This is a function of the cyclonic jet pulling the slurry up – resulting in dilution in-situ – versus the jet system pushing the slurry down.

Jetting is “done” when outlet solids reach <5 vol.% solids. That timing depends on level of solids in the vessel prior to jetting, but if done frequently/properly jetting should be complete in 10-15 minutes.

Next week I will start the discussion discharge slurry piping for jetting systems.

References:

  1. Priestman, G.H., Tippetts, J.R., Dick, D.R., “The Design and Operation of Oil-Gas Production Separator Desanding Systems”, Trans IChemE, Vol. 74, Part A, March 1996, pp. 166-176.
  2. Rawlins, C.H., “Design of a Cyclonic Solids Jetting Device and Slurry Transport System for Production Systems”, paper 166118, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, LA, 30 September – 2 October, 2013. https://doi.org/10.2118/166118-MS

Separator Jetting – Comparison Between Traditional and Cyclonic Design (B-FSM-127)

Note: I recommend you read through post B-FSM-121 regarding troubleshooting of traditional jetting system design before proceeding through the comparison below.

Cyclonic Jetting System (compared to traditional jetting)

  • Less water use
  • Less erosion on vessel wall
  • Less prone to blockage (cyclonic jet suction larger diameter than sand pan slots)
  • Shielded vortex spray pattern – will not create mixing at oil-water interface even when sand not present
  • Does not require bottom discharge from vessel
  • Standardized system design and layout allows for easier installation and design of control system
  • Both types of systems have similar control system set up and use
  • Both types of systems can experience issues with solids consolidation or slurry constipation if the discharge piping is not designed properly

Automating the jetting system will take care of most issues.

Next week I will start the discussion on slurry transport and handling from jetting systems.

References:

  1. Rawlins, C.H., “Design of a Cyclonic Solids Jetting Device and Slurry Transport System for Production Systems”, paper 166118, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, LA, 30 September – 2 October, 2013. https://doi.org/10.2118/166118-MS

Separator Jetting – Cyclonic Jetting Cluster Layout and Control System (B-FSM-126)

The cyclonic jetting units are assembled into clusters to for standardization of installation and control during operation.

Cluster Design

  • Maximum of four-unit heads per cluster
  • Cluster has 2” inlet and outlet piping for vessel penetration
  • Penetration can be from bottom, side, or top
  • Header piping (internal) of stainless steel
  • Example of in-line and square cluster shown in header graphic

Control System

  • Reference graphic below for descriptions
  • Operate one vessel zone at a time (spray jet + discharge). A zone is defined as one cluster (in-line or square).
  • Flow control valve (FCV) to set to control vortex spray
  • Set outlet (slurry) discharge at same flow rate with FCV
  • Density meter (DM) determines when to shut zone isolation valve (recommended when concentration <5 vol.%)
  • Cyclonic jetting heads are quite predictable and normally complete cycle in 5-7 minutes
  • Critical to automate system for effective performance

Next week I will compare traditional jetting versus cyclonic jetting.

References:

  1. Rawlins, C.H., “Design of a Cyclonic Solids Jetting Device and Slurry Transport System for Production Systems”, paper 166118, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, LA, 30 September – 2 October, 2013. https://doi.org/10.2118/166118-MS
 
 
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