Scale-X MFC's Increases Production Output
& Eliminates Chronic Scale Problem

 

Technical Papers Published on this Scale-X Installation

Two engineers from Petronas Carigali (PCSB), owners and operators of the offshore oil platform, and two university professors have published a technical paper on the successful application of Scale-X Magnetic Fluid Conditioners MFC's on flow control valves on a South China Sea oil platform which suffered from calcite and barite scale.  

The paper was presented at the APCChE 2002, Asian Pacific Confederation of Chemical Engineering and Chemeca 2002, the Australasian Chemical Engineering Conference hosted by the University of Canterbury in Christchurch NZ, 29 September to 3 October 2002.

A second technical paper was presented at the Sarawak Shell Bhd Fluid Chemistry Forum in October 2002 by Zulkifli Abdul Rahim of Petronas Carigali.

Two more technical papers co-authored by PCSB have now been published, one on water treatment and one on the long term platform success 19 months after installation of the Scale-X MFC's.

Case History

Petronas/Carigali (PCSB) of Malaysia has an offshore oil platform in the South China Sea which has extreme scale problems.  The platform which services 31 wells, 17 of which are currently producing wells, has a high water cut and the formation water has extreme scale forming properties.  The scale formed is calcite (95%), dolomite (3%) and barite (2%).  Chemical scale inhibitors have not been able to solve the problem and standard commercially available magnetic fluid conditioners MFC's have also proved ineffective.  Note:- This is a single pass system and any scale control treatment or device has only one "shot" at treating the liquid.  Most MFC's are only suitable for recirculating fluid systems.

Magnetic Technology Australia (MT) was then approached in January 1999 to put forward a proposal.  After 2 years of research and development, MT developed a radical new approach to the application of magnetic fluid treatment and a totally new type of equipment.  These newly developed Scale-X MFC's  have proved effective in totally eliminating scale build up of the most severe scaling points on the platform and have exceeded the PCSB's specification in every way.

The following is a brief account of the scale problem, the solution and the outcomes of the installation of Scale-X MFC's.

The Scale Problem

Before installation of the Scale-X MFC's, the PCSB offshore oil platform in the South China Sea was shutdown for de-scaling every 3 months.  The most severe scaling points in the whole platform oil and water separation system were the outlet stand pipes on the second separation vessel (that is, the first liquid separation vessel) and the control valves immediately down stream of the stand pipe outlets.  This vessel has three phase separation, gas/oil/water, and is the worst situation for scaling because of the large amounts of gas liberated.  The pressure drop through the water line control valve is 1300kPa and through the oil line control valve is 600kPa.  Note:- The oil line at this point carries 3 parts crude and 1 part formation water.

The details of the scale problem and its effect on production output and operational parameters were:
1. The scale build up in the stand pipes before quarterly shutdown is shown in the diagram below, the water stand pipe sometimes scaling totally closed.
2.  The rate of scale build up in the block valve reducers following the control valves was 30mm over 3 months, that is, the very fast rate of 1mm every 3 days.
3. Over the 3 months between de-scaling shutdowns, the production output levels dropped by 18% even with the liquid level in the vessel being ramped up by 580mm and the pressure being ramped up by 250kPa to support production output.
4. The control valves were stroked twice daily to mechanically remove the scale build up, however, after de-scaling, the valves became stuck (inoperative) within 15 days when scale inhibitors were not used and within 4 weeks when scale inhibitors were used.  An operator was then stationed 24 hours per day at the bypass valves to manually operate the valves to maintain control until the next quarterly shutdown.

Schematic of the Oil & Water Separation Vessel
and Outlet Control & Non Return Valves
Showing Severe Scaling Points
After 3 Months Running Without MFC's Installed

Oil & Water Separation Vessel 12 inch & 8 inch Standpipes
Scale Build Up at Quarterly Shutdown for De-scaling
Without MFC's Installed.

The rate of scale build up before installation
of the Scale-X MFC's was 1mm every 3 days.

The Oil Outlet Control Valve & Water Outlet Non Return Valve
Scale Build Up Before Shutdown
After 3 Months Running Without MFC's Installed
   

Production Drops 18% Over 3 Months
& Vessel Fluid Level and Pressure
Are Ramped Up to Support Production Output.
   

Control Valves Stroke Is Reduced
& Then Become Inoperative
Due to Scale Build Up

The Solution

Special customised Scale-X Magnetic Fluid Conditioners, incorporating revolutionary new concepts, were designed and developed for this application.  The fluid dynamics of the platform fluid system were not within the required operating range for magnetic fluid treatment to function.  The Scale-X MFC's were designed to replace the vortex breakers and incorporated velocity amplifiers and fluid profilers to modify the fluid dynamics parameters to bring them within the required range for MFC's to function while the fluid transited through the MFC's.  Special field structuring was integrated into these MFC's.  The following photograph shows the water outlet MFC installed in the vessel.  The MFC's were tested in the laboratory by simulating the platform's severe scaling conditions.  The new design approach was fine tuned through this process.  This was carried out in a laboratory approved by the National Testing Laboratory Authority (NATA), Melbourne, Australia.

Schematic of the Oil & Water Separation Vessel
and Outlet Control & Non Return Valves
Showing the Location of the Scale-X MFC's on Standpipes
And the Effective Extent of Treatment Exceeding PCSB Specification

Oil & Water Separation Vessel
Scale-X MFC located on Water Standpipe.
 

The Outcomes

The performance of the Scale-X MFC's was evaluated in terms of their ability to:
    1. Prevent scale build up in the stand pipes and valves.
    2. Improve the performance of the fluid system to maintain full production output, minimise need to ramp up vessel fluid level and pressure to support production output.
    3. Maintain the control valve in a fully operational condition without twice daily stroking to mechanically remove scale.
    4. Produce an acceptable return on investment.

The outcomes were that the Scale-X MFC's were totally successful on all accounts and exceeded the Petronas/Carigali (PCSB) specification in all respects (refer photographs and diagrams below).  Note:- The original PCSB specification only required the rate of scale build up in the stand pipes to be halved, the Scale-X MFC's have proved effective far beyond this requirement and eliminated the scale build up and removed pre-existing scale.  The requirement to treat the control valves was added by PCSB after delivery of the Scale-X MFC's.

After installation of the Scale-X MFC's, the platform was not shutdown at the usual 3 and 6 months points and continued to operate at full output without shutdown.  At 8 months after installation, the platform was shutdown during a general oil field shutdown and an visual inspection of the plant revealed the following: 
    1. Scale build up has been totally eliminated in the stand pipes and control valves and pre-existing scale build ups have been removed.
    2. The production output levels have remained at 100% production.  There has been no increase in vessel fluid level or pressure, that is, the liquid level and pressure did not need to be ramped up to support production output.
    3. Stroking of the valves has been discontinued and the valves have remained fully operational with a 100% stroke.
    4. The increased production output resulted in a return on investment within a couple of weeks.
    5. Use of scale inhibitors has been discontinued.

The successful elimination of the scale problem in the control valves was the subject of a technical article published in Chemical Engineering in Australia, Newsletter of IE Aust.

Control Valve, Block Valve Reducer and Non-Return Valve
After 3 Months Without MFC's Installed and
After 8 Months With MFC's Installed

Production Remained at 100%
& Vessel Fluid Level and Pressure
Remained Unchanged With MFC's Installed
   

Control Valves Stroke Remained Fully
Operational at 100% Stroke With MFC's Installed

Oil and Water Control Valves Remain 100% Operational With MFC's Installed
Valve Stems and Seats Remain Clean and Free of Scale
Without Twice Daily Stroking of Valves To Mechanically Remove Scale
  
Oil and Water Control Valves After 8 Months Operation
With Scale-X MFC's Installed


 Photographs of Stroking of the
Water and Oil Control Valves Showing 100% Stroke
With the Scale-X MFC's Installed

Detailed Comparison of Platform System Performance
With and Without Scale-X MFC's Installed

The platform system has continued to operate without scale problems since the 8 monthly assessment of the Scale-X MFC's performance.  Production output remains at 100% and the valves are fully operational and the stroke is 100%.  Vessel fluid level and pressure remain unchanged.

Comparison of Performance of Scale-X MFCs with Chemical Scale Inhibitors and Other Supplier MFCs

      Note A:  Supplied by Magniflo
Note B:  Supplied by MagWell 

Return on Investment