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Partial Processing – Development History – U.S.A (B-CSS-006)

The development of technology for debottlenecking of produced water treatment systems occurred about 10 years after the liquid-liquid deoiling hydrocyclone was commercialized.  Esso installed the first L/L deoiler in the Bass Strait in 1982.

The first pilot testing of Pre-Separating (bulk oil-water) and Dehydrating (removal of water from oil Applications was in 1989 for Conoco in Grand Isle, LA.  Individual deoiler liners designed for non-traditional oil-water separation was tested.  Results from the testing paved the way to the commercialization of specialized partial processing liners for debottlenecking hydraulically constrained systems.

Photo above illustrates the size of the Pre-separator liner in comparison to the traditional liquid/liquid deoiling hydrocyclone liner.

References:

  1. Rawlins, C.H., “Partial Processing: Produced Water Debottlenecking Unlocks Production on Offshore Thailand MOPU Platform”, paper SPE-187109-MS, presented at the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, TX, October 9 – 11, 2017. https://doi.org/10.2118/187109-MS

Partial Processing – Case for Compact Separation (B-CSS-005)

The purpose of a production facility is to separate well fluids into phase components and process each into salable products or dispose of in an acceptable manner.  Separation is traditionally achieved with gravity-based vessels that can be quite large and inefficient.  With increasing demand from offshore and remote environments, new technology to improve on space, weight and process performance is needed. 

Compact Separation technology does not rely on large gravity-based vessels.  They utilize enhanced physical forces (i.e. cyclonic) for separation and as a result decrease the size/quantity of equipment required to do the same job.  The main driving benefits for compact separation include:

  • Space savings
  • Weight savings
  • Motion tolerance for floating facilities
  • Reduced chemical consumption
  • Reduced instrumentation
  • Reduced environmental effects – i.e. less raw materials, less paint, less heat loss, etc.

Examples of compact separation equipment include interceptor plates, G/L cyclones, L/L cyclones, S/L cyclones, rotordynamic equipment, and flotation cells.  When evaluating the compact separation technologies available, some factors to consider include:

  • Separation performance
  • Cost and overall net benefits
  • Operation and maintenance personnel requirements
  • Flexibility to handle varying process conditions
  • Turndown capability
  • Hold-up time
  • Pressure and energy requirements
  • Velocity/Wear
  • Sparing requirements 

References:

Rawlins, C.H., “The Case for Compact Separation”, paper SPE-80994, Technology Today Series, 2003 Society of Petroleum Engineers. https://doi.org/10.2118/80994-JPT

Partial Processing – System Integration (B-CSS-004)

A successful field trial led to the design and integration of a full-scale Partial Processing (PP) system for a Mobile Offshore Production Unit (MOPU) offshore Thailand.

The schematic of the full-scale PP system installation at the MOPU is illustrated in the figure above.  Two dedicated two-stage hydrocyclone skid packages, each consisting of 1×100% preseparator and 1×100% deoiler, were installed to receive fluids directly from the production manifold. The objective was to increase total liquid production from 100,000 BLPD to 180,000 BLPD at 90% water cut and achieve produced water treatment of <50ppm oil-in-water for disposal.  The yield is an increase of oil production from 10,000 BOPD to 18,000 BOPD, an 80% increase.

There were many challenges faced and overcome on this project including limitations of footprint on the MOPU and the process operations.  Increase in production results were achieved along with other O&M benefits such as:

  • Lowering of pipeline pressure, reducing fuel and power consumption to produced fluids
  • Bulk treating of fluids at the MOPU, reducing volume transferred to and from FSO
  • No extra pumping equipment required for increased production
  • Chemical usage reduction
  • Less fluid storage required at the FSO

References:

  1. Rawlins, C.H., “Partial Processing: Produced Water Debottlenecking Unlocks Production on Offshore Thailand MOPU Platform”, paper SPE-187109-MS, presented at the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, TX, October 9 – 11, 2017.  https://doi.org/10.2118/187109-MS

Partial Processing – PP Methodology Benefits System Hydraulics and Fluid Processing (post B-CSS-003)

Partial Processing methodolgy targets the bulk removal of the constraining phase from Oil & Gas production.  It does not seek complete removal.  PP creates additional spare capacity at the wellhead platform by lowering the backpressure on existing wells and alleviate stress on process equipment that is struggling with over capacity.

A common setup in mature field uses the “Spoke and Hub” structure where multiple wellhead platforms connect to a centralized processing or hub platform, which  then forwards the fluid via pipeline to an onshore processing facility.  Typical process treatment equipment include free water knockout, production separators, and produced water treatment (PWT) systems that are design to handle specific flowrates.  As pipelines gets hydraulically overloaded or constrained, system backpressure increases thus limiting fluid production from the wells and/or equipment.

Process equipment once overloaded are not be able to treat the fluids to process specification and therefore limiting further production.  In the case of PWT, if legal discharge or disposal limits are not met then there will be no way to get rid of the water resulting reduced production – or even worse, shut down.

References:

  1. Rawlins, C.H., “Partial Processing: Produced Water Debottlenecking Unlocks Production on Offshore Thailand MOPU Platform”, paper SPE-187109-MS, presented at the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, TX, October 9 – 11, 2017.  https://doi.org/10.2118/187109-MS

Partial Processing – Debottlenecking Hydraulically Constrained Systems (post B-CSS-002)

Partial Processing (PP) packages are typically installed in marginal or mature fields to unlock its true production potential.  Throughput from these field are often constrained by water or gas or a combination of both. 

High water cut production is usually hydraulically constrained at one or multiple points of the system.  These points include:

  • Flowlines between Wellhead Platform (WHP) and Central Processing Platform (CPP)
  • Processing Plant /Equipment Packages at the CPP
  • Flowlines between WHP and Shore-Based processing facilities

PP packages utilize technology with a well-proven history in large and small scale operations around the of the world.  Successful partial processing at the wellhead platform can increase hydrocarbon production by 50 – 400+% by alleviating the point(s) of constraint.  The level of success will depend on several factors including knowledge of process design and integration, selection of the right equipment for the application, proper control philosophy, and design flexibility to handle varying conditions.

Developing a solid design basis for your partial processing system often requires a field trial. Do not skip this step.  Having a well-experienced company with the Right People to implement partial processing is key.

References:

Rawlins, C.H., “Partial Processing:  Produced Water Debottlenecking Unlocks Production on Offshore Thailand MOPU Platform”, paper SPE-187109-MS, presented at the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, TX, October 9 – 11, 2017.  https://doi.org/10.2118/187109-MS

 
 
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