macro-porous polymer extraction for offshore...

a report by

Ak z o N ob e l MPP S y s t em s

I n t r o d u c t i o n

The macro-porous polymer extraction (MPPE)technology developed in the early 1990s by AkzoNobel removes dissolved and dispersed hydrocarbons.MPPE is basically a liquid–liquid extraction processwhere the extraction liquid is immobilised in a macro-porous polymer particle. This technology can removecompounds with a lower polarity than water to anylevel required (e.g. 99.9999% removal). The MPPEtechnology is applied in process water, offshoreproduced water, wastewater and ground water in awide variety of markets since 1994. The firstapplication was at Total in Harlingen (NL) whereoffshore-produced water and process water from themonoethylene glycol (MEG) and triethylene glycol(TEG) regeneration is treated by MPPE onshore.

Within the Oslo Paris Convention (OSPAR) for theprotection of the marine environment of the NorthEast Atlantic, European governments and industriesare setting offshore emission standards for the future.This has led to testing and evaluating the MPPEtechnology heavily for offshore-produced water.ERT/Orkney water technology center,1 testsTOTAL,2 the Netherlands Oil and Gas Explorationand Produced Association (NOGEPA),3 NAM(Shell/Exxon,)4 and Statoil.5

The MPPE technology has been, for offshoregas/condensate, proven and commercially operationalsince the beginning of 2002 (Total F15A).6 Two otherunits have started up since then: NAM K15A, andNAM K15B. In 2003, successful fieldtests onproduced water form oil production took place onrequest of the OSPAR.9

T h e MPPE P r o c e s s D e s c r i p t i o n

In the MPPE process, hydrocarbon-contaminatedwater is passed through a column packed withMPPE particles (see Figure 3). The particles areporous polymer beads, which contain a specificextraction liquid. The immobilised extractionliquid removes the hydrocarbon components fromthe water. Only the hydrocarbon components,which have a high affinity for the extraction liquid,are removed. The purified water can either bereused or discharged. Periodical in situ regenerationof the extraction liquid is accomplished bystripping the hydrocarbons with low-pressuresteam. The stripped hydrocarbons are condensedand then separated from the water phase by gravity.The almost 100% pure hydrocarbon phase isrecovered, removed from the system and ready forrecycling or disposal. The condensed aqueousphase is recycled into the system. The application

Macro-porous Po lymer Ext rac t ion for Of f shore Produced Water RemovesD i s so lved and Di sper sed Hydrocarbons

B U S I N E S S B R I E F I N G : E X P L O R A T I O N & P R O D U C T I O N : T H E O I L & G A S R E V I E W 2 0 0 4

1

Technology & Services

1. ERT/Orkney Water Technology Center: The removal of dissolved and dispersed organic components from produced water,ERT F92/178, 1997 (Study requested by Exxon/Mobile, TOTAL, Amarada Hess).

2. Pars H M (TotalFinaElf) E & P en D, Th Meijer (Akzo Nobel nv.), “Removal of dissolved hydrocarbons from productionwater by Macro Porous Polymer Extraction (MPPE)”, SPE 46577. SPE International Conference on Health, Safety andEnvironment in Oil and Gas Exploration and Production held in Caracas, June 1998.

3. van der Kaa C C R and Petrusevki B, (Stork) (1998), Report 61944-00-32-301-2, NOGEPA (Netherlands Oil andGas Exploration and Production Association) and Dutch Government by Inventarisation of removal techniques to reduce thebenzene/heavy metal emissions from offshore platforms (in Dutch).

4. Meijer D Th, (Akzo Nobel MPP Systems B.V. and C.A.T. Kuijvenhoven, NAM B.V. JV Shell/Exxon; Shelloperated), “Field-Proven Removal of Dissolved Hydrocarbons from Offshore Produced Water by the Macro Porous Polymer-Extraction Technolgy”, Offshore Technology Conference, Houston, Texas, April–May 2001.

5. Grini P G, Statoil ASA, Trondheim, Hjelsvold M and S. Johnsen, SPE 74002 “Choosing Produced Water TreatmentTechnologies Based on Environmental Impact Reduction”, Copyright 2002, Society of Petroleum Engineers Inc. This paperwas prepared for presentation at the SPE International Conference on Health, Safety and Environment in Oil and GasExploration and Production, held in Kuala Lumpur, Malaysia, March 2002.

6. Meijer D Th, Akzo Nobel MPP Systems, “Field Proven removal of dissolved and dispersed hydrocarbons at commercial scalefrom offshore produced water by the macroporous polymer extraction technology”, NEL Produced Water Workshop,Aberdeen, March, 2003.

of two columns allows continuous operation withsimultaneous extraction and regeneration. A typicalcycle is one hour of extraction and one hour ofregeneration.

S e p a r a t i o n P e r f o rman c e

Dissolved and dispersed components that can beremoved to any level specified are:

• aromatics (benzene and xylene (BTEX));

• polyaromatic hydrocarbons (PAHs);

• naphtalenes, phenanthrenes, dibenzothiophenes(NPDs)

• aliphatics (including mineral oil up to <C20);

• TEOX/TEOC (total extractable organics);

• halogenated hydrocarbons (such as chlorinated,bromated etc.); and

• in principle all other ‘hydrophobic’ components(e.g. CS2, THT).

In current running units, dissolved aromatics(especially benzene), PAHs, aliphatics andchlorinated hydrocarbons are removed for more than99.99% (size of unit is tailored to required separationperformance – reduction factor of one million timesis feasible (= 99.9999% removal)).

With NPDs and PAHs, offshore and onshore, 99.9%removal is obtained. Onshore an industrial unit hasbeen running since 1998, removing 3,500 ppb PAHsto n.d. level (<0.05 ppb). There has been 50% to80% removal of:

• phenol, 50%;

• cresols (ortho-, meta-, para-) 70% to 80%; and

• alkylated phenols.

Heavier alcohols (like isobutanol), esters, ethers andother more polar compounds (like tetra hydrofuran),are removed by 40% to 80%. Some specific etherssuch as dichloro-di-isopropylether (DCPE) can beremoved, even at >99% level.

I n l e t C o nd i t i o n s a n d Wa t e rC ompo s i t i o n

When working with inlet temperatures foraromatics/PAHs, aliphatics removal up to 55ºC to60°C are possible. Other situations have to beviewed case by case. Inlet pressure needs to bereduced to three barg, to flow through the unitleading to an atmospheric outlet. Forgas/condensate production process water the MPPEunit is placed after the degasser (flash vessel) andskimmer (basis – offshore experience). For oilproduction-produced water, after the hydrocyclones and degasser, dissolved (heavy) metals,iron, Ca++ (no carbonate formation) will flowthrough. In case of iron, limited flocculation of ironhydroxide will not affect the performance(anaerobic operation, MPPE material robustness).


2


Figure 1: Produced Water Gas Production

BTEX: 3000 ppm to < 0.1ppm

Flow rate: 6 m3/hr (26 gpm)

Size; dia x h: 0.8 x 2 (m); 2.6 x 6.5 (ft)

7. Hasegawa M H, “Surfactant-enhanced subsurface remediation of DNAPLS at the former Naval air station Alameda,California. Proceedings International Conference on Remediation of chlorinated and recalcitrant compounds”, May, (2000),Monterey, USA.

8. Sluys J T M and Brooks P E, Akzo Nobel MPP Systems B.V. “MPPE in surfactant enhanced DNAPL remediation”,Book of abstracts of the International Congress on Implementation of in-situ Remediation Techniques inUtrecht, The Netherlands, October 2000.

9. Meijer D Th, Akzo Nobel MPP Systems B.V., C.A.T. Kuijvenhoven, Shell International, H. Karup Danish EPA.Results from the latest MPPE field trials at NAM and TOTAL installations, NEL Produced Water Workshop, April2004, Aberdeen (UK).

Macro- porous Po lymer Ext rac t ion for Of f shore Produced Water

Dissolved salt and other dissolved solids will flowthrough, as will methanol, glycols and surfactants.

With scale-corrosion inhibitors, demulsifiers andH2S scavangers, no negative effects have beenexperienced.1,2,4,6–9 With Total our MPPE system istreating produced water from offshore and waterfrom glycol regeneration onshore containing, amongothers, corrosion inhibitors, glycol and methanol.Current MPPE units offshore are treating producedwater containing corrosion inhibitors. It also hasbeen experienced that a major part (approximately50%) of the inhibitor was removed with MPPE.

S u s p e n d e d S o l i d s

Some form of prefiltration may be required dependingon the concentration. The unit is relatively robustagainst solids like sand, etc. There are several outlets forsolids, e.g. part will be prefiltered, part will flowthrough, part will be removed by the hourly backwashduring one of the process steps and part will beremoved when material is replaced. In our offshoredemonstration unit, cartridge filters are used, althoughother prefilters could be applied. In a long durationoffshore field test no pressure drop increase over thepacked bed was measured without prefiltration.Current offshore commercial units are successfullyoperating with standard prefilters.

F l o w R a t e s

A single unit consisting of two columns can treat upto 200m3 or 250m3 per hour; for higher flow ratesunits will be installed parallel.

T e c h n i c a l I n f o rma t i o n

Ideally, there should be minimum operatorintervention and minimum maintenance requirements.Remote control system (by telephone/modemconnection) is included in combination with a fullyautomated MPPE unit for which only normalmaintenance is required. Remote stop, start-up andother changes in process conditions are possible.

Suitable for outdoor placement, the MPPE unitcan be placed in a container. With regards toequipment suitable for offshore application, in thecase of a container, a 20ft container (includingMPPE unit PLC, computer and prefiltration),approximately eight ton (during operation) andapproximately six ton (handling weight) is used. Amodular skid-mounted approach for installation onthe cellar deck has also been implemented.Electricity units required are: 380–415V,maximum load 50kW, instrument air, water forsteam generator and cooling water, as well as otherpossible options. Due to the presence of salt,

possibly influenced by CO2 content in thecondensate, it is advisable to use duplex. Capacitycan be tuned to the changing influent levels to obtainthe required effluent, e.g. in case of a 50% higherinfluent concentration the same effluent level withonly a 10% lower flow. At lower influentconcentrations, higher flow rates can be reached. Atlower capacity, level controlled operation is required(e.g. level of a buffer tank).

Con t am i n a n t R e c o v e r y

The recovered hydrocarbons (as a mixture) areobtained as a practically 100% pure liquid to berecycled and/or reused.

E v i d e n c e o f C o n f i d e n c e a n d E x p e r i e n c e s

Figures for Elf Petroland (TotalElfFina) in Harlingenonshore treatment of offshore gas produced water(since 1994) are as follows:

• six-year successful operation at three to six m3/hr;


3

Figure 2: MPPE Unit NAM (Shell/Exxon)

Figure 3: Schematic Overview of Macro-porous

Polymer Extraction Process

• average concentrations of BTEX at 3,000ppmwith peaks to 7,000 and 10,000 ppm (dispersed).

• continuous >99.9% removal of BTEX andaliphatics; and

• experiences published at SPE conference inCaracas in 1998 (SPE 46577 HM Pars/ElfPetroland BV – D.Th. Meijer/Akzo Nobel NV).

E v a l u a t i o n b y O r k n e y Wa t e rT e c h n o l o g y C e n t e r

• Comparison of technologies on request of Exxon,Amerada Hess and Total Elf Aquitaine.

• Performance was verified on oil and gasproduced water (in 1997) during a three-monthtest with a full scale unit. The test showedinsensitivity for corrosion inhibitors from oiland gas production platforms.

On request of the Dutch government and the DutchOil and Gas Exploration and Production Association(NOGEPA), the MPPE technology was evaluated byengineering bureaus against 55 technologies andselected as one of the best options for removinghydrocarbons from offshore-produced water (1997).NAM (Shell/Exxon) were in a successful four-month offshore trial in 1999, involving:

• north Sea offshore;

• full scale unit treating all produced water(including water from glycol regeneration); and

• consistent continuous removal of hydrocarbons tomeet effluent requirements with an availability ofover 98%.

Data are published in Offshore TechnologyConference (OTC) 13217 paper (May 2001 byShell/Exxon and Akzo Nobel). Also listed as bestavailable techniques (BATs) by the OSPARconvention for the protection of the marineenvironment of the North-East Atlantic (1999):

• recommended by OSPAR and listed as bestavailable technology and best environmentalpractice for produced water management onoffshore oil and gas platforms.

Additional successful offshore demonstrations ongas/condensate offshore-produced water wereconducted by:

• Statoil, North Sea Åsgard A condensateplatform; and

• Shell, South China Sea, Malaysia.

And the first commercial units offshore were:

• Total F15A) April 2002;

• NAM (Shell/Exxon) K15A November 2002;

• NAM (Shell/Exxon) K15B December 2002;

• with Norsk Hydro a four-month field test onTroll B for evaluating the capability of the MPPEtechnology to reduce the environmental impactfactor (poly aromatics, aromatics and aliphatics) ofthe oil produced water stream (1,250m3/) is beingfinalised; and

• successful MTBE removal tests (with a modifiedMPPE particle) from groundwater has beencarried out with Shell in Germany.

E n v i r o nmen t a l A s p e c t s

• Practically pure separated hydrocarbons foruse/reuse

• Low waste of polymer

– Long lifetime

– Reuse of spent material

• Low energy consumption

• Low noise

• No addition of chemicals

• No emission to air

• No sludge information

• No (chemical) iron hydroxide waste ■


4


macro-porous polymer extraction for offshore...

Documents