Compact, inline separation technology â what and why? - NTNU
Compact, inline separation technology â what and why? - NTNU
Compact, inline separation technology â what and why? - NTNU
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<strong>Compact</strong>, <strong>inline</strong> <strong>separation</strong><br />
<strong>technology</strong> – <strong>what</strong> <strong>and</strong> <strong>why</strong>?<br />
Olav Kristiansen<br />
Statoil RDI, Subsea Separation Technologies<br />
<strong>NTNU</strong>, Flerfaseteknikk guest lecture, February 11 2013<br />
2013-02-11
Outline<br />
• Process challenge<br />
• <strong>Compact</strong> separators, working principle<br />
• <strong>Compact</strong> <strong>separation</strong> applications in Statoil<br />
• Future applications, challenges <strong>and</strong> new technical requirements<br />
• R&D in Statoil to meet new technical challenges<br />
• Summary<br />
2 -<br />
2013-02-11
Statfjord B produced water challenge<br />
>60 bar<br />
18’’<br />
(vertical)<br />
Working principle<br />
Gas/liquid stream<br />
Separation<br />
chamber<br />
Separated gas<br />
Gas free liquid<br />
Swirl element<br />
Gas extraction<br />
Increasing <strong>separation</strong> by inducing swirling flow – increasing g-forces<br />
Enable <strong>separation</strong> of two phases with different densities<br />
4 -<br />
2013-02-11
Videos – working principle<br />
• Phase splitter liquid film <strong>and</strong> carry over into gas extraction pipe<br />
− Bulk <strong>separation</strong><br />
− Induce two-phase flow spin ~100g<br />
• Axial cyclone<br />
− Fine <strong>separation</strong>, removing droplets down to a ~30 to 50 microns<br />
− Induce flow spin <strong>and</strong> apply tangential force<br />
The videos are courtesy of FMC Separation Technology<br />
5 -<br />
2013-02-11
Statfjord B - Produced water slugging<br />
Challenge solution<br />
Major problem with slugs <strong>and</strong> strong vibrations in the<br />
Statoil Statfjord B platform produced water system.<br />
• Capacity limitation of the system<br />
• Safety concern due to the vibrations.<br />
• Solution: 18” De-gasser. Since 2003, gas has been<br />
exported instead of flared. Slugging stopped.<br />
Statfjord B<br />
6 -<br />
2013-02-11
Veslefrikk slugging problem<br />
• Production through 150m flexible hoses between Veslefrikk A <strong>and</strong> B<br />
• Two-phase (3phase) flow<br />
• Slugging, pressure fluctuations <strong>and</strong> production instabilities<br />
• Solution?<br />
7 -<br />
2013-02-11
Veslefrikk slugging problem<br />
Phase splitter<br />
Solution: Split gas <strong>and</strong> liquid using a Phase Splitter, produce outside slug flow<br />
region. 2-4000 BOPD production increase (1-2 MNOK/day)<br />
8 -<br />
2013-02-11
Sleipner T – Scrubber Overload<br />
• Scrubber overloaded with liquid due to a<br />
very high gas velocity through the vessel (Kfactor<br />
>0.2 m/s).<br />
• Massive carry-over of condensate with the<br />
outlet gas that is used to superheat the gas<br />
to the amine absorbers.<br />
• Solution: De-liquidiser to<br />
remove the bulk of the<br />
liquid condensate in the<br />
feed stream prior to<br />
entering the scrubber.<br />
• This improves the<br />
operating conditions for<br />
the suction scrubber <strong>and</strong><br />
thereby the <strong>separation</strong><br />
efficiency.<br />
9 - 2013-02-11
Kvitebjørn – huge production increase<br />
• Objective: Increase production capacity<br />
• Solution: Installation of a 20” Phase Splitter<br />
upstream the inlet separator <strong>and</strong> route some of the<br />
gas (30 to 35%) directly to the scrubber.<br />
• New application for Statoil – high pressure, gas<br />
dominated flow (less than 5% liquid by volume in the<br />
incoming flow).<br />
• Qualification tests at K-LAB 2007 (8” unit)<br />
• Gas capacity increase by 35% from 18.5 to<br />
25MMSm 3 /d<br />
10 - 2013-02-11
Hydrocarbon resources<br />
11 - 2013-02-11
Where are the hydrocarbon resources?<br />
Source: Wikipedia ’Peak Oil’<br />
12 -<br />
2013-02-11
Deepwater potential<br />
13 - 2013-02-11
What are the challenges?<br />
Development of new discoveries<br />
• Colder (Arctic)<br />
• Deeper (Gulf of Mexico, West<br />
Africa, Brazil….)<br />
• Longer (Barent region, Arctic)<br />
Enhanced Oil Recovery<br />
• Norwegian Continental Shelf (NCS)<br />
– old fields with steeply declining<br />
production<br />
− Increased reservoir depletion<br />
− Tie-in of marginal fields to existing<br />
infrastructure<br />
New <strong>technology</strong> is required!<br />
14 -<br />
2013-02-11
Deep water boosting – new field development<br />
<strong>and</strong> enhanced oil recovery<br />
• Long tie-ins (Pazflor/Angola)<br />
• Deep water <strong>and</strong> low reservoir pressure<br />
− High static head to be overcomed<br />
− Single-phase pumps required (MPPs give dp
How large separator can we put subsea?<br />
• Tordis separator <strong>and</strong> boosting station<br />
− Diameter 2.1m<br />
− Skid dry weight 1 300 tons.<br />
− Water depth 200m<br />
− Possible <strong>and</strong> in operation<br />
Max 1000m<br />
w.d.<br />
• A Tordis separator at 3000m w.d.<br />
− 17cm wall thickness due to outer<br />
pressure.<br />
− Difficult to produce<br />
− Difficult (if possible) to heave!<br />
Max weight<br />
300tons at<br />
3000m w.d.<br />
16 -<br />
2013-02-11
Conventional vs. compact separators<br />
17 - 2013-02-11
<strong>Compact</strong>, <strong>inline</strong> separators – <strong>what</strong> <strong>and</strong> <strong>why</strong>?<br />
Caltec iSep<br />
Operating principle:<br />
• Cyclonic separators<br />
• Low-G operation (typically
Now <strong>and</strong> the future<br />
Today: De-bottlenecking<br />
• Performance requirement for one outlet phase<br />
• Performance knowledge: “Sufficient”<br />
• Empirical <strong>and</strong> experienced designs.<br />
Increased fundamental<br />
underst<strong>and</strong>ing of the fluid mechanical<br />
processes is required!<br />
New applications<br />
• Replace traditional separators<br />
• Enable ultra deep water subsea processing for boosting<br />
Two/Three/Four-phase <strong>separation</strong> systems<br />
New <strong>and</strong> stricter requirements<br />
• Stricter requirements for both outlet phases<br />
• Exact performance knowledge <strong>and</strong> operational envelope<br />
required.<br />
• Must h<strong>and</strong>le start-up/shut-down, slug flow, large<br />
turndown<br />
• Challenging process controls<br />
19 -<br />
2013-02-11
Tehcnical challenge: performance compared to<br />
conventional separators<br />
<strong>Compact</strong><br />
• Turndown 50 to 120% of design<br />
operational rate. Swirl breakdown at too<br />
low rate.<br />
• Pressure drop 0.5-2 bar<br />
• Optimised for one outlet stream, e.g. low<br />
liquid carry over<br />
Conventional<br />
• Turndown 0 to >100%<br />
• Pressure drop very low<br />
• Two or three clean output streams<br />
• Can h<strong>and</strong>le transients<br />
• Homogenous inflow is required (no stratified<br />
or slug flow)<br />
Systems will be needed to<br />
overcome these limitations –<br />
single-units are not sufficient<br />
20 -<br />
2013-02-11
Slug flow performance – single Phase Splitter<br />
Hydrodynamic slugs upstream<br />
Incoming slugs propagate through the separator<br />
(little or no slug damping)<br />
1<br />
1<br />
0,9<br />
0,9<br />
0,8<br />
0,8<br />
0,7<br />
0,7<br />
Hold-up<br />
0,6<br />
0,5<br />
0,4<br />
GVF Hold-up<br />
0,6<br />
0,5<br />
0,4<br />
GVF liq<br />
GVF gas<br />
Hold-up<br />
GVF liq avrage=0,34<br />
GVF gas avrage=0,78<br />
0,3<br />
0,3<br />
0,2<br />
0,2<br />
0,1<br />
0,1<br />
0<br />
15 17 19 21 23 25 27 29 31 33 35<br />
Time (s)<br />
0<br />
15 17 19 21 23 25 27 29 31 33 35<br />
Time (s)<br />
21 -<br />
2013-02-11
<strong>Compact</strong> separator systems<br />
– to overcome the limitations of single <strong>inline</strong> separators<br />
Positive:<br />
• Can h<strong>and</strong>le turndown 0-100%(+)<br />
− Start-up <strong>and</strong> shutdown<br />
• H<strong>and</strong>les hydrodynamic slugs<br />
• Can be optimised for both outlet streams<br />
• Weight <strong>and</strong> footprint lower than traditional<br />
separator<br />
Negative:<br />
• Pressure drop (several bars)<br />
• Complex process<br />
• Challenging (but manageble) process<br />
control<br />
<strong>Compact</strong>Sep JIP <strong>separation</strong> system<br />
Development project with<br />
Statoil, Petrobras <strong>and</strong> Chevron<br />
Patent Application priority filing date 22-12-2012<br />
PCT/EP2011/073881<br />
22 -<br />
2013-02-11
Turndown problem solved<br />
Production start-up<br />
100% liquid<br />
100% gas<br />
Flow rate (Am 3 /hr)<br />
100% liquid<br />
50% gas<br />
250<br />
200<br />
150<br />
100<br />
50<br />
Inlet liquid flow rate<br />
Inlet gas flow rate<br />
Gas flow rate, Phase Splitter liquid outlet<br />
Liquid flow rate, De-liquidiser gas outlet<br />
Shut-down<br />
100% liquid<br />
100% gas<br />
100% liquid<br />
50% gas<br />
0% production<br />
0<br />
1000 1060 1120 1180 1240 1300 1360 1420 1480 1540 1600 1660 1720 1780 1840 1900 1960 2020<br />
Relative time (s)<br />
Liquid carry over <strong>and</strong> gas entrainment within acceptance criteria during<br />
startup <strong>and</strong> shutdown<br />
0% production<br />
23 -<br />
2013-02-11
Slug flow (rapid transient) problem solved<br />
Variation in<br />
gas quality<br />
Incoming<br />
slugs 5±4m<br />
Variation in<br />
liquid quality<br />
24<br />
2013-02-11
Summary<br />
• Inline, compact separators – working principle<br />
• Examples, <strong>inline</strong> <strong>separation</strong> in Statoil – troubleshooting <strong>and</strong> de-bottlenecking<br />
• Where are the future resources<br />
• Special attention to deep-water developments <strong>and</strong> new technical requriements<br />
• Technology development of compact <strong>separation</strong> systems – solving limitations<br />
related to <strong>inline</strong> separators. Ongoing JIP with one vendor <strong>and</strong> four oil companies.<br />
25 2013-02-11
<strong>Compact</strong>, <strong>inline</strong> <strong>separation</strong> <strong>technology</strong> –<br />
<strong>what</strong> <strong>and</strong> <strong>why</strong>?<br />
Olav Kristiansen<br />
Principle Researcher, Statoil RDI,<br />
Subsea Separation Technologies<br />
olakri@statoil.com<br />
Tel: +4790213317<br />
www.statoil.com<br />
26<br />
2013-02-11