Presentation is loading. Please wait.

Presentation is loading. Please wait.

Flow Control in Oil/Gas Wells and Pipelines Trial Lecture Ph.D Dissertation Even Solbraa 14.February 2003.

Similar presentations


Presentation on theme: "Flow Control in Oil/Gas Wells and Pipelines Trial Lecture Ph.D Dissertation Even Solbraa 14.February 2003."— Presentation transcript:

1 Flow Control in Oil/Gas Wells and Pipelines Trial Lecture Ph.D Dissertation Even Solbraa 14.February 2003

2 Flow Control in Oil/Gas Wells and Pipelines 1. Introduction to flow control 2. Multi-phase flow with emphasis on slug flow 3. Stabilization of flow in Oil/Gas wells and pipelines 4. Examples of flow control for selected oil and gas fields 5. Conclusions Outline

3 Flow Control in Oil/Gas Wells and Pipelines (illustrations: Statoil picture library) Norwegian Oil and Gas Production Platforms Floating production units Pipelines directly to shore Oil to refineries Gas exported to Europe

4 Flow Control in Oil/Gas Wells and Pipelines Trends and Facts in Oil and Gas Production Few new ‘giant’ oil and gas fields are likely to be discovered More than a quarter of the world’s oil and more than 15% of its natural gas lies offshore Most of the new discoveries are expected to occur offshore New large fields are probable in deep waters Develop new and cost effective solutions for small fields Multiphase transport directly to shore Tie-in of well stream from sub sea installation to platform (Oliemans, 1994, Sarica and Tengesdal, 2000)

5 Flow Control in Oil/Gas Wells and Pipelines Multiphase Transport Solutions The Snøhvit solution: Transport directly to shore The Åsgard field : Floating production system (www.statoil.com)

6 Flow Control in Oil/Gas Wells and Pipelines Multi-Phase Fluid Flow (Oil/Water/Gas)

7 Flow Control in Oil/Gas Wells and Pipelines What is the sea depth of future fields ? Norwegian Sea1500 meter Gulf of Mexico 2500 meter West Africa1500 meter Brazil300 meter Caspian Sea600 meter Venezuela300 meter Common: Deep water nature of the provinces

8 Flow Control in Oil/Gas Wells and Pipelines Callenges for Deep Water Developments (Hassanein and Fairhurst, BP 1997)

9 Flow Control in Oil/Gas Wells and Pipelines Flow Control The ability to actively or passively manipulate a flow field in order to effect a beneficial change. (Gad-el-Hak, 1989)

10 Flow Control in Oil/Gas Wells and Pipelines Flow assurance The ability to produce hydrocarbon fluids economically from the reservoir to export over the life of a field in any environment. (Forsdyke 1997) Challenges: Hydrates Wax/paraffin deposition Fluid control Scale Emulsions Slugging Flow control Sand

11 Flow Control in Oil/Gas Wells and Pipelines Flow control: emulsion viscosity Use of emulsion breaker to lower viscosity Oil-water mixtures: Increase in viscosity close to inversion point

12 Flow Control in Oil/Gas Wells and Pipelines Sand Control Sand will follow the oil and gas from the reservoir Sand can deposit in the pipeline and process equipment Oscillating pressure and well production will increase sand production

13 Flow Control in Oil/Gas Wells and Pipelines 1. Introduction to flow control 2. Multi-phase flow with emphasis on slug flow 3. Stabilization of flow in Oil/Gas wells and pipelines 4. Examples of flow control for selected oil and gas fields 5. Conclusions Outline

14 Flow Control in Oil/Gas Wells and Pipelines Multiphase Transport Flow with one or several components in more than one phase –Gas-liquid flows –Gas-solid flows –Liquid-solid flows –Three-phase flows (e.g. gas-oil-water) Simulation tools –Industry standard: OLGA (two fluid model) –PETRA objectoriented implementation in C++

15 Flow Control in Oil/Gas Wells and Pipelines Horizontal Two-Phase Flow Segregated flow –Stratified –Annular –Wavy Intermittent –Slug flow –Plug flow Distributive flow –Bubble/mist flow –Froth flow

16 Flow Control in Oil/Gas Wells and Pipelines Example – horizontal slug flow From Multiphase Flow Laboratory, Trondheim Movie provided by John-Morten Godhavn, Statoil

17 Flow Control in Oil/Gas Wells and Pipelines Inclined flow Waves !

18 Flow Control in Oil/Gas Wells and Pipelines Horizontal Flow Map Flow pattern map for horizontal flow Often specified in terms of superficial velocity of the phases Annular Slug Stratified Wavy Stratified Bubble -1° +1°

19 Flow Control in Oil/Gas Wells and Pipelines Vertical flow Bubble flow –Continuous liquid phase with dispersed bubbles of gas Slug flow –Large gas bubbles –Slugs of liquid (with small bubbles) inbetween Churn flow –Bubbles start to coalesce –Up and down motion of liquid Annular flow –Gas becomes the continuous phase –Droplets in the gas phase

20 Flow Control in Oil/Gas Wells and Pipelines Example - vertical flow From Multiphase Flow Laboratory, Trondheim Movies provided by John-Morten Godhavn, Statoil Slug flowBubble flow

21 Flow Control in Oil/Gas Wells and Pipelines Vertical Flow Map Partly dependent on upstream geometry

22 Flow Control in Oil/Gas Wells and Pipelines Slug Flow - A fascinating but unwanted and damaging flow pattern

23 Flow Control in Oil/Gas Wells and Pipelines Consequences of Slugging Variations in flowrate to 1.stage separator –Shutdowns, bad separation, level variations –Pressure pulses, vibrations and tearing on equipment –Flow rate measurement problems Variations in gasflow –Pressure variations –Liquid entrainment in gas outlet –Flaring –Flow rate measurement problems

24 Flow Control in Oil/Gas Wells and Pipelines ”Normal” steady slugs – Hydrodynamic slugging –Unaffected by compressibility –Incompressible gas (high pressure) or high liquid rate –Normally not an operational problem –Short period Slugs generated by compressibility effects –Severe slugging in a riser system (riser induced) –Hilly terrain slugs(terrain induced) –Other transient compressible effects –Long period Transient slugs –Generated while changing inlet rate Reservoir induced slug flow Slug Flow Classification

25 Flow Control in Oil/Gas Wells and Pipelines Slug flow generation (Oliemans 1994) Wave growth due to Kelvin Helmholtz instabilities Slug growth criteria (the slug has to grow to be stable) Hydrodynamic slug growth Two criteria:

26 Flow Control in Oil/Gas Wells and Pipelines Hydrodynamic slugging Formed when waves reach the upper pipe wall; the liquid blocks the pipe, and waves grows to slugs Short slugs with high frequency Gas rate, liquid rate and topography influences degree of slugging Triggers riser slugging Eksempel fra flerfaseanlegget på Tiller.

27 Flow Control in Oil/Gas Wells and Pipelines Slugs from Gas Lift Annulus Gas lift is a technology to produce oil and gas from wells with low reservoir pressure Gas lifts can result in highly oscillating well flow Casing-heading instabilities

28 Flow Control in Oil/Gas Wells and Pipelines Slug formation in pipeline/riser 1.Initiation and Slug formation Gas velocity too low to sustain liquid film in riser Liquid blocking Gas pressure increases in pipe No/low production 2.Slug production Gas pressure equals liquid head Liquid accelerates when gas enters riser Large peak in liquid flow rate 3.Gas blow down Pressure drops as gas enters riser Gas bubbles become continuous, liquid film at wall Gas velocity too low... 4.Liquid fallback Liquid film flows down the riser

29 Flow Control in Oil/Gas Wells and Pipelines Conditions for severe slugging Flow maps for pipe/riser Conditions from literature –Bøe ’81, Taitel et al ’90, Schmidt et al ’85, Fuchs ‘87 –Pressure limits –Depend on pipe geometry Based on steady state analysis –Inaccessible variables Dynamic simulation When does slugging occur? –Pipelines with dips and humps –Low gas-oil ratio –Decreasing pressure –Long pipelines –Deep water production

30 Flow Control in Oil/Gas Wells and Pipelines Important Severe Slugging Parameters Gas and oil flowrate Pipeline pressure Upstream geometry Graph from Fuchs (1997)

31 Flow Control in Oil/Gas Wells and Pipelines Important Severe Slugging Parameters Gas and oil flowrate Pipeline pressure Upstream geometry Pressure: 30 bar Pressure: 50 bar Figures from Fuchs (1997)

32 Flow Control in Oil/Gas Wells and Pipelines Important Severe Slugging Parameters Gas and oil flowrate Pipeline pressure Upstream geometry Stright pipe upstream Pipe buckling upstream

33 Flow Control in Oil/Gas Wells and Pipelines 1. Introduction to multi-phase flow 2. Slug flow 3. Stabilization of flow in Oil/Gas wells and pipelines 4. Examples of flow control on some oil and gas fields 5. Conclusions Outline

34 Flow Control in Oil/Gas Wells and Pipelines Slug reduction/elimination techniques Design changes –Slug catchers and separators –Rate/GOR change or pressure change –Pipe diameter regulation (use of many smal pipes) (Yocum, 1975) –Gas injection at riser base (Hill, 1990) –Pipe insertion (self induced gaslift) (Sarica & Tengesdal, 2000) –Venturi tubes –Dynamic simulation (Xu et al, 1997) Operational changes –Choking (Schmidt et al., 1979, Taitel, 1986, Jansen et al., 1996) –Feed-forward control of separator level –Dynamic simulation (Xu et al., 1997) –Pigging operations –Use of flow-improver –Foaming (Hassanein et.al., 1998) –Artificial gas lifts –Optimise well production –Increase gas injection in well Feedback control –Miniseparators –Active choking –Model based regulation

35 Flow Control in Oil/Gas Wells and Pipelines Robust design - Gas injection at riser base (Hill, 1990) + Reduced static head (weight of liquid) Prevent severe slugging Smoothen start-up transients Q gas - Large amounts of injection gas needed Extra injection pipe needed

36 Flow Control in Oil/Gas Wells and Pipelines Robust design - Self gas lifting (Sarcia & Tengesdal, 2000) + Reduced static head (weight of liquid) Prevent severe slugging Smoothen start-up transients No extra injection gas needed - Extra injection pipe needed – will be expensive

37 Flow Control in Oil/Gas Wells and Pipelines Robust operation – Choking (Schmidt et al., 1979, Taitel, 1986, Jansen et al., 1996 ) + Higher pressure and smaller severe slug flow regime Easy and cheap technique - Manual work Lower capacity of pipe

38 Flow Control in Oil/Gas Wells and Pipelines Feedback control – Active Choking (Statoil, 2003) + Reduces the slug length by opening the hock valve when the slugs starts to develop – sucks the slug up. Easy and cheap technique - Lower capacity of pipe Can be a problem for deep waters 1.stage separator PIC SP D PT MV PT Used as regulation valve

39 Flow Control in Oil/Gas Wells and Pipelines Robust operation – Optimize Well Production (ABB) OptimizeIT Active Well Control - stabilizes the oil production from the well by active control of the production and/or injection choke

40 Flow Control in Oil/Gas Wells and Pipelines Robust operation – Increased/controled gas injection rate in gas lifts + Increased gas flow rate and GOR (less chance for severe slugging) Less static head - Increased frictional losses Joule-Thomson Cooling Need injection gas Annulus

41 Flow Control in Oil/Gas Wells and Pipelines Feedback control - Miniseparators (Hollenberg, 1995, S3 TM ) Principle is to keep the mixture flow rate constant through the operation with a control vale. Difficulty in measuring flowrates is solved by using minisparators - Lower capacity of pipe

42 Flow Control in Oil/Gas Wells and Pipelines Slug reduction/elimination techniques Design changes –Slug catchers and separators –Rate/GOR change or pressure change –Pipe diameter regulation (use of many smal pipes) (Yocum, 1975) –Gas injection at riser base (Hill, 1990) –Pipe insertion (self induced gaslift) (Sarica & Tengesdal, 2000) –Venturi tubes –Dynamic simulation (Xu et al, 1997) Operational changes –Choking (Schmidt et al., 1979, Taitel, 1986, Jansen et al., 1996) –Feed-forward control of separator level –Dynamic simulation (Xu et al., 1997) –Pigging operations –Use of flow-improver –Foaming (Hassanein et.al., 1998) –Artificial gas lifts –Optimise well production –Increase gas injection in well Feedback control –Miniseparators –Active choking –Model based regulation

43 Flow Control in Oil/Gas Wells and Pipelines 1. Introduction to flow control and multi-phase flow 2. Slug flow 3. Stabilization of flow in Oil/Gas wells and pipelines 4. Examples of flow control on some oil and gas fields 5. Conclusions Outline

44 Flow Control in Oil/Gas Wells and Pipelines 4700m Slugg Control at Heidrun Nordflanken Use of active slug control Simulation before startup indicated slugging Field measurements after startup proved slugging Continuous slug regulation since startup Also in use under startup of new wells D Elevation -355m

45 Flow Control in Oil/Gas Wells and Pipelines Slugging in riser Heidrun D-line Trykk toppside oppstrøms choke Large pressure variations Periods ca. 17 minutes. Disapears when chocking upstream Tetthet toppside

46 Flow Control in Oil/Gas Wells and Pipelines Active Well Control at Brage A-21

47 Flow Control in Oil/Gas Wells and Pipelines Pres. [bar] Downhole pressure Optimize IT Active Well Control on Brage A-21 Starting Active Control

48 Flow Control in Oil/Gas Wells and Pipelines Conclusions Introduction to flow control Unstable multiphase flow – what, why Severe slugging in gas/oil pipelines Methods for control of severe slugging Still an unresolved problem for deep waters Successful practical examples

49 Flow Control in Oil/Gas Wells and Pipelines Thanks Institute for Energy and Process Technology, NTNU Statoil Norwegian Research Council People who have helped my with this trial lecture Lars Imsland, Elling Sletfjerding, John Morten Godhavn

50 Flow Control in Oil/Gas Wells and Pipelines Flow control in petroleum production Noise suppression Drag reduction Water-oil flow Flow assurance Slug control Multiphase flow simulation

51 Flow Control in Oil/Gas Wells and Pipelines Drag reduction Internal flows (pipes, ducts) –~100% skin friction –Increased throughput –Reduced pumping power –Reduced pipe/duct size Wall modifications –Smoothing (paintings, coatings, pigging) –Riblets (shark-skin) –Compliant walls, flexible skin –MEMS (Micro-electromechanical systems) Additives –Particles, dust, fibres –Polymers, surfactants (Drag reducing agents) –Micro-bubbles, fluid films


Download ppt "Flow Control in Oil/Gas Wells and Pipelines Trial Lecture Ph.D Dissertation Even Solbraa 14.February 2003."

Similar presentations


Ads by Google