Liquid Loading mitigation: the right method for the right well at - PowerPoint PPT Presentation

Gas Well De-Liquification Workshop Adams Mark Hotel, Denver, Colorado March 5 - 7, 2007 Liquid Loading mitigation: the right method for the right well at the right time Ewout Biezen, Chad Wittfeld, Gert de Vries, Dick Klompsma, Vincent Hugonet, Gerrit de Jong, Stathis Kitsios, Rob Smeenk (NAM)

Tail-end production management Aspiration Traditional production enhancement activities e.g. re-perf, stimulations Production Improved diagnostics for detecting or predicting onset of liquid loading Typical gas well Non-traditional production enhancement activities, e.g. Production profile foam lifting, velocity/insert strings, mobile wellhead compression, etc Onset of liquid loading Optimise Time Intermittent production • LL affects ~125 million scf/d in the NAM onshore Netherlands area • Deliquification gains 2006: 3.5 billion scf 2007 Gas Well De-Liquification Workshop 2 Mar. 5 - 7, 2007 Denver, Colorado

Typical Well Information NAM • Mostly 3 ½” tubing, some 5” or even 7” • Varying liner sizes – 4 ½”, 7”, 9 5/8” • Subsurface safety valve legal requirement • Liquid loaded production ranges from 0.3–7 million scf/d • Varying perforated interval length: 120 ft – 900 ft gross • Mixture of sandstones and fractured carbonates • Depths of 3,500 – 12,000 ft • Some H 2 S • High-cost environment 2007 Gas Well De-Liquification Workshop 3 Mar. 5 - 7, 2007 Denver, Colorado

NAM: Current deliquification and candidate selection methods • Batch foam – 60 wells, 700 jobs • Continuous foam – 6 installations, 6 more in progress • Velocity strings, tail-end extensions – 10 running, 5 planned in 2007 • Plunger lifting – working first implementation in 2007 • Mobile wellhead compression – start 2008 Candidate selection: – Batch foam – Acoustic logging, FPGs (dynamic liquid level determination) – WGR measurements (well fluid sampling) – In/outflow modeling – Economics based on long-term (4 yr) production forecast 2007 Gas Well De-Liquification Workshop 4 Mar. 5 - 7, 2007 Denver, Colorado

Foam – Candidate Selection Several methods currently being used to select wells for continuous foam application: • Batch foam success – Convert if it makes economic sense to go from batch to continuous • Fluid sampling and foam testing on well fluids – Can be very difficult to obtain good samples that are not corrupted with things such as • Flow from other wells (different reservoirs) • Condensate based corrosion inhibition chemicals – Higher strength foamers being tested for areas with more condensate 2007 Gas Well De-Liquification Workshop 5 Mar. 5 - 7, 2007 Denver, Colorado

Candidate selection: Batch foam 60 wells, 700 jobs • Successful : Clear improvement 19% Not • Inconclusive : Cannot conclude successful either way (more BF jobs) 33% • Not successful : No difference Inconclusive with or without foam 48% Successful • Not applicable (inflow impaired, e.g. HUD or reservoir problem) • Decide on conversion (has to make economic sense) 2007 Gas Well De-Liquification Workshop 6 Mar. 5 - 7, 2007 Denver, Colorado

Candidate selection: Batch foam results COV-40 Foam stability (foam collaps time) COV-40 at 90 °C (3,2 % dose rate) with 10 and 30% condensate (liq vol intake 160 ml) 650.0 • Lab foam testing on well fluids 550.0 Foam height in ml • Batch foam trials 450.0 • In/outflow modeling 350.0 • Economic evaluation 250.0 • Continuous foam candidate 150.0 0 min 1 min 3 min 5 min 10 min Minutes 10 0 1 3 5 3.5 Flow rate 600 Batch Foam Loaded 3 FTHP 500 2.5 Flow rate [1e6 scf/d] 400 FTHP [psi] 2 300 1.5 Unloaded 200 1 100 0.5 0 0 29-Nov-05 13-Dec-05 27-Dec-05 10-Jan-06 24-Jan-06 2007 Gas Well De-Liquification Workshop 7 Mar. 5 - 7, 2007 Denver, Colorado

Candidate selection: Batch foam results ANJ-2 30 Difficult well to kick off: ANJ-2 1,500 Flow rate THP Batch foam 25 1,250 Gas Production [MMscf/day] 20 1,000 FTHP [psi] 15 750 10 500 5 250 0 0 12-Oct-06 22-Oct-06 1-Nov-06 11-Nov-06 21-Nov-06 1-Dec-06 11-Dec-06 21-Dec-06 31-Dec-06 2007 Gas Well De-Liquification Workshop 8 Mar. 5 - 7, 2007 Denver, Colorado

Continuous foam: Operating envelope MKZ-3: 7” completion Flow rate 10 1000 WGR: 110 bbl/1e6 scf FTHP Foam injection rate Foam inj: 50-100 ltr/day 9 900 FTHP [psi]; Foam injection rate [l/day] Gas Production [MMscf/day] 8 800 7 700 6 600 5 500 4 400 3 300 2 200 1 100 0 0 29-Nov-06 04-Dec-06 09-Dec-06 14-Dec-06 19-Dec-06 24-Dec-06 29-Dec-06 2007 Gas Well De-Liquification Workshop 9 Mar. 5 - 7, 2007 Denver, Colorado

Continuous foam: Operating envelope MKZ-3: 7” completion WGR: 110 bbl/1e6 scf With foam injection: Foam inj: 10-25 gal/day Critical rate lowered 30-50% 2007 Gas Well De-Liquification Workshop 10 Mar. 5 - 7, 2007 Denver, Colorado

Acoustic logging: Better Understanding of Liquid Loading • Information available from acoustic logs and FPG’s such as: – Where is the liquid level? – What is the gradient of the gaseous liquid column? – What is the FBHP with liquid hold-up in the well? • Why is it important? – Improves ability to select candidates and solutions for liquid unloading – Improves optimization of currently deployed liquid loading solutions – Improves ability to quantify gains 2007 Gas Well De-Liquification Workshop 11 Mar. 5 - 7, 2007 Denver, Colorado

Candidate selection: Tail-pipe extension Velocity str. • In/Outflow modeling Tail-pipe • Severe (7”) liner Current loading evident from FPG data • 3.5” tubing still OK • Decision: 2” tail-pipe extension, followed by full velocity string when tubing starts loading later on 2007 Gas Well De-Liquification Workshop 12 Mar. 5 - 7, 2007 Denver, Colorado

Candidate selection: WGR Campaign • Select ‘difficult wells’ – mainly Coevorden area – Historically not much success unloading wells – Condensate makes foaming difficult – DH condensate-based corrosion inhibitor injection – No two wells are the same – Two producing reservoirs with different properties • Objectives of campaign: – Unload & clean-up the well – Provide PQ-curve, improve well in/outflow modeling – WGR/CGR measurement – Obtain water and condensate samples for lab foam testing 2007 Gas Well De-Liquification Workshop 13 Mar. 5 - 7, 2007 Denver, Colorado

Foamer selection: Lab testing on well fluids • Tests done at 20°C and 90°C • Foam buildup time < 60 seconds: OK • Foam half-life > 180 seconds: OK Example Well COV-26: COV-26 Foam build-up time [s] COV-26 Foam half-life time [s] 75/25 water condensate ratio (1,000 ppm foam) 75/25 water condensate ratio (1,000 ppm foam) 300 150 Foam build-up time [s] 240 120 180 90 20°C 20°C 120 60 90°C 90°C 30 60 0 0 A B C D quality A B C D quality indicator indicator 2007 Gas Well De-Liquification Workshop 14 Mar. 5 - 7, 2007 Denver, Colorado

New solution for NAM: Plunger lifting New Blocker/Issue data/development Implication Lowest possible plunger setting Significant reduction in Acoustic logs and FPG's (above SPM's & other jewelry) is FBHP can be realized show significant liquid too far away from perfs. Likely from unloading above hold-up above jewelry that no liquid is present. SPM's SCSSV's are required and 2-stage plunger Plunger can be run and prevent running plunger to developed and used controlled below SCSSV surface to control in US Pressure [psi] 0 250 500 750 1,000 0 2,000 4,000 AH depth [ft] 6,000 Lowest possible 8,000 plunger running 10,000 depth in this well Up run Down Run 12,000 Acoustic log 2007 Gas Well De-Liquification Workshop 15 Points Mar. 5 - 7, 2007 Denver, Colorado 14,000

Mobile wellhead compression: Lower THP to 22 psia Low cost THP down Movable booster to 22 psia compression � � Shut in due to Producing at liquid loading To To Central Central low THP pipeline/ pipeline/ compression compression Back Central Central Back Gas wells Gas wells pressure pressure facilities facilities 85-145 psia 85-145 psia Gas well location/satellite Gas well location/satellite Including wellhead compression Well PQ curve Well PQ curve 45 45 45 45 40 40 40 40 Tubing Head Pressure [bar] Tubing Head Pressure [bar] Tubing Head Pressure [bar] Tubing Head Pressure [bar] 35 35 35 35 Liq Liq 30 30 30 30 Load Load 25 25 25 25 20 20 20 20 15 15 15 15 Production Production 10 10 10 10 5 5 5 5 0 0 0 0 0.00 0.00 0.20 0.20 0.40 0.40 0.60 0.60 0.80 0.80 1.00 1.00 1.2 1.2 2007 Gas Well De-Liquification Workshop 0.00 0.00 0.20 0.20 0.40 0.40 0.60 0.60 0.80 0.80 1.00 1.00 1.2 1.2 16 Mar. 5 - 7, 2007 Gas Production Rate [mln m³/d] Gas Production Rate [mln m³/d] Gas Production Rate [mln m³/d] Gas Production Rate [mln m³/d] Denver, Colorado OPK-1 PQ Curve (Jul 2004) OPK-1 PQ Curve (Jul 2004) OPK-1 PQ Curve (Jul 2004) OPK-1 PQ Curve (Jul 2004)