36 th Gas-Lift Workshop Stavanger, Norway February 4 8, 2013 Global Gas Lift Optimization Using WellTracer Surveys Tony Hord, Mike Johnson ExxonMobil Production Company 2013 Gas-Lift Workshop 1
WellTracer What is WellTracer? Patented technology that traces the path of injected CO2 in a producing well Noninvasive method to determine downhole conditions well flow undisturbed How Does WellTracer Work? Requires temporary connection points on gas injection line & production line CO2 is injected in the annulus & sensed when it returns on the production line Well data including tubular design, gas lift valve setting depths, gas lift injection & production rates are input to WinGLUE software along with WellTracer data to establish lift point, possible leaks from casing to tubing, & multi-point injection What Type of Data is Collected? Where Gas Injection is entering tubing string Lift Point Whether well is Multi-point injecting If well has a tubing leak at some point other than a gas lift valve, button or mandrel 2013 Gas-Lift Workshop 2
ExxonMobil Surveys Conducted ExxonMobil s WellTracer Surveys ExxonMobil collected the first WellTracer Surveys in February 2008, since then and through December 2012, 221 surveys have been conducted, 196 total wells including 14 sets of duals (28 wells) 2013 Gas-Lift Workshop 3
Findings From Single Wells Surveyed 168 Wells Surveyed 56% of the wells were Over-Injecting GLG 52% were lifting at deepest valve 49% were Multi-Pointing 11% were lifting Shallower than optimal location 2013 Gas-Lift Workshop 4
Findings from Single Wells Surveyed 168 Single Wells Surveyed 3% (5) of the wells were designed with PPO valves 93% of the wells were designed with IPO valves 68% of the wells were designed with Orifices 6 buttons installed without mandrels 2013 Gas-Lift Workshop 5
Recommendations Made & Work Completed From Findings 177 recommendations made. 49 recommendation follow-ups completed. Types of Recommendations: Multi-Rate Testing, Reduce GLG Inj. Rate, Increase GLG Inj. Rate, GL Re-Design, Install Pack-off s, Install button orifice, Replace IPO/PPO with Orifice for single point injection 28% of Recommendations made were followed-up on 35% INCREASE in Production once Recommendation completed 2013 Gas-Lift Workshop 6
Findings from Dual Wells Surveyed 53 Dual Surveys Conducted, 28 individual wells, 14 Sets 43% of the wells were Over-Injecting GLG 29% were lifting at deepest valve 68% were Multi-Pointing 4% were lifting Shallower than optimal location 2013 Gas-Lift Workshop 7
Findings from Dual Wells Surveyed 28 Dual Wells Surveyed 50% of the Dual wells were designed with PPO valves 43% of the PPO type valves were Multi-Pointing 32% of the Wells were operating with orifice valves 2013 Gas-Lift Workshop 8
Potential BOEPD Build Up 196 Single Wells Surveyed Recommendation made & follow-up completed on 49 wells (28% of total) 35% Increase in Daily Production Recommendation made & follow-up completed on 6 Duals (21% of total) 13% Increase in Daily Production on Dual Wells Potential BOEPD BU between 13% & 35% 2013 Gas-Lift Workshop 9
High Rate GL Well - WellTracer History 2010 Redesign: Well Multi-pointing, due to high oil rate & stability, decided not to replace GL valves. Csg pressure 200 psi over design, GLG inj rate 43% higher than design. 2011 WellTracer Results: CO2 returns show 2 nd gas lift valve leaking & lifting from 5th GL valve. Appears bottom valve failed closed & never opened to remove fluid from the casing at depth. Csg pressure & GLG inj rate @ design. 2012 WellTracer Results: Multi-pointing through 3 rd,5 th & 6 th valves. Significant uplift possible if able to lift from bottom mandrel only. Estimated PI ~2.824. Run FPT, compare results with 2011 & 2012 WT Surveys (Completed). Redesign, current inj rate @ 5.024 MCFPD. Reduce GLG inj rate. 2012 GLG Re-Design: Used WinGLUE predictive on new GL design. New valves installed 11/2012. Reduced GL Injection rate by 2.328 MCFPD & achieved 552 BOEPD BU. Casing pressure currently at design rate. Well is stable. Total Transit 5 (6279 MD - Weatherford R Total Transit 4 (5697 MD - Weatherford R Total Transit 3 (5074 MD - Weatherford R Total Transit 2 (4493 MD - Weatherford R Raw CO2 Concentrations Total Transit 1 (3746 MD - Weatherford R Total Transit 6 (6902 MD - Weatherford R Concentration Vs. Time Well: [GLUE] HOOVER,HA,4,1 05-Aug-2010 12:15:13 Time (hh:mm:ss) 0.05 0:00:00 0:16:40 0:33:20 0:50:00 1:06:40 1:23:20 1:40:00 1:56:40 2:13:20 2:30:00 2:46:40 0.15 Total Transit 4 (5697 Total MD Transit 4 - (5697 MD - Weatherford R R Total Transit 1 (3746 Total MD Transit 1 - (3746 MD - Weatherford R R Total Transit 6 (6902 MD - Weatherford R Total Transit 6 (6902 MD - Weatherfor 0.20 0.25 tion Vs. Time Concentration W ell: Vs. Time Well: [GLUE] HOOVER,HA,4,1 17-May-2011 15:16:46 17-May-2011 15:16:46 Concentration (%) Concentration (%) 8/2010 5/2011 5/2012 0.10 Total Transit 3 (5074 Total MD Transit 3 - (5074 MD - Weatherford R R Total Transit 2 (4493 Total MD Transit 2 - (4493 MD - Weatherford R R GLV:3746 GLV:4493 GLV:5074 GLV:5697 GLV:6279 GLV:6902 CO2 Concentration CO2 Concentration Total Transit 5 (6279 MD - Weatherford R Total Transit 5 (6279 MD - Weatherfor 2013 Gas-Lift Workshop 10 Time (hh:mm:ss) Time (hh:mm:ss) 0.05 0.05 0:00:00 0:16:40 0:00:00 0:16:40 0:33:20 0:50:00 1:06:40 1:23:20 1:06:40 1:40:00 1:56:40 2:13:20 1:23:20 2:30:00 2:46:40 3:03:20 1:40:00 3:20:00 3:36:40 1:56:40 2:13:20 2:30:00 2 0.10 0.10 0.15 0.15 0.20 0.20 0.25 0.25 GLV:3746 GLV:4493 GLV:5074 0.30 0.30 GLV:5697 GLV:6279 GLV:6902 0.35 0.35 GLV:3746 GLV:4493 GLV:5074 GLV:5697 GLV:6279 GLV:6902
WellTracer Learnings Well Selection: High TGLR wells >2500 scf/bbl Wells could be multi-pointing or over-gassing Wells injecting at a Higher than designed gas lift rate Usually highest value problem wells Well Testing: Injection gas measurement must be accurate to minimize WellTracer analysis times Well Tests should be within same period (week) analysis is performed Set up testing equipment to actual operating conditions as possible WellTracer Survey: Locate casing fluid level before running survey, so survey time can be established Collect good quality field notes while surveys are being conducted Understand ALL system variables, both upstream and downstream of well WellTracer Survey Dual Well Recommendations: WellTracer Dual Surveys allows specific design placement of orifice valves and orifice size to initiate single point injection of dual strings simultaneously 2013 Gas-Lift Workshop 11
WellTracer Forward Globally prioritize MOST productive wells (Highest Rate/Profitability), Review top 10-15% Establish goal of ~50 to 70 WellTracer Surveys per year Create common data base for storage of collected WellTracer Survey data Optimize each well to be surveyed week before survey is to be performed Establish commitment from Operation Organization to Follow-Up on recommendations Report Out to Operation Organization, findings and recommendations in a timely manner Ensure accurate gas measurement is available, if not use clamp-on measurement device Track WellTracer Survey results and report information Globally to all Operation Organizations 2013 Gas-Lift Workshop 12
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Disclaimer Exxon Mobil Corporation has numerous subsidiaries, many with names that include ExxonMobil, Exxon, Esso and Mobil. For convenience and simplicity in this presentation, the parent company and its subsidiaries may be referenced separately or collectively as "ExxonMobil." Abbreviated references describing global or regional operational organizations and global or regional business lines are also sometimes used for convenience and simplicity. Nothing in this presentation is intended to override the corporate separateness of these separate legal entities. Working relationships discussed in this paper do not necessarily represent a reporting connection, but may reflect a functional guidance, stewardship, or service relationship. 2013 Gas-Lift Workshop 15