Enhancing the Production Performance of Dual Completion Gas Lifted Wells using Venturi Orifice Valves

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1 37 th Gas-Lift Workshop Houston, Texas, USA February 3 7, 2014 Enhancing the Production Performance of Dual Completion Gas Lifted Wells using Venturi Orifice Valves Presenter(s) Nkilika Grace Nwadike, Shell Sheri Adoghe, Schlumberger Ifeanyichukwu Ofia, Shell Amos Trost, Shell, Oton Enoto, Shell, Benjamin Obong, Shell, Hamzat Kassim Shell, Uwem Essien, Shell. Feb. 3-7, Gas-Lift Workshop 1

2 Presentation Outline Introduction The Business Opportunity/Challenge Candidate Screening/Selection Nova vs Venturi Features/Benefits The Field Trial Well/System Challenges Results Discussion Conclusion 2014 Gas-Lift Workshop 2

3 Business Opportunity/Challenge Circa 70% of SPDC Gaslifted Wells are duals equiped with square edge orifice valves. Optimisation challenges and observed well instability. Deferment reduction associated with gas sharing challenges and inability to produce both arms of dual concurrently. Circa 9000 bopd was deferred during the period under review Gas-Lift Workshop 3

4 2014 Gas-Lift Workshop 4

5 The Niger Delta - A Large Portfolio of Oil and Gas Fields! 2014 Gas-Lift Workshop 5

6 NORTH FIELD SUBSURFACE SNAPSHOT 2014 Gas-Lift Workshop 6

7 NORTH Field Production Performance 2014 Gas-Lift Workshop 7

8 Identified System & Well Challenges Inability to produce both arms of dual concurrently Gas Metering Challenges Well slugging Gas cycling Intermittent production Frequent compressor trips Gas-Lift Workshop 8

9 Square Edge Orifice Valve Challenges 2014 Gas-Lift Workshop 9

10 Nova Orifice Valve Features and benefit Venturi 2014 Gas-Lift Workshop 10

11 Candidate Screening / Workflow STEP 1 STEP 2 Data Acquisition Critical data: THP, CHP, Well test data Establish Instability Fluctuation: THP, CHP, Liquid rate, lift gas rate, CHP, Well test data STEP 3 Analyse cause of instability Poor Design, Over sized orifice, over injection STEP 6 Field Execution 1. Acquire fresh FG/BHP 2. Optimise design 3. Carryout GLVCO STEP 5 Gaslift Design Preliminary design using existing FG and Pressure STEP 4 Establish Subcritical flow Pt/Pc Gas-Lift Workshop 11

12 Candidate Screening Workflow/Criteria 2014 Gas-Lift Workshop 12

13 Well Performance Expectation 2014 Gas-Lift Workshop 13

14 NOVA Series Orifice Venturi Gas Lift Valve (1) Well was reported to have lift gas sharing issues. Both strings could not produce concurrently. Long string was produced preferential to the short string. Selected for NOVA pilot trial. Post nodal analysis and redesign, the Orifice depth was optimized from 4577 to 3626 ft along hole. OBIGBO 08 MANDREL DEPTHS (FT ALONG HOLE) LONG STRING SHORT STRING 1984 Valve 1947 Valve 2953 Valve 2985 Valve 3626 NOVA 3597 NOVA The orifice depth on the short string was optimized from 4107 to 3597 ft along hole Gas-Lift Workshop

15 Results Well O002L Performance Pre and Post installation 2014 Gas-Lift Workshop 15

16 Results Well O002L Performance > 8 Months after 2014 Gas-Lift Workshop 16

17 Results Well O001L Performance 1 Month Post installation 2014 Gas-Lift Workshop 17

18 Results: Well O001L Performance 8 Months Post Installation 2014 Gas-Lift Workshop 18

19 Results Well O002S Performance Post Installation 2014 Gas-Lift Workshop 19

20 Results: Well O002S Performance 8 Months Post Installation 2014 Gas-Lift Workshop 20

21 DATUM_PRESSURE THP Sand Bean Cumulative Oil Produced ( Mbbl ) Gas / Oil Ratio ( Mcf/bbl ) Water Cut ( % ) Results Well Performance Post Pre vs Post Nova PRODUCTION PROFILE OBGN008L:D9000A Time (Year) Time (Year) Figure 5b Well A2S 8 months after venturi data acquisition Gas-Lift Workshop 21

22 DATUM_PRESSURE THP Sand Bean Cumulative Oil Produced ( Mbbl ) Gas / Oil Ratio ( Mcf/bbl ) Water Cut ( % ) Results Well A2SPerformance Post Pre vs Post Nova PRODUCTION PROFILE OBGN008S:C9400A Time (Year) Time (Year) Figure 5b Well A2S 8 months after venturi data acquisition Gas-Lift Workshop 22

23 Results Well A2SPerformance Post Pre vs Post Nova Figure 5b Well A2S 8 months after venturi data acquisition Gas-Lift Workshop 23

24 Results Well F L/S Performance Pre and Post Venturi 2014 Gas-Lift Workshop 24

25 Key Learning s and Recommendations Real Time optimisation of designs was key to a successful implementation. NOVA Orifice valve is not a silver bullet as not all wells with gas sharing challenge require a NOVA solution Inability of one arm of a dual gas lifted well to produce is not necessarily due to gas-sharing issues. Poor gas lift design has been identified as the cause in some cases. Choke size of the venturi orifice needs to be carefully designed and sized to enable passage of optimal amount of lift gas. Candidates must be carefully screened and a case for gas sharing clearly established to enable benchmark of well performance after venturi installation. CHP and THP profile(s) of the candidate well(s) should be recorded for reasonable length of time especially after venturi installation as stability in tubing and casing pressure can only be evident once critical flow is established. Suboptimal lift gas injection and low injection pressures can cause instability and non production of gas lift conduits. Venturi orifice valve can stabilize production from previously unstable wells by attaining critical flow much earlier than with conventional orifice Gas-Lift Workshop 25

26 Conclusion/Go Forward Plans Venturi orifice valve installation in the carefully selected candidate wells stabilised well production and reduced well instability significantly. The Venturi installation improved the efficiency of all the 4 pilot wells(8 strings), improved stability, restored concurrent production and optimised gas injection rate. Circa 700 bopd was restored and sustained in the last 1yr+. Standardise on the Venturi and replace all installed BKF6 Valves at earliest opportunity Roll out in other fields 2014 Gas-Lift Workshop 26

27 Thanks for Listening 2014 Gas-Lift Workshop 27

28 Copyright Rights to this presentation are owned by the company(ies) and/or author(s) listed on the title page. By submitting this presentation to the Gas-Lift Workshop, they grant to the Workshop, the Artificial Lift Research and Development Council (ALRDC), and the American Society of Mechanical Engineers (ASME), rights to: Display the presentation at the Workshop. Place it on the web site, with access to the site to be as directed by the Workshop Steering Committee. Place it on a CD for distribution and/or sale as directed by the Workshop Steering Committee. Other uses of this presentation are prohibited without the expressed written permission of the company(ies) and/or author(s) who own it and the Workshop Steering Committee Gas-Lift Workshop 28

29 Disclaimer The following disclaimer shall be included as the last page of a Technical Presentation or Continuing Education Course. A similar disclaimer is included on the front page of the Gas-Lift Workshop Web Site. The Artificial Lift Research and Development Council and its officers and trustees, and the Gas-Lift Workshop Steering Committee members, and their supporting organizations and companies (here-inafter referred to as the Sponsoring Organizations), and the author(s) of this Technical Presentation or Continuing Education Training Course and their company(ies), provide this presentation and/or training material at the Gas-Lift Workshop "as is" without any warranty of any kind, express or implied, as to the accuracy of the information or the products or services referred to by any presenter (in so far as such warranties may be excluded under any relevant law) and these members and their companies will not be liable for unlawful actions and any losses or damage that may result from use of any presentation as a consequence of any inaccuracies in, or any omission from, the information which therein may be contained. The views, opinions, and conclusions expressed in these presentations and/or training materials are those of the author and not necessarily those of the Sponsoring Organizations. The author is solely responsible for the content of the materials. The Sponsoring Organizations cannot and do not warrant the accuracy of these documents beyond the source documents, although we do make every attempt to work from authoritative sources. The Sponsoring Organizations provide these presentations and/or training materials as a service. The Sponsoring Organizations make no representations or warranties, express or implied, with respect to the presentations and/or training materials, or any part thereof, including any warrantees of title, noninfringement of copyright or patent rights of others, merchantability, or fitness or suitability for any purpose Gas-Lift Workshop 29