Optimization of well performance by use of a semi-permanent dynamic desander

Transcription

1 Optimization of well performance by use of a semi-permanent dynamic desander By Asle Sandven / Ted Brueren MSc. SPE SMN European Sand Management Forum March 2014 Classification: Open

2 Agenda Background information Sand management challenge Solution Result

3 The Gullfaks field Located in the northern part of the Norwegian North Sea Production start-up in 1986 Initial recoverable reserve ~2.1 bn bbl Production peak ~ bbl/d in 1994 Today approx bbl/d

4 The Gullfaks field The Gullfaks field has been developed by: Three large concrete platforms Three satellite fields with subsea wells Recovery factor today approx. 62 % Recovery ambition 74 %. Obtained by: Horizontal and extended wells New completion EOR technology (f.e. WAG injection) Subsea compression Sand control technology

5 Earlier sand management on Gullfaks C Sand trap located at inlet to the test separator Current acceptance criteria per well (ASR): max.15 g/hr in sand trap Sand trap typically captures 1 to 5 % of total sand production Criteria corresponds to 0.3 to 1.5 kg/hr of sand per well

6 Producer 34/10-C-19 Drilled and completed in 1993/1994. Re-completed in 2002 Sand rate rapidly exceeds ASR criteria after sand clean-up The well flow is therefore choked back The flow may then be too low to lift out sand to surface Over time sand will then accumulate in the wellbore Result: Sand plug formed

7 Producer 34/10-C-19 Once sand plug is formed a sand clean-up is necessary E.g. demanding operations as coiled tubing (CT) or snubbing Sand clean-up in C-19 has been done almost every 2nd year Previous CT sand clean-up was done February 2012

8 700 Producer 34/10-C-19 - Average Oil rate (Sm3/D) Aug-96 Jan-98 May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08 May-10 Sep-11 Jan-13

9 CT Sand desander package Desander Choke manifold manually operated Control cabin 3 x sand skips Emergency shutdown valve (ESD)

10 Drawbacks of CT Sand desander package Insufficient sand separation Well shut-in when emptying desander New rig up for each well Sand sent to shore for handling Manually operated choke Big footprint Location in conflict with other operations Qualified as temporary equipment NORSOK Z-015 Pressure rated to 100 bar. Not according to rig specs (345 bar)

11 Requirements new desander package Desander functionality More efficient separation required Need of two desanders Option to flow through desanders in either series or parallel Constant flow without interruption Emptying of desander without shutting down flow Possibility to bypass desander

12 Requirements new desander package Operational functionality Easy access to all wells No pipe handling between each well flowing Flexibility to route flow to either HP or LP test separator Easy sand handling offshore No skips for sand storing Remote operating of choke

13 Requirements new desander package Desander location Avoid conflict with other operations Need to find new placement Preferably at production mezzanin deck (XT-deck)

14 Requirements new desander package Desander location Avoid conflict with other operations Need to find new placement Preferably at production mezzanin deck (XT-deck) At production mezzanin deck Limited space available Limited height available access through 2x2 m 2 opening Need to reduce size of desander unit dramatically

15 Requirements new desander package Rig requirements Not being the weakest link Pressure tested according to rig specs Erosion resistant Automatic pressure release if rig shuts down No emergency shutdown valve (ESV)

16 Solution: semi-permanent dynamic desander Dual 5kPSI Desander Unit Small foot print (LxWxH: 2.0 x 2.0 x 3.2m) Weight: 8.5 tons Dual desander in same frame Serie and parallel flow mode Option to bypass one desander 5000 psi / 345 bar pressure rating

17 Solution: semi-permanent dynamic desander Dual 5kPSI Desander Unit Closed system sand handling No manual handling of sand Separation of solids down to 20 micron Monitoring of: flowrate pressure temperature amount of sand separated from flow

18 Solution: semi-permanent dynamic desander X-Flow Manifold Foot print (LxWxH: 2.0 x 2.0 x 1.2m) Controls the flow direction Enables reversible flow path Integrated remote choke Integrated flowmeter

19 Solution: semi-permanent dynamic desander Combine Desander unit with X-Flow Minimized slot space needed LxWxH: 2.0 x 2.0 x 4.4 Access to wells on both south and north shaft Enables flow to either LP or HP separator Built with erosion resistant material: Duplex UNS31803 Tungsten Carbide

20 Installation of X-Flow and Dual Desander Lifting X-Flow Guiding X-Flow X-Flow in place Lifting desander Guiding desander Desander in place

21 Installation of X-Flow and Dual Desander LP test manifold Tie-in points HP on test test manifolds south shaft HP test manifold LP test manifold Tie-in points on test manifolds north shaft

22 Conventional flow: e.g wells from north to HP Producer on north shaft

23 New flow path: e.g. wells from north to HP Producer on north shaft

24 New flow path of wells animation 25 Classification: Open

25 Result: Benefits achieved Operational Less jetting work for operators Reduced sand problems in process plant Only rigging up once

26 Result: Benefits achieved Operational Less jetting work for operators Reduced sand problems in process plant Only rigging up once Cost saving Sand handling done offshore by reinjection Less need for CT sand clean out More time for alternative CT operations

27 Result: Benefits achieved Operational Less jetting work for operators Reduced sand problems in process plant Only one rigging needed Cost saving Sand handling done offshore by reinjection Less need for CT sand clean out More time for alternative CT operations Improved oil recovery Higher flow rate (without exceeding ASR) Less down time for wells Optimized well performance

28 700 Producer 34/10-C-19 - Average Oil rate (Sm3/D) Aug-96 Jan-98 May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08 May-10 Sep-11 Jan-13

29 Result: Optimized well performance

30 Optimization of well performance by use of a semi-permanent dynamic desander Ted Brueren MSc. Well Intervention Engineer address: tedb@statoil.com Tel: Classification: Open