Self-Stabilizing Gas Lift Valve (Patent Pending)

Transcription

1 Tulsa University Artificial Lift Projects Self-Stabilizing Gas Lift Valve (Patent Pending) Holden Zhang Jose Luis Arellano Chevron

2 Outline Gas lift instabilities Current stabilizing methods New self-stabilizing valve Advantages

3 Gas Lift Instabilities Gas lift widely used onshore and offshore Gas lift instabilities Casing heading Density wave Production fluctuations Instabilities cause equipment, operation, energy and production losses

4 Casing Heading Gas injection reduces mixture density and pressure in tubing Lower tubing pressure allows more gas injection Gas in casing-tubing annulus expands with pressure drop Injection slow down with gas depletion in casing-tubing annulus Tubing pressure increases and injection may even stop A new circle starts

5 Orifice or Venturi Valve P T Orifice valve performance Tubing pressure Unstable Q I

6 Frequency(Hz) Choke(inch/64) Hz Pd (B29ST1 ) WELL IMPERIAL TREND 0 Casing Heading , , , , , , Pwh Pressure (psia) Pressure(psig) Pressure(psi) Pd-Pi Pi Drawdown 4. End Point=Start point for next cycle Just finished bleeding off. GLV just closed. Pump efficiency is highest Pump diff. pres. is highest Liquid level is highest Gas just starting to build up P CGLV <P TGLV GLV open TVD (ft) P CGLV Pi Pwf 36 P TGLV ESP Packer Pd Pwh /01/12 10:46 FLP 5000 AM 09/01/12 04:05 PM 09/01/12 09:25 PM 09/02/12 02:44 AM 09/02/12 08:04 AM 09/02/12 01:24 PM 09/02/12 06:43 PM 09/03/12 12:03 AM 09/03/12 05:22 AM 09/03/12 10:42 AM Time Pressure (psig) ESP Diff Pressure(psi) Draw Dow n(psi) ESP Intake Intake Pressure(psia) pressure Discharge ESP Discharge pressure Pressure(psia) Wellhead pressure Flow ing Tubing Pressure(psig) Flow Line Pressure(psig) VFD Frequency(Hz) Tubing Choke(inch/64) (outflow ) (inflow ) *P TGLV : Pressure in tubing at GLV setting ALDRC depth; PSeminar CGLV : Pressure for Inventors in casing of at New GLV setting depth. (Guo et al., 2013 SPE ESP Workshop, The Woodlands, Artificial TX) Lift Technology

7 Gas Lift Instability Control Surface choke and control valve High pressure (or energy) loss Orifice and Venturi gas lift valves Injection flow rate stabilizes when Vena Contracta velocity reach sound speed High pressure losses

8 Gas Lift Instability Control Throttling valve Responds to both injection and production pressures Not fully open

9 Proportional Response Valve Similar as throttling valve Flow and DP operated Pressure loss is too high Cannot be used for high injection rate Spring and bellows are together Dependent on injection pressure

10 Problems with Current GLV Not effective for stabilization High pressure drop Prone to damage during unloading if flow rate is too high

11 New Gas Lift Valve Requires low differential pressure Suitable for high flow rate injection Responds to flow and differential pressure Opening decreases with differential pressure increase Operate within a DP window Simple Independent on injection pressure

12 New Valve A moving part Backward plug as check valve Forward cone-shape plug to control flow Impinging disk Position controlled by balance of flow/dp and spring forces A nozzle to guide flow

13 Top View of Impinging Disk Ring holes with sufficient flow area distributed around the impinging disk

14 No Flow P A Q I P A -P T P T

15 Valve Opened P A Q I P A -P T P T

16 Maximum Flow P A Q I P A -P T P T

17 Flow Restricted P A Q I P A -P T P T

18 Valve Closed P A Q I P A -P T P T

19 Self-Stabilizing Valve Performance Q I SSGLV performance P T 59th Advisory Board Meeting April 17, 2015

20 Self-Stabilizing Valve P T SSGL valve performance Tubing pressure Unstable Stable Q I

21 Self-Stabilizing Valve Automatically adjusted based on annulus pressure and flow P T SSGL valve performance Tubing pressure 59th Advisory Board Meeting Q I April 17, 2015

22 Simulation Results 59th Advisory Board Meeting April 17, 2015

23 Advantages Self stabilizing (at stable injection point) Injection rate increases with tubing pressure increase Injection rate decreases with tubing pressure decrease Small pressure drop (from annulus to tubing) needed Can be less than 50 psi Great compression energy saving Can avoid damage due to high pressure drop and high shear