6 installing vapor recovery units

Installing Vapor Recovery Units to Reduce Methane Losses: 

Installing Vapor Recovery Units to Reduce Methane Losses Lessons Learned from Natural Gas STAR Producers Technology Transfer Workshop Devon Energy and EPA’s Natural Gas STAR Program Casper, Wyoming August 30, 2005

Vapor Recovery Units: Agenda: 

Vapor Recovery Units: Agenda Methane Losses Methane Savings Is Recovery Profitable? Industry Experience Discussion Questions

Slide3: 

Methane Losses from Storage Tanks Storage tanks are responsible for 6% of methane emissions in natural gas and oil production sector 96% of tank losses occur from tanks without vapor recovery Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 - 2003 Pneumatic Devices 61 Bcf Meters and Pipeline Leaks 10 Bcf Gas Engine Exhaust 12 Bcf Well Venting and Flaring 18 Bcf Storage Tank Venting 9 Bcf Other Sources 21 Bcf Dehydrators and Pumps 17 Bcf

Sources of Methane Losses: 

Sources of Methane Losses 9 Bcf methane lost from storage tanks each year from producers* Flash losses - occur when crude is transferred from a gas-oil separator at higher pressure to an atmospheric pressure storage tank Working losses - occur when crude levels change and when crude in tank is agitated Standing losses - occur with daily and seasonal temperature and pressure changes * Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 - 2003

Methane Savings: Vapor Recovery Units: 

Methane Savings: Vapor Recovery Units Capture up to 95% of hydrocarbon vapors vented from tanks Recovered vapors have higher Btu content than pipeline quality natural gas Recovered vapors are more valuable than natural gas and have multiple uses Re-inject into sales pipeline Use as on-site fuel Send to processing plants for recovering NGLs

Types of Vapor Recovery Units: 

Types of Vapor Recovery Units Conventional vapor recovery units (VRUs) Use rotary compressor to suck vapors out of atmospheric pressure storage tanks Require electrical power or engine Venturi ejector vapor recovery units (EVRUTM) or Vapor Jet Use Venturi jet ejectors in place of rotary compressors Do not contain any moving parts EVRUTM requires source of high pressure gas and intermediate pressure system Vapor Jet requires high pressure water motive

Standard Vapor Recovery Unit: 

Standard Vapor Recovery Unit Control Pilot Vent Line Back Pressure Valve Suction Line Condensate Return Bypass Valve Electric Control Panel Electric Driven Rotary Compressor Gas Sales Meter Run Gas Liquid Transfer Pump Check Valve Source: Evans & Nelson (1968) Sales

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Vapor Recovery Installations: 

Vapor Recovery Installations

Venturi Jet Ejector*: 

Venturi Jet Ejector* High-Pressure Motive Gas (~850 psig) Flow Safety Valve Pressure Indicator Temp Indicator PI TI TI PI (-0.05 to 0 psig) Low-Pressure Vent Gas from Tanks (0.10 to 0.30 psig) PI TI Discharge Gas (~40 psia) EVRUTM Suction Pressure *Patented by COMM Engineering

Vapor Recovery with Ejector: 

Vapor Recovery with Ejector Oil to Sales Gas to Sales @ 1000 psig LP Separator Oil Gas Compressor Ejector Oil & Gas Well 5,000 Mcf/d Gas 5,000 Bbl/d Oil 900 Mcf/d Ratio Motive / Vent = 3 = 900/300 300 Mcf/d Gas 40 psig 6,200 Mcf/d Crude Oil Stock Tank (19 Mcf/d Incr.fuel) 281 Mcf/d Net Recovery

Vapor Jet System*: 

Vapor Jet System* *Patented by Hy-Bon Engineering

Vapor Jet System*: 

Vapor Jet System* *Patented by Hy-Bon Engineering Utilizes produced water in closed loop system to effect gas gathering from tanks Small centrifugal pump forces water into Venturi jet, creating vacuum effect Limited to gas volumes of 77 Mcfd and discharge pressure of 40 psig

Criteria for Vapor Recovery Unit Locations: 

Criteria for Vapor Recovery Unit Locations Steady source and sufficient quantity of losses Crude oil stock tank Flash tank, heater/treater, water skimmer vents Gas pneumatic controllers and pumps Outlet for recovered gas Access to low pressure gas pipeline, compressor suction or on-site fuel system Tank batteries not subject to air regulations

Quantify Volume of Losses: 

Quantify Volume of Losses Estimate losses from chart based on oil characteristics, pressure and temperature at each location (± 50%) Estimate emissions using the E&P Tank Model (± 20%) Measure losses using recording manometer and well tester or ultrasonic meter over several cycles (± 5%) This is the best approach for facility design

Estimated Volume of Tank Vapors: 

Estimated Volume of Tank Vapors Pressure of Vessel Dumping to Tank (Psig) Vapor Vented from Tanks- cf/Bbl - GOR 110 100 90 80 70 60 50 40 30 10 20 10 20 30 40 50 60 70 80 Under 30° API 30° API to 39° API 40° API and Over

What is the Recovered Gas Worth?: 

What is the Recovered Gas Worth? Value depends on Btu content of gas Value depends on how gas is used On-site fuel - valued in terms of fuel that is replaced Natural gas pipeline - measured by the higher price for rich (higher Btu) gas Gas processing plant - measured by value of NGLs and methane, which can be separated

Value of Recovered Gas: 

Value of Recovered Gas Gross revenue per year = (Q x P x 365) + NGL Q = Rate of vapor recovery (Mcfd) P = Price of natural gas NGL = Value of natural gas liquids

Value of NGLs: 

Value of NGLs

Cost of a Conventional VRU : 

Cost of a Conventional VRU

Is Recovery Profitable?: 

Is Recovery Profitable?

Top Gas STAR Partners for VRUs: 

Top Gas STAR Partners for VRUs Top five companies for emissions reductions using VRUs in 2003

Industry Experience: Chevron: 

Industry Experience: Chevron Chevron installed eight VRUs at crude oil stock tanks in 1996

Industry Experience: Devon Energy: 

Industry Experience: Devon Energy For 5 years Devon employed the Vapor Jet system and recovered more than 55 MMcf of gas from crude oil stock tanks Prior to installing the system, tank vapor emissions were ~ 20 Mcfd Installed a system with maximum capacity of 77 Mcfd anticipating production increases Revenue was about $91,000 with capital cost of $25,000 and operating expenses less than $0.40/Mcf of gas recovered This paid back investment in under 2 years

Lessons Learned: 

Lessons Learned Vapor recovery can yield generous returns when there are market outlets for recovered gas Recovered high Btu gas has extra value VRU technology can be highly cost-effective in most general applications Venturi jet models work well in certain niche applications, with reduced O&M costs. Potential for reduced compliance costs can be considered when evaluating economics of VRU, EVRUTM or Vapor Jet

Lessons Learned (cont’d): 

Lessons Learned (cont’d) VRU should be sized for maximum volume expected from storage tanks (rule-of-thumb is to double daily average volume) Rotary vane or screw type compressors recommended for VRUs where Venturi ejector jet designs are not applicable EVRUTM recommended where there is gas compressor with excess capacity Vapor Jet recommended where less than 75 Mcfd and discharge pressures below 40 psig

Discussion Questions: 

Discussion Questions To what extent are you implementing this BMP? How can this BMP be improved upon or altered for use in your operation(s)? What is stopping you from implementing this technology (technological, economic, lack of information, focus, manpower, etc.)?