H 2 S Treating Options and Factors Influencing Decisions. June 30, 2016

Transcription

1 H 2 S Treating Options and Factors Influencing Decisions June 30, 2016

2 Agenda Calculation for lbs. of sulfur per day Factors affecting scavenge rates Treating applications and chemistries Pros/cons each Applications of each CAPEX vs OPEX in relation to H 2 S concentration

3 Sulfur Calculation PPM H 2 S x MMSCFD/ =lbs. of Sulfur/day Ex. 100 ppm H 2 S x 1 MMSCF/ =8.99 lbs S Ex. 200 ppm H 2 S x 5 MMSCF/ =89.8 lbs S

4 Factors Affecting Scavenge Rates Production ratios (O/W/G) Flow regime Temperature and pressure H 2 S output concentration needs Contact time Mixing efficiency Ø Most applications are between 40-80% effective

5 Treating Applications Solid media Amine Unit Bubble Tower Continuous Surface Downhole Batch

6 Solid Media Metal oxides Iron Sponge Iron oxide on wood chips SulfaTreat (MI) Iron oxides on clay Zinc Oxide Neat, or with calcium oxide lbs/h 2 S per lb/scavenger

7 Solid Media Pros/Cons Pros Fast reaction High capacity Inlet Flow Inlet Flow Cons By products are pyrophoric High CAPEX investment High disposal costs 2 vessels typically required Little to no capacity for CO 2 scavenging Outlet Flow Outlet Flow

8 HIGH CAPEX Amine Unit Primary and Secondary amines Ethanolamines Glycols Typical plant design Regenerative chemistry lb/h 2 S per gallon Used when greater than 100 lbs. sulfur per day

9 Bubble Tower Towers are best for efficient, maximum contact Distributor and sparger at bottom and demister at top, no other internals are needed Best when installed after 3 phase separation Operate 2/3 full with gas superficial velocities of 6-10 ft/min Chemical injection upstream can help Higher velocities can result in chemical carryover and/or foaming

10 Bubble Tower Chem Amine-Formaldehyde Products Triazines MEA DEA MDEA.75-2 lbs/h 2 S per gallon scavenger Conflicting reports on CO 2 effect on efficiency Dillon, 1990 Yes Salma, 2000 No Sour Gas Inlet AI Demister LI LI Sparger Sweet Gas Out Vent & Relief Spent Chemical Fresh Fill & Dump Pump SulfaClear

11 Bubble Tower Pros/Cons Pros Low CAPEX Easily changed out Maximum contact Low cost chemistry Cons Difficult in high velocity Effective range up to ~100 lbs/h 2 S

12 Continuous Injection Injected into gas or liquid stream Only requires an injection pump and a quill or atomizer Multiple injection points may be needed to maximize Sour Gas Line surface area contact Same chemistries as used in bubble tower application Injection Quill Pump Injector Should Be 100m Upstream of Separator Fresh SulfaClear Liquid Chemical Production Separator Two or Three Phase Sweet, Treated Gas Produced Water Disposal

13 Continuous Considerations Downhole injection is discouraged CaCO 3 and corrosive sulfur develop Triazines degrade above 160 F Injection point should allow for at least 10 minutes contact time.5-1 lb/h 2 S per gallon of scavenger High water cut reduces efficiency

14 Continuous Pros/Cons Pros No CAPEX Can be placed anywhere in the system Minimum footprint Low cost chemistries Cons Can be high OPEX Attempt with high H 2 S% can cause insoluble solids High treating rates can cause CaCO 3 scale (some newer chemistries have scale inhibitor)

15 Batch Treating Aldehyde based Acrolein Glyoxal Glutaraldehyde Oxidizers Chlorites Nitrites Persalts Bromates

16 Aldehyde Based Acrolein Has to be treated inside of a closed system by trained individuals Fast reaction, 50/50 partitioning 3 function product Hazardous when exposed to atmosphere Glyoxal Sometimes mixed with glut/formaldehyde Scavenge rate x more than triazine No solid precipitation 98% water partitioning

17 Oxidizers Chlorites, Nitrites, Bromates Persalts (Peroxides) Sulfur by-products Inexpensive Nitrites can be treated into the formation and serve a dual purpose Peroxides need high ph for max effectiveness Fast reactions Highly corrosive Biocidal properties Assist with water quality Sulfate by-products Expensive Peroxides need high ph for max effectiveness

18 Application Choices Solid Media Amine Treating % H 2 S Continuous Injection Bubble Tower Gas Volume

19 Review Contact time is the primary goal At >100 lbs/h 2 S/day, solid and regenerative systems may be analyzed Combination continuous and bubble tower can also work, depending on motivators Products must be chosen with consideration to production dynamics