PTAC Methane Venting Reduction Case Studies. October 15, 2015

Transcription

1 PTAC Methane Venting Reduction Case Studies October 15, 2015

2 Outline Methane venting reduction study by Accurata and Sentio Hexa-Cover by Greatario Small blower compressor skid by Go Technologies SlipStream CHOPS by REM Technology 2

3 Methane Venting Reduction Study To understand the applicability, operability, cost and potential for technologies to reduce methane venting at cold heavy oil wells and well pads. Approximately 80% of vented volumes in Alberta are from the Bonnyville and Wainwright regions and are related to cold heavy oil production Collaboration and funding from Devon, Husky, CNRL, Alberta Innovates Energy and Environment Solutions, and Alberta Energy 3

4 Technologies Considered VRU; SlipStream CHOPS; T.O.P. Tank; Hexa-Cover; Solution gas compression; HY Bon combustors, Black Gold Industries combustor, flaring, Cool TCI Incinerator, Questor incineration; New technologies from a literature search. 4

5 Scope of Work Brief description of each technology Key equipment components; Any piping and control requirements; A process schematic; Any operational challenges; Any safety concerns; The costs for greenfield and brownfield installations; Life cycle cost estimates 5

6 Description of CHOPS Facilities The facility typically consists of a well equipped with a gas engine which drives a hydraulic power unit which in turn drives a Progressive Cavity Pump (PCP). The engine jacket water can used as the heat medium for the heat tracing. Alternatively, the engine skid can generate electricity for electrical heat tracing. Oil produced from the well flows from the wellhead to a heated, insulated tank. The tank vents to the atmosphere. Tank heat is required to maintain the appropriate viscosity of the oil for tank unloading. Oil is periodically trucked out of the tank to a plant for processing. 6

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9 CHOPS Emissions Sources of emission are from the well casing vent and from the production tank on site. The maximum transient flow rates for this study are 2,000 m 3 /d (71,000 scfd) from the casing gas and 100 m 3 /d (3,500 scfd) from the tank. Flow rates will vary significantly from zero to the maximum value m 3 /d carbon tax credits could be available for emissions reductions; Above 900 m 3 /d conservation must be evaluated and is mandatory if criteria are met. 9

10 Tank Emissions Temperature has an impact on tank emissions. More emissions are generated when temperature variation is higher. If a tank is sufficiently insulated and temperature controlled, the thermal exchange with the ambient conditions is small and tank venting is minimized. However, where there is inflow or outflow from the tank, emissions will be generated. 10

11 Casing Gas Oil production is maximized when the backpressure on the well casing annulus is minimized. Casing gas is produced through the casing valve on the wellhead. Closing the casing valve will cause build-up of gas in the annulus, which can push the liquid column down to the pump intake and risk gas being drawn into the pump intake. The presence of gas at the pump suction can cause the pump to run dry and cavitate with pump motor failure to follow. Casing gas is wet and flow rate is variable to intermittent. 11

12 Casing Gas The PCP is normally engine driven. The fuel for the engine can be casing gas. On many sites the operational difficulty with using sporadic volumes of casing gas to power the site is very challenging. Propane has the added advantage of consistent quality with a constant flow rate which will improve pump reliability and optimize engine availability. Casing gas is also used as fuel for the tank burner. Engine jacket cooling water is used for the heat trace required on the casing gas line to prevent freezing. 12

13 Operational Challenges Gathering wet gas is problematic because free water drops out creating freeze problems, corrosion problems, and higher pressure drop in gathering systems. All these problems require fuel gas conditioning to resolve. If the casing gas is used as fuel, the lines need to be heat traced and insulated to prevent freezing. The high water and variable hydrocarbon dew point of the casing gas can provide challenges when used as fuel for the fired equipment. Venting gas is a safety issue. Intermittent flow from the casing gas at low pressures requires a wide operating range for venting and control components. 13

14 Vapour Recovery Unit (VRU) Comprised of compressors designed to boost gas pressure. Requires a gas blanket in tanks to ensure no oxygen enters the VRU compressor. To be effective, it should be installed on a grouping of tanks such as at a battery. Even with tying in the venting from a number of tanks, the volume of emissions can still be so small that it may still be costly. 14

15 Compressor Styles Scroll - $140,000 Sliding Vane - $300,000 Screw - $300,000 Reciprocating - $400,000 15

16 VRU Conclusion The VRU solution is not likely a viable solution to reduce GHG emissions from single well CHOPS sites. The design and operation are complex and the installation is costly and only addresses up to 5% of the emissions coming from the site. These installations also require blanket gas to operate safely. 16

17 SlipStream CHOPS In prototype development by REM Technology An auxiliary burner in the stack of the main burner to burn any casing gas and tank vents not consumed by the main burner or the engine. Operated when excess fuel is available after the main burner demand is satisfied. A heat tracing system using waste heat from the main burner vent stack in order to avoid the problems associated with using engine coolant for heat tracing. 17

18 SlipStream CHOPS The auxiliary burner is sized to limit the radiant heat against the tank wall from the auxiliary burner. The product is currently in development and the final configuration is likely to change once product testing is completed. 18

19 T.O.P. Tank Thermal Optimized Production (T.O.P) Tank by Newco. Relocates the engine from the shack to inside the production tank and eliminates the need for a firetube by utilizing the engine glycol and exhaust heat that would normally be wasted and circulating it through the tank to heat the product. 19

20 T.O.P. Tank 40%of the engine heat needed to heat the tank comes from the glycol (coolant), 40% from the exhaust and 20% from the radiant heat from the engine. The design can put out 700,000 Btu/hr in water. The engine to run the PCP could utilize either captured casing gas or propane. The engine does not change: it has just been relocated to inside the tank. 20

21 T.O.P. Tank Conclusion There are limited operating sites currently. The Area Classification for the electrical design may need to be addressed to ensure it passes the operating company s requirements. 21

22 Hexa-Cover Hexa-Cover is a floating tile system designed to minimize odours, emissions and organic growth. Consists of individual hexagonal, plastic tiles approximately 25 cm across. The tiles are manufactured from an engineered polymer material. Designed with anti-static material for oilfield applications. The tiles are dumped into a tank through the thief hatch or other opening and can be installed whether there is liquid in the tank or not. Husky trial in 2015; several CNRL installations. 22

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24 Hexa-Cover Laboratory tests using toluene yielded 65% reduction of headspace vapour generation. Lehder Environmental Services conducted field tests at Mann Lake on a tank with 60 m 3 /week oil production in it. The results showed 53% reduction in water content in the vapour space, and 93% reduction in C6 content of the vapour. One company has reported a 20% reduction in burner fuel costs with an associated reduction of 27 kt CO2e/year based on ten years forecast; however, these findings have not been qualified by peer review. 24

25 Hexa-Cover Conclusion Appears promising to reduce some of the emissions that are vented off the tanks. There are several studies that are ongoing to gather and quantify the claims for emissions reduction and reduction of fuel gas to maintain tank temperatures. The costs are low, the risk is small. 25

26 Solution Gas Compression Vented volumes are too small for CNG (e.g. CanGas, Ferus). Examples of compressors: SMD Centrifugal Compressor Busch rotary lobe compressor Gardner Denver blower (i.e. Go Technologies) Need to dry and QC gas before shipment from the lease. 26

27 Solution Gas Compression - Conclusion Due to the small and sporadic volumes of gas, there is potentially only one proven solution using casing gas compressors to capture the gas. Go-Technologies have numerous casing gas compressor installations working for several clients. Some of the installations have been working for 3 years with very little maintenance required. 27

28 Combustors and Incinerators Flare stacks Enclosed vapour combustors (e.g. Black Gold) TCI Cool incinerator Questor 28

29 Combustors and Incinerators - Conclusion Combustion, if a stable flame can be kept, is one of the easiest and cost effective solutions to reduce emissions from a CHOPS site. The installed costs are relatively low, the design is not complex and it reduces the GHG emissions as CO2 is less of a GHG gas than methane. The challenge will be to not create more GHG emissions if a pilot is required on the design of combustor chosen. However, some combustor designs do not require a pilot light. 29

30 Alternate Technologies Power generation would require fuel conditioning Fuel cells Methane reforming to liquids or fertilizer 30

31 Hexa-Cover Field Trial By Husky at McMullan in tanks with Hexa-Covers and 5 tanks without Measure fuel gas consumption Evaluate concern about clean-out for maintenance 31

32 Go-Technologies Trial By Devon in CHOPS areas in sites To replace reciprocating compressors and achieve low back-pressure on the well. 32

33 SlipStream CHOPS Prototype By REM Technology in To construct and lab-test the prototype Generate information to support a future field trial. 33

34 Conclusion PTAC has a number of active projects aimed at reducing methane emissions and other sources of greenhouse gas. Results will be shared through the TEREE Committee when available. Additional projects could be undertaken in 2016 if support funding is available. 34