Welcome the Hydrators Use of Hydrates for Natural Gas Storage Busola Odunuga & Ben Aseme Objective Major gas storage methods: Aquifers Depleted Gas Reservoirs Salt Caverns Proposed method: Hydrates The three.
Download ReportTranscript Welcome the Hydrators Use of Hydrates for Natural Gas Storage Busola Odunuga & Ben Aseme Objective Major gas storage methods: Aquifers Depleted Gas Reservoirs Salt Caverns Proposed method: Hydrates The three.
Welcome the Hydrators Use of Hydrates for Natural Gas Storage Busola Odunuga & Ben Aseme Objective Major gas storage methods: Aquifers Depleted Gas Reservoirs Salt Caverns Proposed method: Hydrates The three major methods of storing natural gas are compared with the use of hydrates. Outline Gas Hydrates Storage Use of Depleted Reservoirs Use of Salt Caverns Use of Aquifers Natural Gas Storage - A brief history “After WW II, natural gas consuming countries noticed that the seasonal demands for natural gas could not possibly be met by then present pipeline delivery methods alone. The sizes and deliverability of pipelines would have to be increased dramatically to meet this challenge. The technology to construct such pipelines to transport the gas to major consumers was unattainable. Thus began the natural gas storage movement”. Why Hydrates as Storage Method? Cost factor Hydrates could be relatively cheaper than other forms of storage method. Hydrates can be used for economic storage of natural gas in cold countries and the associated cost can be relatively minimized. Accessibility Tanks can be easily accessed when needed especially during peak periods. Safety Incase of an explosion, hydrates burn slowly due to the presence of ice. Natural Gas Hydrates Gas hydrates are naturally occurring solids composed of water molecules forming a rigid lattice cage containing molecule(s) of natural gas. Natural Gas Hydrate Structure Options for Storage Pressurized Tank Refrigerated Tank Natural Gas Hydrates • Pressure = 6MPA and Temperature = 293K Natural Gas Hydrates Gas Gas and water slurry after depressurizing Slurry mixture Storage for water and gas mixture Heat Recycled water flowing back to the system Water removed Hydrates gas recovery diagram V-14 Pressurized tank in order to reduce cost. Volume of tank needed was found by Where Q is the inlet flow rate of gas, and R is the rate of formation of hydrates. Important Factors: Temperature and Pressure Storage Method for Hydrates Where R is the rate of hydrate formation, μ2 is the second moment of distribution around particle size for hydrate; f is the fugacity of gas, feq is the fugacity of gas at equilibrium, and K* is the kinetic parameter Volume of reactor used for Hydration/Storage V=Q/R , where V is the volume of the reactor, Q is the gas flow rate in the reactor, R is the rate of hydrate formation. Flare gas Gas and water slurry supply after storage Compressor 129KW Gas and water mixture Gas supply Pressurized vessel heated V-6 Storage for water/gas mixture water Gas Supply Pressurized Tank V-2 V-3 Fresh water supply Fresh water supply Heat Pump Recycle water V-5 Fresh water supply Process flow diagram for Hydrates V-4 V-13 Depleted Gas Reservoirs These are naturally occurring gas reservoirs that have been tapped of all recoverable natural gas. Began in Ontario, Canada 1915. Important Selection factors Porosity Permeability Depleted Gas Reservoirs ‘the Hydrators’ Natural Gas Delivery How’s my driving?..... Gas gathering pipeline Compressor Call: 1-800-Methane Wellheads Valve Pump Injection Well Withdrawal well Depleted Gas Reservoir Working Gas Cushion Gas Depleted Reservoirs – Unique characteristics Well-understood geological make-up. Existing gas processing facilities. Primarily used for baseload gas storage. Advantages Disadvantages Large storage volume Demands ready market Short development period Requires low permeability Poor regional spread Aquifers An aquifer storage field is a sub-surface facility for storing natural gas. Aquifers are water bearing sands topped by an impermeable cap rock Aquifers Summary of parameters used Avg. Bottom Hole pressure Top pressure volumetric flow rate mass flow rate Density k Length of Pipe 7.3 101325 100 4302 0.717 1.31 100 MPa Pa m3/s kg/s kg/m3 m Aquifers Withdrawal pipe Gas supply V-1 Withdrawal pipe V-12 compressor P-19 V-2 V-3 E-9 Injection of gas Process flow diagram for Aquifers Aquifer Underground Storage Aquifers Land for Aquifers Must be well spaced at least 320-640 Acres apart Must be located no less than 100 feet from private homes 150 feet from public streams 50 feet from any streams Land cost= $/acre × amount of acre used for storage (including restrictions) Salt Caverns These are large underground cavities created inside salt domes/deposits using leaching (solution mining) techniques. Relatively new gas storage method (Began by SMGC in 1961). Increasingly popular method of natural gas storage. Primarily located along the Gulf Coast (Texas, Louisiana, Mississippi and Alabama). Salt Caverns ‘the Hydrators’ H2O Delivery How’s my driving?.... Valve Call: 1-800-Solvent Solution mining technology I/W well Salt cavern formation Salt Dome Salt Caverns ‘the Hydrators’ Natural Gas Delivery Gas gathering pipeline Compressor How’s my driving?.... Call: 1-800-Methane Wellheads Valve Pump Injection Well Withdrawal well Salt Cavern Working Gas Cushion Gas Salt Caverns Salt Caverns – Unique characteristics Storage development technology. Smaller storage capacity. Primarily used for peak shaving gas storage. Advantages Disadvantages Cavern volume control Smaller storage volume Low permeability Expensive development technology Minimal cushion gas requirement Environmental concerns Development cost factors Wells Valves Compressors Cushion gas Utilities (Electricity) Pumps Land / Labor Installation costs Pressurized tanks Gathering system Gas flow meters Dehydrators Separators Property Taxes/Insurance Drilling Leaching Gas storage cost breakdown Wells • As conduits for the transport of gas into and from the earth, they are an important part of any gas storage facility. • Primary Gas well components: • Well casing • Well tubing • Average number of gas wells is between 2 and 4 per storage facility. Compressors • Compressors are one of the most expensive components of any gas storage facility. • Compressor-incurred costs come from power requirements, equipment material, etc. Compressor power calculation HP = Theoretical Horsepower Q=flow rate in Million Standard ft3 per day P1=Suction-side pressure in psia P2=Discharge-side pressure in psia T1=Suction-side temperature in degrees Kelvin Z1=compressibility factor k=ratio of natural gas specific heats Gas storage cost breakdown Cushion Gas Provides the minimum deliverability pressure required by law. Influences storage cost based on its ratio to the working gas. Current market price for natural gas is approximately $4.00 per mmbtu. Costs also include injection, withdrawal and storage costs. Gas storage cost breakdown Utilities (Electricity) Gas compressors and pumps are powered by electricity and this adds to the storage facilities total cost. • Storage capacities influence electrical power requirements which in turn influence total cost. • Electricity costs were calculated from compressor and pump power requirements. Pumps • Pumps are required to aid gas delivery when the reservoir pressure is not high enough. • Pump incurred costs come from pump material and deliverability rates. • Deliverability = Withdrawn gas volume(mmscf)/withdrawal period(days). • They can be omitted if reservoir pressure is high enough. Gas storage cost breakdown Land • Leasing or outright purchase of storage facility land is an important cost item. • Land is leased on a yearly basis. • Can be estimated as a fraction of the total capital investment. Labor • Labor is also an integral part of total cost calculations. • Labor cost calculations came from total development and withdrawal time periods. • Estimated using semi-skilled labor pay rates(~$30.00/hr basis). Gas storage cost breakdown Installation costs Cost Factors Separators: 25% Compressors: 20% Include miscellaneous costs associated with installing purchased equipment and sometimes associated labor. Dehydrators: 22.5% Installation costs were derived as a percentage of equipment cost. Flow meters: 30% Pumps: 30% Valves: 28% Piping: 35% Gas storage cost breakdown Property Taxes/Insurance Property taxes are in the range of 2 to 4 percent for highly populated areas and in the range of 1 to 2 percent for less populated areas. Property insurance is about 1 percent the total fixed capital investment per year. “Nothing is certain but death and taxes” – Benjamin Franklin(1706-1790, American founding father and polymath). Depleted Gas Reservoirs Wells • Average depth of 5500ft. • Well casing and tubing made from medium grade steel. • Combined weight of well material is ~ 6 lbs/ft • Current cost estimates of medium grade steel = $1000/ton • Total costs = $35,000,000.00 Depleted Gas Reservoir Compressors • The basic compressor equation was used to estimate the compressor power requirements. • Horse power estimates came up to 41,795 theoretically. • Resulting total compressor cost estimate was approximately $7,877,987.14 . Depleted Gas Reservoir Cushion gas Purchase cost Occupied half of gas is of the total gas approximately reservoir $4.00 per volume. mmbtu. We used estimates of $4.00 per mmbtu. Total cushion gas cost estimates = $22 million for a max. capacity of 10 BCF. Depleted Gas Reservoir Pumps • Pump costs were calculated using the gas delivery flow rates. • Pump cost estimates were approximately $418,619.79. Electricity • Estimated from the horsepower requirements of the compressor and pump. • Total estimates equal $6,370,695.01 . Depleted Reservoirs Land: • Leasing cost estimates came up to about$250,000 per year. Labor: • Estimated at $192,000 over the activation/injection and withdrawal period. Installation costs: • Combined total of percent equipment costs, approximately 40 million dollars. Total cost estimate=$30 million per BCF. Salt Caverns Wells Estimated total cost =$26,525,000.00 Valves Estimated cost = $48,000.00 Compressors Total estimated cost = $2,363,396.04 Salt Caverns Cushion gas Total cost estimate = $1,500,000 per BCF Electricity Total cost estimate = $63,400 per BCF Pumps Total cost = $209,000 Salt Caverns Land Total lease estimate = $257,000 per yr. Piping Estimated at $300,000 per BCF Installation costs Total estimate =$5,000,000 Total cost estimate=$14 million per BCF Comparing the effects of natural gas prices in Aquifer cost calculations $120.00 $100.00 $/mmbtu $80.00 $ 4 cushion gas $60.00 $2 cushion gas $6 cushion gas $8 cushion gas $40.00 $20.00 $0.00 0 2000000 4000000 6000000 8000000 capacity in mmbtu 10000000 12000000 TCI of Acquifer compared to Hydrates $200.00 $180.00 $160.00 TCI/mmbtu $140.00 $120.00 Hydrates $100.00 Aquifer at $4/mmbtu aquifer at $6/mmbtu Aquifer at $8/mmbtu $80.00 $60.00 $40.00 $20.00 $0.00 0 2000000 4000000 6000000 Capacity in mmbtu 8000000 10000000 ROI of Hydrates vs. Aquifer at different Natural gas prices 0.7 0.6 0.5 0.4 ROI Hydrates Aquifer at $4 cushion gas Aquifer at $6 cushion gas 0.3 Aquifer at $8 cushion gas 0.2 0.1 0 0 2000000 4000000 6000000 8000000 Capacity in mmbtu 10000000 12000000 Cost Summary Summary Results for Aquifers and Hydrates Hydrates Aquifers Compressor $291,466.80 Pumps $83,333.34 Cushion Gas Extra Fees Land Utilities Pressurised Tank - $32,000,000.00 $1,800,000.00 $45,000.00 $42,000.00 $24,625,109.00 Valves $182,625.97 Pipes $181,779.20 TCI/mmbtu ROI Total Cost $25,000,000.00 - $15.18 $35.65 0.66 0.28 $25,591,314.31 $60,113,205.31 Cost Comparison for typical Salt cavern and Depleted reservoir $220.00 $200.00 $180.00 $160.00 $140.00 $/mmbtu D.R. at $2.42/mmbtu D.R at $4.42/mmbtu $120.00 D.R. at $6.42/mmbtu D.R at $8.42/mmbtu $100.00 S.C at $2.42/mmbtu S.C at $4.42/mmbtu $80.00 S.C at $6.42/mmbtu S.C at $8.42/mmbtu $60.00 $40.00 $20.00 $0.00 0.00E+00 2.00E+06 4.00E+06 6.00E+06 mmbtu 8.00E+06 1.00E+07 1.20E+07 Return on Investment 0.20 0.18 0.16 0.14 ROI 0.12 0.10 D.G.Reservior Salt cavern 0.08 0.06 0.04 0.02 0.00 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 MMBTU 6.00E+06 7.00E+06 8.00E+06 9.00E+06 1.00E+07 Conclusions Equipment Cost for Hydrates is not as expensive as other existing forms of storage. Return on Investment is Higher than other compared methods. Accessibility/mobility factors favor hydrates. Conclusions/Recommendations ● Hydrates can be used for economic storage of natural gas in countries with colder climates. ● Associated costs of natural gas storage using hydrates can be relatively minimized. ● The use of natural gas hydrates for storage is an alternative that maintains a high degree of safety. An ignited gas hydrate mass burns slowly and doesn’t explode due to the presence of frozen water molecules. Thank you Questions! Questions!! Questions!!!