Question 1. What Is Natural Gas, Png, Cng & Lng?
Natural gasoline as its call shows is a Gaseous fuel, which includes 87-92% of Methane with a small percentage of different better hydrocarbons. PNG, CNG & LNG are one of a kind kinds of Natural gasoline underneath varied temperature & strain.
Piped Natural Gas(PNG) is typically below atmospheric temperatures but the strain can up to as high as 90 Kg/cm2 in transmission strains and restricted to less than 24 Kg/cm2 in City Gas grids because of danger worried in motion of high stress gas inside crowded cities/cities .
Compressed Natural Gas (CNG) approach natural fuel used as gasoline for cars, generally compressed to the stress starting from 200 to 250 kg/cm2 within the gaseous state It is used pre-dominantly for automotive cause because the power requirement for going for walks a vehicle (for 150-2 hundred km) can be packed in a field of size, which can fit in to the luggage compartment or boot area while pressurized gas extent reduces by means of nearly three hundred times.There are few instances of CNG getting used for industrial purposes for delivery desired portions thru cylinder cascades .However in such instances pressure reduction on the stop use is inevitable. (Refer OISD-179 for Safety Requirements for Compression, storage & refueling stations for CNG in Automotive quarter)
LNG (Liquefied Natural Gas)is liquid shape of Natural fuel, normally supposed for transportation of huge volumes thru ships, where move united states of america pipelines are not possible. There could be high degree of financial system in transportation logistics due to massive scale of operations involved.
Question 2. How Is Natural Gas Extracted?
Originally, whilst crude oil became extracted, herbal fuel changed into created as a byproduct, or “fuel associate.” Often, it changed into initially vented or flared off as a waste product, or reinjected into the petroleum properly. But over time uses for natural fuel, and the infrastructure to capture and delivery it, were developed, allowing herbal gasoline to grow to be an an increasing number of critical gas supply for residential and industrial cooking and heating, energy plants, and commercial tactics.
By the mid-twentieth century, a strong domestic natural gas industry had evolved in the United States, producing gasoline from massive consolidated underground reserves unbiased from crude oil manufacturing. More recently, fuel manufacturers have begun generating gasoline from greater dispersed sources in shale and other porous rock formations thru the manner of hydraulic fracturing.
Oil and Gas Interview Questions
Question three. How Lng Is Stored And Handled?
Natural fuel can be reduced to liquid kingdom by using cooling to one hundred sixty C so one can occupy 1/600th of its gaseous extent and it's far referred to as as Liquefied Natural Gas which eliminates more area for gas transportation. In truth at some point of the manner of liquefaction of NG to LNG lot of impurities are eliminated.
Hence LNG is the purest form of Natural Gas.
LNG is saved in big insulated tanks which are especially designed for this reason. The tanks are so-known as “complete containment” tanks. Each tank consists of a special nickel-steel inner tank and a (kind of eighty-cm thick) concrete outer tank. The area among the partitions of the 2 tanks is filled with a thick layer of special insulating material that ensures that truly no heat can get into the inner tank. However, inspite of the maximum green insulation, a few ambient warmness will constantly attain the inner tank. This slight amount of heat will reason a totally small amount of the LNG (about 0.1/2% an afternoon) to turn returned into a gas. All of this so-known as evaporation loss in the tank is amassed, in order that none of it's miles released into the surroundings. It is again condensed into LNG and delivered to the tank as LNG liquid. It can also be used at the terminal as a fuel to heat up the LNG.
At receiving terminals (like Dahej, Hazira), LNG is re-gasified and transmitted for further utilization in NG shape. These receiving terminals also are referred to as Re-Gasification terminals
LNG vessels (Ships) also are there to carry 2,50,000 m3 of Gas at a time
In India we have LNG import-cum-re-gasification terminals and we do now not have liquefaction plant life, as India isn't a gas-exporting kingdom.
Question four. What Is Rich Gas And Lean Gas?
Rich gas contains 5 or 6 gallons or extra of recoverable liquid hydrocarbons according to thousand cubic toes. Whereas Lean gasoline includes much less than 1 gallon of recoverable liquid hydrocarbons in step with thousand cubic feet.
Question five. Why Is Natural Gas Processed?
Natural gasoline is processed in LPG fractionator plant to split it into exceptional fractions as it's far required by means of unique programs.
The following indicates the exclusive packages:
Methane -gasoline and feedstock for urea flora and gasoline for electricity plants
Ethane -Production of petrochemicals
Propane -LPG and industrial fuel
Butane -Production of LPG
C5 and heavier -Production of solvents and pentane
Petroleum Engineering Interview Questions
Question 6. What Is Associated And Non-related Gas?
Based at the type of supply Natural gasoline is classed as associated and non-associated gasoline and there may be of no significance while end use is worried.
Associated fuel is herbal gas located in crude oil reservoirs both dissolved or together with crude oil deposits and it is also referred to as as Oil properly fuel.
Non-related fuel is Natural gas discovered in reservoirs become independent from crude oil wells and it's also known as as Dry gasoline.
Question 7. What Is Sweet & Sour Gas?
Based at the sulphur content the natural gas is assessed as candy & bitter gasoline. Sour gas includes better level of sulphur content in its composition and sweet gas has little or no or nil sulphur.
Gas Detection System Interview Questions
Question eight. What Is Pngrb And What Is Its Role In Awarding Cng Projects?
Petroleum and Natural Gas Regulatory Board External Website that opens in a brand new window (www.Pngrb.Gov.In) (PNGRB) changed into formed on 1st Oct-2007 to
Protect the interest of clients by using fostering truthful trade and competition amongst the entities
Regularize and authorizing entities involved in the business
CGD tasks may be provided to entities based on bidding method in which weightages for specific qualifying parameters will be given for entities collaborating inside the bid.
Question nine. Where The Lng Terminals Are Located In India ?
As of Nov. 2008, India has
Petronet LNG Limited (PLL), Dahej (Gujarat)
Shell Hazira, Hazira (Gujarat)
Dhabol , Ratnagiri for Captive utilization of Power plant at Ratnagiri
Gas Analyzer Interview Questions
Question 10. Can Natural Gas Be Stored?
Generally herbal gas is stored only in CNG retailers and in LNG terminals. Apart from that herbal fuel will no longer be saved and it's miles in continuous flow through pipelines.There are few Natural Gas underground caverns in some elements of the sector.
Question eleven. How Natural Gas Is Generally Traded?
Gas trade is based totally on $/MMBTU (Million British Thermal Units)
What is the composition of natural Gas:
Composition of Natural gas varies broadly from source to source.
Natural gas is a combustible combination of hydrocarbon gases. While natural gasoline is shaped often of methane, it can additionally encompass ethane, propane, butane and pentane. Depending on the utility the client/person can seek pure shape of Methane (as excessive as 95%)
The thermal performance varies from 9000 ok.Cal to 13500 K.Cal in line with Kg based at the composition of Gas.
1 MMBTU is 252000 K.Cal
1 MMBTU (Million British thermal unit) = 19 to 23 kg or 23 to 30 SCM approx. Primarily based on the composition of the fuel.
Gas Compressor Interview Questions
Question 12. What Are The Pros Of Using Natural Gas Instead Of Oil Products?
There are ample substances of easy, reliable, low cost herbal gasoline right right here in North America. As a outcome:
Transitioning from oil to natural gasoline is an crucial step closer to our nation’s lengthy-held policy to lessen our dependence on luxurious foreign oil, particularly oil from risky nations.
The progressed economics of using herbal gasoline as a fuel in place of oil is playing a enormous role inside the revitalization of America’s production economic system.
Carbon dioxide and other emissions from herbal gasoline are considerably lower than the ones from coal or fuel oil.
Oil and Gas Interview Questions
Question thirteen. What Is The Difference Between Lng And Cng?
CNG is compressed herbal fuel. LNG is liquefied natural gas which have to be saved at temperatures near absolute 0. CNG has a decrease price of production and storage in comparison to LNG as it does no longer require an highly-priced cooling system and cryogenic tanks.
CNG, but, requires a miles large garage field to house the equal quantity of Btu. That is why NG Advantage has selected to have the gasoline it promises to a plant drawn immediately from its trailers, now not requiring the customer or the employer to allow, build, and keep big garage tanks.
LNG Advantage and its companion Clean Energy Fuels provide customers CNG and LNG depending on which is satisfactory for the specific customer’s wishes.
Question 14. How Much Cleaner Is Natural Gas To Burn?
Reducing carbon dioxide (CO2) emissions with the aid of 20% to 30%
Reducing carbon monoxide (CO) emissions as much as 75%
Reducing nitrous oxide (NOx) emissions with the aid of about 50%
Reducing up to ninety five% of particle count number (PM) emissions
Reducing unstable natural compound (VOCs) emissions by fifty five%
Question 15. What Is Lng?
Liquefied herbal gasoline, or LNG, is herbal gasoline in its liquid form. When herbal gasoline is cooled to minus 259 tiers Fahrenheit (-161 degrees Celsius), it will become a clean, colorless, odorless liquid. LNG is neither corrosive nor poisonous. Natural gasoline is often methane, with low concentrations of other hydrocarbons, water, carbon dioxide, nitrogen, oxygen and a few sulfur compounds. During the system referred to as liquefaction, natural gasoline is cooled under its boiling point, disposing of maximum of those compounds. The closing herbal gas is more often than not methane with only small quantities of other hydrocarbons. LNG weighs much less than half of the burden of water so it's going to go with the flow if spilled on water.
Question sixteen. How Is Lng Stored?
When LNG is obtained at most terminals, it's miles transferred to insulated garage tanks which can be built to specially preserve LNG. These tanks can be determined above or beneath floor and hold the liquid at a low temperature to decrease the quantity of evaporation. If LNG vapors aren't launched, the stress and temperature within the tank will maintain to rise. LNG is characterized as a cryogen, a liquefied fuel stored in its liquid kingdom at very low temperatures. The temperature in the tank will stay regular if the stress is stored constant by permitting the boil off fuel to break out from the tank. This is known as auto-refrigeration. The boil-off gasoline is accrued and used as a gasoline supply within the facility or on the tanker transporting it. When natural gas is wanted, the LNG is warmed to a degree wherein it converts again to its gaseous state. This is achieved the use of a regasification technique regarding heat exchangers.
Question 17. How Is Natural Gas Stored?
Natural gas can be saved in some of unique approaches. It is maximum commonly saved underground under pressure in three styles of centers. The most generally used in California are depleted reservoirs in oil and/or gas fields because they may be more available. Aquifers and salt cavern formations also are used underneath sure situations. The characteristics and economics of every form of garage web page will dictate its suitability for use. Two of the maximum crucial traits of an underground garage reservoir are its capability to keep natural gasoline for future use and its deliverability charge. The deliverability rate is determined by using the withdrawal ability of the related valves and compressors and the overall amount of fuel inside the reservoir. In other states, natural gas is also stored as LNG after the herbal gasoline has been liquefied and positioned in above-floor garage tanks.
Question 18. Is Lng Flammable?
It relies upon. When bloodless LNG comes in contact with hotter air, it becomes a seen vapor cloud. As it maintains to get hotter, the vapor cloud becomes lighter than air and rises. When LNG vapor mixes with air it's far best flammable if within 5%-15% herbal fuel in air. Less than this isn't sufficient to burn. More than this, there's too much gas in the air and no longer enough oxygen for it to burn.
Petroleum Engineering Interview Questions
Question 19. Is Lng Explosive?
As a liquid, LNG isn't explosive. LNG vapor will handiest explode if in an enclosed area. LNG vapor is best explosive if inside the flammable range of 5%-15% whilst blended with air.
Question 20. How Is Natural Gas Used?
Once separated from fuel associates and contaminants, methane is piped to natural gasoline garage facilities, business factories, and power flowers. Natural gas energy plant life are usually categorized as either “combustion” or “blended cycle.” Combustion power plants inject pressurized natural gasoline into a chamber and ignite it, generating steam that spins a electricity generator and releases waste warmth and carbon dioxide. More green combined cycle energy flora burn methane via a fuel turbine and direct the waste warmth thru a traditional steam turbine. Combined cycle strength flowers are significantly more green compared to combustion flora and maximum other sorts of thermal generation.
Natural gasoline is likewise piped at once to homes for heating and cooking, as a feedstock for ammonia fertilizer and hydrogen production (amongst other commercial strategies), and as compressed herbal fuel (CNG) for cars.
Question 21. What Is Fracking?
Hydraulic fracturing is an strength manufacturing procedure that entails pumping water, sand, and chemical compounds into drilled wells to fracture surrounding rock, freeing oil and/or gas deposits stored within the geologic formations.
Question 22. What Is Hydrostatic Test?
Hydrostatic testing includes water-stress checking out a pipeline. It’s a verified technique of verifying the actual capability of a herbal fuel pipeline. We need our device to perform at a safe stage of stress. Hydrostatic checking out is also used to check such acquainted items as scuba tanks, fireplace extinguishers and air compressor tanks.
A hydrostatic test entails pressurizing a segment of pipe with water. The pressure is tested at a higher percentage of the pipe cloth’s maximum layout strength for herbal gas. This verifies the functionality of a pipeline to soundly operate at the favored degree or stress. The take a look at can also display weaknesses which could lead to defects and leaks within the pipe. To perform a hydrostatic check, the pipeline must be taken out of service for many days.
Question 23. Why Does Natural Gas Smell Like Rotten Eggs?
In its herbal state, natural fuel has no odor. Utility companies add a chemical odorant known as “mercaptan” to herbal gas to assist make fuel leaks simpler to be aware. If you have got a natural gas stove, you can have smelled this rotten egg odor while the pilot mild has gone out.
Question 24. What Is “liquefied Natural Gas?”
When natural gasoline is cooled to 260 degrees beneath 0, it changes from a fuel right into a liquid. Liquid herbal fuel takes up a good deal much less space than herbal fuel, making it easy to move and handy to store. Six hundred cubic toes of natural gasoline turns into just one cubic foot of liquid fuel!
Gas Detection System Interview Questions
Question 25. What Is A “clever Pig?”
A clever pig is an digital tool that can be used to look at the insides of natural gas pipelines. The device travels via a pipeline and transmits photographs of the internal of the pipeline so inspectors can inform if the pipeline desires upkeep.
Question 26. Why Is Natural Gas Called “natural” Gas?
Natural fuel is referred to as “herbal” due to the fact when this kind of gas became first observed, it is able to be used without delay from the ground in its natural country, with none processing. Today, gas utilities technique natural gasoline by using casting off water, sand, and different compounds so that when the fuel is delivered to your private home, it's going to burn as cleanly and successfully as viable. And in its herbal country gasoline has no odor. That’s why gasoline utilities upload a innocent however pungent chemical known as mercaptan; the odor allows human beings scent a leak that otherwise, in the gas’s herbal country, doesn’t scent.
Question 27. What Is Shale Gas?
Shale gas is natural fuel that is trapped inside shale rock formations. Shales are excellent-grained sedimentary rocks that may be rich in oil and herbal gas. In the beyond decade, specially inside the United States, horizontal drilling mixed with hydraulic fracturing has allowed get entry to to big reservoirs of shale gasoline, completely reworking the herbal gasoline enterprise and electricity deliver dynamics.
Gas Analyzer Interview Questions
Question 28. How Different Is Shale Gas From Natural Gas?
There isn't any distinction. Shale gasoline is herbal fuel that comes from shale formations instead of other rock strata like limestone or sandstone. Natural fuel from shale is a much less carbon in depth gasoline relative to other fossil fuels and simply as reliable as a gas supply for European households, agencies and industries.
Question 29. What Is Hydraulic Fracturing?
Hydraulic fracturing is the method maximum normally used to release herbal fuel and oil from deep under the floor of the earth. Hydraulic fracturing is especially vital within the context of shale gasoline improvement. As shale gasoline reservoirs are trapped inside rock formations of very low permeability, the gasoline can best be launched into the properly via stimulating the shale formation through hydraulic fracturing.
Fracturing fluid – on common 99.95% water and sand with a small share of additives – is injected at high stress into the rock strata on common 3km under the surface. The force of the water creates a community of tiny fissures inside the rock and the water float acts as a delivery mechanism for the sand, which finds its manner into those newly created cracks to make sure they continue to be open. This creates passageways through which natural gas can travel to get to the wellbore.
The hydraulic fracturing system is typically performed on the begin of the existence of a well and normally lasts between three to five days after a properly is drilled, cased and cemented, and the drilling rig is removed.
Question 30. Is Hydraulic Fracturing A New Technology?
Hydraulic fracturing is not a new generation. It became first used within the United States in 1947 and because then over 1 million wells were hydraulically fracked global. Over the beyond 60 years, it's been used by energy organizations to release the herbal gas and oil trapped in rock formations, however also to stimulate the drift of water from water wells and to deliver geothermal (renewable power) wells into business viability. Today, almost nine out of 10 onshore natural fuel and oil wells require hydraulic fracturing to grow to be, or to remain, possible.
What is new, but, is using horizontal drilling drilling evolved inside the 1990s which allows hydraulic fracturing to turn out to be commercially viable. In horizontal drilling, numerous wellheads can be located at a unmarried properly site to get right of entry to extra fuel reserves from a single properly, decreasing the impact at ground degree.
Question 31. What Are The Advantages Of Cng As Automotive Fuel?
Low operational fee
Increased existence of lubricating oils
high auto-ignition temperature of 540 C
Question 32. What Is A Typical Cng Storage & Distribution Network?
Mother station and daughter booster stations
CNG is transported via garage cascades from Mother station to Daughter booster stations
Mother station and Online stations (Generally fed by means of pipeline)
Question 33. Cng Is Transported Through Pipeline From Mother Station To Cng Stations Is Cng Safe?
Yes, it's miles secure. The residences of CNG make it a secure gasoline. It is lighter than air, so in case of a leak it simply rises up and disperses into the atmosphere. Besides, a excessive automobile-ignition temperature of 540 ranges centigrade as towards petrol’s 360 C makes it a secure fuel. Also, in case of a leak, if CNG concentration in the air is less than five% or more than 15%, the gas will now not burn even in the presence of a spark.
Gas Compressor Interview Questions
Question 34. What Is The Difference In The Tank Sizes Of Cng And Lpg As Vehicle Fuel Is Concerned?
CNG storage tank is 3 times of LPG storage tank for the same extent.
Question 35. How Cng Is Measured?
CNG is sold in Kg and about 1.Three SCM (widespread cubic meter) of natural gasoline equals 1 kg, as the density is approximately zero.Seventy six and it slightly varies based totally upon the composition of the natural gasoline.
Question 36. We Can Store The Cng In The Cylinder Of Lpg For Automotive Purpose?
We cannot keep CNG in LPG cylinder as the LPG cylinder will be designed for a pressure of most effective 21 kg/cm2; wherein as operating strain of CNG is 240 Kg/cm2