What Exactly is Condensate in Oil & Gas?
Condensates and natural gas liquids are a rapidly growing segment of US and international oil & gas production. The following sections provide a detailed overview of NGLs, their composition, extraction processes, and uses.
Frequently Asked Questions
Have questions? Here are answers to some frequently asked questions.
Is Condensate Liquid or Gas?
Both dry and wet gas contain vaporized liquid hydrocarbons whose density or gravity is much less than crude oil. Condensates are the liquid form of these hydrocarbons that take their name from the process of removing them from the gas stream by processing with specific temperature and pressure.
How Much is a Barrel of Condensate Worth?
Just as crude oil prices vary depending on region, quality, and gravity, condensate prices depend on where it is produced, gravity or BTU, and market demand. As of June 2021, a barrel of East Texas Condensate cost nearly $66.
Is NGL the Same as Condensate?
Natural gas liquids (NGL) and condensate can generally be used interchangeably. NGLs and condensates both comprise a mixed stream of hydrocarbons representing light hydrocarbons, such as ethane, and heavier hydrocarbons, such as pentane.
What Does Condensate Look Like?
Natural gas liquids are typically colorless and odorless under ambient conditions. Because field or lease condensate can contain toxic associated gases, care must be taken to avoid even a few breaths near storage tanks and vents.
What is the Difference Between Crude Oil and Condensate?
Crude oil and natural gas liquids both represent varying grades and densities of liquid hydrocarbons. NGLs can be thought of as a very light oil. However, it is very volatile with higher BTU than crude, making it more dangerous to handle and transport.
How is Condensate Formed?
NGLs are naturally occurring hydrocarbons that are lighter in molecular composition than crude oil or natural gas. They occur as vapor in natural gas and can be dissolved in crude oil or occur separately in oil reservoirs. Condensates form when their vapor pressure is lowered to the point that the natural gas liquids condense out of the gas stream into a liquid that can be stored at room temperature.
Composition of Condensates
Natural gas liquids are composed of primarily natural gas liquids as well as some naphtha material. It’s API is lower than crude oil at 45 to 80. Most condensate is a mixed stream of natural gas liquids that include ethane, propane, butane, isobutane, and pentane.
Different Types of NGL
NGLs can be recovered from both natural gas and crude oil. Some NGLs are extracted in the field while most are extracted through processing plants and fractionation.
Natural Gas Condensate
Natural gas liquids are suspended as vapor in wet and dry gas. NGL produced at the wellhead remains as vapor until condensed out of the gas stream through heat and pressure.
Natural Gas Condensate Uses
Once separated, treated, and refined, natural gas liquids have a wide range of applications, including petrochemical feed stocks used to create plastics, heating, and production of gasoline. Condensates are also a preferred diluent for blending with heavier Canadian crudes to improve pipeline flow.
While most associated gas is separated at the wellhead, some NGLs remain suspended in the liquids. It can be separated through crude oil stabilization and fed into the gas stream for processing.
Crude Oil Condensate Uses
Once extracted from oil, NGL has the same commercial applications as the NGLs that occur in natural gas.
What is Lease or Field Condensate?
Natural gasoline, or drip gas, is a byproduct of water separation, also called lease condensate. It is called lease condensate because the condensation process occurs in the field vs. a processing plant.
What is Plant Condensate?
After NGL stabilization, separation, and fractionation, the remaining product is often referred to as plant condensate. Plant condensate is typically Pentane Plus and heavier natural gas liquids.
Condensate vs. Natural Gas – What is the Difference?
“Natural gas” refers to methane, the lightest gaseous hydrocarbon produced from wells. Vaporized hydrocarbons are considered natural gas liquids starting with the next lightest hydrocarbon ethane, followed by increasingly heavier propane, butane, isobutane, and pentane.
What is the Difference Between NGL, LNG, and LPG?
Natural gas liquids (NGLs) are hydrocarbons that can be condensed out of the gas stream, including ethane and propane, which are often grouped and referred to as liquified petroleum gas (LPG). Liquefied natural gas (LNG) is liquid methane, however unlike condensates that remain liquids following separation or fractionation, LNG must be kept at -160° F primarily as an efficient method of transporting LNG by ship.
Most interstate pipelines limit the hydrocarbons that can be transported to 1,100 BTU per standard cubic foot (SCF). Because condensates can often have a minimum of 1,800 BTU they can only be transported safely following gathering and processing to reduce their BTU to less than 1,100.
Extracting Condensate in Oil and Gas
Pressure and temperature cause the heaviest NGLs to fall out of the gas stream at different stages of the value chain either as a byproduct of gathering (such as compression and water separation) or through specific processes designed to condense and extract NGLs.
Crude Oil Stabilization Unit
Oilfield stabilizers are used to remove suspended natural gas and NGLs and lower the oil’s vapor pressure in order to make it suitable for sale or transportation. The crude oil stabilization process partially distills the oil by increasing heat and pressure inside a fractionation vessel to drive off lighter hydrocarbons, creating stabilized, or dead, oil. Separated NGLs are added to the gas stream for processing.
How Gas Processing Plants Separate NGL
The combined stream of NGLs are transported to gas processing plants where it is often referred to as raw make or y-grade. One method of extracting ethane is cryogenic expansion, where the gas stream is dropped to -120° F to separate the lightest of the NGLs if economic.
What is Condensate Stabilization?
There are hundreds of natural gas processing facilities in the US alone. The purpose of natural gas processors is to stabilize, treat, and separate methane (natural gas) and NGLs from wet and sour gas streams.
NGL Stabilization Facility
Extensive networks of gas gathering and transportation pipelines feed into gas processing facilities where separated dry, residue gas and NGLs exit the plant through the “tailgate.”
Natural Gas Condensate Stabilizer
Following water separation in the field, the gas stream enters the natural gas liquids stabilization unit where it is preheated in the inlet heat exchanger. It then flows to an upper unit of the stabilization tower where lighter hydrocarbons rise and exit the vapor outlet, including methane, ethane, propane, and butane.
Heating Unit Stabilizers
The heating unit stabilizer provides a continuous process in which heavier NGLs descend through the heater to flash off lighter hydrocarbons, which rise and exit the unit. Stabilized NGLs collect in the base of the tower then flow to the inlet heat exchanger where the stabilized liquids cool before flowing to storage tanks.
Vapor that exits the stabilization tower enters an ambient cooler and then to a low pressure NGL separator. Natural gas (methane) then flows to a compressor and exits the tailgate for sale. NGLs flow out of the separator into a blow case for compression and transport by pipeline or truck.
Condensate Stabilization Process Flow Diagram
The pure NGL stream that exits stabilization and separation facilities is a combined stream of hydrocarbons that must be broken down further into their constituent molecules through the fractionation process. NGLs are fed in sequence into vessels with increasing heat and pressure that target specific NGLs. NGLs flow first into the deethanizer and then to the depropanizer, debutanizer, and last the deisobutanizer. The final product after the lighter hydrocarbons have been condensed out of the gas stream is plant condensate, which is typically Pentane Plus.
Ethane Cracking and Ethylene Production
Over the last decade, the infrastructure to transport ethane has steadily improved, enabling it to be exported for the production of ethylene and various plastics that are used in many consumer and commercial products. Ethylene is produced through a complex process known as ethane cracking in which a mixture of ethane and some propane are heated at extreme high temperatures to “crack” the ethylene away, which is then quenched in water, treated, separated, and dried.
NGL Commercial Applications and Products
Once broken out of the gas stream, individual NGL products have a variety of applications with a growing overseas export market.
Ethane is entirely used as a petrochemical feed stock. Through the cracking process, it is transformed into ethylene and various household and commercial products that contain polyethylene, plastics, PVC, and polystyrene.
Propane has some petrochemical uses but is primarily an alternative heating source to methane and is typically used for outdoor grills and commercial heating applications. About 10% of propane is exported.
The majority of butane is used as a blending stock for gasoline. About 20% is used as a petrochemical feed stock and 10% is exported.
Isobutane is entirely used as stock for motor gasoline.
Pentane Plus Uses
About 70% of pentane plus is used as a gasoline blend stock with 10% used as a petrochemical feed stock and 10% used for ethanol denaturing. Approximately 10% of Pentane Plus is exported.
Does the US Export Ban Prevent NGL from Being Exported?
Until recently, the US prohibited the export of all crude oil, with the exception of Canada, due to an energy bill passed in Congress following the 1973 Arab oil embargo. Because the US has been a net importer of hydrocarbons for decades, exporting has been a moot point until the Shale Revolution. In June 2014 Pioneer Natural Resources and Enterprise Products Partners received approval from the Department of Commerce Bureau of Industry and Security to export a limited amount of Eagle Ford condensate which was ruled a “product” and therefore exportable, since it had been processed through a field stabilization unit. Other producers followed suit and after pressure from the industry to begin exporting crude oil, the Obama administration passed the 2016 Consolidated Appropriations Act, which opened the doors for the US to become a crude oil and NGL exporter.
Today, the US exports crude oil and NGLs to more than 30 countries. With the current explosion in unconventional shale development vastly increasing the quantity of NGL being produced, the domestic market has been overwhelmed. Traditionally field condensate was a preferred source of feedstock for petrochemical refineries. However, with the decline in the 1970’s of the lighter grades of crude, domestic refiners switched to refining heavier grades of crude and now have less of a need for lighter feedstock without costly conversions of their facilities. As a result, the US remains a net importer of crude oil because refineries are only configured to process heavy, sour crude. Light, sweet crude oil and NGLs, on the other hand, are increasingly being exported.
Why is OECD Not Reporting Condensate in Oil?
The Organization for Economic Cooperation and Development (OECD) provides reporting on OPEC oil & gas production. The definition of what constitutes NGLs varies widely within OPEC with some members defining it as light crude. As a result, OECD reports NGL production only from those countries who report it separately.
Why is Texas Reported Oil and NGL Production Different than EIA Reported Production?
For reporting purposes, the U.S. Energy Information Administration (EIA) defines lease condensate as crude oil and plant condensate as a natural gas liquid. The Texas Railroad Commission reports all NGLs separately from crude oil. In addition, EIA and TRRC condensate production data may differ because of reporting lags across multiple state agencies and datasets that are continuously being updated as operators revise production volumes over time.
Eagle Ford Condensate / NGL Production
Today, more NGL than oil is exported from the Eagle Ford Shale, which spans 26 Texas counties from Temple and Waco to Laredo and Eagle Pass. The basin was the first to begin exporting condensates in 2014. The Eagle Ford has benefited from its close proximity to the ship terminals at Corpus Christi and exports are only expected to increase in the next decade.
U.S. Field Production of Natural Gas Liquids
(Thousand Barrels per Day)
|Date||U.S. Field Production of Natural Gas Liquids (Thousand Barrels per Day)|
What do you think? Leave a comment below.