System for dehydrating and cooling a produced gas to remove natural gas liquids and waste liquids
View Patent ↗Produced natural gas containing carbon dioxide is dehydrated and chilled to liquefy the carbon dioxide and then fractionated to produce a waste stream of liquid carbon dioxide and hydrogen sulfide. Natural gas liquids may be first separated and removed before fractionation. After fractionation, the waste stream is pressurized and transmitted to a remote injection well for injection either for disposal of the waste stream and preferably to urge hydrocarbons toward the producing well. A hydrocarbon stream proceeds from fractionation to a methanol absorber system which removes carbon dioxide gas. The hydrocarbon stream is thereafter separated into at least hydrocarbon gas, nitrogen and helium. Some of the nitrogen is reintroduced into a fractionation tower to enhance the recovery of hydrocarbons. A methanol recovery system is provided to recover and reuse the methanol. The hydrocarbons are sold as natural gas and the helium is recovered and sold. Excess nitrogen is vented.
1. A process comprising:
obtaining produced gas from a source of produced gas, said produced gas including hydrocarbon gas, natural gas liquids and waste gas including at least carbon dioxide;
dehydrating the produced gas to form an inlet stream;
removing the natural gas liquids from said inlet stream;
cooling said inlet stream;
providing a fractionation tower;
supplying said inlet stream to said fractionation tower;
fractionating said inlet stream in said fractionation tower to form
a first gas stream including said hydrocarbon gas and a portion of said waste gas, and to form
a waste liquid stream including the other portion of said waste gas as liquid;
separating said first gas stream into a stream of hydrocarbon gas and a return stream of separate waste gas;
supplying said return stream for fractionation with said inlet stream in said fractionation tower;
supplying said stream of hydrocarbon gas as an output; and
supplying said waste liquid stream as a waste output.
2. The process of claim 1 wherein cooling of said dehydrated produced gas is effected next in sequence following said dehydrating the produced gas and removal of said natural gas liquids.
3. The process of claim 2 wherein said fractionation is effected next in sequence after cooling.
4. The process of claim 3 wherein said waste gas includes hydrogen sulfide.
5. The process of claim 4 further including injecting said waste output into a well separate from one or more wells supplying said produced gas.
6. A process comprising:
obtaining produced gas from a source of produced gas, said produced gas including NGL, at least one hydrocarbon gas and at least carbon dioxide;
supplying an inlet system for dehydrating the produced gas;
supplying a NGL system to remove NGL's from said produced gas;
supplying a heat exchanger to cool produced gas after dehydration;
supplying a gas processing system for separating gases of the produced gas after cooling;
supplying said produced gas to said inlet system and operating said inlet system to dehydrate the produced gas and to form inlet gas;
supplying said inlet gas to an NGL system and operating said NGL system to remove NGL from said inlet gas;
supplying said inlet gas from said NGL system to said heat exchanger to cool said inlet gas;
providing a fractionation tower;
supplying said inlet gas to said fractionation tower and operating said fractionation tower to form
a first gas stream including said hydrocarbon gas and a portion of said carbon dioxide as a gas and a second stream with the other portion of said carbon dioxide as a liquid;
processing said first stream to separate said carbon dioxide gas into a return stream and to separate said hydrocarbon gas into a hydrocarbon stream;
returning said return stream for incorporation with said dehydrated and cooled produced gas;
supplying said hydrocarbon stream as an hydrocarbon output; and
supplying said second stream as a waste output.
7. The process of claim 6 wherein said return stream is supplied only to said heat exchanger and then to said fractionation tower.
8. The process of claim 6 wherein said produced gas includes hydrogen sulfide and wherein said processing system is operated so that hydrogen sulfide is included in said waste output.
9. The process of claim 6 wherein said produced gas includes recovered helium which is the only source of helium in said process.
10. A process comprising:
obtaining produced gas from a source of produced gas, said produced gas including hydrocarbon gas, natural gas liquids, helium and waste gas including at least carbon dioxide;
dehydrating the produced gas to form an inlet stream;
removing the natural gas liquids from said inlet stream;
cooling said inlet stream;
providing a fractionation tower;
supplying said inlet stream to said fractionation tower;
fractionating said inlet stream in said fractionation tower-to form
a first gas stream including said hydrocarbon gas, said helium and a portion of said waste gas, and
a waste liquid stream including the other portion of said waste gas as a liquid;
separating said first gas stream into a stream of hydrocarbon gas with said helium and a return stream of separated waste gas;
supplying said return stream for fractionation with said inlet stream in said fractionation tower;
separating said helium from said hydrocarbon gas to form a stream of hydrocarbon gas and helium;
supplying said stream of hydrocarbon gas as an output and supplying said helium as an output; and
supplying said waste liquid stream as a waste output.
11. A process comprising:
obtaining produced gas from a source of produced gas, said produced gas including hydrocarbon gas, natural gas liquids, helium and waste gas including at least carbon dioxide;
dehydrating the produced gas to form an inlet stream;
removing the natural gas liquids from said inlet stream;
providing a heat exchanger;
supplying said inlet stream to said heat exchanger and cooling said inlet stream;
providing a fractionation tower;
supplying said inlet stream to said fractionation tower;
fractionating said inlet stream in said fractionation tower-to form
a first gas stream including said hydrocarbon gas, said helium and a portion of said waste gas, and
a waste liquid stream including the other portion of said waste gas as a liquid;
separating said first gas stream into a stream of hydrocarbon gas with said helium and a return stream of separated waste gas;
supplying said return stream to said heat exchanger;
supplying said return stream from said heat exchanger for combination with said inlet stream and for fractionation in said fractionation tower;
separating said helium from said hydrocarbon gas to form a stream of hydrocarbon gas and helium;
supplying said stream of hydrocarbon gas as an output and supplying said helium as an output; and
supplying said waste liquid stream as a waste output.
12. The process of claim 11 wherein said helium is the only source of helium in said process.