RU2294430C1 - Method for gaseous hydrocarbon preparation for transportation - Google Patents

Abstract

FIELD: oil and gas industries, particularly gaseous hydrocarbon treatment with the use of low-temperature operation for preconditioning of product extracted from gas-condensate field.

SUBSTANCE: method involves supplying formation gas into the first stage separator; supplying gas separated at the first stage into the second stage separator through heat-exchanger of the first cooling stage; delivering gas separated at the second stage in the third stage separator through heat-exchanger of the second cooling stage and expansion means, for instance through throttle or ejector; passing gas separated at the third stage sequentially through heat-exchangers of the second and the first cooling stages and discharging liquid from separators into segregators. Instable condensate is alternately supplied from segregators in two accumulation vessels. High pressure gas exiting the primary separator is alternately fed to the accumulation vessels to transport instable condensate from above vessels.

EFFECT: provision of no-pump used instable condensate supply for condensate treatment with the use of pressure of gas flow after the primary separation thereof.

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Description

The invention relates to the oil and gas industry, in particular, to the processing of hydrocarbon gas using a low-temperature process and can be used in field preparation processes for the production of gas condensate fields.

A known method of preparing hydrocarbon gas for transport by the method of low-temperature gas separation (STC) of gas (see A.I. Gritsenko, V.A. Istomin and others. "Collection and field preparation of gas in the northern fields of Russia", M .: because of " Nedra ", 1999, pp. 372-373), which includes a first stage separator, a heat exchanger, a reducing device, a second stage separator and a three-phase separator.

The disadvantage of this method is that at high pressure in the condensate pipe, pumping units are necessary to ensure optimal thermobaric conditions in a low-temperature separator and for transporting hydrocarbon condensate.

The closest analogue in fact to the proposed technical solution is a method of preparing a gas-condensate mixture for transport by three-stage separation (see ibid., P. 378-379), which includes the formation gas supply to the first stage separator, the gas supply separated in the first stage through the heat exchanger of the first stage cooling to the separator of the second stage, the supply of gas separated in the second stage through the heat exchanger of the second cooling stage and the expansion (throttle or ejector) device to the separator of the third stage, the gas is separated in the third stage of the gas sequentially through heat exchangers of the second and first cooling stages and the discharge from the liquid separators to the separators. In front of the heat exchangers, a hydrate inhibitor, methanol, is supplied. In the method, due to the establishment of an intermediate separator (separator of the second separation stage) between the first and third stage separators, the consumption of concentrated methanol and associated operating costs are reduced.

The disadvantage of this method is the need to use pumping units to ensure optimal thermobaric conditions in a low-temperature separator and transporting condensate from the installation at high pressure in the condensate line.

The aim of the invention is to provide a pump-free supply of unstable condensate for processing using the pressure of the gas stream after its primary separation.

The goal is achieved as follows. In the method of preparing the gas-condensate mixture for transport by three-stage separation, which includes the formation gas supply to the first stage separator, the gas separated in the first stage through the heat exchanger of the first cooling stage to the second stage separator, the gas separated in the second stage through the heat exchanger of the second cooling stage and expanding (throttle or ejector) a device in the separator of the third stage, the supply of gas separated in the third stage in series through the heat exchangers of the second and ne a separate cooling stage and discharge from the liquid separators to the separators, in contrast to the prototype, the gas-condensate mixture preparation plant is additionally equipped with two tanks and gas pipelines after the primary separator to these tanks, in which unstable condensate is accumulated in turn and high pressure gas is supplied to transport condensate from the installation .

The invention is illustrated in the drawing.

The products of gas condensate wells are fed through a pipeline 1 to a separator of the first stage 2, where mechanical impurities, water and a liquid hydrocarbon phase are separated from it.

The liquid phase from the bottom of the separator of the first stage 2 through the pipe 3 is diverted to the separator 4, and the separated gas through the pipe 5 is diverted from the separator 2 and served in a regenerative heat exchanger of the first cooling stage 6.

After cooling in the heat exchanger 6, a gas-liquid mixture for separating gas and liquid is supplied through a pipe 7 to the separator of the second stage 8.

The liquid phase from the separator 7 through the pipe 8 is diverted to the separator 10, and the gas phase from the separator 7 through the pipe 11 for further cooling is fed to a regenerative heat exchanger of the second stage 12. Next, this gas is fed through the pipe 13 for cooling due to its expansion into a reducing device ( throttle or ejector) 14. The cooled gas-liquid mixture through a pipe 15 serves in the separator of the third stage 16.

The liquid phase from the separator 16 through the pipe 17 is diverted to the separator 10, and the gas phase from the separator 16 through the pipe 18 is supplied for heating to the heat exchanger 12. Then this gas is fed through the pipe 19 for heating to the heat exchanger 6 and then through the pipe 20 is removed from the installation to gas transportation system.

The water-methanol solution from the separator 4 through the pipe 21 is removed from the installation, the gas phase from the separator 4 is sent via the pipe 22 to the pipe 15, and the unstable condensate is sent through the pipe 23 to the storage tanks 24 and 25, in turn.

The water-methanol solution from the separator 10 through the pipe 26 is fed into the pipe 21 and removed from the installation, the gas phase from the separator 10 is sent through the pipe 27 to the ejector 14, and the unstable condensate is sent through the pipes 23 and 28 to the storage tanks 24 and 25 alternately.

After the unstable condensate has accumulated in the tank 24, high pressure gas is supplied to it through the pipe 29 to empty and transport the unstable condensate through the pipe 31. At the same time, the unstable condensate is switched: from the separators 4 and 26, hydrocarbon condensate flows into the storage tank 25. After the unstable condensate in a tank 25 through a pipe 30 high pressure gas is supplied to it for emptying and transporting condensate from the installation through a pipeline 32. Thus, an unstable hydrocarbon condensate accumulates alternately in tanks 24 and 25 and high pressure gas is alternately squeezed out of pipelines 29 and 30 of hydrocarbon condensate from tanks 24 and 25, respectively.

At the same time, pump-free transportation of unstable hydrocarbon condensate at high pressure in single-phase mode to the place of its subsequent processing (stabilization) is realized. Transportation of unstable condensate in a single-phase (liquid) state within the framework of the proposed method can be carried out over considerable distances (from hundreds of meters to tens of kilometers), since the gas pressure at the first separation stage is much higher than the pressure at which the hydrocarbon condensate is degassed (in the temperature range, at which transport condensate to its processing). This reduces the operating costs of condensate pumping and ensures its economical transport in a single-phase state.

To assess the effectiveness of the proposed method in comparison with the analogue of the prototype, studies were conducted in a field installation for the preparation of a hydrocarbon mixture for transport. The 6th production line of the low-temperature: separation unit (UKPG-2V of the Urengoy field) was supplied with stratum production of a gas condensate field in the amount of 90 thousand m ³ / h.

The results of studies on the processing of gas condensate mixtures according to the prototype and the proposed technical solution are given in table. In the studied modes, the pressure and temperature of the raw material at the inlet to the first stage separators were 7.5 MPa and 15 ° C, respectively. The gas temperature in the separators of the third (low temperature) stage was maintained at minus 30 ° C.

In the existing technology, while maintaining the pressure in the low-temperature separator at 4.5 MPa, the condensate pressure at the outlet of the unit was 4.3 MPa. In the proposed new technology, while maintaining the pressure in the low-temperature separator 2.5 MPa, the pressure of unstable condensate at the outlet of the unit was 7.2 MPa. Therefore, the proposed technology allows you to maintain pressure in the low-temperature separator, which ensures maximum condensation of heavy hydrocarbons, and ensure pump-free transportation of unstable condensate from the installation. At the same time, the cost of transporting condensate is reduced.

Thus, according to the proposed technology, it is possible to provide a pump-free condensate supply at the Urengoyskoye field until the end of field development, initially by using the pressure of the reservoir gas, and later after entering the BC by using the gas pressure after the BC.

The parameters of the installation of low-temperature separation of the prototype and the proposed method. Parameter Unit inlet pressure Pressure in the low temperature separator Unstable hydrocarbon condensate pressure at the plant outlet MPa MPa MPa According to the prototype 7.5 4,5 4.3 According to the proposed method 7.5 2,5 7.3

Claims (1)

A method of preparing a gas-condensate mixture for transport by three-stage separation, comprising supplying formation gas to a first stage separator, supplying gas separated in a first stage through a heat exchanger of a first cooling stage to a second stage separator, supplying gas separated in a second stage through a heat exchanger of a second cooling stage and an expansion device, an inductor or an ejector, to the separator of the third stage, the supply of gas separated in the third stage in series through the heat exchangers of the second and first th stage of cooling and removal of fluid separators, dividers, alternately applying unstable condensate from the separator in two storage tanks alternately supplying high pressure gas separator after the primary to these containers for the transport of unstable condensate of these containers.