RU2625846C2 - Method of non-waste pretreatment of production fluid - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for non-waste pretreatment of production fluid involves stepwise separation of wet gas to produce condensate and gas at each stage, separating the first stage gas under reflux conditions and reducing the second stage gas. The gas of the first stage and debutanization gas are dried. The dried first stage gas is reduced and separated in the second stage by cooling with the reduced second stage gas, which is then mixed with the dried debutanization gas and withdrawn as a sales one. The condensates of the first and second stages are reduced and debutanized to produce gas and sales condensate.

EFFECT: elimination of hydrate formation inhibitor consumption, elimination of light gas components losses and improvement of condensate quality.

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Description

The invention relates to methods for gas preparation by low-temperature condensation and can be used in the gas industry for field preparation of well production of gas condensate fields.

A known method of gas preparation (AM Churakaev Low-temperature rectification of petroleum gas - M: Nedra, 1989, p. 6), including compression, adsorption drying and gas purification using part of the dried gas to regenerate the adsorbent, low-temperature gas processing by regenerative cooling and separation to produce gas and condensate, which are fed to the demethanization column, the first after expansion in the expander, the second after throttling and degassing, the bottom product of the column is heated in regenerative heat exchange nickels and fed into the deethanization column, from the bottom of which NGL is discharged, and from the top, gas is taken which is heated in recuperative heat exchangers, mixed with the mixture of the product of the top of the demethanization column and degassing gas, heated and recovered as commercial gas.

The disadvantages of this method, which complicate its use in field conditions, are complexity, a large number of equipment, the use of fire heating and propane cooling.

The closest in technical essence to the claimed method is a method of low-temperature gas separation (RU 2543867, publ. 03/10/2015, IPC B01D 3/14, B01D 3/28), which includes a three-stage separation of crude gas (well products) with each the condensate and gas stages, the gas of the first stage is separated into the second stage under reflux carried out by cooling with commercial gas and the condensate of the third stage, the gas of the second stage is reduced and, together with the degassing gas, separated in the third stage to obtain a commodity gas condensates obtained is degassed to obtain unstable condensate gas and degassing. A hydrate inhibitor is supplied to the process streams.

The disadvantages of this method are the consumption of a hydrate inhibitor and the low quality of the condensate due to the high content of light components, which in the field are irretrievably lost with the condensate degassing gases.

The objective of the invention is the elimination of the consumption of a hydrate inhibitor, the exclusion of losses of light gas components and improving the quality of the condensate.

The technical result is the elimination of the consumption of a hydrate inhibitor due to drying of the first stage gas and debutanization gas, the elimination of losses of light gas components and the improvement of condensate quality due to its debutanization and mixing of the dried debutanization gas with the reduced heated second stage gas.

The specified technical result is achieved by the fact that in the known method, which includes stepwise separation of raw gas to produce condensate and gas at each stage, separation of gas of the first stage under reflux conditions and reduction of gas of the second stage, the feature is that the gas of the first stage and debutanization gas are drained , the dried gas of the first stage is reduced and separated in the second stage when cooled by the reduced gas of the second stage, which is then mixed with the dried gas of debutanization and removed as ovarnogo, and condensates of the first and second steps of reducing and debutaniziruyut to yield and product gas condensate.

Drying is carried out by any known method, for example adsorption, and debutanization is carried out, for example, by fractionation in a column with a cooled upper and heated lower part. The thermobaric conditions of separation and debutanization are calculated depending on the composition and characteristics of the raw gas.

The drying of the first stage gas and debutanization gas eliminates the consumption of a hydrate inhibitor. The debutanization of the reduced condensates of the first and second stages ensures a high quality of commodity condensate, and the mixing of the dried debutanization gas with the heated reduced gas of the second stage eliminates the loss of light gas components.

According to the proposed method, the raw gas 1 is separated in the first stage 2 to obtain hydrocarbon condensate 3, water condensate 4, which is removed, and gas 5, which is dried in the drying unit 6, the dried gas 7 is reduced using the device 8 and separated in the second stage by cooling the reduced gas of the second stage 9 under reflux conditions carried out in the reflux condenser 10 to obtain condensate 11 and gas 9, which is reduced using the device 12, heated in the reflux condenser 10, mixed with the dried debutanization gas 13 and the conclusion iat as a commercial gas 14. The condensates of the first 3 and second 10 stages are reduced using devices 15 and 16, respectively, and debutanized in column 17 to produce commercial condensate 18 and gas 19, which are dried in block 6 to obtain dried debutanization gas 13.

When implementing the proposed method, the crude gas composition,% vol .: carbon dioxide 0.2; nitrogen 0.7; methane 82.9; ethane 4.9; propane 3.4; butanes 2.6; pentanes 1.7; C ₆₊ - the rest, in an amount of 20.8 thousand nm ³ / h at a temperature of 26.8 ° C and a pressure of 12.0 MPa, is separated in the first stage to obtain 6.5 t / h of condensate and 18.3 thousand nm ³ / hour of gas, which is dried with silica gel to a temperature of dew point in water of minus 40 ° C, is reduced to 3.6 MPa and separated at the second stage under reflux conditions to obtain 1.8 t / h of condensate and 17.5 thousand nm ³ / h of gas , which is reduced to 1.2 MPa, is heated, mixed with dried debutanization gas, and 19.6 thousand nm ³ / h of commercial gas are withdrawn according to STO Gazprom 089-2010. The condensates of the first and second stages are reduced to 1.2 MPa and debutanized to produce 5.7 t / h of marketable condensate according to GOST R 54389-2011 with a saturated vapor pressure of 66.7 kPa according to Reid, and gas, which is dried to a dew point temperature of water minus 40 ° С. A hydrate inhibitor is not used.

Under similar conditions, in the prototype method using methanol as a hydrate inhibitor, condensate was obtained with a saturated vapor pressure of 641 kPa according to Reid, significantly higher than the standard, and the loss of light gas components was 0.7 thousand nm ³ / h.

Thus, the present invention eliminates the consumption of a hydrate inhibitor, eliminates the loss of light gas components, improves the quality of the condensate and can be used in the gas industry.

Claims (1)

A method for non-waste preparation of well products, including stepwise separation of crude gas to produce condensate and gas at each stage, separation of gas of the first stage under reflux and reduction of gas of the second stage, characterized in that the gas of the first stage and debutanization gas are dried, the dried gas of the first stage is reduced and separated in the second stage upon cooling with a reduced gas of the second stage, which is then mixed with the dried debutanization gas and removed as a commodity, and the condensates are first and reducing and second stages to obtain debutaniziruyut gas and product condensate.

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