RU2239124C1 - Method of transporting gas-water mixture - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method includes transporting gas-water mixture by multi-phase pump, removing water, and supplying it to the pipeline downstream of the multiphase pump.

EFFECT: reduced power consumption.

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Description

The invention relates to the oil industry, in particular to methods for transporting a gas-oil mixture, and is intended for use in a system for collecting and preparing high-water oil at a late stage in the development of an oil field.

There is a method of transporting a gas-oil mixture over long distances, which consists in gas separation and subsequent compression of the liquid to a pressure sufficient to deliver the liquid and gas in separate flows to the consumer (Tronov V.P. Oil Field Processing. M .: Nedra, 1977, see p. 117). In oil production, the method is widely used through the construction of booster pumping stations (BPS), where oil is collected and degassed; then degassed crude oil is transported by pumps to an oil treatment unit for deep dehydration and desalination.

The disadvantages of the technology are the high capital and energy costs of transporting oil, due to the need to build separation capacities, as well as a pipeline and compressor installation for delivering gas to a gas processing plant, which requires especially high operating costs for remote fields.

Also known is a method of operating a group of oil wells (see patent No. 2075592, IPC E 21 B 43/00, publ. BI No. 8 of 03/20/97), including transportation of well products at the wellhead with subsequent supply to a common collector and collection and preparation point oil, while at the wellhead they reduce the pressure by installing a multiphase pump in the common collector, with the help of which the products are supplied to the oil collection and preparation point.

The disadvantages of this method are: 1) high capital costs for the used multiphase pump (due to the high cost of high-tech in the production of screw pairs); 2) increased energy costs for pumping the mixture due to an increase in the viscosity of the liquid phase caused by the effect of redispersing exfoliated water; 3) malfunctions of the oil treatment unit, which receives the transported mixture (in particular, the process of “cold” water discharge is disrupted, which leads to the flow of excessive volumes of water into the heating furnaces for the implementation of high-temperature processes of deep dehydration and desalting of oil).

The closest in technical essence and the achieved results to the proposed one is “A method of transporting a gas-oil mixture using a multiphase pump (MFN)” (see patent No. 2098714, IPC F 17 D 1/14, issued by BI No. 34 of 10.12.97), including pre-processing it with a demulsifier, creating a discharge pressure and flow velocity in the pipeline in the terminal phase divider, which ensure the separation of the mixture into phases, their selection in separate streams and transportation to the destination, while I select from the terminal phase divider t of water, and the released oil with a residual gas and water content at the same time as the gas in separate streams is sent for additional mixing, respectively, in the upper and middle parts of the filter mixer, and then the mixture is fed to a multiphase pump.

The disadvantages of this method are the limited and low efficiency of its use in remote fields, where there are no consumers of discharged water. As a result, for pumping a gas-oil mixture, high capital costs are required for the multiphase pump used (due to the high cost of high-tech screw pair production); increased energy costs for pumping the mixture due to an increase in the viscosity of the liquid phase caused by the effect of redispersing exfoliated water; malfunctions of the oil treatment unit, to which the transported mixture enters (in particular, the process of “cold” water discharge is disrupted, which leads to the flow of excessive volumes of water into the heating furnaces for the implementation of high-temperature processes of deep dehydration and desalting of oil).

The technical task to be solved is to create such a method for transporting carbonated water-cut oil, which, at the minimum cost of reconstructing existing industrial schemes, would ensure energy-efficient pumping of the gas-oil mixture with a reduction in the cost of subsequent oil treatment.

The goal is achieved by the described method of transporting a gas-oil mixture, including its transfer by a multiphase pump.

What is new is that before the multiphase pump, the released water is selected and compressed by a single-phase pump, followed by supply to the pipeline after the multiphase pump.

The method is as follows. From a gas-oil mixture stratified in the pipeline from the fields, a gas-oil emulsion with a predominant content of gas and oil is fed to a multiphase pump. Separated water from the bottom of the pipeline or sump is fed by a single-phase pump to the pipeline after the MFD. Thus, the gas and oil and water flows are combined again and transported together further to the oil treatment unit.

Concrete example

Hourly, 200 m ^{3 of} gas and 100 m ^{3 of} liquid consisting of 50 m ^{3 of} water and 50 m ^{3 of} emulsion are supplied to the CSF every hour. The concentration of water in the emulsion is 60%. Therefore, 50 m ^{3 of} emulsion contains 30 m ^{3 of} dispersed water. Thus, a total of 80 m ^{3 of} water and 20 m ^{3 of} oil are transported. The mixture comes from the fields under pressure of 0.12-0.18 MPa. Gas in an amount of 200 m ³ / h and an oil-water emulsion in an amount of 50 m ³ / h are received at a multiphase pump. Pressure at the exit of MFN -2.0 MPa. Water in an amount of 50 m ³ / h is taken out by a single-phase pump (type TsNS-90) and fed into the pipeline after a multiphase pump. The comparison results of the known and proposed methods are presented in the table.

Notes:

1) In the known method, a viscosity increase of 1.6 times

2) can be excluded with acceptable separation of the emulsion in the pipeline

The table shows that after passing MFN in the known method, part of the free water (14.5 m ³ ) is redispersed, which leads to an increase in the viscosity of the emulsion by 1.6 times from 603 MPa · s to 945 MPa · s. In contrast to the known, the proposed method allows to prevent an increase in the viscosity of the emulsion and, therefore, to reduce the pressure loss in the pipeline from 2.38 MPa to 1.52 MPa. In addition, given the increase in pumping efficiency to 0.4, the cost of electricity for pumping the same volume of gas-oil mixture by the proposed method is reduced by 2.1 times. Moreover, the capital costs for implementing the proposed method are lower than for the known (4590 ... 5190 thousand rubles against 6000 thousand rubles) due to the fact that the total capital costs for implementing the proposed method include a multiphase pump of lower productivity (4500 against 6000 thousand rubles) and additional equipment: a single-phase pump [TsNS-60] (90 thousand rubles) and, in some cases, an end phase divider or sump (600 thousand rubles). A positive effect of the proposed method is also a reduction in the cost of additional processing with a demulsifier and energy costs for heating redispersed water.

The technical and economic efficiency of the proposed method consists of saving energy costs for pumping a multiphase mixture by reducing the viscosity of the pumped medium, capital costs for pumping through the use of a multiphase pump of lower productivity, as well as reducing the cost of subsequent oil treatment.

Claims (1)

A method of transporting a gas-oil mixture, including its pumping by a multiphase pump, characterized in that before the multiphase pump, the released water is taken out and its supply by a single-phase pump to the pipeline after the multiphase pump.