RU2503801C2 - Method for down-hole treatment of gaslift well product - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes use of de-emulsifying compound and pour point depressant (PPD). According to invention at bottom hole temperature up to 80°C both reagents are supplied together into pressure-actuated operating agent - gas. When bottom hole temperature exceeds 80°C, PPD is supplied to pressure-actuated operating agent and de-emulsifying compound is supplied into the product at wellhead. Note that water-soluble de-emulsifying compound is used for watered product of 40%, and for watered product of more than 60% there used is an oil-soluble de-emulsifying compound. Any of the said reagent types can be used in interval 40-60%.

EFFECT: increase of gaslift well operation efficiency via reduction of water-oil emulsion viscosity, obtaining non-hardening stream in well as well as in submerged pipeline due to high temperature use at bottom-hole and rational use of reagents depending upon the temperature at bottom-hole.

2 ex

Description

The invention relates to the oil industry and can in particular be used in gas lift well operations.

The gas lift method of operating wells is the only mechanized method of oil production used in the offshore Dragon field in Vietnam. The oil of the field is a paraffin wax. There is a problem of reducing energy costs for the extraction of fluid from wells and its preparation for transport via an underwater pipeline to a technological platform.

It is known that watered high-paraffin oil (emulsion) must be treated with a demulsifier and a depressant additive. At the same time, a depressant additive that reduces the pour point of oil and oil should be heated above the melting point of paraffins, and heating of a demulsifier that reduces the viscosity of the emulsion above 80 ° C is not allowed.

A known method of preparing paraffin and solidifying oil for transport (see ed. Certificate. No. 1543181), which provides for the simultaneous introduction of reagents - demulsifiers and depressant additives.

The disadvantage of this method is that it can only be used in installations, which include oil heating furnaces. On offshore production platforms there are no heating furnaces for processing according to ed. testimonial. No. 1543181.

In the current situation, the oil produced by the gas-lift method is transported to the central technological platform via the underwater pipeline and cooled to the temperature of sea water in the Dragon field, therefore it freezes during stops, causing an emergency.

Thus, the technical problem arises: to process the production of gas-lift wells on the production platform in the absence of oil heating furnaces.

The purpose of the invention is to increase the efficiency of a gas-lift well by reducing the viscosity of the oil-water emulsion and its preparation for transport to the technological platform by obtaining a non-freezing flow both in the well and in the underwater pipeline due to the use of high temperature at the bottom and rational use of reagents depending on the temperature slaughter.

This goal is achieved in that at a temperature at the bottom of the well up to 80 ° C, both reagents are fed together to the injected working agent (gas); at a temperature at the bottom of the well above 80 ° C, the depressant additive is fed into the injected working agent, and the demulsifier is introduced into the product at the wellhead, while water-soluble demulsifier is used for water-cut products up to 40%, and an oil-soluble demulsifier is used for water cuts over 60%, in the water cut range of 40-60% use any of these types of reagents.

The injected working agent containing reagents is mixed at the bottom of the well with the hot produced products, and during the ascent to the wellhead, the products are prepared for transport to the technological platform.

The mechanism of action of reagents for various temperature zones at the bottom of the wells. When the temperature at the bottom of the well is up to 80 ° C, the supply of both reagents together into the injected working agent allows to reduce the viscosity of the oil-water emulsion and to obtain a non-setting stream both in the well and in the underwater pipeline due to the use of high temperature at the bottom. At a temperature at the bottom of the well above 80 ° C, the depressant additive is fed into the injected working agent, and the demulsifier is introduced into the product at the wellhead. In this case, the above described positive effects are realized, and the demulsifier is protected from excessively high temperature, since demulsifiers, unlike depressant additives, are subject to thermal degradation at temperatures above 80 ° C. For waterlogged products up to 40% use a water-soluble demulsifier. This avoids the increased costs of the reagent, given that it partially dissolves in the aqueous phase without producing useful work. In the water cut range of 40-60%, any of the above types of reagents are used, based on their cost.

Using the alleged invention will allow:

- to prepare the production of gas lift wells for transport to the technological platform through the use of high temperature at the bottom without the use of oil heating furnaces;

- eliminate possible emergency situations on the underwater pipeline after long stops;

- will save demulsifying reagents;

- facilitate the operation of the installation of thermochemical oil dehydration on a technological platform;

- improve the condition of the air basin, because there is no need to build heating furnaces on the mining platform.

Example 1

On the offshore stationary platform at well No. 1, paraffin oil with a water cut of 35% is produced by the gas-lift method. The temperature at the bottom of the well is 69 ° C. The pour point of oil is 25 ° C. Produced products through an underwater pipeline 3.8 km long are transported to a technological platform for processing and receiving marketable oil. The temperature of sea water is 18 ° C. During planned shutdowns of the production and transport systems, in order to avoid oil freezing in the pipeline, it is displaced by sea water. There are problems with the disposal of contaminated water when putting the pipeline into operation.

During unscheduled shutdowns of the system, emergency situations occur when the frozen pipeline is put into operation.

To eliminate such complications, a Flexoil CW-288 depressant additive with a dosage of 600 g / t and a water-soluble demulsifier SNPCH-4114 manufactured by OJSC NIIneftepromkhim are fed into the well by dosing into the working agent. As a result, the pour point of oil is reduced to 12 ° C and low-viscosity products, partially prepared to produce marketable oil, enter the technological platform.

Example 2

On the offshore stationary platform at well No. 11, paraffin oil with a water cut of 70% is produced by the gas-lift method. The temperature at the bottom of the well is 87 ° C. The pour point of oil is 25 ° C. Produced products via an underwater pipeline 3.1 km long are transported to a technological platform for processing and receiving marketable oil. The temperature of sea water is 18 ° C. During planned shutdowns of the production and transport systems, in order to avoid oil freezing in the pipeline, it is displaced by sea water. There are problems with the disposal of contaminated water when putting the pipeline into operation.

During unscheduled shutdowns of the system, emergency situations occur when the frozen pipeline is put into operation.

To eliminate such complications, a Dodiflow 5200 depressant additive with a dosage of 600 g / t is fed into the well by dosing into the working agent. Oil-soluble imported demulsifier R-11 or domestic SNPCH-4204B manufactured by OJSC NIIneftepromkhim is fed to the flow line at the wellhead. As a result, the pour point of oil is reduced to 12 ° C and low-viscosity products, partially prepared to produce marketable oil, enter the technological platform.

Claims (1)

A method for downhole processing of gas-lift well products, including the use of a demulsifier and a depressant additive, characterized in that at a bottomhole temperature of up to 80 ° C, both reagents are supplied together to a pumped working agent — gas; at a temperature at the bottom of the well above 80 ° C, the depressant additive is fed into the injected working agent, and the demulsifier is introduced into the product at the wellhead, while water-soluble demulsifier is used for irrigated products up to 40%, and an oil-soluble demulsifier is used for water cut of over 60%, in the water cut range of 40-60% use any of these types of reagents.