RU2282102C2 - Method to protect well discharge pipelines from solidification at abnormal oil fields - Google Patents

Abstract

FIELD: oil producing industry.

SUBSTANCE: according to proposed method protection of discharge pipelines of oil well from solidification at abnormal oil fields, when well is shut down, annulus gate valve on wellhead equipment is opened, liquid from discharge pipeline is drained by gravity into well annulus space, and liquid is replaced by annulus gas. Before bringing well into production, annulus gate valve is closed, and communication of well annulus space with discharge pipeline through check valve installed on line connecting discharge pipeline with annulus space is provided.

EFFECT: improved efficiency of protection of discharge pipelines.

1 dwg

Description

The invention relates to the oil industry and helps to prevent the hardening of highly viscous oils and emulsions in flow lines of wells.

It is known that in the case of well shutdowns in the winter, it is possible to freeze viscous products in the flow line. When attempting to start, the deep-pumping equipment experiences stresses not only from the column of products being lifted from the well, but also from the loss of fluidity in the flow line piping. If the flow line is sufficiently long (commensurate with the depth of the pump suspension in the well), an attempt to start often leads to emergency situations.

A known method of protecting flow lines from freezing (a.s. 1714287) when stopping wells. It provides for the replacement of produced products in the flow line with a foam structure supplied by a foam generator. Foam is created on the basis of water, antifreeze, surfactants and acetylene, obtained at the wellhead from calcium carbide.

The disadvantage is that the method for its implementation requires the installation of additional equipment (foam generator) and reagents (surfactants, antifreeze, calcium carbide).

A known method of displacing a liquid from a flow line by gas injection (as.with. 1499055). The disadvantage is that the method for its implementation requires the installation of an expensive and complex additional unit - a compressor.

Thus, the problem arises of creating a simple and reliable way to protect flow wells of pipelines from freezing in abnormal oil fields.

This problem is solved by the proposed method for protecting flow wells of pipelines from solidification. According to the invention, the method includes a technological operation for replacing the produced products in a flow line with a low-viscosity non-curing agent. To implement the method, do not use any additional units and generators: when stopping, they open the annular valve on the wellhead fittings and by gravity drain the liquid from the flow pipe into the annulus of the well, while replacing it with annular gas, and before starting the well, the annular valve is closed and provides communication annular space of a well with a flow line through a check valve.

The gate valve opens and closes manually or by command from the control room.

The proposed method is characterized by a new technological operation - the replacement of liquid in the flow line with a low-viscosity non-curing agent is carried out through the use of gravity. To do this, open the annular valve on the wellhead and drain the fluid from the flow line into the annulus of the well by gravity. The merging fluid is replaced by gas from the annulus of the well. The fluid in the well can be in the liquid state indefinitely due to the thermal field of the earth. The temperature in the well is quite high and is determined by the magnitude of the geothermal gradient in the area.

The purpose of the invention is to increase the efficiency of protection flow wells of pipelines from solidification through the use of the thermal field of the earth.

This goal is achieved by the fact that when the well stops, the annular valve on the wellhead valve is opened, gravity is drained from the flow pipe into the annular space of the well, the fluid is replaced by annular gas, and before the start of the well, the annular valve is closed, and the annular space of the well is connected to the flow pipeline through a check valve installed on the line connecting the flow line with the annulus.

The drawing shows a schematic diagram of the layout of the equipment for implementing the method of protecting flow wells from freezing in the fields of abnormal oils, which contains wellhead valves 1, flow tubes 2, mounting valve 3, annular valve 4, check valve 5.

A method of protecting flow wells of pipelines from solidification is as follows:

when the well is operating well, the produced products through the flow line 2 enter the oil collector, the valve 3 is open, and the valve 4 is closed. Gas accumulating in the annulus of the well through the check valve 5 also enters the annulus. During steady well operation, the cross section of the flow line is filled with oil and gas. In the event of a well shutdown, individual sections of the flow pipeline due to the separation of the gas-liquid mixture can be completely filled with highly viscous oil and emulsion, which freezing in winter time in flow pipes often leads to emergency situations.

To protect the flowlines of the wells from freezing in the anomalous oil fields according to the invention, when the well is shut off, an annular valve 4 is opened on the wellhead and gravity is drained from the flow pipeline into the annular space of the well through open valves 3 and 4, while the merging fluid displaces the gas from the annulus wells in the flow line and replaces it with annular gas.

If the amount of fluid in the flow pipe is less than the volume of the annulus, it completely drains into the well, where the temperature is much higher than at the depth of the pipeline. If there is more liquid and it does not completely merge from the pipeline, the remainder of it in the discharge pipe will occupy only part of the section. Putting such a pipeline into operation after long stops is straightforward.

Before the start of the well, the annular valve 4 is closed and the annulus of the well is connected to the flow pipe through the mounting valve 3 and the check valve 5. After the start of the well, the flow of produced relatively warm products enters the flow pipe, which is completely or partially filled with gas and practically does not render hydraulic resistance to a stream. Gas accumulating in the annulus of the well, as soon as its pressure exceeds the pressure in the flow line, through the mounting valve 3 and the check valve 5 is vented into the flow line.

The proposed method for protecting flow wells of pipelines from solidification at abnormal oil fields has the following advantages:

does not require the installation of additional equipment (foam generator) and reagents (surfactants, antifreeze, calcium carbide);

does not require the installation of an expensive and complex additional unit - a compressor;

uses free geothermal heat;

does not pollute the extracted products with extraneous reagents and chemical reaction products;

does not worsen the environmental situation;

characterized by industrial safety.

Claims (1)

A method for protecting flow wells from freezing in anomalous oil fields, including replacing the produced products in flow ducts with a low-viscosity non-pouring agent, characterized in that when the well stops, the annular valve on the wellhead valve is opened, gravity is drained from the flow duct into the annulus of the well, replaced fluid with annular gas, while before starting the well, the annular valve is closed, they provide a connection between the annular space of the well and the flow m duct via a check valve mounted on a line connecting the flowline pipe to the annulus.