RU2376451C1 - Complex automation system of hydrat formation ihybitor distribution and dosage - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: invention related to oil-and-gas production meant for control of inhibitor supply into natural gas streams, for prevention hydraling process in it. The system consists of pump with drive, pressure collector, pipeline for inhibitor withdrawal from collector, pressure stabilisation independent loops, one of which formed with pressure control instrument in pressure collector, its outlet connected with frequency transformer automatic controller, which its outlet connected with pump drive. The second stabilisation loop forms direct action pressure control block, included in group of withdrawal devices between pressure collector and production devices.

EFFECT: broadening of inhibitor streams control system functionality, supplied through independently controlled canals in every point.

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Description

The present invention relates to the gas production industries and is intended to control the flow of the supplied inhibitor to the natural gas flows to prevent hydrate formation in them.

The task of regulating the supply of inhibitors for the gas industry has become especially urgent at the present time, when it was time to exploit the "old" gas condensate fields, such as Urengoyskoye, Yamburgskoye, which have developed their potential by 60-70 percent. The gas wells of these fields are more susceptible to flooding of the bottom-hole zone and to moisture transfer to the gas gathering network than in the newly developed ones.

In this case, the gas temperature decreases, which leads to the formation of hydrates in the wells, in the gas gathering network of the field, plumes and technological devices.

The gas hydrate mode during field operation is one of the most negative phenomena causing emergency situations at gas pipelines and wells. This, in turn, requires the use of various measures to prevent hydrate formation, one of which is the introduction of an inhibitor into gas streams.

The inhibition process consists in supplying an inhibitor through a special pipeline network to the protected sections of gas pipelines, which can be produced in various ways.

To introduce methanol (the most common inhibitor) into the gas stream, either special methanol containers (methanol containers) or metering pumps are used.

The methanol tank is set slightly above the entry point of the inhibitor and is communicated both on the bottom and top with the gas stream so that methanol can by gravity enter the gas line. The methanol flow rate is then controlled manually using a needle valve or automatically, according to a signal from an electric contact pressure gauge that measures the gas pressure in the pipeline. The disadvantage of this method is the frequent periodic maintenance and replenishment of methanol capacity, which is very problematic in the conditions of northern deposits, especially in the winter season.

When using dosing pumps, methanol is supplied to each point with its own pump (individual dosing). At the same time, flow control is carried out manually, by changing the performance of metering pumps.

Dosed supply by pumps to each point is carried out using domestic pumps ND, or when using multipoint metering devices with a common electric drive, for example, metering multipoint units of Bran & Lyubbe company.

The disadvantage of this method is the high cost of dosing equipment, as well as the fact that individual dosing requires considerable labor to maintain a fleet of pumping equipment, since the number of entry points in one gas collection network is about 100, and on the other hand, it is complex and expensive equipment. All these factors predetermined the limited application of the method.

Methods of centralized supply of an inhibitor from a high-capacity electric pump unit that overlaps the total supply at all input points to a common collector with subsequent distribution from it are most widely used in domestic fields.

It is known, for example, a device for controlling the flow of an inhibitor of hydrate formation in gas pipelines along the AS No. 1393901, which contains a system for collecting natural gas from wells to an integrated gas treatment unit (UKPG) through gas pipelines. The system also contains a centralized point of supply of a hydrate inhibitor, for example methanol, which supplies it from the pumping unit through the collector to the points of entry into the gas pipeline. On each supply line of the inhibitor to the input point, electrically controlled on-off valves are installed connected to the control device. The disadvantage of the considered system (prototype) is that when the flow is distributed over multichannel devices with independent channels of controlled supply for each channel, the excess liquid pumped by the pump must be dumped to the receiving tank, which is energetically impractical, since it assumes constant operation of the pump unit with high capacity at full power .

The aim of the invention is to eliminate this drawback, and the technical result is the expansion of the functionality of the flow control system of the inhibitor supplied through independent controlled channels to each point.

This goal is achieved by the fact that the proposed system functionally combines technical means that provide centralized injection of the inhibitor to the actuators, and technical means that provide the specified injection mode for excessive working pressure in the supply and distribution system of the inhibitor.

The drawing shows a diagram of the proposed system, which contains:

- one or more pumping units (pos. 1) with electric drives (pos. 2), supplying the inhibitor to the common collector (pos. 3);

- a pressure accumulator (pos. 4) installed on the discharge line of the pumps to smooth out pulsations during operation of the units on a common collector;

- an overpressure sensor (pos. 5) on the common collector (pos. 3), the output signal of which is supplied to the PID controller of the frequency converter (pos. 6), which controls the frequency of rotation of the electric drive (pos. 5);

- direct pressure regulator of type “to oneself” (pos. 7), the input of which is connected to the discharge line of high pressure, and the output to the discharge line of low pressure;

- direct pressure regulator of the type "after oneself" (pos. 8), connected between a common collector (pos. 3) and actuators (pos. 9) for supplying an inhibitor to technological equipment (pos. 10) and providing an allowable pressure difference per group inhibitor dosing valves to technological devices, the pressure of which is significantly lower than the total supply pressure;

- controlled actuators of inhibitor input units (pos. 11) installed at the inputs of individual methanol pipelines (pos. 12) that supply methanol to gas wells (pos. 13);

- uncontrolled blocks of distribution of the inhibitor between the wells of the cluster (pos. 14), connected to the outputs of the methanol pipelines (pos. 12);

- a control device (pos. 15) that controls the executive valves K ₁ ... K _n (pos. 9, 11). Valves K ₁ ... K _n provide dosing of the inhibitor to the protected points, and the valves are controlled by the inhibitor input control unit according to the specified program in a time-pulse manner, in which the valve having a limiting throttle opens for a predetermined time.

Valves K _2.1 ... K _2.n provide dosing of the inhibitor to well _clusters or individually to the well. The valves are also controlled by an inhibitor input control unit (key 15). The distribution of the inhibitor flow between the wells of the cluster, which does not have external power supply and remote control, is carried out by means of actuators (pos. 13), manually adjusted to a given flow rate for each well and automatically providing a predetermined flow ratio when the pressure in the common pipeline changes.

The system operates as follows.

The inhibitor from the receiving tank is fed by an electric pump unit to a common collector, the pressure in which is stabilized by an automatic control circuit "pressure sensor - frequency converter - pump electric drive" using the built-in PID controller in the frequency converter. The pressure in the manifold is maintained at the level set by P _ass due to the automatic control of the rotational speed of the pump unit drives.

In order to protect equipment and pipelines during transient pressure control in the supply system, a direct-acting pressure regulator is installed on the discharge manifold, which has a high speed and ensures the discharge of fluid from the manifold to the pump inlet line at the time of overshoot.

The stabilized pressure in the injection system of the inhibitor is distributed at the points of entry. The accuracy of a given flow rate at each point is ensured by a direct-acting flow regulator installed on a selective line between the discharge manifold and actuating valves. The pressure regulator ensures the maintenance of the required differential pressure on the actuators (valves).

Setting the regulator (pos. 8) ensures that the required pressure P _{1 is set} in a wide range, which gives the system universality when used at various gas production facilities according to the technological mode.

If the pressure at the entry points P _{2 is} higher than the pressure P ₁ , then the input of the inhibitor is made directly from a common reservoir with a stabilized pressure P.

The combination of the proposed devices and their interconnection make it possible to ensure the supply of an inhibitor and to quickly manage its value at each point or group of points with minimal energy and pumping equipment resources.

Claims (4)

1. A comprehensive automated system for the distribution and dosing of a hydrate inhibitor containing an electric pump unit, a pressure manifold, inhibitor withdrawal pipes from the manifold, characterized in that it contains independent pressure stabilization circuits, one of which is formed by a pressure sensor in the pressure manifold, the outlet of which is connected with an automatic regulator of the frequency converter, and the output of the latter is connected to the electric drive of the pump unit, the second stabilization circuit ION unit forms a direct-operated pressure regulator, included in the group of selected devices between the pressure manifold and the actuators. 2. The system according to claim 1, characterized in that it contains a pressure regulator "after itself", which forms, together with actuators, one controlled group of devices that supply the inhibitor to the protected points of the technological equipment according to a given algorithm and program. 3. The system according to claim 1, characterized in that it contains a group of actuators that provide direct controlled programmatic supply of the inhibitor to the well clusters from a common reservoir. 4. The system according to claim 1, characterized in that it contains adjustable devices on each inhibitor supply pipe to the well that provides an inhibitor flow distribution between the well wells in accordance with the individual settings for each well and automatically maintains a given pressure differential ratio.

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