RU2760183C1 - Method for operating gas wells at later stage of natural gas field development and device for its implementation - Google Patents

Abstract

FIELD: gas fields development.SUBSTANCE: method for operating gas wells at a late stage in the development of natural gas fields is claimed. The method includes the production of a gas-liquid mixture from wells. Separation of free gas from liquid and its subsequent supply to the inlet of the mixing chamber of the jet apparatus, which reduces the wellhead pressure of gas wells and increases the actual flow rate of the produced gas-liquid mixture from the bottom of the well. A high-pressure flow for ejection of a low-pressure gas is created with a water-methanol solution, which is used in the recirculation mode. The captured produced gas is separated in the first section of the bullet due to centrifugal and gravitational forces and is directed through the gas pipeline-loop to the complex gas treatment unit. Part of this gas is sampled, which is periodically pumped into the annulus of individual production wells to remove the accumulated column of liquid from their tubing. The selection of tubing is carried out by the APCS according to the values of the parameters controlled by its telemechanics system at the wellheads, which make it possible to identify the wells that require this operation. The degassed liquid released in the separator is sent to the second section of the bullet, from which it is pumped back into the field formation below the level of the gas-water contact through the least productive or inactive well of the cluster. The well has the maximum distance from the bottom of other wells in the cluster. Also claimed is a device for implementing the method.EFFECT: increasing (maintaining) the production rate of wells, ensuring stable technological modes of well operation at the final stage of the development of gas fields, increasing the gas recovery factor, as well as expanding the field of application of jet devices in gas production.2 cl, 1 dwg

Description

The invention relates to the gas production industry, namely to the operation of gas wells at the final stage of field development, in particular to the operation of self-restraining wells, in which the gas flow rate is insufficient to remove liquid from the bottomhole.

The production of hydrocarbons at the final stage of the development of gas and gas condensate fields is characterized by a low energy potential of the reservoir and unstable well operation. Under conditions of reduced reservoir pressure and a drop in the gas flow rate below the required value for the removal of the liquid phase along the wellbore, at the bottom and in the bottomhole zone of the formation, a process of fluid accumulation occurs, which leads to an increase in backpressure to the formation, an accelerated rate of decline in hydrocarbon production, transition to operation in a periodic mode, and then to spontaneous shutdown of wells.

With a cluster scheme for piping gas wells that penetrate various production facilities, when the minimum permissible wellhead pressure for stable operation is determined by the line pressure of the common gas-gathering reservoir, the situation becomes much more complicated. In most cases, when the wellhead pressure of one of the wells drops to a critical value, the latter is temporarily transferred to an inactive stock until the line pressure decreases due to the depletion of reserves and a decrease in the wellhead pressure of the remaining wells in the cluster.

Currently, many methods have been proposed to neutralize the negative effect of fluid accumulation in a well on gas production and to improve the efficiency of operation of watering gas wells. However, along with the advantages, each of them has disadvantages that limit their use.

A known method of operating gas wells at a late stage of development of natural gas fields [see. Muravyov, V.M. Operation of oil and gas wells: a textbook for technical schools / V.M. Muravyov. - M .: Nedra, 1978. - S. 367-369], including periodic blowing of the wellbore with its development on a flare device.

Significant disadvantages of this method are the need for maintenance personnel to travel to the well, temporary disconnection of the well from the gas collection network and the resulting loss of gas production; release of greenhouse gases into the atmosphere, which leads to significant irretrievable gas losses and harm to the environment.

A known method of operating gas wells at a late stage of development of natural gas fields [see. Kozintsev, A.N. Experience of using surfactants at the Medvezhye deposit / A.N. Kozintsev, A.N. Laperdin, A.V. Velichkin, O. M. Ermilov // Science and technology in the gas industry. - 2013. - No. 3. - S. 35-38], including the treatment of the bottom hole with solid and liquid surfactants. For this, the surfactant is lowered to the bottom of the well. The properties of the liquid-gas interface change, as a result of which foam is formed, which is removed from the well by the gas flow.

Significant disadvantages of this method are the low foaming capacity with highly mineralized water, the possibility of the formation of stable emulsions, the absence of a long-term effect, and also, in some cases, the influence of the reaction products on the operation of the equipment of the gas treatment system.

A known method of operating gas wells at a late stage of development of natural gas fields [see. Fedorov, A.O. Analysis of gas well operation technologies taking into account the effect of self-locking / A.O. Fedorov // Problems of Geology and Subsoil Development: Proceedings of the XX International Symposium named after Academician M.A. Usov of students and young scientists, dedicated to the 120th anniversary of the founding of Tomsk Polytechnic University. - 2016. - P. 431-433], including the use of concentric tubing, when a central tubing of a smaller diameter descends into the existing main tubing, which provides the necessary flow rate for removing liquid from the bottomhole, while gas moves along the annular space at a speed below the critical one, and these gas streams are combined in the gas-collecting manifold. In the central tubing, the flow rate is automatically maintained, which is 10-20% higher than that required to remove fluid from the bottomhole. The control of the technological parameters of the well operation in both channels is carried out using an automated complex.

Significant disadvantages of this method are expensive equipment, an increase in frictional resistance against the pipe walls of the produced gas-liquid mixture, a decrease in well flow rate with partial overlap of the annular space to ensure the removal of fluid along the central tubing string.

The closest in technical essence to the claimed technical solution is a method of operating gas wells at a late stage of development of natural gas fields [see. Ponomarev and A.I. Provision of stable technological modes of operation of gas wells at a late stage of field development with the use of wellhead gas-jet devices / A.I. Ponomarev, B.C. Verbitsky, A.E. Fedorov, A.A. Ibatulin // Actual problems of gas production. - 2018. - No. 1 (33). - P. 171-180], including the use of jet devices to reduce the wellhead pressure of gas wells and increase the actual flow rate of the produced gas-liquid mixture from the bottom of the well.

A significant disadvantage of this method is the need for a source of high-pressure gas flow, which is used as a well with high wellhead pressure, the energy potential of which is not unlimited. In addition, with a cluster layout of wells, the difference in wellhead pressures across the wells of one cluster is insignificant, which excludes their use as a high-pressure source.

The purpose of the proposed technical solution is to increase (maintain) the flow rate of wells, ensure stable technological modes of well operation at the final stage of gas field development, increase the gas recovery ratio, and expand the scope of application of jet devices in gas production through the use of a high-pressure flow (water-methanol solution (BMP) ) and low-pressure flow (gas from wells).

The technical result of the claimed invention is achieved by ensuring the gas flow rate required to remove liquid from the bottom of the well, and increasing the volume of gas production.

The specified problem is solved and the technical result is achieved due to the fact that the method of operating gas wells at a late stage of development of natural gas fields includes the production of a gas-liquid mixture from wells, separation of free gas from liquid and its subsequent supply to the inlet of the mixing chamber of the jet apparatus, which reduces the wellhead pressure gas wells and increases the actual flow rate of the produced gas-liquid mixture from the bottom of the well.

A high-pressure flow for ejection of a low-pressure gas in a jet apparatus is created with a water-methanol solution, which is used in the recirculation mode. The produced gas captured by the flow is separated in the first section of the bullet due to centrifugal and gravitational forces, and is directed through the gas pipeline-loop to the integrated gas treatment unit (CTP). At the same time, part of this gas is periodically withdrawn and pumped into the annulus of individual production wells to remove the accumulated column of liquid from their tubing. The selection of wells for carrying out this operation is carried out by an automated process control system (APCS) according to the values of the parameters controlled by its telemechanics system at the wellheads of the wellheads, which make it possible to identify such wells.

The degassed liquid separated in the separator is directed to the second section of the bullet, from which it is pumped back into the reservoir formation below the level of the gas-water contact. To do this, use the least productive or inactive well of the cluster, which has the maximum distance from the bottom of other wells in the cluster.

The device for implementing the method includes a separator, the inlet of which is connected to the plume of the cluster of production wells, and the outlet for the produced gas is connected to the inlet of the mixing chamber of the jet pump unit. The block of jet pumps is selected based on the maximum possible production capacity of the well cluster on which the unit is located.

In the device, in the oven, a bullet is installed, which consists of two sections. The inlet of the first section of the bullet is connected to the outlet of the jet pump. Its lower outlet is connected by a pipeline for supplying a water-methanol solution to the inlet of a centrifugal pump, the outlet of which is connected to an inlet for supplying a water-methanol solution to a block of jet pumps operating in parallel. The upper outlet of the first section of the bullet is connected to the complex gas treatment unit by means of a gas pipeline-loop, at the beginning of which a branch with a remotely controlled field telemechanics system is installed with a valve. The valve provides periodic gas supply along the line with branches connecting it to the annulus of the production wells through their individual valves controlled by the telemechanics system connected to the corresponding valves of the Christmas tree.

The inlet of the second section of the bullet is connected by a branch pipe with the outlet of the separator for supplying degassed liquid from it to the bullet. The lower outlet of the second bullet section is connected to the system for pumping the produced fluid into the formation. This system is connected by a pipeline with an absorption well for utilization of the produced degassed liquid into the formation. Another outlet of the second bullet section is made in the form of a vertical pipe installed inside it. A float valve is installed at the top of the branch pipe, which provides an emergency discharge of degassed liquid from the bullet into the underground tank in case of an increase in the level of degassed liquid in the second section of the bullet above the level of the valve installation. The lower end of the emergency discharge branch pipe is connected by a pipeline to an underground tank, the installation depth of which excludes freezing of the degassed liquid in it during an interval of time sufficient for its removal from this tank.

FIG. shows a block diagram of a modular ejection unit of a cluster of gas producing wells, which implements the proposed method. It uses the following designations:

1. Separator;

2. Jet ejection pump;

3. Bullet;

4. The first section of the shootout;

5. Second shootout section;

6. Centrifugal pump;

7. Gas pipeline-loop;

8. Underground tank for liquid coming from the bullet 3;

9. Float valve at the inlet of the liquid discharge line from the bullet 3 to the underground tank 8;

10. Line of periodic gas supply to the annular space of the wells;

11. Gate valve at the inlet of line 10;

12. Heating cabinet.

The device contains a separator 1, the inlet of which is connected to the plume of a cluster of production wells, and the outlet for the produced gas is connected to the inlet of the mixing chamber of the jet ejection pump 2. Bullet 3, consisting of two sections 4 and 5, is placed in a heating cabinet 12. Inlet of the first section 4 of the bullet 3 is connected to the outlet of the jet ejection pump 2, and its lower outlet is connected by a pipeline for supplying a water-methanol solution to the inlet of a centrifugal pump 6. Its outlet is connected by a pipe to the inlet of the jet ejection pump 2. The upper outlet of the first section 4 of the bullet 3 is connected to the gas pipeline 7 for supplying the extracted gas at the GPP. At the beginning of the gas pipeline-loop 7, a branch pipe is installed for diverting gas to line 10. Between the branch pipe and line 10, a valve 11, which is remotely controlled by the field telemechanics system, is installed, providing periodic gas supply along line 10. Line 10 forks, and each of its branches has at its end a valve controlled by a telemechanics system, through which it is connected to the annulus of a specific production well through the annular valve of its Christmas tree.

The inlet of the second section 5 of the bullet 3 is connected by a pipe to the outlet of the separator 1 for degassed liquid. A pipeline is connected to the lower outlet of the second section 5 of the bullet 3, the second end of which is connected to an absorption well, which ensures the utilization of the extracted degassed liquid into the formation. Another outlet of the second section 5 of the bullet 3 is made in the form of a vertical branch pipe, on the top of which a float valve 9 is installed. This outlet provides an emergency discharge of the degassed liquid from the bullet 3 in case of an increase in its level above the valve 9. a pipeline into an underground tank 8, the installation depth of which excludes freezing of the degassed liquid in it during an interval of time sufficient for its removal from this tank.

The method is carried out as follows. The gas-liquid mixture from the production wells enters the separator 1, where the formation liquid is separated from the gas. This makes it possible to significantly reduce the likelihood of liquid accumulation in the gas pipeline-loop 7 during operation, as well as to reduce the possibility of hydrate formation in the gas-collecting manifold. Nevertheless, methanol is fed from time to time to avoid hydrate formation.

Further, the separated gas is ejected by the BMP flow in the block of jet ejection pumps 2 (in the diagram, for ease of understanding, one pump is shown). Due to the ejection effect of the high-pressure BMP flow, organized in the recirculation mode, the pressure of the produced gas decreases at the inlet to the ejector of the jet pump, i.e. wellhead pressures of water-cut gas wells to a value at which there is a complete and continuous removal of the gas-liquid mixture from their bottom.

The mixture of products obtained in the mixing chamber of the jet pump is sent to the first section 4 of the bullet 3, where the BMP is separated from the gas due to centrifugal and gravitational forces. The separated gas is sent for further drying to the gas processing plant. BMP from the first section 4 of the bullet 3 by means of the centrifugal pump 6 is re-directed to the jet ejection pump 2, and the cycle is repeated. The pressure drop created in this cycle at the inlet of the separator 1 prevents weak wells from being "squeezed" by strong ones. To compensate for the carryover of a part of the BMP together with the gas along the loop 7, it is periodically fed into the first section 4 of the bullet 3.

As the column of liquid accumulates in the tubing of production wells, their productivity decreases, which is recorded by the flow meter of the gas field telemechanics system installed at the mouth of each well (not shown in the figure). A telemechanics system with an automated process control system detects wells that require special operations according to the values of the controlled parameters at their wellhead when they reach the values specified by the technological regulations. At this moment, the APCS supplies part of the separated gas to the annulus of these wells from the gas pipeline 7, through the valve 11, line 10 and its branches to the selected wells. Gas is supplied through these branches by the APCS by opening the valves at their ends simultaneously with the valve 11. The valves at the ends of the branches are connected by branch pipes with the valves of the Christmas tree, which provide access to the annular space of the wells corresponding to them. This procedure has a double effect: firstly, the gas flow rate becomes more than the minimum allowable, at which the conditions for the removal of fluid from the bottom hole of the wells are met; and, secondly, the separated gas injected from the surface, mixing with the formation gas, reduces its moisture content and prevents the accumulation of condensation moisture at the bottomhole.

The degassed liquid collected in the lower part of the separator 1 is sent to the second section 5 of the bullet 3 and then back into the gas-bearing formation, to a level below the gas-water contact through the absorption well. Thus, with its help, they solve the problem of utilizing the produced water and protecting the environment.

A device that implements the proposed method is a modular ejection unit designed to be placed on a cluster of gas producing wells, which operates as follows.

The produced gas-liquid mixture containing natural gas and formation fluid from the bottom of the production wells through the tubing goes to the surface (at the mouth of the production well). From the wellhead, through the string valve, the produced gas-liquid mixture enters the separator 1, where the liquid phase is separated from the gas (see Fig.). The separated gas leaving it is "picked up" by the BMP flow, which is injected into the block of jet ejection pumps 2 using a centrifugal pump 6. Then the resulting mixture of BMP with gas is sent to the first section 4 of the bullet 3, where the BMP is separated from the gas due to centrifugal and gravitational forces ... The separated gas is sent through the gas pipeline-loop 7 for further drying at the GPP.

BMP from the first section 4 of the bullet 3 with the help of the centrifugal pump 6 is again directed to the jet ejection pump 2, and then, to the same section 4, realizing its recirculation mode with "picking up" the gas flow coming from the wells by the ejection method. Then it is separated from the gas and again goes along the same route.

Part of the separated gas from the gas pipeline 7, as the liquid column accumulates in the tubing of specific production wells, is periodically fed into the annulus of one or more production wells through line 10 and its branches by means of a remotely controlled telemechanics system (not shown in Fig. ) valve 11 and valves installed at the ends of the corresponding branches from the line 10 and connecting them with the annular space of the corresponding wells through their Christmas tree. The specified procedure is implemented using a gas field telemechanics system with an automated process control system that detects wells that require this operation according to the values of the parameters monitored at its mouth.

Degassed liquid from the second section 5 of the bullet 3, through its lower outlet, is directed back into the gas-bearing formation below the gas-water contact through the absorption well. The well for the discharge of degassed liquid is selected from those available in the cluster with the lowest productivity and with the maximum distance from the bottom of other wells. In emergency cases, the liquid is discharged from the bullet 3 into the underground tank 8. The liquid is discharged through the outlet from the second section 5 of the bullet 3, made in the form of a vertical branch pipe, on the top of which a float valve 9 is installed, providing an emergency discharge of the degassed liquid. Discharge from bullet 3 occurs in case of an increase in the liquid level in it above the installation site of the float valve 9. When the liquid in section 5 of the bullet 3 reaches a certain level, valve 9 rises and, accordingly, the water is drained into the underground tank 8. As the liquid level decreases valve 9 closes gradually.

To prevent possible freezing of water in bullet 3, it is placed in oven 12.

The use of the proposed method for operating gas wells at the final stage of gas field development allows to increase the flow rate of gas wells, to provide the required flow rate for the removal of liquid from the bottom of the well, to prevent irreversible gas losses, to increase the gas recovery coefficient and to reduce the damage to the environment.

Claims (2)

1. A method of operating gas wells at a late stage in the development of natural gas fields, including the production of a gas-liquid mixture from wells, the separation of free gas from the liquid and its subsequent supply to the inlet of the mixing chamber of the jet apparatus, which reduces the wellhead pressure of gas wells and increases the actual flow rate of the produced gas-liquid mixtures from the bottom of the well, characterized in that the high-pressure flow for the ejection of low-pressure gas is created with a water-methanol solution, which is used in the recirculation mode, and the extracted gas captured by it is released in the first section of the bullet due to centrifugal and gravitational forces and is directed through the gas pipeline-loop to the installation complex gas treatment, while a part of this gas is taken, which is periodically injected into the annulus of individual production wells to remove the accumulated liquid column from their tubing, the selection of which is carried out by an automated system process control system (APCS) according to the values of the parameters controlled by its telemechanics system at the wellheads, which make it possible to identify wells that require this operation, and the degassed liquid released in the separator is sent to the second bullet section, from which it is pumped back into the formation of the field is below the level of gas-water contact through the least productive or inactive well of the cluster, which has the maximum distance from the bottom of other wells of the cluster. 2. A device for implementing the method, including a separator, the inlet of which is connected to the plume of a cluster of production wells, and the outlet for the produced gas is connected to the inlet of the mixing chamber of the jet pump, characterized in that a bullet is installed in it, consisting of two sections and placed in a heating cabinet, the inlet of the first section of the bullet is connected to the outlet of the block of jet pumps operating in parallel, and its lower outlet is connected by a pipeline for supplying a water-methanol solution to the inlet of a centrifugal pump, the output of which is connected to the inlet of the supply of a water-methanol solution to the block of jet pumps, and the upper outlet of the first section of the bullet is connected to the installation complex gas treatment by means of a gas pipeline-loop, at the beginning of which a branch with a remotely controlled telemechanics system of a gas field is installed with a gate valve that provides periodic gas supply along a line with branches connecting it with the annulus of production wells through their individual, controlled system gates telemechanics connected to the corresponding valves of the Christmas tree, and the inlet of the second section of the bullet is connected by a branch pipe to the outlet of the separator for supplying degassed liquid from it to the bullet, and the lower outlet of the second section of the bullet is connected to the system for pumping the produced fluid into the formation, which is connected by a pipeline to the absorbing a well for utilization of the extracted degassed liquid into the formation, and the other outlet of the second section of the bullet is made in the form of a vertical pipe, at the top of which a float valve is installed, which provides an emergency discharge of degassed liquid from the bullet into the underground tank in case of an increase in the level of degassed liquid in the second section of the bullet above the valve installation level , and the lower end of the emergency discharge branch pipe is connected by a pipeline to an underground tank, the installation depth of which excludes freezing of the degassed liquid in it during an interval of time sufficient for its removal from this tank.

Images