WO2012134327A1

WO2012134327A1 - Well operating method

Info

Publication number: WO2012134327A1
Application number: PCT/RU2011/000283
Authority: WO
Inventors: Владимир Константинович ШАРАПИНСКИЙ; Иван Викторович ГРЕХОВ; Роман Васильевич САХНОВ
Original assignee: Общество С Ограниченной Ответственностью "Дискрит"
Priority date: 2011-03-29
Filing date: 2011-04-29
Publication date: 2012-10-04
Also published as: RU2457320C1

Abstract

The invention relates to the oil and gas extracting industry and can be used for the extraction of product, in particular oil, from a well, in the event of complications associated with an increased gas factor - a high content of casing-head gas in the extracted product. The technical result of the invention is an increase in the well operating efficiency by more fully using the energy of the casing-head gas while simultaneously increasing the coefficient of extraction of the useful product with a reduction in the water content thereof. The essence of the invention: according to the method, an uptaking pipe string with a rodless pump in the lower part and a by-pass unit above said pump is lowered. Stratal fluid is removed with the aid of the rodless pump with casing-head gas being accumulated in an annular space up to an overpressure providing the possibility of the fluid being forced back out of the annular space into the uptaking pipe string via the by-pass unit. The stratal fluid is removed in a forced mode - with simultaneous operation of the rodless pump and natural gas lift until the provision of a specified depression and scouring of the bottom region of the stratum. A transfer is made to a cyclic mode of operation of the well until the water content of the stratal fluid is reduced and stabilized. The rodless pump is switched off and the well transferred into the basic mode - the gas lift operation mode. The gas lift operation is carried out up to a natural increase in the water content of the stratal fluid. The operations are repeated with removal of the stratal fluid with the aid of the rodless pump.

Description

Method of operating a well

The invention relates to the oil and gas industry and can be used in the production of products from a well, in particular oil, in case of complications associated with an increased gas factor - a high content of associated gas in the produced products.

State of the art

A well-known method of operating a well, including the descent of a rodless pump — a deep centrifugal pump on a tubing string and pumping well production through said pipes (RU 2380521, January 27, 2010).

A disadvantage of the known method is that the associated gas energy is not used and has a detrimental effect on the operation of the downhole pump. Associated gas accumulated in the annular space of the well under excessive pressure is periodically vented through the bypass valve on the wellhead into the flow line of the well.

A well-known method of operating a well, including the descent of a column of lifting pipes with a rodless pump in the lower part and a bypass valve above the pump, the selection of reservoir fluid using a rodless pump, a temporary stop of the pump in violation of the stable mode of operation, purging the pipe string and wellhead valves associated gas to remove fluid from the pipe string with clearly pronounced thixotropic properties and plugs of various nature that violate the stable mode of operation of the well, the resumption of exploitation Ata tion rodless pump wells with the required mode eksplua- tation (SU 1599526, 15.10.1990).

A disadvantage of the known method is the partial use of the associated gas energy and, therefore, an unjustified overspending of electric energy due to the use of the pump operation mode as the main one.

However, in most cases, after killing a well by a killing fluid, for example, for the period of a well overhaul, use associated gas is associated with increased development difficulties - bringing the well to a stable operating mode. A traditional associated gas operation requires a number of start-up gas lift valves. However, gas-lift start-up systems are effective only when using a pressure-stabilized gas source, which is not associated gas for a certain time. Therefore, at the start-up time, the traditional solution involves the use of a pressure-stabilized gas source — a high-pressure compressor unit — expensive equipment with expensive maintenance, especially in the winter season. All this again does not contribute to the optimal expenditure of energy, time and other related means during the operation of the well.

Disclosure of invention

The objective of the invention is to use the energy of associated gas during the operation of the well as much as possible.

The technical result of the invention is to increase the efficiency of the operation of the well due to a more complete use of the energy of associated gas while increasing the recovery rate of useful products with a decrease in its watering.

The required technical result is achieved by the fact that the method of operating the well includes lowering the column of lifting pipes with a rodless pump in the lower part and a bypass gas inlet node to the column of lifting pipes installed at a design depth above the pump, collecting reservoir fluid using a rodless pump with accumulation Associated gas in the annular space is bore to overpressure, which allows the fluid to be displaced from the annular space of the well into the riser string overflow unit, selection of formation fluid in forced mode - with the simultaneous operation of a sucker-rod pump and natural gas lift to ensure a predetermined depression and cleaning of the bottomhole formation zone, a cyclic mode of well operation to reduce the watering of the formation fluid and stabilize the watering, shut off the rodless pump and transfer wells in the main mode - gas-lift operation mode wells using associated gas (in-house produced gas for a given well), performing gas lift operations to naturally increase the water cut (not higher than a given value) of the formation fluid, and then repeating the operations to select formation fluid using a rodless pump.

In addition, as a rodless pump, a centrifugal or screw, or diaphragm, or any other electric pump is used;

as a bypass unit, a differential unit for introducing gas into the column of lifting pipes is used (to ensure periodic — continuously-discrete operation of the natural gas lift in a particular case);

the cyclic mode of operation of the well is set by changing the productivity of the selection of formation fluid and / or periodic stops in the selection of this fluid; the duration of stops in the selection of formation fluid is different, including with respect to the operation of the differential unit for introducing gas into the column of lifting pipes (a wide range of settings for the said differential unit is accepted);

in the case of a killing operation during the operation of the well, the bottom-hole zone of the formation is cleaned until traces of the killing fluid are removed.

Embodiments of the invention

The essence of the invention lies in the fact that when operating a well, a rodless pump and natural gas lift (associated gas gas lift) are used. A rodless pump is mainly used as a means for starting a well after technological shutdowns associated with a major or underground well repair and putting it into stable operation of a gas lift. Using a rodless pump and a natural gas lift, a short-term forced mode of well operation is provided to clean the bottom-hole zone of the productive formation - further the formation. After that, using a rodless pump and / or natural gas lift, an unsteady - cyclic mode of well operation is provided for inclusion in the drainage of the formation along its entire thickness and reduction, while watering the produced production of the well. Then, the rodless pump is turned off and they switch to the main mode of well operation — the gas-lift operation mode. It is carried out until the well begins, for example, to “stall” from water accumulating over time. In this case, the well is switched to a different mode of operation - the rodless pump is switched on without plugging the well. After some time, the well is switched back to the main mode - gas-lift operation mode. At the same time, the necessity of repeating the forced and cyclic well operation modes is established based on the actual data of the well operation. As a possible variant of gas-lift operation of a well, a variant of gas-lift operation in periodic mode (continuous-discrete gas-lift operation) can be adopted.

Such a solution provides the possibility of optimal well operation practically on its own energy resource - associated gas, which is little dependent on external conditions. A small energy feed is used only at the preparatory stages - to start or restart the well, or to set the well to the optimum mode when it deviates from it during operation. The invention’s ability to adjust the well to its optimal operating mode is ensured by a cyclic mode of well operation, i.e., for example, a change in productivity over time, production pressure, periodic shutdown, etc. The cyclic mode provides the necessary pressure drop - I wait for low-permeability and high-permeability zones of the reservoir and significantly increases the mass transfer between them.

In irrigated productive formations, for example, with oil in the form of disparate dislocations, such an exposure mode ensures the connection of hydrodynamic processes to low-permeable oil-saturated zones, capillary and / or gravity-capillary processes, as well as a mechanism for reducing the viscosity of well production, for example, oil from its continuous movement under the action of constantly acting pressure gradients. An inhomogeneous filter medium along the height of the reservoir under such conditions becomes more uniform in the nature of the filtration, and less viscous well production is most favorably removed by gas lift. The effects of hydrodynamic effects are manifested to a greater extent if the effects (variable pressure and well conditions) have a sufficiently high degree of non-stationarity. It is the non-stationarity that does not allow the development of familiar filtration channels and an increase in the water cut of well production through these channels. A rodless pump, namely a centrifugal or screw, or diaphragm, or other electric pump is used because it provides a wider (flexible) ability to control its operation, especially when paired with a gas lift, than, for example, a rod pump.

As a bypass unit providing a periodic mode of operation of the well, a unit (valve) can be used, made, for example, in the form of a movable nozzle for communicating its entrance with the annular space of the well and a springed plunger with a locking tip, inside which a diffuser is placed - a potential control mechanism that provides the possibility of periodic operation of the well (see, for example, RU 2239696, 10.1 1.2004).

The periodic gas lift operation under certain conditions (determined individually for each case) may be more preferable than the continuous gas lift operation. Likewise, in other cases, a variant providing continuous operation of the gas lift may be more preferable. For this case, a node in the form of, for example, high and low pressure nozzles, between which a sleeve with a calibrated axial bore is located, as well as a plug, can be adopted as a bypass assembly, which makes it possible to increase or decrease the volume of produced products ( see, for example, RU 7916 U1, 10.01.2009). The above bypass nodes are given as examples to prove the feasibility of the method using known means.

This method does not limit the possibility of using other bypass nodes to ensure the operation of natural gas lift in discrete or continuous mode.

Changes in the productivity of reservoir fluid selection and / or the use of periodic stops in the selection of this fluid, as well as the fact that the duration of the stops in the reservoir fluid selection are different (from cycle to cycle) increase the degree of unsteadiness of the well and increase even more the effectiveness of the method in terms of ensuring or accelerating the well’s output to the regime with a decrease in watering of the produced products.

The operation mode for a continuously-discrete gas lift is carried out by changing the operating modes of the rodless pump and / or natural gas lift. At In this case, a rodless pump and / or natural gas lift can be periodically shut off. The latter, as an option, can be turned off by means of cable technology, lowered from the wellhead under pressure without killing the well.

At the same time, the periodicity of the natural gas lift operation, as an option, can be used in the general scheme of organizing the cyclic mode of the well operation, for example, in alternating with stops of the rodless pump. Moreover, the order of organization of the cyclic mode, from cycle to cycle, is preferably carried out in different ways - possibly even according to a random law.

The method is as follows.

For example, an oil well is run into a column of lifting pipes, for example tubing pipes that perform elevator functions, with a rodless pump in the lower part, for example, an electric centrifugal pump. Above the electric centrifugal pump, at the calculated depth, a bypass assembly is installed to provide hydro-gas-dynamic communication of the annular space of the well with the tubing string. As a bypass unit, for example, a unit (valve) made in accordance with the aforementioned patent RU 2239696 or a unit in accordance with RIJ 7916 U1 is used to allow fluid from the annular space of the well to enter the tubing string. Start the electric centrifugal pump. When the well enters a constant mode, associated gas enters the electric centrifugal pump from the reservoir along with oil. Part of the gas volume as a result of natural separation at the reception of the electric centrifugal pump is released from oil and accumulates in the cavity above the liquid level in the annular space of the well (in the space between the casing of the well and the tubing string). As it accumulates in the annular space, the pressure increases. Under the influence of this pressure, the liquid level is pushed to the bypass assembly. A gas breakthrough occurs through the bypass assembly. Then, during the operation of the pump, a monotonous gas supply is established under excess pressure through the bypass assembly from the annular space into the oil flow (usually watered) inside the tubing. After the overpressure is established, the well begins to function in steady state. Overpressure provides the necessary pressure difference between the pressure in the annular space and the pressure in the tubing at the level (depth) of the installation of the bypass unit. Ensuring a stable gas supply to the tubing string through the bypass assembly leads to additional aeration of the oil flow and thereby decrease its density the entire length of the tubing string. Bubbles of gas, falling through the bypass node into the oil stream, expand in the volume of the stream and give it additional energy. This increases the rate of rise of the gas-liquid flow up. An additional supply of associated gas energy to the oil flow from the electric centrifugal pump helps to increase the rate of oil rise in the tubing. If necessary, they increase the productivity of the electric centrifugal pump and select formation fluid in the forced mode, with the simultaneous operation of the electric centrifugal pump and natural gas lift. This is continued until the desired depression and cleaning of the bottomhole formation zone is achieved. If a well is launched after overhaul or underground repair of a well, then the bottom-hole zone of the formation is cleaned up upon completion of the removal of traces of killing fluid at the wellhead. Establish the degree of watering of the produced oil from the samples taken at the wellhead. With not acceptable values of watering, for example, above 80%, they switch to a cyclic mode of operation of the well. For this, for example, the performance of the electric centrifugal pump is changed - at first it is increased, then it is reduced, it is increased again and then the electric centrifugal pump is stopped. At the same time, oil flooding is controlled. When the watering responds to certain actions, these actions are taken as a basis, but with variations to create an unsteady regime as much as possible. With a decrease in oil flooding and its stabilization, they switch to the main mode of operation - the natural gas lift mode of constant or periodic action. At the same time, oil flooding continues to be controlled. Over time, during the operation of the well until a natural increase in flooding of the reservoir fluid, operations with the start of the electric centrifugal pump are repeated.

Industrial applicability

The invention may be applicable in the production of products from a well, in particular oil, in case of complications associated with an increased gas factor - a high content of associated gas in the produced products.

Claims

Claim

1. A method of operating a well, including the descent of a column of lifting pipes with a rodless pump in the lower part and a bypass assembly above the pump, the selection of reservoir fluid using a rodless pump with the accumulation of associated gas in the annular space to an overpressure that allows fluid to be forced out of the annular space into a column of lifting pipes through the transfer unit, the selection of reservoir fluid in forced mode - with the simultaneous operation of a rodless pump and natural gas lift to about Maintenance of a given depression and cleaning of the bottom-hole zone of the formation, cyclic operation of the well to reduce water cut of the formation fluid and stabilization of watering, shutting off the rodless pump and putting the well into the main mode — gas-lift operation, gas-lift operation to a natural increase formation fluid irrigation, subsequent repetition of operations with formation fluid sampling using a rodless pump.

2. The method according to p. 1, characterized in that as a rodless pump, a centrifugal or screw pump or a membrane pump with an electric drive is used.

3. The method according to claim 1, characterized in that a device made with the possibility of its periodic operation is used as a bypass node.

4. The method according to p. 1, characterized in that the cyclic mode of operation of the well is set by changing the productivity of the formation fluid and / or periodic stops in the selection of this fluid.

5. The method according to claim 4, characterized in that the duration of stops in the selection of formation fluid is different.

6. The method according to p. 1, characterized in that in the case of the operation of killing during the operation of the well, the bottom-hole zone of the formation is cleaned before traces of the killing fluid are removed.