RU2544204C1 - Development of oil seam by horizontal wells - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: drilling of new wells or selection of drilled wells are executed. Intervals of productive bed are isolated. Pump is lowered in the well. Selected sections are separated by packers. Well products are extracted from every said section. At development of terrigenous or carbonate bed the afflux profile is predetermined. Sections with afflux profile are revealed that differ in specific oil yield by 20% and more. Packers are fitted at points of specific yield variation. One pump is lowered on separate tubing or coiled tubing to the centre of every section. Spacing between lowered pumps over horizontal holes is set not to exceed 200 m.

EFFECT: accelerated oil extraction, uniform development, higher bed oil yield.

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Description

The invention relates to the oil industry and may find application in the development of heterogeneous terrigenous or carbonate reservoirs.

The known method of simultaneous and separate operation of multilayer wells, including the descent into the well of at least one pipe string with a constant or variable diameter and an open or drowned lower end, equipped between layers or above and between layers, one or more packers for separation of layers and a control device for controlling fluid flow rate during production, while in the well at the level of its formation, a pipe string or control device is equipped with a measuring transducer for transmitting information measurement of the surface of the well and determination of the technological parameters of the fluid during production, for which a cable or impulse tube is lowered into the well outside or inside the pipe string and connected to a measuring transducer or regulating device, or both to a measuring transducer and to a regulating device made removable type, and after installation of the wellhead, fluid is produced, directing it through the regulating device and the measuring transducer, information on measuring t of the measuring transducer and determine the technological parameters of the fluid for the formations, and if they differ from the design value, the throughput section of the control device is changed until the design value of the technological parameters for each of the formations is reached. Moreover, an interface is installed in the measuring transducer for storing information about the measured technological parameters. The measuring transducer is installed in the form of a pressure sensor or differential pressure, temperature or temperature differential, or a flow meter, or volumetric, or mass flow meter. The control device is made in the form of an electric or electromagnetic, or pulse valve with a shut-off element, the degree of opening of which is controlled from the surface of the well by supplying a signal or pulse through a cable or pulse tube. To implement the method, a device is used consisting of a pipe string equipped with one or more packers, one or more control devices, and the pipe string or control device is equipped with a measuring transducer with an interface, cable or impulse tube (RF patent 2313659, class E21B 43/14 published on 12/27/2007).

Closest to the technical essence of the proposed method is a method of separation and management of the development of reserves drained by a horizontal well, including the descent into the well of a pipe string with a cable, control devices in the form of electric valves, pressure and temperature measuring sensors and with one or more packers that disconnect the downhole space. Sensors are used, the information from which is fed to a measurement unit installed at the wellhead. The signals for opening and closing the control devices are fed by cable from the wellhead control unit. The rise of products to the surface is carried out by a pump along the in-tube space. According to the invention, a well is constructed with a horizontal section extending over the formation with different zones of permeability. Packers are installed in a horizontal section of the well, dividing formation zones with different permeabilities. The inner tube space is separated by a plug, above which upper and lower control devices are placed one above the other, placed in a vertical barrel and equipped with measuring sensors. Zones with the same or similar permeability communicate with each other, grouping in two streams communicated with the downhole space and the input of the upper control device or the in-pipe space and the input of the lower control device. The outputs of the regulating devices are communicated with the pump inlet, and the magnitude of the opening of the regulating devices is frequency-separated by one cable, through which the parameters are taken from the measuring sensors, the readings of which determine the opening value of each of the regulating devices. Each regulating device is made in the form of an electric motor located in the motor housing with a gearbox, the rotary shaft of which is connected by means of a screw-nut connection with a pusher and a valve made with the possibility of tight interaction with the seat, below which there is a glass with an entrance in the form of channels, in which a compensation chamber with elastic walls filled with lubricant and in communication with the interior of the pusher and a sealed space located above the pusher. (RF patent No. 2488686, class E21B 43/14, publ. 07.27.2013 - prototype).

A common disadvantage of the known methods is the difficulty of using these structures in a horizontal well. Also, due to the uneven distribution of bottomhole pressure along the horizontal wellbore, as well as the heterogeneity of the reservoirs, oil reserves are not being developed efficiently along the horizontal wellbore, some of which may not work at all.

The proposed invention solves the problem of increasing the rate of oil extraction, the uniformity of the development of reserves and, as a result, the increase in oil recovery of the reservoir.

The problem is solved in that in the method of developing an oil reservoir by horizontal wells, including drilling or selecting already drilled horizontal wells, identifying sections in the form of intervals of the reservoir, lowering the pump into the well, separating the sections with packers, selecting well products from each section, characterized in that when developing a terrigenous or carbonate formation, the inflow profile is preliminarily determined, areas with an inflow profile are identified that differ from each other in specific oil production by 20% or more, in the places where the specific oil production rate changes, packers are installed, one pump is lowered into the center of each section on a separate column of tubing or coiled tubing sleeveless pipes, the distance between the pumps along the horizontal shaft is set to no more than 200 m.

If the sections on the inflow profile differ from each other by the specific oil production rate by less than 20%, the horizontal well is taken for one section, in the center of which a pump is placed.

SUMMARY OF THE INVENTION

The oil recovery of a terrigenous or carbonate oil reservoir, developed by horizontal wells, is significantly affected by the uniformity of oil reserves. Existing technical solutions do not fully allow to perform this task. Studies show that the bottomhole pressure along the horizontal trunk is unevenly distributed, the central part of the horizontal trunk in most cases works the worst. In addition, the reservoir is almost always heterogeneous, which leads to uneven development of reserves and low oil production rates of wells. The proposed invention solves the problem of increasing the rate of oil extraction, the uniformity of the development of reserves and, as a result, the increase in oil recovery of the reservoir. The problem is solved as follows.

In FIG. 1 is a schematic illustration of a section of an oil reservoir with a horizontal wellbore with pumps. Designations: 1 - productive formation, 2 - horizontal production well, 3 - horizontal wellbore, 4 - packer, 5 - pipe string, 6 - pump, L - distance between pumps. In FIG. 2 is a graph of the profile of oil flow along a horizontal wellbore.

The method is implemented as follows.

The section of the oil reservoir 1, represented by a terrigenous or carbonate type of reservoir and a purely oil zone, is opened by a horizontal well 2 with a horizontal wellbore 3 (Fig. 1).

, где количество i численно равно длине горизонтального ствола в метрах. Таким образом, горизонтальный ствол делят на несколько участков. В каждый участок спускают на отдельной колонне труб 5 насос 6 (например, типа 2СП45/24) и устанавливают в центре каждого участка. Расстояние между насосами L не должно превышать 200 м.Determine the profile of the influx (Fig. 2) along the horizontal trunk 3 (open or reopened). On the profile, sections are identified that differ in the specific oil production rate by more than 20%, and decide to install packers 4 in the places of their change (for example, water swelling, TAM companies). The specific oil production rate q is defined as the oil production rate per meter of horizontal shaft length. In this case, the oil production rate of well Q is defined as the sum of the specific oil production rates in an amount equal to the length of the horizontal well, i.e. $$Q={\displaystyle \sum _{i}q}$$

where the quantity i is numerically equal to the length of the horizontal trunk in meters. Thus, the horizontal trunk is divided into several sections. A pump 6 (for example, type 2SP45 / 24) is lowered into each section on a separate pipe string 5 and installed in the center of each section. The distance between the pumps L must not exceed 200 m.

The calculations showed that if the specific oil production rate along the horizontal well differs by less than 20%, this does not have a significant effect on oil recovery and the formation can be considered relatively homogeneous. In this case, one pump is lowered, which is placed in the center of the horizontal trunk (open or second opened).

In the general case, the number of pump-down pumps is limited by the diameter of the casing strings and pipe strings 5. To run two pumps on different tubing, a casing string diameter of at least 6 inches is required.

The use of coiled tubing sleeveless pipes having a small diameter as pipe columns allows you to lower up to 5 pumps into the well.

The maximum distance L = 200 m is determined for reasons that downhole pressure starts to drop significantly at large distances. For example, according to calculations, for wells with a horizontal wellbore of more than 500-600 m, installation of less than 3 pumps leads to low rates of recovery and oil recovery due to uneven production of reserves along the wellbore. The constructed profile of the inflow to the wellbore of such wells almost always has at least three sections with a specific oil production rate that differs from each other by more than 20%.

The well is put into operation. Similar operations are carried out in other horizontal wells.

Development is carried out until a complete economically viable development of the reservoir.

The result of the implementation of this method is to increase the rate of oil extraction, the uniformity of the development of reserves and, as a result, the increase in oil recovery of the reservoir.

Examples of specific performance of the method

Example 1. The section of the oil reservoir 1 (Fig. 1), represented by the carbonate type of the reservoir and the pure oil zone, lying at a depth of 950 m and a thickness of the reservoir h = 10 m, was opened by a horizontal well 2 with an open horizontal well 3 of 300 m in length. Diameter The well casing is 146 mm.

The inflow profile is determined (Fig. 2) along the horizontal trunk 3. Two sections are revealed on the profile, which differ in specific oil production rate by 20%. The specific production rate of the first section is 0.04-0.07 t / (day · m), of the second section 0-0.03 t / (day · m). An electric centrifugal pump 6 of type 2SP45 / 24 on a separate tubing 5 with a diameter of 73 mm is lowered into each of the sections. The distance between the pumps is L = 100 m. A TAM 4 water swellable packer is installed between the sections.

The well is put into operation. Development is carried out until the full economically viable development of the reservoir 1.

Example 2. Perform, as example 1. The reservoir is relatively uniform. One pump is lowered into the center of the horizontal barrel. Packer is not installed.

As a result of the development, which limited the watering of the production well to 98%, 153.6 thousand tons of oil were produced from one horizontal well during 28 years of development, the oil recovery ratio of the reservoir section (CIN) was 0.332. According to the prototype, ceteris paribus, 120.2 thousand tons of oil was produced in 34 years of development, oil recovery factor amounted to 0.260. The increase in recovery factor by the proposed method is 0.072.

The proposed method allows to increase the rate of selection, oil recovery factor and to ensure uniformity of oil reserves.

The application of the proposed method will allow to solve the problem of increasing the rate of oil extraction of a terrigenous or carbonate formation, uniformity of oil reserves and, as a result, an increase in oil recovery of a productive formation.

Claims (1)

A method of developing an oil reservoir by horizontal wells, including drilling or selecting already drilled horizontal wells, identifying sections in the form of intervals of the reservoir, lowering the pump into the well, separating the sections with packers, selecting well products from each section, characterized in that when developing a terrigenous or carbonate formation pre-determine the inflow profile, identify areas with an inflow profile that differs from each other in specific oil production by 20% or more, in the places of change in specific packers are installed at the oil production rate, one pump is lowered into the center of each section on a separate column of tubing or coiled tubing sleeveless pipes, the distance between the pumps along the horizontal shaft is set to no more than 200 m.

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