RU2773088C1 - Gravitational method of oil production by two-shed wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry and can be used in the development of oil from old fields in the interval of a horizontal section. The gravity method for oil production by two-head wells is characterized by the construction of a two-head well with a horizontal section. Casing strings are mounted in the completed well from the side of the injection and production mouths into the formation cavity. Inside the casing strings with a loop with access to the productive horizon, a production string is mounted, isolated in the wellhead parts from the casing string by seals. In the horizontal sections of the casing and production strings, holes are made for drainage from the reservoir cavity into the inline space of the production string under the action of the own gravity of the oil-water emulsion. As the intrapipe space is filled, the oil-water emulsion is displaced from the injection wellhead to the production wellhead by cleaning elements launched from the side of the injection wellhead by the launcher and removed together with the oil-water emulsion from the side of the producing wellhead by the receiving device. At the same time, said cleaning elements are pushed in the production string to the production wellhead by high pressure of neutral gas supplied through the discharge wellhead from the compressor connected to the starter. The oil-water emulsion from the receiving device of the producing wellhead is supplied with the help of a main pump for further processing or storage.

EFFECT: reduction of labor intensity and labor costs of oil development.

1 cl, 2 dwg

Description

The invention relates to the oil and gas industry and can be used in the development of old oil fields in the interval of the horizontal section [E21B 43/16, E21B 43/24, E21B 43/241].

In modern conditions, the prospects for the development of the oil industry are associated with the development of deposits of heavy oil and natural bitumen. The keen interest in heavy oil and natural bitumen deposits can be fully explained by the constant increase in prices for hydrocarbon raw materials, the gradual depletion of traditional light oil reserves, and the development of technologies for the extraction of "unconventional" oil. Most of the world's heavy oil reserves are located in Canada, Venezuela and Russia. Extraction of unconventional oil requires an unconventional unique approach. There are various ways to develop deposits of heavy oil and natural bitumen, which differ in technological and economic characteristics. Conventionally, technologies and methods for the development of heavy oil and natural bitumen deposits, which have been tested and used in the practice of oil production in Russia and abroad, can be divided into three groups:

career and mine methods of development;

the so-called "cold" mining methods;

thermal extraction methods.

Naturally, the applicability of a particular technology is determined by the geological structure and conditions of the formations, the physicochemical properties of the formation fluid, the state and reserves of hydrocarbon raw materials, climatic, geographical conditions, etc.

The idea of using the high density of bitumen as a driving force in the process of mining using thermal impact was first realized at the Yaregskoye field, which is being developed by the so-called shaft-borehole method. With the development of horizontal drilling technology in Canada, the technology of steam-assisted gravity treatment using a pair of horizontal wells was developed, better known in the world industry as SAGD (Steam Assisted Gravity Drainage).

In the classical description, this technology requires the drilling of two horizontal wells located in parallel one above the other. Wells are drilled through oil-saturated thicknesses near the bottom of the formation. The distance between two wells is usually 5 meters. The length of horizontal wells reaches 1000 m. The upper horizontal well is used to inject steam into the formation and create a high-temperature steam chamber.

The process of steam-gravity impact begins with the preheating stage, during which (several months) steam is circulated in both wells. At the same time, due to the conductive heat transfer, the formation zone between the production and injection wells is heated, the viscosity of oil in this zone decreases, and, thereby, hydrodynamic communication between the wells is provided.

At the main stage of production, steam is already injected into the injection well. The injected steam, due to the density difference, makes its way to the upper part of the reservoir, creating an increasing steam chamber. At the interface between the steam chamber and cold oil-saturated thicknesses, a heat exchange process is constantly taking place, as a result of which the steam condenses into water and, together with the heated oil, flows down to the production well under the action of gravity.

The upward growth of the steam chamber continues until it reaches the top of the formation, after which it begins to expand laterally. The oil is always in contact with the high temperature steam chamber. Thus, heat loss is minimal, which makes this development method economically advantageous.

The results of SAGD pilot projects have shown that the development of high-viscosity oil deposits (10,000-45,000 mPa·s) by a new method increases the oil recovery factor up to 60% compared to 10% with cyclic steam treatment of wells.

There are several key challenges that companies using SAGD technology must overcome in order to achieve cost-effective technology. It:

achieving maximum energy efficiency;

optimal process for separating oil and water;

purification of water for reuse in steam generation.

Efficient use of reagents is the main condition for the successful solution of these problems. One of the promising directions for increasing the efficiency of SAGD projects from a technological, economic and, importantly, from an environmental point of view is the use of hydrocarbon solvents. In recent years, a number of SAGD modifications have been developed:

Vapor Extraction (VAPEX) - extraction of oil by means of a vaporous solvent;

Expanding Solvent SAGD (ES-SAGD) - steam-gravity effect with the addition of a solvent;

Solvent Aided Process (SAP) - a process with the addition of a solvent;

Steam Alternating Solvent (SAS) - alternating steam and solvent injection.

Despite the variety of technologies, they can be divided into 3 groups: technologies in which steam is completely replaced by solvent, technologies in which steam and solvent are injected together, and sequential (cyclic) injection of steam and solvent.

The need for SAGD modifications is due to the desire to improve the economic performance of projects, take into account the specific geological and physical conditions of the field, as well as stringent requirements in the field of environmental protection. SAGD projects are the largest consumers of fresh water in the production regions, and the payment for greenhouse gas emissions from steam production can become a significant cost item in the foreseeable future.

Advantages of the steam gravity drainage technology: high oil recovery factor, reaching 75% under favorable conditions, continuous oil recovery process, balance between steam production at bottomhole conditions and heat loss and, as a result, maximum recovery volumes, optimal total steam-oil ratio.

The disadvantages of the steam gravity drainage technology are the high cost of oil associated with the cost of steam generation, which requires a source of a large volume of water, as well as water treatment equipment, as well as high requirements for the reservoir being developed in terms of uniformity and relatively large power.

A METHOD FOR OIL DISPLACEMENT FROM A HORIZONTAL WELL [RU2421608 (C1), publ.: 06/20/2011] is known from patent sources, including installation of a perforated production string in a drilled well, isolation of the annular space to a horizontal wellbore, installation of tubing in the production string, sealing annular space with an isolation unit, injection of a displacing agent into the end part of the production string behind the isolation unit and withdrawal of the product at the beginning of the horizontal section of the production string, characterized in that before lowering the production string into the well, a casing string is installed to the horizontal section with its subsequent cementing, and between the beginning of the horizontal section and the end part from the outside, the production string before running is equipped with an inflatable packer, which is connected from the inside by bypass holes located on the side of the wellhead from the isolation unit, with the production string, and the injection of the working The agent is carried out through the annular space through the process valve, which communicates with the output of the end part of the production string, and the product is withdrawn through the tubing string, which communicates with the annulus of the production string by radial channels.

The disadvantage of the analogue is the high labor intensity of oil production, due, as in the SAGD technology described above, to the use of a working agent to displace oil from the annulus, which, among other things, leads to an increase in the cost of oil production.

The closest in technical essence is the METHOD FOR THE DEVELOPMENT OF A HEAVY OIL OR BITUMEN FIELD USING TWO-SHELL HORIZONTAL WELLS [RU 2431746 (A), publ.: 20.10.2011], including the construction of two-well upper injection and lower production wells with horizontal sections located one above the other , injection of a coolant, for example, superheated steam through an injection well with formation heating by creating a steam chamber and extraction of products through a production well, characterized in that superheated steam mixed with combustible fuel combustion products is used as a coolant, which is pumped through one of the mouths of the injection string, at the same time, moisture condensed on the inner surface of the injection string is withdrawn through another wellhead, and if the reservoir properties deteriorate and / or the total production of the formation is reduced by more than two times over a period of not more than three months, one of the wellheads of the production well The pipes are sealed, and an oil-water emulsion is pumped through the other in a volume that is at least twice the volume of the horizontal wellbore of the production string, after technological exposure, the coolant is injected and the product is taken in the usual mode.

The main technical problem of the prototype is the problem of SAGD technology, namely the high cost of oil, the practical impossibility of oil production in the absence of a water source, labor costs for additional water treatment equipment and special requirements for the reservoir being developed. In addition, the use of the method described in the prototype invariably leads to a negative impact on nature.

The objective of the invention is to eliminate the disadvantages of the prototype.

The technical result of the invention is to reduce the complexity and labor costs of oil development.

The specified technical result is achieved due to the fact that the gravity method of oil production by two-head wells, characterized by the construction of a two-head well with a horizontal section, characterized in that casing strings are mounted into the completed well from the side of the injection and production mouths into the reservoir cavity, inside which a loop with access to the productive horizon a production string is mounted, isolated in the wellhead parts from the casing string by seals, while in the horizontal sections of the casing and production strings, holes are made for drainage from the formation cavity into the intrapipe space of the production string under the action of the own gravity of the oil-water emulsion, as it is filled, the oil-water emulsion is displaced from injection to the producing wellhead by cleaning elements launched from the side of the injection wellhead by the launcher and extracted together with the oil-water emulsion from the side of the producing wellhead at the same time, said cleaning elements are pushed in the production string to the producing well with high pressure of neutral gas supplied through the discharge well from the compressor connected to the start-up device, the oil-water emulsion from the receiving well is fed with the main pump for further processing or storage.

Brief description of the drawings.

Figure 1 shows a schematic representation of the gravity method of oil production with double-headed wells - side view.

Figure 2 shows a schematic representation of the gravity method of oil production double-headed wells - top view.

The figures indicate: 1 - productive horizon, 2 - casing string, 3 - string perforation, 4 - production string, 5 - stuffing box seal, 6 - start-up and receiving devices, 7 - cleaning element, 8 - compressors, 9 - collection tank, 10 - main pump, 11 - oil and gas treatment plant, 12 - filling riser.

Implementation of the invention

The gravity method of oil production with two-head wells is characterized by the fact that in the productive horizon 1 (see Figure 1) horizontal wells are drilled with a diameter of, for example, 500 mm with a horizontal end of the trunk having two mouths, a length depending on the geometric dimensions of the deposit. There can be several such wells at the oil production site. A casing string 2 is mounted in the completed well, in which perforation 3 is made along the entire length.

A production string 4 is lowered into the casing string 2, with a diameter smaller than that of the casing string 2. For example, for a well with a diameter of 500 mm, a production string 4 with a diameter of 350 mm is selected. Along the entire length of the production string 4, as well as in the casing string 1, perforation 3 is made. The production string 4 is isolated from the casing string 2 in the wellhead parts by a gland seal 5.

Starting and receiving devices 6 are mounted from the side of the injection and production wells to the production string 4, equipped, respectively, with launching and receiving chambers (not shown in the figures) of cleaning elements 7, made in the form of, for example, polyurethane balls, torpedoes, pistons, etc. d.

As the oil-water emulsion draining through the perforation of the columns 3 accumulates in the tubular space of the casing 2 and production columns 4, a compressor 8 is connected to the discharge mouth of the production string 4 to the launch chamber of the start-up and receiving device 6, which is configured to produce nitrogen from atmospheric air. A cleaning element 7 is placed in the start-up chamber of the start-up and receiving device 6 and the high pressure nitrogen supplied by the compressor 8 (see Fig.2) starts the cleaning element 7 along the production string 4 from the injection to the production wellhead. The cleaning element 7, when passing inside the production string 4, pushes the oil-water emulsion accumulated in it from the injection to the production well, and through the latter, the oil-water emulsion is poured out. The oil-water emulsion is fed into the collection tank 9, from where, using the main pump 10, it is pumped through the oil pipeline to the oil and gas treatment plant 11 or through the loading riser 12 it is pumped into tanks (not shown in the figures).

As the entire oil-water emulsion accumulated in the tubular space of the production string 4 is displaced, the cleaning element 7 reaches the receiving chamber of the start-up and receiving device 6 mounted on the second (producing) wellhead of the production string 4 and at this the process in this well stops until the next cycle of filling the pipe space production string 4 oil-water emulsion. To alert about the filling of the pipe space of the production string 4 with an oil-water emulsion, level sensors are mounted in the said space (not shown in the figures).

The process of displacing the oil-water emulsion accumulated by the gravity method in the production string 4 of a plurality of two-head wells can be performed sequentially.

The described example is a special case of the implementation of the invention and does not limit its scope, which is determined by the claims, taking into account possible options.

EFFECT: reduction of labor intensity and labor costs of oil development is achieved due to a simple but effective technology that does not require the cost of introducing steam or reagents into the oil reservoir, but involves the implementation of double-head wells with installation of casing 2 and production 4 in them and one inside the other columns with perforation 3 in their horizontal sections and with a loop output of the production string 1 into the productive horizon. Through the perforated sections of the casing 2 and production string 4, the oil-water emulsion, under the action of its own gravity, first enters the annular space, and then into the tubular space of the production string 4. As it is filled, the said oil-water emulsion is displaced through the production mouth of the production string 4 by pushing inside the production string 4 from the injection to the production wellhead cleaning element 7 created by means of a compressor 8 high pressure of neutral gas supplied through the launcher 6, which is also the start-up device of the cleaning element 7. receiving device 6, to which the main pump 10 is also connected, supplying the oil-water emulsion to the oil and gas treatment plant 11 or to the loading riser 12.

Claims (1)

Gravity method of oil production by double-headed wells, characterized by the construction of a double-headed well with a horizontal section, characterized in that casing strings are mounted in the completed well from the side of the injection and production mouths into the formation cavity, inside which a production string isolated in the wellhead is mounted with a loop with access to the productive horizon. parts from the casing string with seals, while in the horizontal sections of the casing and production strings, holes are made for drainage from the formation cavity into the intrapipe space of the production string under the action of the own gravity of the oil-water emulsion, as it is filled, the oil-water emulsion is displaced from the injection to the production wellheads by cleaning elements, launched from the side of the injection mouth by the launcher and extracted together with the oil-water emulsion from the side of the producing wellhead by the receiving device, while the said cleaning elements are alky in the production string to the producing wellhead by high pressure of neutral gas supplied through the discharge wellhead from the compressor connected to the start-up device, the oil-water emulsion from the receiving device of the producing wellhead with the help of the main pump is fed for further processing or storage.

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