RU2339807C1 - Method of extraction of heavy and high viscous hydrocarbons from undeground deposits - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to method of extraction of tar sand or of heavy oil with high viscosity from underground deposit. The essence of the invention is as follows: the method includes boring and preparing to operation with installation of case columns of pressure wells with horizontal end sections and producing wells with horizontal end sections in the deposit below the level of the pressure well for extraction of hydrocarbons; then formation of a permeable zone between the pressure and producing wells. According to the invention boring of pressure and producing wells is carried out on base of one of the aerial systems with a distance of not less, than five meters between them. Each case column lowered before forming of end sections of pressure and producing wells is opened along the whole perimeter at direct proximity from a bottomhole with a distance for height not less, than five meters between opened sections of pressure and producing wells. Further, a deflector with outgoing valves directed into an opened section is lowered into each well before interaction with the bottomhole. A required number of horizontal end sections of a well, each equipped with filters connected to each other with flexible links is arranged successively through each opened section of the cased column; the said filters consist of links connected between themselves with flexible components insulating the space between inputs of the horizontal sections and an upper link of filters. After lowering of thermo-insulated tube column in each well above the opened section there is installed a packer, insulating annular space between the cased column and thermo-insulated tube column to exclude thermal influence onto the well above the packer.

EFFECT: facilitating increased efficiency of underground deposit development and extension of service life of well till capital repair.

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Description

The invention relates to a method for producing hydrocarbons from an underground tar sand deposit or a heavy oil reservoir having a high viscosity. To obtain hydrocarbons from such deposits, their heating is necessary.

A known method of developing an oil field (patent RU No. 22113857, IPC 7 ЕВВ 43/24, published in Bulletin No. 28 of 10.10.2003), including drilling vertical wells with sidetracks, pumping coolant into the reservoir through sidetracks and selection oil through them, and vertical wells are drilled to the bottom of the lower object with their placement in one of the areal systems, while before the start of areal injection of a working agent, for example, water, sidetracks are drilled into the formation in each vertical well in each production facility of the formation, then by sequential treatment sidetracks by feeding them to subsequent selection of coolant through the lateral holes of oil well production to reduce to a minimum viable level, the injection of steam and selection cycles oil repeated until the maximum allowable water cut oil.

The disadvantage of this method is that the selection of products from the well is carried out cyclically, combining it with steam injection to the maximum allowable water cut of the produced product, which reduces the amount of oil produced and leads to significant heat energy costs for heating the formation.

There is also known a method of developing high-viscosity oil and bitumen deposits with horizontal wells (patent RU No. 2237804, IPC 7 ЕВВ 43/24, published in Bulletin No. 28 dated 10.10.2004), including drilling wells on a specific grid, pumping out agent through injection wells and selection of formation fluids through production wells, while drilling wells along a radial grid so that injection wells are located along the productive formation closer to the upper boundary of the formation along the most permeable layers, and production - lizhe to the lower limit of the formation, wherein the initial stage of development in all wells is carried thermocyclic treating the formation with steam stimulation, followed by transfer to selection of formation fluids through the production wells with areal influence on the formation through injection wells.

The closest in technical essence is a method of producing hydrocarbons from an underground deposit of tar sand or a heavy oil deposit (patent RU No. 2098613 MKI 6 ЕВВ 43/24, published in bul. 34 from 12/10/1997), containing drilling and preparation for operation injection well, which ends in the reservoir, and production wells, which ends in the reservoir below the level of the injection well, the creation of a permeable zone between the injection and production wells, while drilling and preparation for operation carry out at least thinking of pairs of wells, where each pair includes an injection well ending in the reservoir, and a producing well ending in the reservoir below the level of the injection well, the second pair of wells facing the first pair of wells, create a permeable zone between the injection well and the producing well of each pair of wells, water injection is carried out through injection wells, the simultaneous extraction of hydrocarbons is carried out by producing wells, while the injection pressure in the injection wells and the first pair exceeds the injection pressure in the injection well of the second pair of wells, each injection and producing well having horizontal end sections extending inside the reservoir.

Both analogues and prototypes to one degree or another have common disadvantages:

firstly, during operation, collapse and backfill of rocks with one or more technological channels is possible, which leads to a decrease in the production rate of the mined products;

secondly, the lack of filtration in the technological channels of the produced products can lead to a partial or complete loss of the cross section in the technological channel (s) and a quick failure of the pumping equipment.

thirdly, in the process of pumping the coolant, a thermal effect is exerted on the borehole walls, which negatively affects the strength of the fastening (cement stone) of the casing of the well and leads to premature destruction of the cement stone behind the casing of the well.

The objective of the invention is to increase the operating efficiency of a multilateral well and increase the life of pumping equipment, as well as reduce the thermal effect on the walls of the well during operation.

The stated technical problem is solved by a method of producing heavy and highly viscous hydrocarbons from an underground deposit, comprising drilling and preparing for operation injection wells with horizontal end sections and production wells with horizontal end sections in the reservoir below the level of the injection well for hydrocarbon recovery, creating a permeable zone between the injection and producing wells.

What is new is that injection and production wells are drilled using one of the areal systems with a distance of at least five meters between them, with each casing being lowered before the formation of the end sections, injection and production wells are opened around the entire perimeter in the immediate vicinity of the bottom hole a distance of at least five meters in height between the exposed areas of the injection and production wells, then a diverter guiding the outlet is lowered into each well before interacting with the bottom hole e channels of the deflector into the exposed section, and form the required number of horizontal end sections of the well sequentially through each opened section of the casing, installing in each filter, consisting of links interconnected by flexible elements, and isolating the space between the entrances of the horizontal sections and the upper link of the filters, after the descent of the insulated pipe string in each well above the exposed section, a packer is installed that insulates the annulus between the casing th and thermally insulated pipe string to exclude thermal effects on the well above the packer.

The figure 1 in a longitudinal section schematically shows an image of an underground reservoir of heavy and high viscosity hydrocarbons with producing and injection wells.

Figure 2 in section AA shows a schematic representation of an underground reservoir of heavy and high viscosity hydrocarbons with producing and injection wells.

The essence of the method is as follows.

First, the construction of one pair of wells is carried out, consisting of production 1 (see Fig. 1) and injection 2 wells, for example, first the construction of production well 1 is carried out, which, after drilling, is cased and cemented.

Then the casing of the producing well 1 is opened (by any known method) in section 3 along the entire perimeter in the immediate vicinity of the bottomhole. Next, in the casing of the producing well 1, a deflector is lowered onto the pipe string before interacting with the bottom hole (not shown in FIGS. 1 and 2) (see, for example: patents “Method for the construction of a multilateral well” RU No 2252563, 2259457, 2265711, ЕВВ 7 / 06, published respectively BI No. 20 of 07/20/2005, 24 of 08/27/2005 and 34 of 12/10/2005). Then in the pipe string, lowered into the casing of the production well 1, filters 4 are lowered, interconnected by flexible links 5, located, for example, at the end of the flexible pipe with the possibility of disconnection. During the descent, the filters 4, interconnected by flexible links 5, located at the end of the flexible pipe along the pipe string, through the guide output channels (not shown in Figs. 1 and 2) fall into the exposed section 3 of the casing of the producing well 1.

Further, in the underground reservoir 6, a horizontal end section 7 of length L is formed (by any known method). After that, the flexible pipe is disconnected from the filters 4 connected by flexible links 5 and removed at the mouth (not shown in FIGS. 1 and 2) wells, and the filters 4, interconnected by flexible links 5, remain in the horizontal end section 7 of length L, the space between the entrance to the horizontal end section 7 and the upper link of the filters 4 is isolated, for example, using a packer 8 made in the form self sealing I cuffs, lowered into the well on the upper end of the upper filter unit 4.

Next, filters 4 ′ are connected to the flexible pipe, interconnected by flexible links 5 ′, and the next horizontal end section 7 ′ is similarly formed and the space packer 8 ′ is isolated between the entrance to the horizontal end section 7 ′ and the upper link of the filters 4 ′.

Thus, sequentially through the opened section 3 of the casing string of the producing well 1, the required number of horizontal end sections 7 ′ ... 7 ^{n are formed} , installing in each of them, respectively, filters 4 ′ ... 4 ⁿ connected by flexible links 5 ′ ... 5 ⁿ , and isolating with the packer 8 ′ ... 8 ^{n the} spaces between the entrance to the horizontal end section 7 ′ ... 7 ⁿ and the upper link of the filters 4 ′ ... 4 ⁿ .

Then, the construction of injection well 2 is carried out. For this, the casing of injection well 2 is opened in section 9 along the entire perimeter in the immediate vicinity of the bottomhole. Then, a diverter is lowered into the casing of the injection well 2 before interacting with the bottom hole. Then in the pipe string, lowered into the casing of the producing well 1, filters 10 are connected, interconnected by flexible links 11, placed, for example, at the end of the flexible pipe with the possibility of disconnection.

During the descent, the filters 10, interconnected by flexible links 11, located at the end of the flexible pipe along the pipe string and through the guiding output channels of the deflector enter the exposed section 9 of the casing of the injection well 1.

Further, in the underground reservoir 6 form (for example: patents "Method for the construction of a multilateral wellbore" RU №2256763, 2259457, 2265711, ЕВВ 7/06, publ. Respectively BI No. 20 from 07.20.2005, 24 from 08.28.2005 and 34 from 10.12. 2005) a horizontal end section 12 of length L. Then, the flexible pipe is disconnected from the filters 10 connected by flexible links 11 and removed at the wellhead (not shown in FIGS. 1 and 2), and the filters 10 connected to each other flexible links 11 remain in the horizontal end section 12 of length - In, with the space between the entrance to the horizon flax end portion 12 and the upper filter element 10 is insulated for example by a packer 13, configured as a self-sealing cuff, lowered into the well on the upper end of the upper link 10 of the filter.

Next, filters 10 ′ are connected to the flexible pipe, interconnected by flexible links 11 ′, and the next horizontal end section 12 ′ is similarly formed and the space packer 13 ′ is isolated between the entrance to the horizontal end section 12 ′ and the upper link of the filters 10 ′.

Thus, successively through the opened section of the casing of the producing well 1, the required number of horizontal end sections of the well 12 ′ ... 12 ^{n are formed} , installing in each of them, respectively, filters 10 ′ ... 10 ⁿ connected to each other by flexible links 11 ′ ... 11 ⁿ , and isolating with the packer 13 ′ ... 13 ^{n the} spaces between the entrance to the horizontal end section 12 ′ ... 12 ⁿ and the upper link of the filters 10 ′ ... 10 ⁿ .

During the construction of production 1 and injection 2 wells, it is necessary to take into account the fact that the height (see Fig. 1) between the opened section 3 of the casing string of the production well 1 and the opened section 9 of the casing string of the injection well 2 is determined by calculation, but must be at least 5 meters to prevent breakthrough of the coolant during its injection from the horizontal end sections 12 ′ ... 12 ⁿ directed towards each other in the injection well 2 into the horizontal end sections 7 ′ ... 7 ⁿ in the production well 1. Pr for the same purpose, as indicated above, that is, the distance C (see FIG. 2) between the axes of the producing 1 and injection 2 wells must also be at least 5 meters.

If necessary, within the same areal system, the following pairs of wells are constructed, consisting of producing 1 ′ ... 1 ⁿ (not shown in FIGS. 1 and 2) and injection 2 ′ ... 2 ⁿ wells, respectively.

Upon completion of the construction of wells, they begin their preparation for operation.

To do this, the production well 1 is equipped with a heat-insulated pipe string 14 (see Fig. 1) with a pump 15 of any known design, lowered to the exposed section 3 of the casing of the production well 1.

Then, the injection well 2 is also equipped with a heat-insulated string of pipes 16 for supplying a coolant deflated to the exposed section 9 of the casing of the injection well 2.

Next, a packer 17 is installed above the opened section 3 of the casing string of the producing well 1, and a packer 18 is installed above the opened section 9 of the casing string of the injection well 2.

Packers 17 and 18 isolate the annulus 19 and 20, respectively, reducing the thermal effect on the walls of the casing of the producing 1 and injection 2 wells.

Next, start the operation of wells. To do this, coolant (hot water vapor) is pumped from the mouth of injection well 2 into a heat-insulated pipe string 16, which, having reached the exposed section 8, enters the filters 10 ′ ... 10 ⁿ , interconnected by flexible links 11 ′ ... 11 ⁿ and located in the respective horizontal end sections 12 ′ ... 12 ^{n of the} injection well 2, through which the coolant extends deep into the underground reservoir 6, while heating occurs along the entire height of the underground reservoir 6 radially directed from each horizontal end of the 12 ′ ... 12 ⁿ section of the injection well 2 ... 2 ⁿ .

Next, the pump 15 of the producing well 1 is started. The heated product (heavy viscous oil) of the underground reservoir enters the filters 4 ′ ... 4 ⁿ , interconnected by flexible links 5 ′ ... 5 ⁿ and located in the corresponding horizontal end sections 7 ′. ..7 ^{n of the} producing well 1, through which heavy viscous oil enters the producing well 1 ... 1 ⁿ to the intake of the pump 15, which pumps the warmed heavy viscous oil to the day surface through a thermally insulated pipe string 14.

The use of insulated columns of pipes 14 and 16, as well as packers 17 and 18, can significantly reduce the negative impact of thermal effects on the fastening of the walls of the well during operation.

The proposed method improves the efficiency of the development of underground deposits, since the technological channels are cased with filters interconnected by flexible links, which eliminates the destruction of the horizontal end sections of the wells, and also filtering the liquid, which allows to extend the life of the pumping equipment. In addition, the isolation of the spaces between the entrances to the horizontal end sections and the upper links of the filters eliminates the backflow of fluid from the wells to receive filters, and reducing the thermal effect on the walls of the well during operation will extend the life of the well until overhaul.

Claims (1)

A method for producing heavy and highly viscous hydrocarbons from an underground deposit, comprising drilling and preparing for operation with installation of casing strings of injection wells with horizontal end sections and production wells with horizontal end sections in the reservoir below the level of the injection well for hydrocarbon recovery, creating a permeable zone between the injection and producing wells, characterized in that the injection and production wells are drilled in one of the area systems from a distance we’ve got at least five meters between them, and each casing run before the formation of the end sections of the injection and production wells is opened around the entire perimeter in the immediate vicinity of the bottom with a height distance of at least five meters between the opened sections of the injection and production wells, then each well, before interacting with the bottom hole, a deflector is lowered with output channels directed to the exposed section, and the successive casing string is formed sequentially through each open section the acceptable number of horizontal end sections of the well, installing in each filter, consisting of links connected by flexible elements, and isolating the space between the entrances of the horizontal sections and the upper link of the filters, after lowering the insulated pipe string in each well above the opened section, a packer is installed that insulates the annular the space between the casing and the insulated pipe string to prevent thermal effects on the well above the packer.

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