RU2331762C2 - Method to produce heavy and viscous hydrocarbons - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: invention is referred to the method of hydrocarbon production from tar sand or reservoir of heavy oil challenged by high viscosity. The method contains drilling and pre-commissioning with casing injecting wells with horizontal bores and producing wells with horizontal bores to the reservoirs below level of the injecting well and creation of permeable zone between injecting and producing wells. Injecting and producing wells are drilled by one of the grid systems with certain space between the wells. After the casing is completed but before horizontal bores are developed, injecting and producing wells shall be deepened to estimated depth. Then whipstock shall be run in each well till tags the bottom in order to direct its discharge channels to the open well section developed after deepening and successively form required number of horizontal bores via each open well section. After that, heat-insulated tubing string shall be run in each well and packer shall be set above perforated section in order to isolate annulus between casing and heat-insulated tubing string to prevent thermal influence to the well above the packer.

EFFECT: higher accuracy of orientating horizontal bores in the reservoir, development efficiency due to larger covered cross-sectional area of the reservoir and simpler method.

2 dwg

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, with each of the injection and production wells having horizontal end sections extending inside the reservoir.

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

firstly, the complex process of the method;

secondly, the small area covered by horizontal deposits and, as a consequence, the low efficiency of the development of deposits;

thirdly, the difficulty of orienting horizontal sections of injection and producing wells in the reservoir;

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

An object of the invention is to simplify the process of implementing the method and increase the accuracy of orientation of horizontal sections of wells in the reservoir, as well as increase the efficiency of developing deposits by increasing the coverage area of the reservoir of heavy and highly viscous hydrocarbons in horizontal sections and 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 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 injection and production wells.

New is that the injection and production wells are drilled according to one of the areal systems: the injection and production wells are deepened to the design depth, and after installing the casing strings, but before the formation of the horizontal end sections, the injection and production wells are deepened to the design depth, then to each well, before interacting with the bottom, a deflector is lowered, directing the output channels of the deflector to the open section of the well formed by its deepening, and the through each open section of the well, the required number of horizontal end sections in the well, after lowering the insulated pipe string in each well above the open section of the well, a packer is installed that insulates the annular space between the casing and the insulated pipe string to eliminate thermal effects on the well above the packer.

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 image of an underground reservoir of heavy and high viscosity hydrocarbons with producing and injection wells.

The essence of the method is as follows.

First, on one areal system, one pair of wells is drilled, consisting of injection 1 (see Fig. 1) and producing 2 wells with a certain distance L between them, with a casing being installed in each well after drilling, which is then cemented.

Next, the injection 1 and production 2 wells are deepened to the calculated depth (for example, by 10 meters), while in the wells, recesses 3 and 4 are formed, respectively. Then, in each of the wells, the formation of horizontal end sections begins. To this end, a diverter is lowered into each of the wells before interacting with the bottom (Figs. 1 and 2), which directs the diverter output channels (see US patents No. 5413184 publ. 05.09.1995, PCT WO No. 99/29997 dated 06/17/1999, RU No. 2259457, publ. Bull. No. 24 dated 08/27/2005) into open sections 5 and 6, respectively of injection 1 and producing 2 wells, formed by their recesses 3 and 4, respectively.

Then form through each open area 5 and 6, respectively, of injection 1 and producing 2 wells, the required number of horizontal end sections 7; 7 ′; 7 ′ ′; 7 ′ ′ ′ ... 7 ⁿ and 8; 8';8''; 8 ′ ′ ′ ... 8 ^n, respectively, and the height H (see FIG. 1) between the above horizontal end sections in the injection 1 and production 2 wells should be at least 5 meters to exclude the breakthrough of the coolant during its injection from the branched horizontal end sections 7; 7 ′; 7 ′ ′; 7 ′ ′ ′ ... 7 ^{n of} injection well 1 into branched horizontal end sections 8; 8';8''; 8 ′ ′ ′ ... 8 ^{n of} production well 2.

The above distance L (see figure 2) between the axes of the producing 1 and injection 2 wells is determined by calculation and depends on the length of the horizontal end sections 7; 7 ′; 7 ′ ′; 7 ′ ′ ′ ... 7 ^{n of} injection well 1 and lengths of branched horizontal end sections 8; 8';8''; 8 ′ ′ ′ ... 8 ^{n of} production well 2.

Upon completion of the construction of wells, they begin their preparation for operation. For this, the injection well 1 (see Fig. 1) is equipped with a thermally insulated pipe string 9 for supplying a heat carrier, the lower end of which is lowered into a recess 3 opposite the open section 5.

Next, the production well 2 is equipped with a heat-insulated pipe string 10, the lower end of which is also lowered into the recesses 4 opposite the open section 6.

Then, above each of the open sections 5 and 6, respectively, of injection 1 and production 2 wells, packers 11 and 12, respectively, are installed, isolating the annular space of each well between the casing and the heat-insulated pipe string, to exclude thermal effects on the walls of injection 1 and production 2 wells above packers 11 and 12, respectively.

Then, a pump 13 of any known construction, for example a screw, is lowered into a heat-insulated pipe string 10 of the producing well 2.

Then, from the mouth of the injection well 1, the coolant (hot water vapor) is pumped into the heat-insulated pipe string 9, which, having reached the open section 5 of the recess 3, enters the horizontal end sections 7; 7 ′; 7 ′ ′; 7 ′ ′ ′ ... 7 ^{n of} injection well 1, through which it extends deep into the reservoir of heavy and highly viscous hydrocarbons 14. Next, the pump 13 of the production well 2 is launched into operation.

Heating takes place over the entire height of the reservoir of heavy and highly viscous hydrocarbons 14 radially directed from each horizontal end section 7; 7 ′; 7 ′ ′; 7 ′ ′ ′ ... 7 ⁿ injection well 1

The heated product (heavy viscous oil) deposits of heavy and highly viscous hydrocarbons 14 fall into the horizontal end sections 8; 8';8''; 8 ′ ′ ′ ... 8 ^{n of the} production well 2, through which it enters the open section 6 of the recess 4 of the production well 2, from where it enters the intake of the pump 13, which pumps the heated heavy viscous oil to the surface.

The use of heat-insulated columns of pipes 9 and 10, as well as packers 11 and 12, can significantly reduce the negative effect of thermal effects on the fastening of well walls during operation.

Then, for example, in a checkerboard pattern within the same areal system, a similar construction of the following pairs of wells is carried out (not shown in FIGS. 1 and 2), consisting of injection 1 ′ ...... 1 ⁿ and production wells 2 .... ..2 ^n, respectively, while observing the above distance L between the axes of nearby wells, which are also similarly prepared and put into operation.

The proposed method allows to increase the accuracy of the orientation of horizontal sections of wells in the deposits, as well as the efficiency of the development of deposits by increasing the coverage area of the deposits of heavy and highly viscous hydrocarbons in horizontal sections, and the simplification of the technological process of the method allows to save material and financial costs. In addition, 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 according to one of the area systems with defined the distance between them, and after installing the casing strings, but before the formation of the horizontal end sections, the injection and production wells are deepened to the calculated depth, then a deflector is lowered into each well before interacting with the bottom to direct its output channels to the open section of the well formed by its deepening , and form sequentially through each open section of the well the required number of horizontal end sections in the well, after the descent of the insulated column pipes in each well above the open section of the well, a packer is installed that insulates the annulus between the casing and the insulated pipe string to prevent thermal effects on the well above the packer.

Images