RU2418162C1 - Method for improving permeability of bed during extraction of high-viscosity oil - Google Patents

Abstract

FIELD: oil and gas industry. ^ SUBSTANCE: method involves drilling of vertical well, lowering and cementing of production string with further perforation, lowering of tubing and pump. Prior to sealing of annular space at interval below extraction level in production string there installed is removed blind packer, and on its head a sand bridge is installed. After that, hydraulic fracturing of formation is performed; and after that sand bridge is washed away by lowering process pipe string. Then by means of standard catching tool there removed is blind packer from production string; after that, to production string there lowered and installed between extraction level and level of hydraulic fracturing of formation is packer with through channel. Above level of hydraulic fracturing of formation there installed is additional packer with process pie string, inside which tubing is lowered till there is tight interaction with through channel of packer. ^ EFFECT: reduction of financial and material costs during implementation of method; improvement of permeability of near-roof part of formation. ^ 2 cl, 2 dwg

Description

The invention relates to the field of oil field development, and in particular to methods for the production of highly viscous oil by thermal action on the reservoir.

The well-known "Method for the development of oil fields" (patent RU No. 2070284, E21B 43/24; 43/40, publ. Bull. No. 34 of 12/10/1996), including heating the oil reservoir containing heavy oil and oil displacement by injection into the coolant reservoir, characterized in that the wells of complex profile are drilled so that when they enter the oil reservoir, the wells are drilled stepwise parallel to the oil reservoir, covering the oil layer, while the upper and lower stages of each well are located in one vertical plane, each stage of the well is used alternately ak pumped, how extractive, while injecting coolant and selection of oil from each well is performed simultaneously, wherein the intermediate stage of each subsequent hole located above (below) the previous steps.

The disadvantage of this method is that it is applicable mainly in the initial stage of field development at high reservoir pressures.

A known method of producing highly viscous oil (Baibakov N.K., Garushev A.R. Thermal methods for developing oil fields. M., Nedra, 1981, p. 78), including drilling a vertical well, launching and cementing a production string with subsequent perforation , descent of tubing and sucker rod pump, steam injection into the well and oil production. One of the variants of the method involves the injection of steam into the formation by tubing, followed by exposure for several days with the subsequent commissioning of the well (oil selection using a rod pump). Another embodiment of the method provides for steam injection through the annular space to the bottom of the well, equipped with a special packer. At the same time, the fluid is pumped out by the downhole pump through the tubing.

The disadvantage of this method when it is used in weakly cemented formations containing highly viscous oil is that when using the most common well design, cemented before the bottom by a continuous production string with perforation in the formation interval, problems arise associated with the development of wells for steam injection. This is due to clogging of the permeable part of the bottomhole zone with cement mortar.

The well-known "Method of production from underground deposits of heavy and / or highly viscous hydrocarbons" (patent RU No. 2310744, E21B 43/24, publ. Bull. No. 32 from 11/20/2007), containing drilling and preparation for operation by at least two pairs wells, consisting of an injection well that ends in the reservoir and a production well that ends in the reservoir below the level of the injection well, creating a permeable zone between the injection and production wells, pumping coolant into the injection well, and simultaneously taking hydrocarbon from the production well, thus for increasing the permeable area between the production and injection well prior to commissioning in each well to produce a hydraulic fracturing proppant injection layer.

The disadvantage of this method is the high cost of its implementation, since it is necessary to build wells in pairs (production and injection).

The closest in technical essence is the "Method for the production of highly viscous oil" (patent RU No. 2232263, E21B 43/24, publ. Bull. No. 19 dated 07/10/2004), including drilling a vertical well, launching and cementing the production string followed by perforation , descent of tubing and sucker rod pump, sealing the annulus, for example, with a packer, pumping coolant into the well and taking oil, while the bottom of the vertical wellbore is located below the bottom of the oil reservoir with the formation of a tight cement cups, a sidetrack is drilled from a vertical wellbore, while the mouth of the lateral wellbore is located above the roof of the oil reservoir, its bottom is above the oil-water contact, and the lateral well is cased with an uncemented slit-like shank, while the coolant is pumped into the lateral well, and oil is taken from the vertical well wells with a rod pump installed on the bottom, and steam is injected into the sidetrack through the annulus and at the same time oil is taken from the vertical stem, with the packer in the annulus th space set below the mouth of the lateral trunk.

The disadvantages of this method are:

- firstly, the large financial and material costs associated with drilling an additional side trunk, which is equipped with a slit-like shank;

- secondly, the low permeability of the bedside part of the formation, which reduces the efficiency of heating the formation and leads to a decrease in the selection of high viscosity oil, and, accordingly, the cost per ton of high viscosity oil is sharply increased.

The objective of the invention is to reduce financial and material costs during the implementation of the method, as well as increasing the permeability of the bedding part of the formation.

The problem is solved by a method of increasing the permeability of the formation during the production of highly viscous oil, including drilling a vertical well, lowering and cementing the production string, followed by perforation, lowering the tubing and tubing, sealing the annulus above the level of oil withdrawal by the packer, pumping coolant into the well above the oil-water contact (WOC), which is carried out through the annulus of the tubing, and the selection of oil through the tubing.

What is new is that before sealing the annular space into the interval below the extraction level, a retrievable blind packer is installed in the production casing, onto which the sand bridge is installed, after which hydraulic fracturing is performed in the side part of the formation, then the sand bridge is washed and the blind packer is removed from the production string, then a packer with a passage channel is lowered into the production casing and installed between the withdrawal level and the hydraulic fracturing level, and set up to the hydraulic fracturing level to an additional packer with a technological string of pipes, inside of which the tubing is lowered to hermetically interact with the packer through passage.

It is also new that, as the level of KNK decreases, an additional packer with a tubing string, a tubing string and a packer are removed from the well, an additional hydraulic fracturing is performed above the KNF level, after which a through packer is installed in the well below the additional hydraulic fracturing zone, and above the hydraulic fracturing level install an additional packer with a technological string of pipes, inside of which a tubing string is lowered until tight interaction with the through packer.

The figure 1 shows a diagram of the implementation of the method before conducting hydraulic fracturing.

The figure 2 shows a diagram of the implementation of the method after hydraulic fracturing.

A method of increasing the permeability of the formation during the production of highly viscous oil involves drilling a vertical well 1 (see figure 1). The descent and cementing of production casing 2, followed by perforation 3 and 4. In the interval below the level of extraction in the production casing 2, a removable blank packer 5 of any known construction is installed.

A sand bridge 6 is poured onto the “head” of the removed deaf packer 5, for example, from quartz sand 5-10 meters high. Sand bridge 6 is installed by washing along the tubing string (not shown in Figs. 1 and 2).

The sand bridge 6 over the retrievable deaf packer 5 is installed so that the retrievable deaf packer 5 does not move along the production string 2 due to the increased pressure in the production string 2 during hydraulic fracturing.

According to the known technology, hydraulic fracturing is performed in the cover part of the formation 7 in the range of perforations 3 with the formation of horizontal cracks 8.

By lowering the process pipe string (not shown in FIGS. 1 and 2), a sand bridge 6 is washed over the removed deaf packer 5 by means of washing liquid, and then, using a standard fishing tool, for example, lowered into a well on a rope (not shown in FIG.), capture under the "head" of the removed deaf packer 5. Then remove the deaf packer 5 from the production casing 2.

Next, the annulus is sealed.

To do this, in the production casing 2 (see figure 2) lower and install between the level of selection and the level of hydraulic fracturing, the packer 9 with the passage channel 10, and above the level of hydraulic fracturing - an additional packer 11 with the process pipe string 12, into which the pump string is lowered -compressor pipes (tubing) 13, provided at the lower end with radial holes 14 until tight interaction with the passage channel 10 of the packer 9.

The coolant 1 (for example, steam) is pumped into the well 1 through the annulus 15 of the tubing string 9 above the oil-water contact (WPC) (see Figs. 1 and 2) through the perforation holes 3 of the production string 2 and horizontal cracks 8, and the selection of heated high-viscosity oil produced on the tubing string 9 through the perforations 4 of the production casing 2 using a pump of any known design (not shown in figures 1 and 2).

During the operation of well 1, a decrease in the level of VNK occurs, therefore, as the level of VNK decreases, the first pipe string 12 with an additional packer 11 is removed from the well 1, and then the tubing string 13 is passed through the packer 9. Next, an additional hydraulic fracturing is performed (in figures 1 and 2 not shown) of the formation 7 above the level of the OWC, after which in the well 1 below the zone of additional hydraulic fracturing, a through packer 9 is installed, and above the hydraulic fracturing level, an additional packer 11 with a process pipe string 12, into which OSCAL tubing 13 to sealingly interact with the packer through passage 9.

The proposed method of increasing the permeability of the formation during the production of highly viscous oil allows to reduce financial and material costs during the implementation of the method, since in comparison with the prototype it avoids sidetracking, and the increase in permeability of the near-side formation while carrying out the method involves hydraulic fracturing in the near-side part the formation of horizontal cracks.

Claims (2)

1. A method of increasing the permeability of the formation during the production of highly viscous oil, including drilling a vertical well, lowering and cementing the production string followed by perforation, lowering the tubing and tubing and pump, sealing the annulus above the level of oil withdrawal by the packer, pumping the coolant above the water-oil into the well contact - VNK, which is carried out through the annular space of the tubing, and the selection of oil through the tubing, characterized in that before sealing the annular space in the interval below the level a withdrawal blind packer is installed in the production casing, on which the sand bridge is installed, then hydraulic fracturing is performed in the near-bed part of the formation, then the sand bridge is washed and the blind packer is removed from the production string, then the production string is lowered and installed between the selection level and the level of hydraulic fracturing a packer with a passage channel, and above the level of hydraulic fracturing, an additional packer with a process pipe string is installed, into which a NK string is lowered to sealingly interact with the passageway of the packer. 2. The method according to claim 1, characterized in that, as the level of the oil and gas concentration decreases, an additional packer with a column of process pipes, a tubing string and a packer are removed from the well, additional hydraulic fracturing is performed above the level of the oil and gas complex, and then a passage is established in the well below the additional hydraulic fracturing zone a packer, and above the fracturing level, an additional packer is installed with a process pipe string, inside of which the tubing string is lowered to hermetically interact with the feed packer.

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