RU2631512C1 - Method for isolating inflow of bottom water in oil wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes stopping a well, in which the level of water-oil contact overlapps lower openings of a perforation interval. A downhole equipment is extracted from production column of a main shaft. A plug packer is set to 1 m below the water-oil contact. A grouting composition, for example, based on grouting portland cementportland cement - PCT-100 is injected into the lower interval of the perforation holes followed by formation of water-insulating screen. An assembly with a cutter is lowered into the well. The plug packer is drilled. The assembly with the cutter is lifted out of the well, and a guide assembly with a through channel and an outlet hole equipped with anchor-packer device is lowered on the drill pipe string. The drill pipe string is extracted leaving the guide assembly in the production column. A hydromonitor nozzle is lowered on the flexible pipe (FP) into the guide addembly to the outlet hole of the guide assembly through hole. The jets of sand-liquid mixture (SLM) cut a hole in the wall of the production column. After the hole is cut in the wall of the production column, the SLM is replaced with hydrocarbon-based solution (RBS). The RBO jets flush at high pressure the cement stone behind the production column, and the hydromonitoring nozzle subsequently moves in the radial direction to flush the water-insulating screen and rock of the productive formation to form an elongated radial branch. Upon formation of the first radial branch, the FP with a high-pressure hose and the hydromonitoring nozzle is extracted from the well. The guide assembly is turned in the same plane by 45 degrees and similar operations to form the next radial branch are carried out. Next, similar operations to form the next radial branchs are carried out after turning the guide assembly by the next 45 degrees. After drilling the radial channels in one plane of the productive formation, the radial channels are drilled below this plane, but in the thickness of the existing water-insulating screen. After formaton of all planned radial branches, a water-insulating composition (WIC) is pumped therethrough to create a water-insulating screen along the radius and provide a spatial and long-term barrier on OWC movement path and leaving a cement cup in the well cavity no higher than the water-insulating screen.

EFFECT: increase of efficiency of water-proofing works in oil wells, formation of extended and thick water-insulating screen.

7 dwg, 2 tbl

Description

The invention relates to the oil and gas industry, and in particular to a method for isolating bottom water inflows in oil wells.

In recent years, in Western Siberia, deep-seated low-amplitude, complex-built oil deposits confined to transitional oil-water zones, gas cap deposits containing hard-to-recover oil reserves have been discovered. Most of the oil deposits are lined with partially or completely bottom waters or are delineated by regional waters. In the process of development and pilot works, especially during the operation of wells, as a result of the active advancement of the interface, as a rule, two-phase inflows are obtained with the advance movement of water or gas. When developing such fields, very complex tasks arise, and their rational exploitation is impossible without knowledge of the geological and production features and patterns of watering and gas contamination of oil deposits and wells.

Insufficient scientific substantiation of approaches to impacting oil-saturated reservoirs on the borehole zone, intervals of deposits with various oil saturations, bottom water deposits, marginal waters or gas caps with a gas cap to limit water and gas inflows reduce the efficiency of preparing recoverable oil reserves of industrial categories and oil and gas production.

From these positions, increasing the productivity of wells and obtaining anhydrous industrial inflows of hydrocarbons is an urgent problem, the solution of which will affect the efficiency of preparing recoverable oil and gas reserves of industrial categories, the degree of utilization of raw materials and increasing the overall economic potential of the West Siberian region [G. Zozulya ., Kleshchenko I.I., Geykhman M.G., Chabaev L.U. Theory and practice of selecting technologies and materials for repair and insulation works in oil and gas wells: a Training manual. - Tyumen: Tsogu, 2002. - 138 p.].

In order to eliminate cone formation, especially when operating homogeneous reservoirs, waterproof screens are installed between the oil-saturated and water-saturated parts of the formation. The installation of artificial impermeable screens, as a rule, does not give a significant effect, since it is not possible to create a screen of large length along the radius from the axis of the well. Moreover, in the water-pressure mode, when the bottom water pressure is the main source of energy during oil displacement, the stationary position of the screen limits its (mode) energy capabilities by creating large hydraulic resistances.

Currently, there are many ways to carry out waterproofing works, having one or another advantages and disadvantages.

There is a method of isolating the influx of formation water, including pumping grouting mortar under pressure into the water-developing part of the reservoir and holding the well for the time of setting cement grout [Reference book for the current and overhaul of wells / A.D. Amirov et al. - M .: Nedra, 1979. - S. 238-241].

The disadvantage of this method is the insufficient radius of the waterproofing screen, beyond which plantar water will bypass the waterproofing screen and watering of the well will continue.

There is a method of isolating the influx of bottom water, including pumping cement slurry under pressure into the water-developing part of the formation and holding the well for the time of setting cement slurry [RF Patent No. 2127807, E21B 43/32, published on March 20, 1999].

The disadvantage of this method is the insufficient radius of the waterproofing screen, beyond which bottom water will bypass the waterproofing screen and watering of the well will continue, as well as the difficulty of pumping the grouting composition into low-permeability reservoirs.

A known method of conducting waterproofing works, including sequentially pumping into an isolated interval a buffer of fresh water, water swelling polymer (GNP) AK-639, closed on fresh water and cement mortar (Kurochkin B.M. New technologies and materials for repair and insulation works in wells // NefteGazoPromyslovoy ENGINEERING. - 2003. - No. 2. - S. 17-19).

The disadvantage of this method is that when carrying out waterproofing work, already during the injection of GNP into the well, it, absorbing water, increases many times in volume. For a 0.1% suspension in fresh water of GNP grade B 415, the use of which is most common when working in wells, the water absorption for 30 minutes is about 50 g / g. The amount of water absorption is proportional to the amount of GNP swelling. When carrying out waterproofing works using the specified method in a well with a specific injectivity typical of flooded oil-bearing reservoirs, which is usually 0.5–2.0 m ³ / (h⋅MPa), which increases many times already during pumping into the well GNP cannot be pumped into the reservoir in an amount that ensures the creation of an extended waterproofing screen that is resistant to the pressure drop existing in the reservoir-well system. In this case, plugging occurs only in the area of the reservoir immediately adjacent to the well. A small amount of water-swellable acrylic polymer in water, which can be pumped into the formation, does not provide the creation of an extended waterproofing screen that is resistant to the pressure drop existing in the reservoir-well system. As a result, carrying out waterproofing works will be ineffective or the effect will be short-lived.

The closest technical solution chosen for the prototype is a method of isolating the influx of formation water in the well [patent RU 2580532], including drilling from the main well of a stopped well into the flooded part of the productive formation of radial branches along the radius below the interval of perforation of the well. A water-proofing composition is pumped into said radial branches with the creation of a water-proof screen along the radius of the main wellbore. The well is left for the reaction period of the injected composition under pressure and a subsequent inflow is made through the existing perforations in the perforation interval. The technical result is an increase in the radius and area of the waterproofing screen and a delay in the time of watering the well.

The disadvantages of this method is the insufficient thickness of the formed waterproofing screen.

The objective of the invention is to increase the efficiency of waterproofing work in oil wells, the formation of an extended and powerful in thickness of the waterproofing screen.

Achievable technical result, which is obtained as a result of the invention, consists in increasing the area and thickness of the waterproofing screen and delaying the time of watering the well.

The task and technical result are achieved by the fact that the method of isolating the inflow of bottom water in oil wells includes shutting down the well, in which the level of the oil hole blocked the lower holes of the perforation interval, the downhole equipment is removed from the production casing of the main trunk, a packer plug is installed 1 m below the oil-water contact grouting composition (for example, based on PCT-100) is pumped into the lower interval of the perforations with the subsequent formation of a water-proof screen, assembly with a milling cutter into the well, drill the packer plug, raise the assembly with a milling cutter from the well and lower the guide assembly with the through channel and outlet in the kit with the anchor-packing device on the drill pipe string, remove the drill pipe string leaving the guide assembly in the production casing , the hydraulic monitor nozzle is lowered into the guide assembly on a flexible pipe (GT) to the outlet of the through hole of the guide assembly, by jets of sand-liquid mixture (ПЖС) about they cut a hole in the wall of the production casing, after cutting through the wall of the production casing, the ПЖС openings are replaced by the CBR, with the high-pressure CBR jets the cement stone is washed behind the production casing and subsequent radial nozzle movement erodes the water-proof screen and the formation rock with formation of an elongated branches, after the formation of the first radial branch from the well, GT with a high pressure sleeve and an ontory nozzle, they rotate the guide assembly in the same plane by 45 degrees and carry out similar operations for posting the next radial branch, then similar operations for posting the next radial branches are carried out after the guide is rotated by the next 45 degrees, after the operation for drilling the radial channels in one plane of the reservoir, radial channels are drilled below this plane, but in the thickness of the existing water barrier, after the wire All planned radial branches through them pump the water-proofing composition (VIC) with the creation of a water-proof screen along the radius, providing a spatial and long-term barrier to the movement of the oil-and-gas complex, and leaving a cement cup in the well cavity not higher than the water-proof screen.

In FIG. 1-7 are diagrams of the implementation of the method of isolating the influx of formation water.

The method is as follows.

A well 1 operating a productive formation 2 of an oil deposit with a bottom bedding of produced water 3 and in which the level of the oil-water contact 4 blocked the lower holes of the perforation interval 5 is stopped. The cessation of oil production from the well stabilizes the flow of produced water to the bottom of the well 1 and even reduces the level of liquid in the production casing of the main wellbore 1 by returning part of the produced water through the perforation holes of the perforation interval 5 to the non-watered part of the producing formation 2 outside the well. When stabilizing the liquid level in the well 1, downhole equipment 6 is removed from the production casing of the main wellbore (Fig. 1).

Instead, on a drill pipe string (BT) 7 with a packer 8, lower and install a packer plug 9 1 m below the oil-water contact 4. Activate the packer 8 in well 1, pump the grouting composition (for example, based on PCT-100) into the lower interval perforation holes 5 with the subsequent formation of a waterproofing screen 10 (Fig. 2). After the OZZ and the formation of a stable waterproofing screen 10, the assembly with the cutter 11 is lowered into the well 1, the packer plug 9 with cement residues is drilled with the subsequent washing of the well (Fig. 3).

The assembly with the milling cutter 11 is lifted from the well and the guide assembly 13 with the through channel 14 and the outlet 15 complete with the anchor-packing device 16 is lowered on the drill pipe string 12 (Fig. 4). The anchor-packing device 16 allows you to install, fix and seal the guide assembly 13 in the production casing of the well 1, the guide assembly 13 provides orientation of the descent equipment in one of the directions of the productive formation 2. The guide assembly 13 is lowered into the flooded 2 part of the productive formation interval in existing waterproofing screen.

After that, the drill pipe string 12 is removed from the well with the guide assembly 13 left in the production string. The guide assembly 13 is lowered onto the flexible pipe (HT) 17 by means of a high pressure transfer sleeve 18 with a hydraulic monitor nozzle 19 to the outlet 15 of the through hole 14 of the guide assembly 13 ( Fig. 5). The jets of sand-liquid mixture (PZhS) 20, consisting of sand and a hydrocarbon-based solution, cut a hole 21 in the wall of the production casing (Fig. 5).

After cutting through the wall of the production casing, the openings 21 of the ПЖС 20 are replaced by RUO 22, the cement stone behind the production casing is washed out under high pressure with the jets of the RUO 22 and the water-jet packing 19 and the rock of productive formation 2 are radially washed out therefrom with the formation of an elongated branches 23 (Fig. 6).

After the first radial branch 23 is formed, GT 17 is removed from the well with a high pressure sleeve 18 and a hydraulic nozzle 19, the guide assembly 13 is rotated 45 degrees in the same plane and the same operations for the next radial branch are carried out, then the same operations for subsequent subsequent radial branches are carried out after rotation of the guide arrangement to the next 45 degrees. Eight is considered to be the optimal number of radial branches, which provides almost complete coverage of the near-wellbore zone of the formation, although depending on the diameter of the production string and the length of the radial branches, there may be more.

After carrying out operations for drilling radial channels in one plane of the reservoir 2, radial channels are drilled below this plane, but in the thickness of the existing water-proof screen 10 according to the same operations described above.

After posting all the planned radial branches through them, the water-proofing composition (VIC) 24 is pumped (Fig. 7) with the creation of a water-tightening screen along the radius, providing a spatial and long-term barrier to the movement of the KSS 5, and leaving the cement cup 25 in the well cavity not higher than the water-proofing screen.

At the end of the waterproofing works, the well is left for the reaction period of the injected compositions under pressure, followed by the inflow through the existing upper perforation interval 5. If necessary, intensification of the inflow can be repeated perforation or acid treatment, etc.

The proposed method of isolating the influx of formation water in the wells allows to increase the radius, thickness and area of the water barrier and increase the anhydrous period of operation of the well, delaying the inevitable flooding of the well.

As a second waterproofing composition, a solution is recommended that contains a 2.0% aqueous solution of PVA-B1H polyvinyl alcohol and a mixture of microdura "U" with calcium hypochlorite Ca (ClO) ₂ in the following ratio of components, vol.%: 2.0% - aqueous PVA-B1H aqueous solution - 50.0, a mixture of microdura "U" with calcium hypochlorite Ca (ClO) ₂ - 50.0, including microdura "U" - 48, Ca (ClO) ₂ - 2.0. [Pat. 2326922 Russian Federation, IPC S09K 8/504 (2006.01). Composition for repair work in wells / Kleschenko II and others. - Application No. 2006134101/03, 09.25.2006; publ. 06/20/2008, Bull. Number 17. - 6 p.].

The composition and results of determining the curing time and the formation of durable waterproofing material are presented in table 1.

The change in the relative permeability of core samples after treatment with the composition for repair work is presented in table 2.

Description:

1 - well;

2 - reservoir;

3 - plantar water;

4 - water-oil contact;

5 - perforation;

6 - downhole equipment;

7 - drill pipe;

8 - packer;

9 - packer plug;

10 - waterproofing screen;

11 - layout of the drill pipe with a mill;

12 - drill pipe string;

13 - guide arrangement;

14 - through hole of the guide arrangement;

15 - outlet;

16 - anchor-packing device;

17 - flexible pipe;

18 - a sleeve of a high pressure;

19 - a hydraulic nozzle;

20 - supply of sand-liquid mixture;

21 - hole in the production casing;

22 - the supply of a hydrocarbon-based solution;

23 - an elongated radial branch;

24 - second waterproofing screen;

25 - cement glass.

Claims (1)

A method of isolating bottom water inflows in oil and gas wells involves shutting down a well in which the oil-water contact level has closed the lower holes of the perforation interval, removing downhole equipment from the production casing of the main trunk, installing a packer plug 1 m below the oil-water contact, pumping the grouting composition, to for example, on the basis of cement Portland cement - PCT-100 - in the lower interval of the perforations with the subsequent formation of a waterproofing screen, lower to assembly with a milling cutter into the well, drill a packer plug, raise the assembly with a milling cutter from the well and lower the guide assembly with a through channel and outlet in the kit with the anchor-packing device on the drill pipe string, remove the drill pipe string leaving the guide assembly in the production casing , the hydraulic monitor nozzle is lowered into the guide assembly on a flexible pipe (GT) to the outlet of the through hole of the guide assembly, with a jet of sand-liquid mixture (ПЖС) open a hole in the wall of the production casing, after cutting through the wall of the production casing, the PZhS holes are replaced with a hydrocarbon-based solution (CBR), blast the cement stone behind the production casing with high-pressure CBR jets and then radially shrink the water barrier screen and rock productive formation with the formation of an elongated radial branch, after the formation of the first radial branch from the well, GTs are removed from the hands high pressure and hydraulic nozzle, rotate the guide assembly in the same plane by 45 degrees and carry out similar operations for posting the next radial branch, then similar operations for posting subsequent radial branches are carried out after the guide is rotated by the next 45 degrees, after operations drilling of radial channels in one plane of the reservoir, drilling of radial channels below this plane, but in the thickness of the available water After conducting all the planned radial branches through them, they pump the water-proofing composition (VIC) with the creation of a water-proof screen along the radius, providing a spatial and long-term barrier to the KSS movement, and leaving a cement cup in the well cavity not higher than the water-proof screen.

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