RU2455458C1 - Method of sealing recovery of production string - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: sand bridging is installed before injection in the well below the defect of production string and cement bridging 5-10 m is installed above the perforation interval. The oil is injected through tubing on the basis 2 m per 1 m of the strata net thickness and water is forced out of the insulation zone. After that the solution of Mikrodur R-U with sulfatsell is pumped in with water-cement ratio 0.8-0.9 on the basis of 0.5-2.0 m per 1 m of the strata net thickness with the following component ratio, wt %: Mikrodur R-U 51.4-54.9; sulfatsell 2.3-1.1; water 46.3-44.0.

EFFECT: increase of insulation reliability in case of sealing failure of production string, reduction of insulating works period.

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Description

The invention relates to the oil and gas industry and is aimed at improving the efficiency and reducing the period of water insulation works while limiting water inflow, restoring the tightness of casing strings, restoring the tightness of the annulus, as well as insulating work when drilling wells in conditions of intensive water development.

A known method of restoring the tightness of casing strings by cementing under pressure, which consists in pumping a plugging mixture into a casing string filled with flushing fluid and then filling this mixture into a leak zone (Restoring tightness of casing strings in oil and gas wells. M .: VNIIOENG ser “Drilling” , 1972, p. 49-55).

The disadvantages of this method include the weak adhesion of the grouting composition to the walls of the insulated channel, due to the presence on the walls of the channel of the washing fluid.

Closest to the proposed technical solution is a method of eliminating defects in casing strings, which consists in pumping through a tubing pipe (tubing) into the well of an aqueous solution containing calcium chloride, cement mortar, before pumping into the well, a packer or any slaughter, then 10–15% solution of calcium chloride, water, 15–50% solution of sodium naphthenate, or potassium, or a mixture thereof, water, 0.5–5.0 m ³ per linear meter are pumped sequentially through tubing solution defects element with a water-cement ratio (W / C) of 0.5-0.8 with the addition of 20-50% of the volume of the cement solution of 20-50% sodium or potassium naphthenate, or a mixture thereof, followed by forcing the entire mass into the well with formation water from the calculation of 1-2 m ³ per 1 m of formation thickness before creating a technological screen (RF Patent No. 2170333, IPC 7 Е21В 33/13, publ. 10.07.2001).

This method has insufficient insulation reliability, since it can be used to eliminate leakage in the production string within the oil reservoir, as evidenced by the sequence of injection of solutions: 10-15% calcium chloride solution, water to displace oil from the zone of the production string defect, 15- 50% solution of sodium or potassium naphthenate, or mixtures thereof, water to remove an oil film and hydrophilize the formation to ensure reliable setting of cement with the production string and rocks and reservoir. In case of leakage of the production string within the aquifer, there is no need for oil displacement and hydrophilization of the formation, and the injection technology and composition of the solutions need to be changed.

This method has a significant consumption of reagents and does not have sufficient insulation in aquifers.

The technical result is to increase the reliability of insulation during the elimination of leaks in the production casing in the intervals of the wells located above the reservoir, through the use of new chemical components that increase the strength and adhesive properties of the technological screen.

The specified technical result is achieved by the fact that the method of restoring the tightness of the production casing, which consists in the fact that before injection into the well below the defect of the production casing, a sand bridge is installed and a cement bridge 5-10 m high, then through the tubing to displace the water above the perforation interval oil is pumped from the isolation zone at a rate of 2 m per 1 m of effective thickness, after which a solution of microdura RU with sulfacell is pumped, with a water-cement ratio of 0.8-0.9 at a rate of 0.5-2.0 m ³ per 1 m of effective formation thickness in the following ratio of components, wt.%:

microdur R-U 51.4-54.9 sulfacell 2.3-1.1 water 46.3-44.0

This method is based on the creation of a technological screen in water-producing formations adjacent to the leakage interval of the production string. Leakage elimination is achieved by injecting the R-U microdura solution with sulfacell due to the penetration of the R-U microdura solution and sulfacell and the chemical reaction between them, the leakage is eliminated, a waterproof technological screen is created and the penetration of water through the leakage zone is eliminated.

The main component of the solution is microdur RU - a mineral hydraulic binder with a certain stable chemical and mineralogical composition, is divided into three grades according to the maximum particle size, which should not exceed a weight percentage of d ₉₅

- X - d ₉₅ <6.0 µ m;

- U - d ₉₅ <9.5 µ m;

- F - d ₉₅ <16.0 µ m.

Produced by DyukkerHoff-Sukhoi Log LLC, Sukhoi Log. Sulfacell is produced in accordance with TU 2231-013-32957739-2001 of Polycell CJSC, Vladimir.

The method is as follows. According to geophysical data, the place of leakage is detected, the well is plugged, underground equipment is removed from the well, the face is flushed, a sand bridge is installed above the perforation interval and a cement bridge is 5-10 m high. The tubing, the 2PD-YAG packer is lowered into the well at a specified interval, 10 -15 m above the leakage interval. Before starting the injection of reagents, the injectivity of the leakage interval is specified, then the calculated amount of oil is separately injected into the well through the tubing with one unit to displace water from the isolation zone at the rate of 2 m of oil per 1 m of effective thickness of the formation, and with the help of another unit, the calculated amount of the solution of microdura RU is pumped with sulfacell (W / C 0.8-0.9) at the rate of 0.5-2.0 m ³ per 1 m of effective formation thickness. The injection is carried out with constant monitoring of the injection pressure and injectivity at a maximum injection pressure not exceeding 0.8 formation pressure. At the end of the injection, the tubing string and the 2PD-YAG packer are raised to a height of 50-100 m and the well is flushed. After sealing the annulus, the well is left under pressure for 8 hours to solidify the solution, the production casing is pressed, the cement bridge is drilled and the sand is washed out of the production casing.

For experiments on checking the quality of insulation, experiments were carried out with two solution compositions with different water-cement ratios W / C - 0.8; W / C - 0.9.

Samples with the same components and different H / C showed excellent adhesion and strength characteristics, which turned out to be significantly higher for the sample with H / C - 0.8 (table).

Table The composition of the solution, wt.% Water-cement ratio, W / C, share units. Time
hardened
ny, h Total time from mixing to solidification,
h Adhesion,
MPa Strength characteristic, MPa microdur R-U 51.4 0.9 5.5 45.3 24.0 74.5 sulfacell 2.3 water 46.3 microdur R-U 54.9 0.8 5.5 7.0 32,0 77.5 sulfacell 1.1 water 44.0

Claims (1)

The method of restoring the tightness of the production casing, which consists in the fact that before injection into the well below the defect of the production casing, a sand bridge is installed and a cement bridge 5-10 m high is installed above the perforation interval, then oil is pumped through tubing to displace water from the isolation zone from the calculation 2 m ³ per 1 m thickness of the effective layer, then pumped mikrodura RU sulfatsellom solution with water to cement ratio of 0.8-0.9 based 0.5-2.0 m ³ per 1 m thickness efficient soot formation at the next Ocean, wt.%:
microdur RU 51.4-54.9 sulfacell 2.3-1.1 water 46.3-44.0