RU2569941C2 - Bottom water isolation method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to oil and gas producing industry, and namely to isolation of brine water inflow and oriented towards improved efficiency of bottom water isolation at development of oil and gas deposits. The bottom water isolation method includes perforation of production casing within interval of flooded formation, injection of hydrocarbon fluid in order to remove water from bottom-hole zone, hydrochloride acid treatment of the bottom-hole zone in order to increase permeability, flushing of water shutoff compound in order to set a water shutoff screen, reinforcement of the screen with MICRODUR RU solution with sulphacell, setting of a cement plug in the watered interval, testing its strength and hermeticity, washing of the well and development of the formation.

EFFECT: improving bottom water insulation, providing the reduction of water content of wells during development of oil and gas deposits.

Description

The invention relates to the oil and gas industry, namely, to isolate water inflow of formation water, and is aimed at improving the efficiency of isolation of bottom water in the development of oil and gas fields. In Western Siberian fields, isolation of bottom water inflows is carried out by installing cement bridges in the wellbore and pumping water-insulating compounds into the flooded sections of the reservoir.

There is a method of isolating the influx of bottom water into the well, which consists in pumping an aerated cement solution into the bottomhole zone, and then a fluorosilicate fluid product (USSR Author's Certificate N 939789 E21B 43/62).

The disadvantage of this method of isolating the inflow of plantar water is the low efficiency of water isolation, the increased complexity of the technology for injecting solutions into the bottomhole formation zone (PZP).

Closest to the proposed technical solution for isolating the bottom water inflow is a method according to which the production string is perforated in the flooded interval of the formation below the oil-water or gas-water contact, the water-proofing composition is pumped into the perforations under the gas-water or oil-oil contact. To prevent behind-the-casing flow of water or gas, a cement bridge is installed inside the production casing, re-opening of the reservoir and inflow are performed (RF Patent N 2231630 E21B 43/00, E21B 45/32).

The disadvantage of this method is the insufficient reliability of isolation of the bottom water inflow, since a screen is formed in the formation, which is represented by an unstable gel composition, which is destroyed by contact with the formation water, which leads to the dissolution of the waterproofing screen and the penetration of the bottom water into the perforation interval.

The objective of the invention is to develop an effective way to reduce water cut in oil and gas wells.

The technical result of the invention is improving the quality of insulation of bottom water, which reduces water cut in wells in the development of oil and gas fields.

The specified technical result is achieved by the fact that in the method of isolating the bottom water inflow in the well, the saturation of the formation and the position of the oil-water or gas-water contact are established according to geophysical studies, the production string is perforated in the interval of the oil-water or gas-water contact, hydrocarbon liquid gas condensate or diesel are pumped into the bottomhole zone fuel to remove formation water; hydrochloric acid is pressed into the formation with the waterproofing composition and left in the reaction formation, the reaction products and the remaining hydrochloric acid are displaced from the formation by the water-proofing composition and the water-proof screen is fixed with a solution containing microdur RU, sulfacell and water at a water-cement ratio of 0.8-0.9, a cement bridge is installed and the well is developed.

This method is based on the creation of a waterproofing screen to reduce water cut in wells during their operation. The creation of a waterproofing screen is achieved by injecting a waterproofing composition, for example, a gel with its fastening with a solution containing RU microdur. In the practice of waterproofing works, the following waterproofing compositions can be used as waterproofing compositions for well overhaul:

- modifier (113-53 or 113-85) + ethyl silicate (ETS-40 or ETS-16) + hydrophobic organosilicon liquid;

- ethyl silicate (ETS-40 or ETO 16) + synthetic grape acid + calcium chloride (CaCl ₂ ).

Then, the waterproofing screen is fixed with a solution containing microdur RU, sulfacell and water at a water-cement ratio of 0.8-0.9. For a terrigenous formation, the volume of the solution is 0.5-2.0 m ³ per 1.0 m of effective thickness. In the interval of the waterlogged formation, a cement bridge is installed that overlaps the perforations.

As a result of the work, a water-proof screen will be created on the border of the non-watered well production.

The method is as follows.

In the well, according to geophysical research, the nature of oil and gas saturation is established and the position of the oil-water or gas-water contact is established. 5-7 m above the oil-water or gas-water contact, the production casing is perforated. The tubing is lowered into the well with a packer, for example, 2PD-YAG, which is placed 5-10 m below the perforation interval of the production formation. After that, the calculated amount of hydrocarbon fluid, for example gas condensate, is pumped into the well through the tubing with a cementing unit to remove water from the bottomhole zone of the well. To increase the permeability of the bottom-hole zone and remove the clay component of the cement of rocks, a solution of 10-12% hydrochloric acid is pumped into the well in a volume of 0.4-0.6 m ³ per 1 m of effective thickness for low-permeable rocks and 0.6-1.0 m ³ per 1 m of effective thickness for highly permeable rocks and left to react at reservoir temperature from 30 to 60 ° C for eight hours.

Then, a water-proofing composition is pumped through the tubing string into the formation, for example, modifier 113-53 or 113-85 + ethyl silicate, for example ETS-40 or ETS-16 + hydrophobic organosilicon fluid at the rate of 0.5-2.0 m ³ per 1 m of effective thickness , which displaces the reaction products and unreacted acid deep into the reservoir. 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. The waterproofing screen is fixed with a solution of microdura RU and sulfacell, for example, with the following ratio of components, wt.%), Microdura RU - 54.6-53.7, sulfacell - 0.6-0.6, water - 44.8-45.7 .

In the interval of the flooded part of the reservoir, a cement bridge is installed.

After OZZ and testing of the cement bridge for strength and tightness, the tubing string and 2PD-YAG packer are raised to a height of 50-100 m and the well is washed and the formation is developed.

An example implementation of the method.

In a production well with a depth of H = 2500 m, terrigenous pore rocks - reservoirs are operated. To install a waterproofing screen with a radius of r _e = 6.0 m, the effective thickness of the reservoir rock is opened by perforation h _e = 5 m. The coefficient of open porosity is determined according to geophysical data K _p = 0.22. The radius of the treatment of the bottom-hole zone with a solution of hydrochloric acid in order to increase its permeability is R = 1.0 m, and the radius of the well r _s = 0.08 m.

In this case, the volume of the hydrochloric acid solution for treating pore reservoir rocks is determined by the formula:

. $$V=\pi \cdot \left(R^2-r_{\mathrm{from}}^2\right)\cdot K_P{}_{\cdot }{h}_{\mathrm{uh}}$$

.

where K _p - coefficient of open porosity, fraction of units;

R is the radius of the treatment of the bottom-hole zone, m;

r _s - well radius, m;

h _e - effective thickness, opened by perforation, m

The volume of a hydrochloric acid solution for treating porous reservoir rocks is determined by the formula:

. $$V=\pi \cdot \left(R^2-r^2\right)\cdot K_P{}_{\cdot \cdot }{h}_{\mathrm{uh}}$$

.

$$V=\left(\mathrm{1,0}-0.0064\right)\cdot 3.14\cdot 0.22\cdot 5.0=3.45m^3$$

The volume of the waterproofing composition for installing the waterproofing screen is determined by the formula:

, $$V=K_{P\cdot }{h}_{\mathrm{uh}\cdot }\pi \cdot r_{\mathrm{uh}}^2$$

,

where K _p - coefficient of open porosity, fraction of units;

h _e - effective thickness, opened by perforation, m;

r _e - the radius of the installation of the waterproofing screen, m

The volume of the waterproofing composition for installing the waterproofing screen is

$$V=K_{P\cdot }{h}_{\mathrm{uh}\cdot }\pi \cdot r_{\mathrm{uh}}^2$$

. $$V=0.22\cdot 5.0\cdot 3.14\cdot 36.0=124.34m^3$$

.

Claims (1)

A method of isolating the bottom water inflow, including perforation of the production string in the interval of the waterlogged formation, injection of hydrocarbon fluid to remove water from the bottomhole zone, hydrochloric acid treatment of the bottomhole zone to increase permeability, pushing into the formation a water-proofing composition in order to install a water-proof screen, fastening the screen with a solution of microdrills RU with sulphacell, in the waterlogged interval, the installation of a cement bridge, its testing for strength and tightness, flushing the well and ix formation.