RU2604100C1 - Method of reducing sand production of oil wells - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to oil industry and can be used in oil production with sand production in production wells. Method involves well killing. Downhole equipment is removed. Equipment assembly is lowered with "root" on tubing string to sand plug. Sand plug is washed. Tubing string with "root" is removed. Tubing string is lowered into well and packer-plug is installed at depth of 1-2 m below oil-saturated formation interval. Tubing string is disconnected from packer-plug. Tubing string is withdrawn from well. Perforated tubing string of smaller diameter having in its upper part an upper packer is lowered until it rests against packer-plug. Upper packer is unpacked. Flexible pipe is lowered into inner cavity of perforated tubing string. Proppant is pumped through flexible pipe with polymer composition into perforated tubing string by its pressing into annular space between casing and perforated string. Well is held time and cross-linking of proppant is provided. Then well is developed and brought out to operating mode.

EFFECT: technical result is reduction of sand production of oil wells due to creation of downhole anti-sand filter.

1 cl, 3 dwg

Description

The invention relates to the oil industry and can be used in oil production with water showers in producing wells.

It is known that the appearance of sand at the bottom of oil wells is due to various reasons, associated mainly with the mechanical properties of the reservoir. With a decrease in reservoir pressure in the process of field development, the oil-water contact (WOC) rises and the intense water-based occurrence of sand occurs and sand falls to the bottom of the well with sand plug formation [Theory and practice of overhaul of gas wells under conditions of low formation pressure / M.G. Geykhman et al. - M.: IRC Gazprom. 2009. - 208 p.].

The movement of produced water from the reservoir to the bottom of the oil well entails the acceleration of the processes of destruction of the reservoir and the removal of sand to the bottom of the well, the formation of a sand plug there, which overlaps the interval of perforation of the well and prevents the movement of oil to the surface until the hydrocarbon production ceases completely.

Moreover, the initial flooding and destruction of the reservoir can occur before the start of the oil-water supply rise by pulling the bottom water cone to the bottom.

For normal operation of an oil well, the sand plug should be removed.

In the practice of repair work, methods of removing sand plugs by flushing the well and taking measures to limit sand occurrences are widely used [Bulatov A.I. Coiled tubing technology for drilling, completion and repair of oil and gas wells. - Krasnodar: Publishing House "Enlightenment-South", 2008. - 310 p.].

The known method implemented in the borehole sand separator [patent RU 2191261, IPC ⁷ E21B 43/38, published October 20, 2002], comprising a housing, lower two-sided and intermediate sub with transverse and longitudinal channels and tubes for downward flow, fishing chambers. Sand in this device is deposited in the chambers under the action of inertia and gravity. The device has no grids, and its throughput is kept constant during operation.

However, if the velocity of the fluid flow exceeds the rate of deposition of the grains of sand, such grains of sand fall into the pump and lead to its abrasion and accident at the well.

A known method (taken as a prototype), implemented in the design of the filter (A.S. USSR No. 1629497, E21B 43/08, 1991). The filter consists of a frame with longitudinal rods and a filter element in the form of separate spiral links. Between the spiral links are additional links made of elastic material. Semi-rigid fastening of coils of spiral links provides their relative mobility, slotted filter gratings are made of V-shaped wire.

The disadvantage of the device adopted in the present invention as a prototype is the relatively low efficiency of preventing sand removal, as well as the complexity of the design, high cost and the need for a packer device.

A distinctive feature of the claimed invention is that a sand filter is formed directly inside the well. Instead of a V-shaped wire, the filter contains proppant.

The objective of the invention is to develop an effective way to reduce sand occurrence of oil wells.

The technical result of the proposed solution is to increase the efficiency of reducing the sand formation of oil wells by creating a downhole sand filter.

The task and technical result are achieved by the fact that in order to reduce sandblasting of oil wells, a method is proposed that includes killing a well, extracting downhole equipment, lowering the layout of the equipment with the pen on the tubing string to the head of the sand plug, flushing the sand plug, removing the tubing string with the pen, descent into the well at the tubing string and installing the packer plug to a depth of 1-2 m below the oil saturated interval of the formation, disconnecting the packer plug from the tubing string, removing the tubing string from the well, to the perforated tubing of small diameter, with the upper packer placed on it in the upper part, against the stopper of the packer plug, unpacking the upper packer, lowering the flexible pipe into the inner cavity of the perforated tubing string, pumping the proppant with the polymer composition through the flexible pipe into a perforated tubing with its transfer into the annulus between the casing and the perforated tubing, proppant stitching with time delay, well development and output to the regime.

In FIG. 1 shows flushing sand plugs.

In FIG. 2 shows the descent of a perforated pipe.

In FIG. 3 shows the injection of proppant with a polymer composition.

The method is implemented as follows:

1. The production well (1), in which the perforation interval (2) is blocked by a sand plug (3), is jammed by a liquid of a certain density, which prevents oil and gas manifestations (Fig. 1).

2. Downhole equipment (not shown) is removed from the well.

3. A layout with a pen on the tubing (4) down to the head of the sand plug (3) is lowered into the well and its washing is carried out.

4 A tubing with a feather is removed from the well, the packer plug (5) is lowered and installed below 1-2 m of the oil-saturated interval of the formation.

5. The perforated tubing (6) (diameter 73 mm or 89 mm) (with the installed packer in the upper part (7)) is lowered onto the plug packer (5) and the upper packer (7) is unpacked (Fig. 2).

6. The flexible tubing (8) descends into the perforated tubing (6).

7. The proppant with the polymer composition (9) is pumped into the perforated tubing (6) with a groove in order to fill the interval between the casing and the perforated tubing, time delay for crosslinking the proppant, development of the well and output to the regime (Fig. 3).

Proppant is a spherical ceramic material. Currently, proppants are used to fix cracks formed as a result of hydraulic fracturing.

The most commonly used proppants with granule sizes of 0.425-0.85 mm (20/40 mesh), rarely 0.85-1.7 mm (12/20 mesh), 0.85-1.18 mm (16/20 mesh) 0.212-0.425 mm (40/70 mesh).

The proppants usually include alumina (alumina) and silica (silica), the content of which affects the qualitative characteristics of the granules. Alumina gives proppants strength, and silica affects the elasticity of the material, which allows the formation of spherical granules for subsequent hardening - mullitization.

The proppant particles are coated with a polymer composition that adheres to each other after the proppant is placed between the casing and the perforated tubing, thereby ensuring the stability of the packing. As a rule, proppant packs formed by larger particles and better sphericity are more permeable, i.e. have a higher conductivity.

The composition "Geotherm-01", including resin "Geotherm-001" and hardener "Geotherm-101", is used for fastening weakly cemented collectors and proppants (sand insulation works).

The polymer composition "Geotherm" includes resin and hardener.

Geotherm resins are products of polycondensation of phenol with formaldehyde in an alkaline environment, modified with alkylresorcinol. Hardeners "Geotherm" are solutions of hexamethylenetetramine (urotropine) in formalin, modified with ethylene glycol. The designation of Geotherm polymer compositions consists of letters and numbers indicating: Geotherm is the trade name of the product, numbers are the serial number and functional purpose of the composition. Repair and insulation compositions developed by LLC NPF Geotherm in conjunction with LLC RN - Purneftegas can improve the efficiency of work to limit water and sand occurrences by increasing the strength and permeability of the formed collector while simplifying the work. In addition, the proposed method allows to reduce the duration of the repair work to remove the sand filter, which, as a rule, is sprinkled with sand during operation, and also significantly increase the overhaul period of the wells. This development allows ultimately to increase the efficiency of development of deposits composed of weakly cemented reservoirs, as well as in fields with annular flows.

Causal relationship of the elements of the formula: Filling the annular space between the perforated tubing and the casing with proppant, impregnated (processed) with the polymer composition, ensures the integrity of the sand screen and prevents sand from entering the well and abrasion, the presence of a packer plug at the bottom and top packer at the top contributes to targeted selective proppant in the required interval.

Industrial applicability: The proposed technical solution allows eliminating sand formation at oil production wells with minimal labor costs without contamination of the bottom-hole formation zone through the use of a coiled tubing installation and selective treatment of the bottom-hole formation zone.

Claims (1)

A method of reducing sandblasting of an oil well, including plugging a well, extracting downhole equipment, lowering the equipment layout with a “feather” on the tubing string — tubing to the head of the sand plug, flushing the sand plug, extracting the tubing string with a “feather”, and lowering it into the well the tubing string and installing the packer plug to a depth of 1-2 m below the oil-saturated interval of the reservoir, disconnecting the packer plug from the tubing string, removing the tubing string from the well, lowering the perforated tubing of small diameter, with on it, in the upper part, by the upper packer until it stops against the packer plug, unpacking the upper packer, lowering the flexible pipe into the inner cavity of the column of perforated tubing, pumping the proppant with the polymer composition through the flexible tube into the perforated tubing and pushing it into the annular space between the casing a column and perforated tubing, ensuring proppant cross-linking with time delay, well development and output to the regime.

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