RU2278960C2 - Method and device for drainage system forming in productive bed - Google Patents

Abstract

FIELD: oil production from drill-holes, particularly to stimulate productive beds by bed drainage and formation fluid filtering channel forming.

SUBSTANCE: method involves forming at least one opened horizontal well bore or one opened horizontal well bore with at least one opened side branch bore extending along the strike in productive area thereof; filling the bore with hydrophobic granular material, wherein bore and branch bore filling is performed in portions along with compacting each portion of granular material up to material subsidence and existent natural bed cracks opening under the action of material compaction; installing and fixing filtering unit in well bore. Device comprises sectional or continuous pipe string, conical flared body fixedly secured to pipe string. Arranged in the body is system including pusher with central through channel and with cone. The pusher is hung inside the body and connected to cylindrical spring so that the pusher may be axially displaced and perform self-oscillations. Flared body and pusher cone are axially joined and form valve couple. Freely sliding impact bush is located over pusher anvil.

EFFECT: increased hydrocarbon material output and increased oil and gas recovery factors.

4 cl, 1 ex, 3 dwg

Description

The present invention relates to the field of oil and gas production from boreholes, and in particular to methods of increasing the productivity of productive formations by draining them and creating channels for filtering formation fluids.

A known method of hydraulic fracturing of oil and gas reservoirs [1], which allows you to create drainage cracks in the bottom of the reservoir, which are then filled with proppant dispersed material (for example, sand). As shown by wide field practice in this way, one can multiply the inflow of a productive object.

This method and its technology are similar to the solution proposed here.

Among the common disadvantages of the analogue are the following:

1) conventional hydraulic fracturing and its modifications cannot be applied in horizontal wells due to the possibility of rock fracture across the strike of the formation, which will lead to the connection of the gas and water parts of the formation with its oil part;

2) conventional fracturing technology is an expensive operation; it usually requires casing of the well and opening it with perforation, as well as the use of special fluids for fracturing the rock, special materials for filling cracks and special solutions for the subsequent cleaning of drainage channels;

3) for the production of hydraulic fracturing, special equipment is needed (high-pressure hydraulic units, mixing machines and a number of other auxiliary technical means), which makes the operation difficult.

An alternative way to drain productive formations is to drill horizontal wells [2], which open up an oil or gas reservoir along the strike of the formation. Oil or gas inflows increase 2-70 times due to the large coverage of the reservoir. However, hydraulic fracturing using conventional technology [1] with the aim of creating a network of drainage cracks is impossible and even harmful, because deep cracks can connect the stratified gas-oil-water system, which will lead to disastrous consequences.

The European Patent [2] describes a method for draining a formation in a horizontal well using high-pressure jets that create lateral cracks or expand them.

The main disadvantages of the known solution:

1) to implement this method, high pressure hydraulic units are required to create high-pressure jets at the bottom of the well;

2) it is impossible to create a system of branched cracks with a jet;

3) the efficiency of the erosive action of the jet does not exceed 20 calibers (20 × D is the diameter of the outgoing jet) and it is not able in most cases to overcome stresses from rock pressure in order to expand and deepen the embryonic cracks.

The technical result of the invention is the creation of a drainage system in the volume of the reservoir, in particular the oil reservoir, to increase the productivity of hydrocarbon production and increase the coefficient of oil and gas recovery.

The required technical result is achieved in that the method for creating a drainage system of a productive formation includes one at least an open horizontal wellbore or one open horizontal wellbore with at least one open lateral branch of this wellbore along the strike of the formation in its productive part, which are filled with hydrophobic granular material, while filling the wellbore and its branches is carried out portionwise with ramming each portion of granular material until it subsides material and opening by tamping existing natural fractures in the formation, after which a filter assembly is installed and rigidly fixed in the wellbore.

In addition, quartz sand, glass or plastic beads, and proppant are used as a hydrophobic bulk material.

Hydrophobic bulk material is delivered to the bottom of the well using a thixotropic carrier, the pumping of which is carried out continuously to ensure ramming of the bulk material.

The applicant has not identified from the prior art known devices that could be used as a prototype of the claimed invention. It was found that as the basis of the device for tamping bulk material in the well, a striker can be used to release the stuck drilling tool in the well [3].

The disadvantages of the known device are the following:

1) the impossibility of its operation in self-oscillating mode, which leads to high costs of hydraulic power;

2) the inability to throttle part of the liquid in the annulus, which contributes to the leaching of bulk material sent to the bottom;

3) the frequency of impacts insufficient for ramming bulk material at the bottom, which does not provide the effect of dilatancy.

The required technical result is also achieved by the fact that a device for filling a well and ramming bulk material includes a pipe string, detachable or continuous, a body with a conical socket rigidly connected to the pipe string, inside of which there is a system in the form of a pusher with a central flow channel and a cone suspended in the housing on a coil spring with the possibility of movement in the axial direction and the implementation of self-oscillations, while the conical bell of the housing and the cone of the pusher are aligned coaxially and represent oh couple together the valve and the pusher located above the fifth impact sleeve to slide freely.

The simplest options for drainage of a horizontal well and a horizontal well with a branch are shown in figures 1 and 2, where:

1 - productive (oil) layer;

2 - horizontal well drilled along the strike of the formation;

3 - branch horizontal wellbore;

4 - fractures of fracturing rock formations;

5 - portioned borehole packing with hydrophobic bulk material;

6 - hydrophobic bulk material;

7 - filter unit.

A device for filling a well and tamping bulk material is presented in figure 3 in section. It consists of a housing 8, a pusher 9, coaxially integrated in the housing 8 and suspended on a spring 10. Above the fifth 11 of the pusher 9 there is a freely sliding shock sleeve 12. The device operates as follows: when pumping a viscous and thixotropic suspension carrier (for example, clay mud ) the housing 8 and the pusher 9 act as a valve pair in self-oscillating mode. The movement of the suspension carrier is shown by arrows. The shock sleeve 12 has a free run, enters the oscillation mode and strikes the heel of the pusher 11, which ensures the tumbling of the bulk material 13 entering the bottom of the well and the opening of side cracks.

The physical effect that is used to form lateral drainage cracks during tamping of bulk material (sand, beads, proppilant) in the well is called dilatancy. It can be shown in a simple diagram (figure 4).

Bulk material not only produces expansion of the embryonic cracks, but also, filling them, wedges and then does not close. In this case, the fluid located in the well, under the influence of shock loads, helps rupture cracks.

An example of the practical implementation of the proposed method and device

The proposed device is lowered into a drilled horizontal well and, at low productivity of the mud pumps, flushing fluid is pumped. From time to time, a pack of loose material (for example, proppant) mixed with clay or another viscous and thixotropic carrier is introduced into the circulation system and delivered to the bottom of the well, where it is accumulated and compacted. As the rammed pack of loose material subsides, which indicates its introduction into the lateral cracks, the ramming process is stopped and the device is moved higher up the wellbore. Then, the above operations are repeated until the horizontal part of the well is completely filled with hydrophobic bulk material. After that, a removable filter assembly, which essentially acts as a filter plug, is installed and fixed in the wellbore.

Industrial utility

An analysis of flow rates in horizontal drilled wells in the oil fields of the Russian Federation shows that if the network of tectonic fractures in the reservoir is laid crosswise, then oil inflows increase by tens and hundreds of times compared to vertical wells. But if the fracturing of the formation is oriented differently, the tributaries differ little. Hence the need arises to artificially create a system of lateral cracks by the proposed method, especially since conventional hydraulic fracturing in horizontal wells is not suitable, because long-distance main cracks can connect the gas and water parts of the reservoir with the oil and thereby block oil production or cause its catastrophic flooding.

Filling the horizontal wellbore with hydrophobic bulk material with the installation of a filter unit will allow:

- prevent the removal of colmatants (sandy and clay particles) from the collector;

- to prevent the proppant from flowing loose material into the well (sand, beads, proppant);

- improve phase permeability to oil and retain water;

- to exclude the fastening of the horizontal part of the well by the casing string, re-opening the formation or installing filters;

- get the maximum inflow of a productive object.

INFORMATION SOURCES

1. Zheltov Yu.P. Mechanics of the oil and gas reservoir. Moscow, "Nedra", 1975, p. 159-170.

2. EP 0851094 A2, 07/01/1998.

3. Mishchevich V.I. Handbook of a drilling engineer. V.2, Moscow, Nedra, 1973, p. 80-82.

Claims (4)

1. A method of creating a drainage system of a productive formation, including one at least an open horizontal wellbore or one open horizontal wellbore with at least one open lateral branch of this well along the strike of the formation in its productive part, which is filled with a hydrophobic granular material, while filling the wellbore and its branches is carried out portionwise with ramming each portion of bulk material until this material subsides and is opened by tamping Nia existing natural fractures of the formation, and then set in the wellbore and is rigidly fixed filter assembly. 2. The method according to claim 1, characterized in that as the hydrophobic bulk material using quartz sand, glass or plastic beads, proppant. 3. The method according to claim 1, characterized in that the hydrophobic bulk material is delivered to the bottom of the well using a thixotropic carrier, the pumping of which is carried out continuously to ensure ramming of the bulk material. 4. A device for filling a well and ramming bulk material, including a pipe string, detachable or continuous, a body with a conical socket, rigidly connected to the pipe string, inside of which there is a system in the form of a pusher with a central flow channel and a cone suspended in a housing on a coil spring with the possibility of movement in the axial direction and self-oscillations, while the conical bell of the housing and the cone of the pusher are aligned coaxially and represent together a valve pair, and above the fifth of the pusher races put the shock sleeve with the possibility of free sliding.

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