RU2309244C1 - Filtering well construction method - Google Patents

Abstract

FIELD: mining, particularly construction of underground leaching wells, water or another fluid production wells and to prevent sand production during well completion.

SUBSTANCE: method involves lowering downhole screen connected to flushing pipe provided with flushing bush in well; inwashing gravel filling; removing washed-out particles and pumping well before well operation. Flushing bush has telescopic valve and radial channels, as well as closed central channel formed in lower part thereof. Removal of washed-out particles and well pumping is carried out through well chamber when the valve is installed in upper position and radial channels of flushing bush are communicated with well hole annuity and when the valve is in lower position and radial valve channels are communicated with downhole screen correspondingly.

EFFECT: increased efficiency of drill cuttings and formation sand removal and natural filter forming.

2 cl, 1 dwg

Description

The present invention relates to mining, in particular, to a method for constructing wells for underground leaching, water and other fluids, and can be used to complete wells during drilling or to repair wells to combat sand removal.

A known method of constructing a filter well, including the descent into the well of production, filter columns with a double wash pipe, gravel wash, downhole flushing [1].

The disadvantage of this method is flushing the well through a filter column, which does not provide reliable cleaning of the filter zone and pre-operational pumping of the well.

The closest is the method of constructing a filter well, including the descent into the well of production, filter columns, flushing sleeve and flushing pipe, flushing the well [2].

The disadvantage of this method is the washing of the filter zone through the production string, which does not provide reliable cleaning from drill cuttings and formation sand and the formation of a natural filter. In addition, the known method is not intended for underground leaching.

The objective of the present invention is to increase the reliability of cleaning from drill cuttings and formation sand and the formation of a natural filter.

The problem is solved in that in the method for constructing a filter well, including lowering the well filter into the well on a flushing pipe with a flushing sleeve, washing the gravel pack and taking out the washed particles, the flushing sleeve is provided with a telescopic valve with radial channels and a blocked central channel in the lower part, the removal of washed particles and pre-operational pumping is carried out through the borehole chamber, respectively, in the upper position of the valve with the radial channels of the valve and flushing second coupling with an annular cavity wells and the lower position of the valve with the valve communicated by radial channels with a downhole filter.

In addition, the pumped liquid is discharged into the well and used as a squeeze.

The invention is illustrated in the drawing.

The tool according to the method includes a downhole filter 1, a flushing sleeve 2, a flushing pipe 3. The flushing sleeve 2 is provided with a valve 4.

The valve 4 is telescopically mounted in the flushing sleeve 2 and is made with a drive unit 5 in the form of a spline or key connection with the flushing sleeve 2 and is equipped with a supporting nut 6.

The flushing sleeve 2 is provided with an additional flushing pipe 7, and the flushing pipe 3 is double in the upper part.

The valve 4 is made with a blocked central channel in the lower part by a plug 8 and radial channels 9 connected to the annulus of the well through a flushing sleeve 2 and to the downhole filter through an additional and flushing pipe 7, respectively, in the upper and lower positions of the valve 4. The flushing pipe 3 is connected to downhole chamber 10 with a flexible sleeve.

The flushing sleeve 2 is connected to the downhole filter 1 by a left sub. The downhole chamber 10 is made with two compartments for cleaning the pumped liquid.

The work of the tool according to the method is as follows.

The downhole filter 1 is lowered into the well, installed on the bottom and the valve 4 is moved to the lower position when the radial channels 9 are communicated through an additional washing pipe 7 with the internal cavity of the downhole filter 1.

Flushing fluid is supplied and gravel packing is filled in an upward flow of flushing fluid.

In this case, small fractions of gravel packing and drill cuttings together with the formation sand are washed out of the filter zone, and the filter packing settles in the annular cavity, forming a natural filter, and the washed particles are taken out of the filter zone by backwashing through the wash pipe 3 when valve 4 is moved to the upper position and communication with the annular cavity of the radial channels 9, valve 4 through the flushing sleeve 2, into the borehole chamber 10, and from it to the well.

The process of filling gravel packing is carried out in batches with successive removal of washed particles by backwashing, turning on airlift pumping. Pre-operational pumping is carried out through the borehole chamber 10 with a discharge into the well, the pumped liquid is used as a squeezing liquid.

After the completion of technological processes, the tool is detached from the downhole filter and carried out of the well.

The technical result.

1. Reliable and complete cleaning of the well from drill cuttings and formation sand.

2. Ensuring the formation of a natural filter.

An example implementation of the method.

A pumping well with a depth of 400 m is to be constructed at site No. 1 PV

Sequence of work.

1. Drilling a well with a diameter of 245 mm to 350 m

2. The descent and cementation of the casing string 168 mm.

3. Drilling with expansion of the filter zone 350-400 m to 350 mm.

4. Descent of the filter ⌀118 mm on the tool for the construction of the filter well, NKM ⌀73 mm.

5. Flushing the well with simultaneous filling of gravel with a grain size of fractions from 0.5 to 10 mm and adding as small fractions and sand are removed and a natural filter is formed.

6. Pre-operational pumping of the well through the borehole chamber with a discharge into the well.

Information sources

1. A.S. USSR No. 804819, ЕВВ 43/04, 43/28, 02/15/81.

2. RF patent No. 2179628, IPC 7, ЕВВ 43/04, 02.20.2002.

Claims (2)

1. The method of constructing a filter well, including the descent into the well of a downhole filter on a flushing pipe with a flushing sleeve, gravel packing, removal of washed particles and pre-operational pumping of the well, characterized in that the flushing sleeve is equipped with a telescopic valve with radial channels and a closed central channel in the lower parts, the removal of washed particles and pre-operational pumping is carried out through the borehole chamber, respectively, in the upper position of the valve with the reported radial channels of cells apana and flushing couplings with an annular cavity of the well and the lower position of the valve with communicated radial channels of the valve with a downhole filter. 2. The method according to claim 1, characterized in that the pumped liquid is discharged into the well and used as a squeezing liquid.