SU1740633A1 - Method for forming borehole filtration zone - Google Patents

Abstract

The compacted reservoir material is pumped out from the bottom of the filter in the volume determined from the ratio On Opfz (Bp - Bp) / Bp, where On is the maximum volume of formation material to be extracted, m3, Opfz is the volume of the prefiltrated zone formed with the compacted material, m &;deg;; Bc - the volumetric weight of the formation rocks in the natural occurrence. kg / m3; BP - volumetric weight of the decomposed formation material, kg / m3. After that, overlap the lower part of the filter and wash the working part until the pumped out solution is completely clarified. 1 hp f-ly, 2 ill.

Description

The invention relates to mining and can be used in the development and restoration of the performance of well filters in unstable rocks with a porous reservoir.

A filter for a well fluid is known, consisting of a casing with holes, the diameter of which along the filter decreases from bottom to top.

The closest to the invention is a method of disintegrating the filter space of process wells, including pumping clogging particles through the windows of the filter column and becoming a pulp-lifting pipes with simultaneous flow of washing liquid

The purpose of the invention is to increase the injectivity of the well by equalizing the hydraulic resistances along the length of the filter.

The goal is achieved by pumping the formation material through the windows.

in contrast to the prototype, the filter column is used to pump the reservoir material out of the bottom of the filter in the amount determined from the ratio

Oi OpfzH- In Ј, BP

where Oi is the maximum volume of formation material to be extracted, m3;

On fz - the volume of the formed filter zone with a decompacted material m3

BV - volumetric weight of rocks of the reservoir in natural occurrence, kg / m;

BP is the volumetric weight of the expanded formation material, kg / ms, after which the lower part of the filter is overlapped, and the working part is washed after the material of the filter zone is decompacted and the lower part of the filter is closed until the pumped solution is completely clarified. In the presence of chemical products in the professional zone

ABOUT

about

s s

colmating to remove them after blocking the lower part of the filter and before washing the working part in the filter zone serves solvent.

FIG. 1 shows an embodiment of the method; in fig. 2 - option to overlap the bottom of the filter.

The method is carried out as follows.

The exploited layer 1 is surrounded by a filter 2, the lower part of which is equipped with windows 3. The filter 2 can be equipped with windows 3 either during manufacture on the surface or after installation by means of a bullet or other known perforation method. The geometrical dimensions of the windows 3 are selected depending on the particle size distribution of the material composing the layer 1. The width (diameter) of the window 3 should exceed the diameter of 98 particles composing the layer 1 (skip almost all particles by size), but also prevent spontaneous dumping of formation material into the filter 2, i.e. the width of window 3 should be less than three diameters of 98. In the presence of gravel dusting (not shown) the width of windows 3 should be less than the size of gravel dust particles. The total area of the windows 3 make less or equal to the area, with the expiration through which with a really achievable flow rate of liquid. the rate of the expiration of the latter will not be less than the speed of the critical (the beginning of the suffusion process) for the maximum particle size of the formation material. It should be noted that in the absence of the possibility of forming windows 3 of a predetermined diameter, for example, on a constructed well, windows 3 are formed with a larger than indicated above width (diameter), but this will entail an increase in labor costs when the lower part of the filter 2 overlaps. windows 3 from the bottom of the filter 2 are carried out in a stream of fluid withdrawn from the well. Liquid extraction is carried out by any of the known methods (airlift, ejector, pump, etc.). The intensity of extraction is increased until the formation of formation material in the pumped liquid.

The volume of the extracted reservoir material should not exceed the calculated one, determined from the ratio:

Oi OpfzH P.

Vg

where Oi - the maximum allowable to extract the volume of the reservoir material, m:

Op fz volume of prefilter zone 4 formed with decompacted material, m;

BV - volume weight of rocks of formation 1 in

natural occurrence, kg / m:

BP - volumetric weight of decompressed reservoir material, kg / m. When the filter 2 is placed directly under the stable water-pressure, it is correct to determine Qn fz as the volume of the cone with an angle at the base a. Equal to the angle of repose of formation 1 and a height equal to the length of filter 2. When operating in more complex geological conditions

(remoteness or instability of the upper water seal) the propagation of the decompaction wave along the height of the filter zone is monitored by successive flow meter logs along the length of filter 2. As the specific flow rate of the upper part of the filter 2 increases, pumping of the formation material is stopped. For formations composed of medium-fine sands, it is possible to use

by ratio

Ou 0,050l fz.

Observing this restriction, prevent the collapse of overlying rocks in the formed filter zone 4.

After removing the required volume of reservoir material, pumping is stopped and the lower part of the filter 2 is blocked in one of two ways.

In the first case, when window 3 is

below the working part of the filter zone 4, reduce the pumping rate or stop it. The pumped material in this case settles and closes the lower part of the filter 2 with a sand plug. The maximum efficiency of this method of overlapping is achieved by selecting the optimal size and number of windows 3.

If it was not possible to achieve non-receipt of reservoir material,

block the lower part of the filter 2 with a stopper, a pipe, injection of a hardening compound, etc.

In the second case, when the windows 3 are within the working part of the filtering

zone 4, overlap the window 3 with an internal filter 5 (FIG. 2), which can be equipped, for example, with a sealing ring 6.

Washing the material of the working part

filtering zone 4 is carried out by pumping reservoir solutions through it, by a hydrochrom or by another known method. The end of the process of forming filter zone 4 is determined by reducing the number of mechanical suspensions in the pumped solution (by clarifying it) when the pumping rate is not lower than the design one.

If the characteristics of the filter 2 deteriorate during operation or the quality is not satisfactory, the process is repeated, for which the lower part of the filter is opened (the drill is drilled or removed, the sand plug is washed out, the races are: hardening composition is formed with chemical reagents, etc.) or re-punched by known methods. In the presence of chemical clogging processes in the filtering zone, the solvent used to remove the matting agents is fed into the dilated filter zone 4 after blocking the lower part of the filter 2. The solvent penetrates filter zone 4 evenly along the entire length of the filter 2, and the dissolution proceeds more intensively, since the decompression increases the active surface of the particles. After holding the solvent in the filter zone 4 for the time required for the dissolution reaction to take place, wash the filter filter zone 4 until the pumped-out solution is completely clarified.

The application of the method allows to increase the well productivity by 10-15% and increase the turnaround time by 15%.

Formula-invention

Claims (2)

1. A method of forming a prefix zone of a well, including pumping out formation material through the windows of a filter column, which is different from that. in order to increase the injectivity of the well by equalizing the hydraulic resistances along the length of the filter, the formation material is pumped out from the bottom of the filter in a volume determined from the ratio Oi - Optfz (Bp Vr) / BP, where Oi is the maximum allowable volume of formation material to be extracted, m3; Opfz - the volume of the formed pre-filter zone with decompacted material. m3; BV - volumetric weight of rocks of the reservoir in natural occurrence, kg / m; Bp is the volumetric weight of the decompressed formation material, kg / m3, after which they overlap the lower part of the filter, and the working part is washed after the material of the filter zone is decompacted and the lower part of the filter is blocked until the pumped solution is completely clear. 2. A method according to claim 1, characterized in that, in order to remove chemical clogging products. after overlapping the lower part of the filter and before washing the working part, solvent is supplied to the filter zone. Fig / FIG. 2