RU2277165C2 - Method for filter de-mudding - Google Patents

Abstract

FIELD: oil production, particularly for well output increase and well repair, namely cleaning in situ of down-hole filters, screens, or gravel packs.

SUBSTANCE: method involves forcing liquid or gas flow through filter in direction opposite to that of formation fluid filtration through the filter; extracting formation fluid from formation and supplying the formation fluid with liquid or gas flow from filtered space to well head via hole annuity; determining well technical conditions; lowering flexible pipe of coiled tubing facility in well up to filter bottom; removing sand-clay plug from filter by flushing thereof with the use of the flexible pipe, wherein liquid or gas flows are forced through the filter by supplying thereof via the flexible pipe along with water-jet effect creation. Filter is de-mudded by feeding surfactant substance mixture into the flexible pipe. Methanol may be supplied in doses to prevent hydrate growth. Before flexible pipe removal the well is purged.

EFFECT: increased efficiency.

1 dwg

Description

The invention relates to oil and gas production, and in particular to technologies for stimulating and repairing wells in weakly cemented reservoirs, in particular for decolmatization of production well filters.

Known methods for decolmating filters by mechanical removal of the filter cake or using acids, alkalis, etc., i.e. chemical methods [see V.M. Gavrilko, B.C. Alekseev. Drill hole filters. Vol. 2, revised and supplemented. M., "Nedra", 1976, p.307-338].

The disadvantages of these methods include the relatively low degree of purification of the filters.

Of the known methods closest to the claimed one is the method of decolmatization of the filter according to the patent of the Russian Federation 2018637, cl. E 21 In 37/08, 1994, in which a pulse mode with a pressure amplitude greater than the maximum depression created in the filter during well operation and less than a pressure drop destroying the filter while simultaneously taking fluid from the reservoir is used to decolmate the filter. To ensure the necessary amplitude of the pulse mode, a plug with a diameter exceeding the inner diameter of the narrowing of the sub located above the filter is made of plastic (polyethylene). Experimentally determine the pressure at which the cork is pressed through the hole of the sub, provided that the filter is of maximum depression strength, since decolmation by a pulsed method can destroy it. The cork is installed in the tubing and proceed with the sale of liquid, foam or gas. At the same time, a well is put into operation through an annulus (on a torch) to prevent liquid from entering the formation. A washer with a diameter of 10 mm is installed on the annulus to limit the flow rate and the possibility of formation destruction. Selling of the cork is carried out before the registration of the pressure jump, indicating the passage of the cork through the narrowing of the filter sub. In this case, a shock wave with amplitude acts on the filter and cleans the filter. After cleaning the well from the liquid, the annulus is closed and the well is put into operation through tubing.

The disadvantage of this method is that decolmatization is carried out by forcing liquid, foam or gas through a filter tube, i.e. there is no selectivity of cleaning, as well as the impossibility of carrying out work in the absence of narrowing in the filter tubes and the presence of a sand-clay plug inside the filter. In addition, the filter strength may be lower than the required amplitude in a pulsed mode for its effective decolmation.

The technical result of the proposed method is to increase the efficiency of decolmatization by eliminating these disadvantages.

The technical result is achieved by the fact that in the present invention, which includes pumping liquid or gas through a filter in a direction opposite to the direction of filtration of formation fluids through it, at the same time, formation fluids are taken from the formation and sent together with the liquid or gas from the filtered space through annular space at the wellhead, the pumping of liquid or gas is carried out through a flexible pipe from a coiled tubing unit with a hydraulic monitor effect but.

The method is based on the fluidization process - the transformation of a layer of granular material (formation sand and clay particles) into a "pseudo-fluid" (the so-called fluidized bed) - and its removal to the wellhead under the action of an upward fluid flow coming from the perforation interval or from the donor well [ cm. I.F. Davidson, D. Harison. Fluidization. Ed. M., "CHEMISTRY", 1974, 718 pp.]. At the same time, the hydromonitoring effect obtained by using the device for cleaning the well filter (special nozzles), which we have declared as a utility model, is used.

It is known in the art to use the hydromonitor effect in bits for efficient well drilling [see E.G. Leonov, V.I. Isaev. Hydroaeromechanics in drilling. M., "Nedra", 1974, p.128].

The method consists in sequential work on:

- determination of the technical condition of the well (a study with sampling in various modes or for bleeding, breaking the current face using rope technology). If there is a sand-clay plug in the filter, it is removed by washing through a flexible pipe of a coiled tubing unit using a nozzle with a direct hole;

- the descent of the flexible pipe from the coiled tubing to the filter shoe (roofing of sand-clay cork);

- decolmation filter special. a nozzle feeding a solution of surface-active substances into a flexible pipe before artificial slaughter, while dosed methanol is supplied to prevent hydrate formation;

- blowing the well to the flare for the purpose of removing clay particles and formation sand from the wellbore, followed by extraction of the flexible pipe;

- well research after repair.

The method is illustrated in the drawing, which shows a schematic diagram of the decolmation of the filter.

The method was first used by us in 5 gas wells Nos. 11571, 934, 5141, 173 and 1731 of the Urengoy field, equipped with FSK-114 anti-sand filters with gravel packing in the interval of an open reservoir after cutting the production string. At the same time, the production capabilities of the wells increased by 10 ... 15% with a decrease in depression on the reservoir by 1.5 ... 2 times.

Due to the implementation of the method, more than 10 million m ^{3 of} gas is produced annually in one gas well; the actual economic effect is more than 400 thousand rubles.

Claims (1)

A method for decolmating a filter, including pumping liquid or gas through it in a direction opposite to the direction of filtering formation fluids through it with simultaneous selection of formation fluids from the formation and directing them together with the liquid or gas from the filtered space through the annulus at the wellhead, characterized in that the technical condition of the well is determined, the flexible pipe from the coiled tubing unit is lowered into the well, sand and clay are removed by washing through the flexible pipe of the coiled tubing unit if there is a blank plug in the filter, the flexible pipe is lowered from the coiled tubing unit to the filter shoe, the liquid or gas is pumped through the filter through a flexible pipe from the coiled tubing unit to provide a hydromonitor effect, while the filter is decolmated by supplying a surface solution to the flexible pipe -active substances, for the prevention of hydrate formation, a dosed supply of methanol is made, and before removing the flexible pipe, the well is flushed to the flare.