A well completion method

Abstract

The method pertains to the oil and gas industry and can be used in the development of producing formations. A producing string (6) together with a sealing device (7) are lowered into a well (1) and the well (1) is divided into an upper cavity (8) and a lower cavity (9) with the aid of said sealing device (7) to establish a hydraulic connection between the well opening and the upper cavity and between the lower cavity and the producing formation, respectively. The installation of equipment (10) and a check valve is carried out stepwise. A washer fluid (4) is replaced by a washer fluid (15). The equipment (10) is passed through the sealing device (7) and the hydraulic connection between the well opening, the lower cavity and the producing formation is re-established along the annular channel. The well (1) is deepened using the equipment (10) until an inflow of formation fluids occurs, the differential pressure in the hydraulic system “well opening—producing formation” being adjusted using the check valve and a blowout preventer (3). The equipment (10) is withdrawn from the lower cavity (9) upon completion of deepening, the device (7) is closed during separation of the cavity (9) from the cavity (8) and cutting-off the hydraulic connection between the producing formation and the upper cavity. The technical solution increases the efficiency and quality of technical operations and prevents the undesired inflow of formation fluids.

Description

TECHNICAL FIELD[0001]The invention pertains to the oil and gas industry, namely to drilling and operation of oil and gas wells, and can be used in the development of producing formations and well completion.PRIOR ART[0002]According to a known method of primary development of producing formations in the course of drilling for oil and gas, optimum conditions for primary development are produced with the use of different compositions of drill fluid, RU No. 2283418 C2, E21B21 / 00, 10 Sep. 2006.[0003]The known method relates to selection of reagents added to the drill fluid depending on the stage of operations performed on development of producing formations.Another known method of well completion consists of primary development of the producing formation, fastening of producing strings and secondary development of the producing formation, RU No. 2140521 C1, E21B33 / 13, 27 Oct. 1999.[0004]The known method provides decrease in the overbalance on account of overlapping of high-pressure forma...

AI Technical Summary

Benefits of technology

[0016]The invention solves the problem of increasing the efficiency and quality with which technical operations can be carried out and prevent the undesired inflow of formation fluids.

[0028]When the washer fluid ceases to create overbalance on the producing formation due to installation of the sealing device in the producing formation top, which prevents undesired inflow of formation fluids, this decreases the washer fluid flow rate and increases the well productivity.

[0029]Subdivision of well by means of sealing device into the upper and the lower cavity provides creation of the hydraulic connections between the well opening and the upper cavity and between the lower cavity and the producing formation, correspondingly, thus cutting-off the direct hydraulic connection between the producing formation and the well opening and preventing undesired inflow of the formation fluids.

[0030]The sealing device, capable of separating, during the downhole equipment installation, and re-establishing the hydraulic connection between the well opening, the upper cavity, the lower cavity and the producing formation, limits the action time of the direct hydraulic connection between the producing formation and the well opening, thus reducing the action time of the formation fluids inflow.

[0031]Well deepening by means of the downhole equipment (drill string) until an inflow of formation fluids occurs, with adjustment of the differential pressure in the hydraulic system “well opening—producing formation” being adjusted using the check valve and a blowout preventer allows preventing the inflow of the formation fluids and increasing the efficiency of the well completion.

Problems solved by technology

When washer fluid is pumped, the overbalance on the bottomhole (accounting for the pressure loss in annulus and pressure of immersed jet coming from the bit nozzles) increases.

In the “closest analog”, during the development of producing formation the formation fluid inflows are prevented by creation of overbalance by the washer fluid column, which leads to absorption, increase in washer fluid flow rate, reduction of effective permeability of the producing formation and decrease in oil production.

Excess of washer fluid pressure over the formation pressure leads to its inevitable overflowing to the producing formation.

Intensity and volumes of absorption depend on collecting properties of the developed formations and make up from several cubic meters to tens and even hundreds cubic meters; besides, the washer fluid which came into producing formation significantly decreases effective permeability and, consequently, well productivity, which leads to decrease in oil production, and increase in the cost and time of operations.

Development defects lead to deterioration of collecting properties of the producing formation—its blockage.

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