RU2451173C2 - Device for pulse alternating-sign processing of formation well bore zone - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: device is made in the form of implosive chamber. The role of a charge is performed by facing powder pressure generator made from elements of ballistite gun powder, located at the outer surface of implosive chamber casing with the possibility of approaching the wall of casing. There is the possibility of facing powder pressure generator ignition, generating of gaseous combustion products and pressure pulse with destruction - cracking of formation rocks in well bore zone and depressurisation of implosive chamber casing after pressure decrease till hydrostatical level. Note that there is provision of wave process of pressure fluctuations with the values of maximum and minimum pressure and duration providing further development of cracks in formation well bore zone.

EFFECT: possibility to develop pressure generator for oil and gas production intensification on the base of gun powder that is characterised by reduced charge mass and comparable to the existing more powerful samples of generators in efficiency.

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Description

The invention relates to the oil and gas industry, and in particular to the field of pulsed technologies for intensifying oil and gas production and device designs for their implementation.

One of the promising methods of stimulating oil and gas production is the treatment of wells with pressure pulses using powder pressure generators. Gaseous products of combustion of generator charges create a pressure in the well that ensures the formation of residual cracks in the near-well zone of the formation, exerts a thermal, chemical and physico-chemical effect on this zone, thereby improving its filtration properties and increasing well productivity. The most powerful and effective among the known pressure generators is the PGDA generator (RF patent No. 2151282, 1999). A distinctive feature of this generator is that the combustion of its fuel cells proceeds in a vibrational mode with a frequency of 4-20 kHz and an amplitude of up to several MPa, which significantly enhances the efficiency of its use in comparison with other samples of powder generators.

The disadvantages of powder pressure generators are that the powerful charges used in them are predominantly thick-walled fuel blocks with a diameter of 42 to 105 mm and a length of 400 to 1200 mm and are characterized by calorific values commensurate with the calorific values of the casing material, which negatively affects the operational properties of the latter. In some cases, sintering of rocks occurs, the pores of the reservoir melt in the bottom-hole zone, which reduces its filtration properties. Under the influence of the high-temperature gas environment of the products of fuel combustion, the geophysical equipment burns out and the surface fluid is ejected, wellhead equipment may also be damaged. An important factor in restraining the use of these generators is their cost.

Cheaper pressure generators based on artillery gunpowders are significantly inferior to pressure generators based on thick-block blocks in efficiency, while maintaining their disadvantages. This is due to the significantly shorter duration of the combustion process of the powder charges, as a result of which the combustion products quickly float to the surface, having less impact on the formation.

The closest analogue of the developed device is an implosive device (Technologies for increasing the productivity of low-production wells in oil fields. / Sadykov I.F., Chepalin A.I., Marsov A.L.) // Proceedings of the 12th European Symposium "Enhancing Oil Recovery" Kazan. 2007), equipped in the bottom with a charge of a slowly burning fuel composition as a combustible cork, the combustion products of which, in addition, floating up to the surface, warm the bottom-hole zone.

The aim of the invention is to develop a pressure generator based on ballistic artillery gunpowders with a lower charge mass, approaching in efficiency to the best samples of powder pressure generators.

The goal is achieved by a technical solution, which consists in a radical reduction in free space in which the powder charge is located in the processing zone of the well by placing it on the outer surface of the cylindrical body of a given size. The organization of the combustion process of the charge in a narrow annular space between the walls of the casing and the cylindrical body makes it possible to increase the efficiency of the effects of combustion products on the bottomhole formation zone due to the high charge density, which provides high momentum values. At the same time, a higher ratio of the total area of the perforations to the free cross-sectional area of the casing than in conventional pressure generators, and the convergence of the combustion zone to the walls of the casing ensures the injection of a larger fraction of the combustion products and the well fluid heated by them into the bottomhole formation zone.

In this technical solution, an implosive chamber is used as a cylindrical body.

An implosive chamber is a hollow sealed steel container containing air under atmospheric pressure. The camera is equipped with a depressurization unit, which is activated in the processing zone. The developed version of the depressurization unit is made in the form of a plastic or metal partition that tightly closes the radially located windows in the chamber walls. The partition is destroyed at a given point in time under the action of a discontinuous charge placed on the surface of this partition. Initiation of a bursting charge is carried out by an assembly consisting of a detonator capsule, a flame-retardant cord and an electric fuse.

As a powder charge in the developed device, a facing powder pressure generator (PGDO) is used, made of elements of ballistic artillery gunpowders, placed on the outer surface of the body of the implosive chamber. PGDO is driven by an ignition assembly. The ignition unit consists of a ring-shaped powder charge equipped with an electric filament, placed together with the lower end of the facing charge in the cavity between the outer surface of the housing and the steel coupling fixed to the housing.

The ignition and depressurization units are connected to the inlet mounting wire in a parallel circuit and are driven simultaneously. The depressurization delay time is determined by the length of the flame-retardant cord.

The housing of the implosion chamber is closed in the upper part by a cable head, which serves, in addition, to connect to the geophysical cable, and in the lower part by the bottom cover.

The processing of the well by the device is accompanied by the following processes. After the device is lowered into the treatment area under the influence of an electric signal, the facing charge ignites.

The pressure pulse generated by the charge acting on the perforation channels produces a destructive effect on the rocks composing the bottomhole formation zone. The gaseous products of the combustion of gunpowder and the well fluid heated by them heat the resinous deposits, reducing their viscosity and adhesive strength. After the pressure drops to the hydrostatic level, the case of the device is depressurized. Under the influence of a significant pressure difference in the chamber cavity and in the well, the borehole fluid is pumped into the chamber. In this case, the pressure in the well in the processing zone instantly decreases to almost zero values and remains at this level until the chamber is full. During this period of time, molten resinous deposits and clogging particles enter the well, and then into the chamber. At the same time, under the action of the opposite directional in-situ pressure, further cracking of the formation rocks takes place.

After filling the chamber with borehole fluid, the pressure in the borehole instantly rises again and has a destructive effect on the bottomhole zone. These pressure surges excite a gradually decaying wave process of pressure fluctuation, which produces further development of cracks in the bottomhole formation zone, improving its filtration properties.

It should be noted that, regardless of the design of the powder generators and their power characteristics, the maximum value of the pressure pulse that is created during their operation should not exceed the threshold values associated with the strength of the casing.

The combination of thermogasdynamic treatment of the borehole zone of the formation with the combustion products of the facing powder charge with exposure to alternating pressure pulses under the influence of the implosive chamber provides a longer processing time and the creation of a high difference of the maximum and minimum values of pressure in the well, unattainable when using only one of the devices, which can significantly increase effectiveness of bottom-hole mining.

Claims (2)

1. Device for pulse alternating treatment of the borehole zone of the formation, made in the form of an implosive chamber, characterized in that the charge is a facing powder pressure generator made of elements of ballistic artillery gunpowder, placed on the outer surface of the body of the implosive chamber with the possibility of approaching the casing wall columns, while it is possible to ignite the facing powder pressure generator, generating gaseous combustion products pressure pulse with destruction - cracking rock formation near the wellbore and depressurization implosion camera body after a pressure drop to hydrostatic level and provided with a wave process pressure fluctuations with values of maximum and minimum pressures and duration, providing further development of cracks in the bottom zone. 2. The device according to claim 1, characterized in that the facing powder pressure generator has the ability to actuate the ignition unit, consisting of a ring-shaped powder charge, equipped with an electric filament and placed in a cavity formed by the outer surface of the housing and the coupling mounted on the housing .