RU2423604C1 - Procedure for development of payable carbonate bed - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure consists in exposure of payable bed by drilling, in flushing with drill polymer agent, in string cementing and in its perforation by drilling to big depth with interval between perforation orifices 1-3 m, in lowering production string or drilling pipes with packer, in disconnection of upper perforation channels from lower ones of one of bed intervals with packer, and in treatment of bed with acid by circulation in annular space. To accelerate operation of treatment and for increase of its efficiency, there is cyclically created vacuum, for example, by swabbing under the packer simultaneously with treatment of bed in the bottomhole zone. Also, operation of treatment is commenced from an upper interval near a bed roof at pressure below pressure of bed hydraulic break created over the packer through tube space. ^ EFFECT: raised efficiency of procedure due to simplified process and reduced time. ^ 4 cl, 2 dwg

Description

The invention relates to the field of the oil and gas industry, in particular to a method for processing a bottom-hole zone (BHP) of a productive pore-fractured carbonate formation in order to restore reservoir characteristics of the formation or increase the injectivity of the formation in injection wells.

A known method of treating a formation in order to increase processing efficiency and increase production capabilities of the formation (see RD-39-0147585-020 VNII-86 "Instructions on the technology for processing the bottom-hole zone of a well based on heterogeneous fluids and hydrodynamic effects").

The method involves lowering into the well a string of tubing (tubing) with a device for generating hydraulic pulses in the interval of the reservoir and pumping acid or other processing fluids through them into the reservoir with a capacity with which the reservoir receives, while creating hydraulic pulses (hydraulic shocks).

The disadvantage of this method is the lack of efficiency due to technological features, i.e. processing is not in optimal mode. This is explained by the fact that in the process of forcing acid into the formation, the frequency and amplitude of the generated hydraulic pulses, as well as the generated well-formation pressure, are not controlled, i.e. processing is carried out uncontrollably.

There is also known a method of processing a productive carbonate formation (see patent RU No. 22005950, 7E21B 43/27, published in BI No. 16, 06/10/2003), including the descent of the tubing string into the well, the installation of the shoe shoe in the processing interval, the injection of acid solution through the pipes and their impact on the rock of the reservoir. In this case, before the descent of the pipe string, the shoe of the column is equipped with a device with hydromonitor nozzles separately located at angles of 90 or 120 ° along the generatrix, and the acid is injected into the formation in portions in the mode of hydromonitor exposure to a surface-active substance (surfactant), which performs hydro-sandblasting effects on the formation . The alternation of acid hydro-monitor and hydro-sand blasting is carried out alternately in the middle of each processing interval.

The disadvantage of this method is the complexity of the processing technology, requires the presence of sand of a certain fraction, and the need to wash out of the well after the completion of the processing operation requires additional tripping operations in the case of using sand of a large fraction.

There is a known method of well completion (see description to AS No. 1696674, ЕВВ 33/13, published in BI No. 45, 12/07/1991), providing for the acid treatment of the bottom-hole zone. The method includes the following technological operations:

1) The opening of the reservoir with a drilling fluid with high loss, containing chemically destructible filler.

2) The formation of chemically destructible clay crust in the interval of the reservoir by circulation of the drilling fluid.

3) Well cementing and perforation.

4) The descent of the pipe string with the packer.

5) Dissociation of the upper perforation channels from the lower.

6) Removing the clay crust by chemical destruction by circulation of an aqueous surfactant solution in the annulus through the lower perforations with the return of the solution into the annulus through the upper holes.

7) Squeezing acid into the formation and circulating it in the annulus.

This method is by technical nature closer to the proposed one and can be adopted as a prototype.

The disadvantages of this method are the complexity of the technology, the large investment of time and low efficiency.

The technical task of the present invention is to remedy the above disadvantages of the prototype.

The stated technical problem is solved by the described method, including opening a productive formation by drilling with drilling mud, cementing the column and perforating it, lowering the tubing string or drill pipe with a packer, uncoupling the upper perforation channels from the lower one of the formation intervals, treating the formation with acid by their circulation in the annulus.

New is that in order to accelerate the processing operation and increase its efficiency simultaneously with the formation treatment in the bottomhole zone under the packer, a vacuum (vacuum) is cyclically created, and the treatment operation is carried out starting from the upper interval at the formation roof under pressure below the hydraulic fracturing pressure created by above the packer through the annulus, a vacuum in the bottomhole zone under the packer is created by swabbing, while drilling the productive formation by drilling with clay-free polymer solution, and the perforation of the well is carried out by drilling to a great depth with an interval between perforations of 1-3 m

Patent research to determine the technical level and the compliance with the criterion of "novelty" was carried out according to the patent fund of the TatNIPIneft Institute with a retrospective of 20 years. The results of patent studies showed the absence of similar technical solutions that have such a combination of essential features as the claimed object, were not found. Therefore, in our opinion, the proposal of the authors is new.

Figure 1 shows a cased well, where perforations and channels made by drilling are visible, and a deflated additional pipe string with a packer in the lower part, and a swab deflated along the additional pipe string, in longitudinal section. Figure 2 is a view of A (enlarged), in section according to figure 1.

The method is carried out in the following sequence.

A casing pipe 3 is lowered into the well 1, drilled to the design depth with the opening of the productive carbonate formation 2 by washing with a polymer drilling fluid, 3 and cemented using traditional technology using cementing aggregates of the CA 320M type and, at the end of the cement 4 hardening wait, drilling perforation is performed on great depth of up to 3 meters or more. The opening of the reservoir using clay-free polymer drilling fluid eliminates the formation of a permeable filter cake formed when using the clay-clay drilling fluid provided in the prototype, which eliminates the operation to remove the filter cake. As a clay-free drilling fluid, the composition given in the regulations for completion of wells can be used (see RD 39-0147585-232-01, Bugulma, 2001, developed by the TatNIPIneft Institute, p. 13). The specified clay-free drilling fluid contains in wt.%:

Polyacrylamide (PAA) - 2-3.

Carboxymethyl cellulose (CMC) - 2-5.

Soda ash - 3-5.

Starch - 3.

Technical water - the rest.

Below are the values of the technological parameters of the polymer solution.

Density, g / cm ³ - 1.00.

Conditional viscosity, s - 23-25.

Plastic viscosity, MPa · s - 17-25.

Dynamic shear stress, dPa - 5-20.

Static shear stress, dPa

after 1 min - 1-2

after 10 minutes - 5-6

Indicator filtration, cm ^3/30 min - 5.6

Hydrogen indicator, pH - 8-9

The thickness of the polymer crust, mm - 0.5

Electrical resistivity, Ohm · m. - 1-3

As a device for drilling, you can use the technical solution according to the patent of the Russian Federation No. 2182961, 7E21B 43/114, publ. in BI No. 15, 2002, lowered by electric cable. It contains a housing, inside of which there is an engine, a gearbox, as well as a mechanism for pressing the device against the well wall, a drill feed assembly, a drill rotation assembly, and a cassette for accommodating drill pipes.

At the end of the drilling operation, a tubing string 5 (tubing) with a packer 6 is lowered into the well and the required volume of a solution of 20% concentration of hydrochloric acid 8 is pumped through the pipe space 7 at a rate of 1-2 m ³ for each meter of thickness of the treated reservoir. Next, the upper perforation openings 9 are disconnected from the lower hole 10 by the same packer. Under pressure, the acid through the upper perforations 9, entering the drilled channels 11 in the rock, begins to penetrate into the pores of the formation, simultaneously reacting with the carbonates of the formation and thereby increasing its permeability. At the same time, a swabbing installation is started up (the installation is not shown), which can be used as a technical solution according to RF patent No. 2264534, containing a mast made of welded tubular structures, to the posts of which the bases are fixed - upper and lower with guide rollers, the lower of which can be connected to the column flange of the well with a bolted connection. Mentioned lower roller is mounted with the possibility of orientation relative to the drum with a winch rope, incorporating a gearbox and an electric motor. When the swab 12 is moved upward, a vacuum (vacuum) is created under it, which helps to accelerate the circulation of acid in the annulus. The spent acid together with the reaction products, as well as the oil-water emulsion, are transported through the lower perforation channels into the well and from there swab to the surface.

With a decrease in acid concentration by a factor of 2–3, its circulation is stopped and the treatment of the underlying interval of the formation is started. To do this, the packer is brought to its original position and by feeding the pipe string down the packer is installed in the interval of the next formation being processed and after packing, the cycle is repeated according to the technology described above and until all intervals of the formation are processed. In this case, swabbing is continued until the expected production rate of the well according to the design, after which the swab is removed to the surface and the well continues to be operated in a mechanized way, for example, by deep pumps.

The technical and economic advantage of the proposal consists of reducing the time spent on processing and increasing the flow rate of the well due to increased processing efficiency.

Claims (4)

1. A method of processing a productive carbonate formation, including drilling a productive formation with drilling mud, cementing the column and perforating it, lowering the tubing or drill pipe string with a packer, uncoupling the upper perforation channels from the bottom of one of the formation intervals, treating the formation with acid by circulating them in the annulus, characterized in that to speed up the processing operation and increase its efficiency simultaneously with the treatment of the formation in the bottomhole zone under the packer cyclically create vacuum rarefaction, while the processing operation is carried out starting from the upper interval at the roof of the reservoir under pressure below the hydraulic fracturing pressure created above the packer through the annulus. 2. The method according to claim 1, characterized in that the vacuum in the bottomhole zone under the packer is created by swabbing. 3. The method according to claim 1, characterized in that the drilling by the drilling of the reservoir is carried out with washing clay-free polymer solution. 4. The method according to claim 1, characterized in that the perforation of the well is carried out by drilling to a greater depth with an interval between perforations of 1-3 m

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