RU2375555C1 - Method for secondary opening of production stratum - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: invention related to oil-and-gas production, particularly to oil fields development, and used for executing of production stratum secondary opening. Essence of the invention is in cementing of the well and descending piping strings with installed on a case with a plug fitting made of acid-soluble material, washing out of the well and pumping an acid into the production stratum, well development. According to invention case is installed on tubing strings using automatic locker. Case has a centraliser and supports. Between the free end of the well and its bottomhole create a gap big enough to dislocate plugs. Before the cementation the horizontal well bore wash it out with high content foam with 5-10% magnesium content, with a volume equal to two volumes of horizontal well. After that cement horizontal well with a slurry, which have a certain filtrating qualities, based on polyurethane hydrophilic polymer, pumped with volume equal to cemented gap volume. Therefore lift up tubing pipes and disconnect them from case, supply them with slurry and hydrochloric acid, separate them from a well fluid and each other with acid resistant plugs with the immediate well fluid displacement along the gap between tubing pipes and well wall. To be supplied untill slurry reaches the bottom hole. After that connect tubing pipes with a case and continue supply till the pressure drop, triggered by interaction of the second plug with case supports. After some times well to be developed.

EFFECT: diversified range of application due to slightly cemented collectors use, and increase in efficiency due to non-perforated opening of the collector, and decrease of a well product watering.

1 tbl, 1 dwg

Description

The invention relates to the oil industry, in particular to the development of oil fields, and is intended for the secondary opening of reservoirs.

A known method of developing an oil well (RF patent No. 2108447, IPC EV 43/00, publ. 1998.04.10). Glasses with a viscoplastic substance are inserted into the holes of the filter. The casing string with the filter is lowered into the well. The well is cemented above the filter. After setting the cement slurry, a tubing string with a funnel is lowered into the well. The well is washed. Cut off the ends of the glasses with a funnel. The well is washed a second time. Depressurize the reservoir and at the same time put the well into operation. The disadvantage of this method is its narrow scope, associated with the inability to use in poorly cemented reservoirs, and low efficiency associated with the destruction of the reservoir and high water cut of well products.

There is a method of secondary opening of the reservoir, adopted for the prototype (AS USSR No. 1614561, IPC ЕВВ 43/11, publ. 1996.01.20). Before lowering the body into the well, check valves are installed outside the holes, and the holes are closed with plugs made of acid-destructible material. A housing with plugs is placed opposite the reservoir and the aquifer. Then the well is cemented and the tubing string is lowered into it. The well is washed with water and acid is pumped into the interval of the reservoir and the aquifer. Destroy the cement ring opposite the openings and simultaneously in both intervals of the layers. Then acid is pumped into the strata. After the destruction of the acid-degradable element, the aquifer is isolated. Then develop the reservoir after the isolation of the aquifer. The disadvantage of this method is its narrow scope, associated with the inability to use in poorly cemented reservoirs, and low efficiency associated with the destruction of the reservoir and high water cut of well products.

The technical result of the invention is to expand the scope due to the possibility of use in weakly cemented reservoirs and to increase efficiency due to non-perforation opening of the collector and to reduce water cut in well products.

The technical result is achieved by the fact that in the method of the secondary opening of the reservoir, including cementing the well and lowering into it a string of tubing with a body mounted on it with plugs of acid-soluble material, flushing the well and injecting acid into the interval of the producing reservoir, developing the well, according to According to the invention, the housing is installed on tubing by means of an automatic coupler, the housing has centralizers and stops, and left between the free end of the housing and the bottom of the well there is a gap sufficient to accommodate the plugs; before cementing the horizontal wellbore, it is washed with high-pressure foam with magnesium particles of 5-10% volume, in an amount equal to two volumes of the horizontal wellbore, and then the horizontal wellbore is cemented with grouting composition with specified filtration properties on based on a polyurethane hydrophilic prepolymer supplied in a volume equal to the volume of the cemented interval, for which lift the tubing and disconnect them from the body, p they give grouting composition and hydrochloric acid to the tubing, which are separated from the wellbore fluid and from each other by acid-resistant plugs while simultaneously displacing the wellbore fluid in the gap between the tubing and the borehole wall, they are fed until the bottom of the tubing reaches the grouting composition then the tubing is connected to the casing and continues to supply until the pressure jump caused by the interaction of the second cork along with the stops of the casing after holding well, if necessary, the hydrochloric acid treatment is repeated.

The application of the proposed method will expand the scope due to the possibility of use in weakly cemented reservoirs and increase efficiency due to non-perforation opening of the reservoir and reduce water cut in well products.

The method of secondary opening of the reservoir is illustrated in the drawing, which shows a general schematic diagram of the design of the well, where:

1 - horizontal wellbore of a directionally horizontal well;

2 - well filter of cement composition based on a polyurethane hydrophilic prepolymer;

3 - cement ring;

4 - tubing string;

5 - automatic coupler connecting the string of tubing 4 with the housing 6 with plugs 7 of acid-soluble material;

6 - case with centralizers 8 and plugs 7 of acid-soluble material;

7 - plugs of acid-soluble material;

8 - centralizers of the housing 6;

9 - the gap between the casing 6 and the bottom of the well;

10 - stops of the housing 6.

The method of secondary opening of the reservoir is as follows. Before the development of the field, a vertical well is drilled to the sidehole mark and cemented to form a cement ring 3. After the cement has hardened, a horizontal well is drilled 1. Then, the casing 6 is lowered into the tubing string 4 with centralizers 8, stops 10 and plugs 7 from acid-soluble material. The housing 6 is connected to the tubing string 4 using a coupler 5 necessary for remote coupling and uncoupling operations. When installing the housing 6 between it and the bottom of the well, a gap of 10 is sufficient to accommodate all the plugs necessary to separate the reagents supplied to the horizontal wellbore 1 from the wellbore fluids (not shown conditionally). Before cementing the horizontal barrel 1, it is washed with high-volume foam in a volume equal to two volumes of the horizontal barrel 1. The foam contains magnesium particles in a volume of 5-10% of the volume of the foam. The use of high-level foam in the above volume will make it possible to efficiently clean the wellbore from sludge. In turn, magnesium powder (particles) are necessary for mudding the walls of the well and preventing the grouting composition from interacting with the aggressive formation medium at the time of filing (cementing) and hardening of the composition. The content of magnesium particles in the amount of 5-10% of the volume of the foam allows for quite effective colmatization, feeding in a smaller volume will not lead to the desired result, feeding in a larger volume will not improve the quality of the mudding. Multiple foam with magnesium particles is injected into the inner space of the column 4 of tubing with simultaneous displacement of it together with the borehole fluid along the gap between the walls of the well and the tubing string 4.

Foams are dispersed systems with a gas dispersed phase and a liquid or solid dispersion medium. Foams are usually relatively coarse, highly concentrated systems (dilute systems such as gas-liquid are called gas emulsions). The volumetric content of the dispersion medium is usually characterized by multiplicity. The multiplicity of the foam is characterized by a value equal to the ratio of the volume of the foam to the volume of the solution contained in the foam (in fact, the multiplicity of the foam β is the ratio of the volume of the foam V _cm to the volume of the solution V _W from which it is formed: β = V _cm / V _W (V _g + V _W ) / V _W , where V _g is the volume of gas). Depending on the magnitude of the multiplicity, the foam obtained from foaming agents is divided into: foam of low multiplicity (not more than 20); medium-frequency foam (from 20 to 200); foam of high multiplicity (more than 200).

The multiplicity of foams is estimated by the methods of weighing, Clark’s electrical conductivity, and radioactive in an installation consisting of a source of radioactive radiation (cesium-137) and a counter (scintillator). The multiplicity of the foam depends on the pressure of the medium, therefore, for each case of the implementation of the proposed method, it is necessary to take a foam of high multiplicity for the corresponding working pressure.

Then the horizontal wellbore 1 is cemented with a cement slurry based on a polyurethane hydrophilic prepolymer with predetermined filtration properties (RF patent No. 2258798). Filtration properties are selected in accordance with the properties of a weakly cemented reservoir. As a binder, the grouting composition contains a polyurethane hydrophilic prepolymer, as a builder, it contains sodium chloride that does not contain hydrated water, and as an additive the composition contains sand, in the following ratio, wt.%:

Polyurethane hydrophilic prepolymer 7-15; Salt 18-48; Sand 24-55; Water rest.

Each oil reservoir has certain permeability and strength properties. When a collector is opened by a well, these properties change significantly, which often leads to a decrease in the stability of the reservoir and a decrease in its permeability. Creating well filters with permeability and strength properties similar to reservoir properties will increase reservoir recovery by preserving most of the reservoir properties (mainly permeability). The polyurethane hydrophilic prepolymer has the ability to cure when water is added, therefore delivery to the bottom of the well is carried out in sealed bags. The indicated mass ratios are included in the range of the most effective use of the composition (see table). When using the composition for mounting the collector and filling the filter frame in the well outside the indicated intervals, either a reduced strength of the resulting filter or its insufficient permeability is observed. The use of a hydrophilic prepolymer as a binder polyurethane will allow the formation of a filter with hydrophilic properties and thereby increase the efficiency of oil production. As a builder, table salt is used that does not contain hydrated water (the salt is calcined on the surface before use). Salt dissolves when rinsed with fresh water and creates permeable channels in the filter frame. Excessive addition of sodium chloride leads to a decrease in the strength of the filter frame. As an additive, sand is used to increase the strength of the filter frame.

Table Composition for mounting the collector, wt.% Water permeability coefficient K, m / day Strength at 10% deformation, MPa Polyurethane hydrophilic prepolymer Salt Sand Water 17 16 22 45 2.5 1,1 fifteen 38 31 fifteen 8.81 0.96 12 48 24 16 25.92 0.43 7 40 33 twenty 16.22 0.41 9 eighteen 55 eighteen 3,58 0.5 6 42 thirty 22 30,43 0.35

The composition for mounting the collector and filling the filter frame in the well is prepared as follows: mixed in dry form in the required proportions, wt.%:

Polyurethane hydrophilic prepolymer 7-15; Salt 18-48; Sand 24-55.

Then, with constant stirring, add the required amount of water.

A composition based on a polyurethane hydrophilic prepolymer is fed into the gap between the borehole wall and the casing 6 with centralizers 8. Centralizers 8 are designed to center the casing 6 relative to the horizontal wellbore 1 and then create a borehole filter with walls of the same thickness and permeability. When cementing a horizontal wellbore 1, a composition based on a polyurethane hydrophilic prepolymer in a volume equal to the volume of the cemented interval is fed into the well to create a well filter. To do this, lift the column 4 of tubing and disconnect them from the housing 6. In the column 4 of tubing install a plug that separates the grouting composition from the wellbore fluid (not shown conventionally), then grouting composition is supplied, and the next acid-resistant tube is installed. Acid-resistant plugs can be made of acid-resistant materials (acid-resistant materials) - metal and non-metallic materials that are resistant to the destructive effect of acids. Among metal acid-resistant materials, the most widely used are deformed and cast high-alloy steels, alloys based on Ni, Cu and Al, pure metals: Ni, Al, Cu and Pb. The use of Ti and alloys based on it is promising. For especially critical structures, Zr, Ta, Nb and their alloys are used. When choosing metallic acid-resistant materials, the redox properties of the medium (redox potential), as well as the nature of the anions, concentration and temperature of the acids are taken into account. In oxidizing media, materials are successfully used on the surface of which, under the influence of an aggressive environment, a film of a chemical compound with high protective properties is formed (stainless steels, nichromes, Al and alloys based on it, Ti, high-chromium and high-silicon cast irons). In highly oxidizing environments, the passivation of many stainless steels and nickel alloys occurs. In reducing environments, metallic materials are used having high thermodynamic stability: Cu; Ni; nickel alloys containing Mo (hastelloy) or Cu (monel metals); Mo alloyed titanium alloys. In mildly oxidizing and weakly reducing environments, chemically complex steels and alloys are used alloyed with metals that increase their passivability and thermodynamic stability: highly alloyed Ni, Mo, and Cu stainless steels, nickel alloys with Cr, Mo, W, Ti additives with a small amount of Pd, etc. Non-metallic acid-resistant materials are divided into organic and inorganic. Among organic acid-resistant materials, polymeric materials are increasingly used: faolite, polyvinyl chloride, polyethylene, polypropylene, polycarbonate, fluoroplastics, etc. Fluoroplastics are characterized by the highest chemical resistance, they are not destroyed even in highly oxidizing environments. Sheets, pipes, rods, and shaped products are made from these materials. Many of them are well welded, glued, reinforced with glass fiber. As a heat-conducting acid-resistant material, graphite is used, including impregnated with various resins. Inorganic acid-resistant materials include: acid-resistant ceramics, stone casting, silicate and quartz glasses, glass, asbestos, porcelain, acid-resistant enamels, putties, concrete and cement. Hydrochloric acid, which is separated from the wellbore fluid by the next plug, is fed and grouting composition and hydrochloric acid are forced through a column of 4 tubing pipes. Simultaneously with the supply, water (well fluid) is displaced through the gap between the tubing string 4 and pipes and the well walls. If necessary, use tubing 4 of smaller diameter. The filing is carried out until the cement composition reaches the bottom of the column 4 tubing. Then, the tubing string 4 is connected to the housing 6 by means of an automatic coupler 5 and the flow is continued until the second pressure surge caused by the interaction of the second stopper (conventionally not shown) separating the grouting composition from the acid and the stops 10 of the housing 6. After exposure necessary for dissolving the plugs 7 from an acid-soluble material and magnesium particles that collect the collector, as well as hardening the cement slurry, develop the well by swabbing or other known method based on lowering and hydrostatic pressure in the well. The dissolution time of the plugs 7 is taken equal to the hardening time of the grouting composition based on a polyurethane hydrophilic prepolymer. The result is a downhole filter 2 from a cement composition based on a polyurethane hydrophilic prepolymer with predetermined filtration properties. If necessary, in the absence of the created channel of hydrodynamic communication with the collector, the hydrochloric acid treatment is repeated.

The use of this method of secondary opening of the reservoir provides the following advantages:

- expansion of the scope due to the possibility of use on weakly cemented collectors;

- non-perforation opening of the collector;

- improving efficiency by reducing water cut in products.

Claims (1)

The method of secondary opening of the reservoir, including cementing the well and lowering tubing string into it with a casing installed on it with plugs of acid-soluble material, flushing the well and injecting acid into the interval of the producing reservoir, developing the well, characterized in that the casing is installed on the pump -compressor pipes using an automatic coupler, the housing has centralizers and stops, and between the free end of the housing and the bottom of the well leave a gap sufficient to accommodate traffic jams, Before cementing the horizontal wellbore, it is washed with high-pressure foam with magnesium particles of 5-10 vol.% in an amount equal to two volumes of the horizontal wellbore, after which the horizontal wellbore is cemented with grouting composition with predetermined filtration properties based on a polyurethane hydrophilic prepolymer supplied in a volume equal to the volume of the cemented interval, for which they lift the tubing and disconnect them from the body, feed the grouting composition into the tubing and hydrochloric acid, which are separated from the wellbore fluid and from each other by acid-resistant plugs while simultaneously displacing the wellbore fluid in the gap between the tubing and the borehole wall, are fed until the bottom of the tubing reaches the grouting composition, after which the tubing is connected with the casing and continue supplying until a pressure jump is caused by the interaction of the second cork along with the stops of the casing; after exposure, the well is drilled, if necessary, hydrochloric acid treatment weave repeat.

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