RU2401381C1 - Method of bench treatment - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: proposed method consists in that, first, bench is hydraulically fractured by hydraulic fracturing fluid to produce preset-length development fracture. Then hydraulically active fluid is pumped in the well and forced, by chaser, into the bench, formed fracture and adjoining rock pores. Said chaser reacts with water and suspension of aluminium-containing material activated by at least gallium, in anhydrous fluid-carrier to cause thermo baric effect on the bench so that rocks and fluid contained therein are heated by 20°C and higher due to decrease in oil viscosity to below 10 MPa·s, fluidising of paraffinic and asphaltene-pitchy hydrocarbons, extraction of gas-phase products and formation of asset of additional micro fractures branched off produced development hydraulic fracturing and communicated with the system of the bench natural fractures.

EFFECT: higher filtration properties of bench.

7 cl, 1 ex

Description

The invention relates to the oil and gas industry and can be used to increase productivity in the development of new, as well as existing production and injection wells in oil fields with viscous and heavy oils.

The chemical methods of influencing the bottom-hole formation zone (BFZ) are widely known in order to intensify oil production of production wells and increase the injectivity of injection wells for both terrigenous and carbonate rocks (SU No. 1480413, 1994, SU No. 1756546, 1992, SU No. 1816035, 1996, SU No. 1607481, SU No. 1647202, SU No. 1648108, SU No. 1682542, RU No. 2013528, 1994, RU No. 2054533, 1996, RU No. 2070964, 1996).

When implementing these methods, the intensification of oil production is achieved mainly by increasing the drainage area, dissolving asphalt-resinous and paraffin deposits in the perforation, decolmatization (wedging) zone. At the same time, the reservoir properties of the bottomhole formation zone are restored, additional filtration channels are formed in the rock, due to which the influx of fluid into the well is intensified, and the injectivity of injection wells is increased.

However, these processing methods have a local character of action and are ineffective in fields with productive formations represented by reservoirs of medium and low quality and containing viscous and heavy oils.

There is a method of intensifying oil production with hydraulic fracturing, consisting in fracturing the rock as a result of pumping a fracture fluid into the well with an injection rate providing pressure at the bottom of the well above the fracture pressure, followed by pumping into the well a suspension of fixing material in the carrier fluid and production fluid, technological holding and commissioning of the well (Recent Advances in Hydraulic Fracturing. JLGidley, SAHolditch, DENierode, RWVeatch. - Monograph SPE, Volume 12, 452 p. 1989).

This method allows you to create highly conductive hydraulic fractures in the reservoir, as a result of which the production of oil reserves is intensified and increased.

The disadvantages of this method include the low efficiency of the process in formations containing viscous and heavy oils.

Widely known methods of heat treatment, providing heating of the bottomhole formation zone for the purpose of melting paraffin and lowering the viscosity of asphalt-tar deposits. The restoration of the permeability of the bottom hole occurs as a result of the removal after heating of these components into the well under the influence of reservoir pressure. (O.V. Kozhemyako, V. A. Sirotko. Status and development of thermal methods of oil production. - Dep. VNIIOENG No. 1515, 1988.).

Such methods include the following: methods of heat treatment of PPP by electrically heating or pumping hot coolant — superheated steam or water (Technological gas generators for intensifying oil recovery. V.V. Bashirov, N.Sh. Khairetdinov, Z.G. Shaikhutdinov, etc. - M ., VNIIOENG, 1984.), autonomous thermogas heaters and powder batteries (RF Patent, No. 2092682, CL ЕВВ 43/263, 1996), the use of various pyrotechnic compositions, for example, iron-aluminum or manganese-aluminum termites (US Patent, No. 4372213, MKI C06D 5/00, NKI 166-3 01, 1983), injecting metallic magnesium into the well in the form of a colloidal suspension (US Patent No. 4530396, MKI ³ Е21В 29/02, Е21В 43/25, НКИ 166-63, 1985), using the reaction of alkali metals with water (N.K. Prikhodko, A.V. Perevalov, T. Atakulov. Use of chemical explosives to intensify the development of oil and gas fields // Oilfield business: express information. Issue 19, VNIIOENG, 1981).

The above-mentioned thermal methods for restoring the permeability of PZP either have low efficiency, or an increased risk of damage to the well or downhole equipment, explosion and fire hazard.

The closest in technical essence is the method of treatment of the reservoir, which ensures the restoration of permeability of the bottom-hole zone of oil and gas reservoirs in a variety of geological conditions through the use of substances that react with water and water-containing compounds with the release of heat. The method involves placing isolated charges of a hydroreacting aluminum-containing substance in the well with its subsequent contact with the well fluid, the pressure and temperature in the interval of the reservoir being maintained at a level that restores the permeability of the bottomhole zone (RU No. 2186206, 2001).

The result of this formation treatment is a local gas-hydraulic fracturing, which leads to the formation of one or several cracks diverging from the well by 3-5 m, connecting the well with the productive formation, and combining gas-hydraulic fracturing with thermal acid treatment of the formation improves the filtration characteristics of the bottom-hole formation zone that, in a number of wells that have lost their productivity during operation, provides a fairly effective recovery of their flow rate.

However, due to its local impact, this method is ineffective when used in developing new wells and treating wells that have lost their productivity in fields with hard-to-recover oil reserves belonging to groups of viscous and highly viscous (non-Newtonian) liquids, in conditions of fields with low-permeability reservoirs , as well as characterized by low reservoir temperatures and pressures, the number of which among the developed reserves of representatives of liquid hydrocarbons to The standing time begins to prevail substantially. Even in those cases when the formation treatment is accompanied by a sufficiently large heat and gas emission, the depth of exposure is small, especially in reservoirs with low rock permeability and porosity, and the heat generated in this process is used to melt the refractory fractions of paraffin and resinous substances, which again solidify and partially clog the pores of the formation in the bottomhole zone, reducing processing efficiency.

The objective of the invention is to create an effective way to develop new wells and restore the flow rate of wells that have lost their productivity in viscous and heavy oil fields in wells by increasing the filtration properties of the reservoir by creating additional fluid filtration paths in the form of a system of technogenic fractures, including: the main main fracture , “Fissuring” its cracks, usually of shorter length and revealing natural cracks.

The problem is solved by the described method of processing the formation, which consists in the fact that the hydraulic fracturing of the formation is preliminarily carried out with the formation of a technogenic hydraulic fracture of a given length, and then injection into the well and forcing through the squeezing fluid into the formation, into the adjacent hydraulic fracture and adjacent to it pores of rocks of a hydroreacting composition that enters into a heterogeneous chemical reaction with water and includes a suspension of an aluminum-containing material ooze activated at least by gallium in an anhydrous carrier fluid, providing a thermobaric effect on the formation with heating the rocks and the fluids contained in them by 20 ° C or more, lowering the viscosity of the oil below 10 MPa · s, transferring to a fluid state paraffin and asphaltene-resinous hydrocarbon compounds, the release of gas-phase products and the formation of a network of additional microcracks branched off from the created technogenic fracture and communicating with the system of natural formation fractures.

And also the fact that:

- the length of a technogenic fracture is from 30-50 m to 100-150 m.

- use a suspension of aluminum-containing material activated by gallium, indium and tin;

- the suspension of activated aluminum-containing material pumped into the well is isolated from the fracturing fluid and the squeezing fluid containing water in portions of an anhydrous dividing liquid;

- when treating terrigenous formations, proppant is introduced into the well in the form of a suspension in an anhydrous carrier fluid or a carrier fluid based on water;

- when processing terrigenous seams, proppant is introduced into the well before the injection of activated aluminum-containing material;

- the particle size of the injected suspension of aluminum-containing material for reservoirs of medium and low quality is 0.5-5.0 μm and does not exceed 0.5 of the diameter of the pore channels of oil-containing rocks or proppant packing in a fracture.

The term "aluminum-containing material" within the framework of this application is understood to mean both aluminum and its alloys, in particular structural, activated at least gallium. It is possible to use aluminum scrap.

When implementing the described method using the following process fluid:

1. Anhydrous carrier fluids for granular materials (proppant, activated aluminum):

- linear gel based on anhydrous hydrocarbon liquids (diesel fuel, kerosene, condensate, oil). To form a gel, gel-forming additives are used, for example from ester phosphate.

- a crosslinked gel, which is obtained from a linear one by adding a crosslinker to it, for example, from an organo-metal complex.

2. Water-based fluids used as burst fluids and proppant carrier fluids:

- a linear water-based gel, which is obtained by adding a gelling agent to the water, for example, based on hydroxypropyl guar.

- a crosslinked gel, which is obtained from a linear one by adding a crosslinker to it, for example, based on borate.

3. Aqueous liquids used as squeezing liquid:

- fresh water

- produced water,

- water-alcohol solution.

Hydraulic fracturing of rock continuity can also be carried out using fracturing fluids of various compositions and physicochemical properties, in particular, including an aqueous solution of ammonium nitrate, an aqueous solution of hydrochloric acid with additives, in particular, a corrosion inhibitor, iron correction, and other standard additives .

The essence of the method is as follows.

In the reservoir by means of hydraulic fracturing, a technogenic crack is created, which can be connected to a system of natural fractures. Hydraulic fracture is characterized by length, height and width (opening). An optimal length crack, which depends on the permeability of the formation, is created by performing the calculated injection schedule. The height and width of the crack are arbitrary values. For oil reservoirs, depending on the permeability of the reservoir, the optimal crack length is from 30-50 m to 100-150 m. Hydraulic fracturing of terrigenous reservoirs is usually carried out with fixing the cracks with proppant, carbonate formations - without fixing the cracks.

The term "technogenic crack" means a system of separate, interconnected cracks, fairly close spatial orientation obtained by hydraulic fracturing.

The created fractures are filled with a hydroreactive composition based on activated aluminum, which is a suspension of a powder of activated aluminum-containing material in an anhydrous carrier fluid. It is preferable to use a suspension of aluminum-containing material activated by a metal selected from the group of gallium and / or indium and / or tin. The composition is not capable of burning due to internal resources and has the ability to enter into a heterogeneous chemical reaction with water with the release of heat and gas-phase products, that is, have a thermobaric effect on the formation. The particle size of the injected suspension of aluminum-containing material is 0.5-5.0 microns for medium and low quality reservoirs and does not exceed 0.5 of the diameter of the pore channels of oil-containing rocks or proppant packing in a fracture.

Several methods for filling cracks with a hydroreactive composition are used. The simplest method is used for hydraulic fracturing without fixing the proppant crack. In this case, the composition is pumped into the crack after the fracturing fluid after the crack has reached a predetermined length, in particular, from 30-50 to 100-150 m

When carrying out hydraulic fracturing with fixing the crack with proppant, the following methods are used:

- after hydraulic fracturing, the hydroreacting composition is introduced into the flow of a suspension of proppant in an anhydrous carrier fluid during its injection into the well;

- after hydraulic fracturing, the proppant is first pumped, and then the hydroreacting composition is forced into the intergranular pores of the proppant packing that fills the crack. In this case, the grain size of aluminum should not exceed 0.5 of the diameter of the pore channels of the proppant packing in the fracture. This method can be used for relatively short cracks with multilayer packaging of proppant.

Next, a chemical reaction of activated aluminum injected into the crack with water or aqueous solutions is initiated. In this case, the initiation of a heterogeneous chemical reaction is carried out by contacting the hydroreacting composition with formation water, or with water previously pumped into the formation together with proppant, or with water contained in the selling fluid.

To do this, after forcing the process fluids from the tubing into the fracture, close the well for the duration of the destruction of the carrier fluid. A portion of anhydrous dividing liquid is pumped into the “head” of the squeezing liquid. After a technological pause, injection is resumed at a low flow rate corresponding to the bottomhole pressure, which is lower than the crack opening pressure. In this case, the anhydrous carrier fluid located in the fracture is replaced with a squeezing fluid. Then the injection is stopped and the well is closed for the duration of the reaction, after which they begin to develop the well.

As a result of the reaction of a suspension of activated aluminum with water, a complex effect on the formation occurs: thermal due to heat and baric due to the release of gas-phase products. At the same time, by regulating the reaction rate, one type of effect can be strengthened, respectively, weakening the other. So, for example, when treating a medium and high permeability formation (more than 50 mD) containing highly viscous oils (more than 10 cP), the reaction is more efficiently carried out at a low speed, resulting in heating of a larger volume of rock. For low-permeability formations with light oils, it is more efficient to carry out the reaction at high speed, which leads to a sharp increase in pressure in the fracture and creates, in addition to the main hydraulic fracture, a system of branched fractures, thus increasing the zone of increased permeability. With average reservoir parameters, it is advisable to apply a complex thermobaric effect at medium reaction rates.

The reaction rate of activated aluminum with water can be controlled within wide limits by varying the technological parameters of the preparation of hydroreacting compositions.

The reaction rate is actually determined by the particle size (grain) of the suspension. Thus, the latter is a natural parameter for controlling the speed of a process. Upon receipt of a hydroreactive powder, effective control of grain size in a fairly wide range is achieved by introducing a small amount of indium and tin into its composition.

The reaction rate substantially affects the reaction rate. The reaction rate of activated aluminum in weak hydrochloric acid solutions is much higher than in most neutral and alkaline solutions. When using an aqueous solution of ammonium nitrate as a reaction medium, in addition to increasing the reaction rate, the processing energy parameters are almost doubled.

Example 1

As an example of the implementation of the described method of treating the formation, a description of the technology of acid hydraulic fracturing (FGR) in combination with the thermobaric effect (TBW) on the oil-containing reservoirs of the carbonate composition of the Artinskian Stage of the Lower Permian in a vertical production well of the Orenburg oil and gas condensate field.

In the section of the well, a productive oil-containing stratum lies in the depth interval 1852-1958 m. Above it, at a depth of 1784-1852 m, gas-saturated rocks are located. The effective thickness of oil-saturated reservoir rocks in the section of the well according to geophysical research is 18.6 m. The porosity of the rocks varies between 5-15% with an penetration of 0.1-1.2 mD. The viscosity of the oil contained in the pores of the reservoir in reservoir conditions (at a pressure of 20.6 MPa and a temperature of + 38 ° C) is 1.5-2.0 cP.

The well was drilled with a diameter of 216 mm to a depth of 2050 m and has artificial bottom at a depth of 2000 m. In addition to the direction, conductor and technical string, a production string of pipes with an external diameter of 139.7 mm was lowered to a depth of 1994 m. The annulus is cemented to the mouth and the well is perforated in the depths of 1852-1860 m, 1896-1908 m and 1916-1946 m. A string of tubing (tubing) with a diameter of 73 mm was lowered to a depth of 1940 m, at a depth of 1800 mm m packer installed. Before the completion of hydraulic fracturing + TBW, the well production rate was 12.6 tons / day.

Option one - without the use of proppant.

Work on the integrated impact on productive oil-bearing rocks is carried out in 4 stages.

The first stage: at the technological site of the well, arrangement and strapping of the equipment required for the work is carried out, including: two pump units AN-2000, pump unit SIN-31, mixing unit USA-1, manifold block BM-700, control station for the SK-process 1, cementing unit ЦА-320, three containers of 30 m ³ each for the preparation and storage of process fluids. Then, they pressurize the high-pressure manifold by 700 atm, install the pressure limiters of the pumps by 550 atm, and the pressure relief valve on the well annulus by 120 atm and turn on the equipment that records the pressure and flow rate of the liquid at the wellhead.

The second stage: acid fracturing is carried out with the creation of a “technogenic” crack in the interval of the perforated part of the reservoir and the treatment of its walls with an acid solution. For this, 20 m ^{3 of} cross-linked water-based gel is pumped into the well with a flow rate of 3.8 m ³ / min. Then, at the same flow rate, 30 m ^{3 of an} acid solution (hydrochloric acid of 12% concentration with a standard complex of additives) is pumped, which is squeezed with a squeezing liquid (water with friction reducer) in a volume of 8 m ³ into the created “technogenic” crack and the void space adjacent to its walls of reservoir rocks. An acidic solution comes into contact with rock-forming carbonate minerals (calcite, dolomite), dissolves them, increasing the conductivity of cracks and natural pore channels of rocks adjacent to their walls.

Third stage: at a rate of 0.5-1.0 m ³ / min, 6 m ^{3 of} anhydrous gel based on diesel fuel is pumped into the well in the following sequence: 1.5 m ³ - lower buffer pack, 3.0 m ³ mixed with 75 kg of a suspension of aluminum activated by gallium, with a particle size (fraction) of 3-5 microns (while the particle size of the suspension does not exceed 0.5 of the diameter of the pore channels of oil-containing rocks), 1.5 m ³ is the upper buffer stack. Then, the injection rate is raised to 3.8 m ³ / min and the suspension is forced through with squeezing liquid (water with friction reducer) in a volume of 8 m ³ into the “technogenic” crack and the pores of the adjacent rocks. The calculated values of the temperature increase of rocks and fluids (oil, water and gas) in the area of the “technogenic” crack from the interaction of the introduced activated aluminum with water are at least 100 ° C, and the additional repression is at least 20% of the created reservoir pressure during hydraulic fracturing.

The fourth stage, all units are stopped, the pressure in the manifold is reduced to a safe level, the valve on the wellhead is closed and after a technological pause of 36 hours, they begin to develop the treated well. After treatment, the well production rate was 50.5 tons / day.

Proppant example

Work on the integrated impact on productive oil-bearing rocks is carried out in 3 stages.

The first stage is similar to the first stage in the version without the use of proppant.

The second stage: hydraulic fracturing is performed with the creation of a “technogenic” crack in the interval of the perforated part of the reservoir. First, 20 m ^{3 of} water-based crosslinked gel is pumped into the well with a flow rate of 3.8 m ³ / min, as a result of which a hydraulic fracture is formed in the formation. Then, at the same flow rate, 30 m ^{3 of} crosslinked gel based on diesel fuel is pumped. When injected into the gel stream, 10 tons of ceramic proppant of a fraction of 0.4-0.8 mm with an increasing concentration from 100 kg / m ³ to 700 kg / m ³ are introduced. At the same time, in a separate line, a SIN-31 pumping unit is injected with a flow rate of 0.4 m ³ / min 3.0 m ^{3 of} diesel-based gel mixed with 75 kg of aluminum suspension with a particle size of 3-5 μm (the particle size suspension does not exceed 0.5 packing diameter of proppant in the crack) activated by gallium, indium and tin. After filling the hydraulic fracture with proppant in a mixture with activated aluminum, 10 m ^{3 of an} acid solution (hydrochloric acid of 12% concentration with a standard complex of additives) is pumped into the well with a flow rate of 0.5-1.0 m ³ / min, which is pressed into the crack with a squeezing liquid ( water with friction reducer) in a volume of 8 m ³ . The acid solution comes into contact with aluminum, which gives the effect of thermobaric effect on rocks and fluids (oil, water and gas) in the area of the “technogenic” crack.

The third stage is similar to the fourth stage in the version without the use of proppant.

After treatment, the well production rate was 50.7 tons / day.

Thus, the method according to the invention allows to increase the flow rate by improving the filtration properties of the formation by creating additional fluid filtration paths, which provides a 4-fold increase in the oil flow rate. The described technology allows almost 2-fold increase in efficiency compared to traditionally used methods of acid hydraulic fracturing.

A similar technical result is achieved when any of the process fluids described above is used during the process implementation, for other agreed numerical values of the particle sizes of the suspension of activated aluminum-containing material, and also when processing terrigenous seams in case proppant is introduced into the well before injection of activated aluminum-containing material.

Claims (7)

1. A method of treating a formation, which is that the hydraulic fracturing of the formation is preliminarily carried out with the formation of a technogenic fracture of a predetermined length, after which injection into the well and forcing through the squeezing fluid into the formation, into the formed fracture and adjacent pores of the rocks hydroreacting composition that enters into a heterogeneous chemical reaction with water and includes a suspension of aluminum-containing material activated at least gal in an anhydrous carrier fluid, providing a thermobaric effect on the formation with heating of the rocks and the fluids contained in them by 20 ° С or more, lowering the viscosity of oil below 10 MPa · s, transferring paraffin and asphaltene-resinous hydrocarbon compounds into a liquid state, the release of gas-phase products and the formation of a network of additional microcracks branched off from the created technogenic fracture and communicating with the system of natural formation fractures. 2. The method according to claim 1, characterized in that the length of the technogenic fracture is from 30-50 to 100-150 m 3. The method according to claim 1, characterized in that a suspension of aluminum-containing material activated by gallium, indium and tin is used. 4. The method according to claim 1, characterized in that the suspension of activated aluminum-containing material pumped into the well is isolated from the fracturing fluid and the squeezing fluid containing water in portions of an anhydrous dividing fluid. 5. The method according to claim 1, characterized in that when processing terrigenous formations, proppant is introduced into the well in the form of a suspension in an anhydrous carrier fluid or an aqueous carrier fluid. 6. The method according to claim 5, characterized in that when processing terrigenous formations, a suspension of proppant is injected into the well before injection of a suspension of activated aluminum-containing material. 7. The method according to any one of claims 1 or 4, characterized in that the particle size of the suspension of activated aluminum-containing material is 0.5-5.0 μm for medium and low quality collectors and does not exceed 0.5 of the diameter of the pore channels of oil-containing rocks or packaging proppant in the crack.