RU2464410C1 - Method of stabilisation of producing formation with unstable rocks - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: proposed method comprises creating anti-sand filter by forcing polymer composition into bottomhole formation zone via exposed productive formation. Prior to forcing polymer composition, bottomhole formation zone is temporarily isolated by mortar with filler including saw dust. Then, productive formation is isolated to top by forcing composition of cement bridge. Then, casing string is exposed 1-2 m above made isolation with total section area of perforated channels making, at least, 3000 mm². Then, service string is lowered to isolate tube space by parker some 10-15 m above top level of perforated channels. Then breakdown of non-reservoir bed and productive bed is carried out by inclined fractures to force polymer proppant therein. Then service string with parker is withdrawn to produce oil to yield decreased by over 50% of initial yield. Now, productive bed isolation is destructed to expose again the productive bed in its interval.

EFFECT: higher efficiency due to ruled out sand production.

3 dwg

Description

The invention relates to oil and gas production, and in particular to methods for preventing the removal of sand from wells.

A known method of preventing the removal of sand from the well (patent RU No. 2136853, IPC 8E Е21В 43/04, ЕВВ 33/13, published in Bull. No. 25 dated 09/10/1999), including the injection of a gravel pack into the cavernous cavity of the bottomhole zone characterized in that the gravel packing is made of several gravel fractions of variable fractional composition, from the smallest to the largest gravel fraction, increasing to the wellbore, and after the gravel packing is completed, a permeable grouting composition with the particle sizes of soluble composites is pumped nents do not exceed the size of the largest particles of the gravel fraction with a gravel pack is performed by sequentially alternating pumping gravel fraction composition.

The disadvantages of this method are the complexity of the process and the insufficiently strong fastening of floating sands.

Also known is a method of fastening the bottom-hole zone of the reservoir (patent RU No. 2172811, IPC 8E ЕВВ 33/13, ЕВВ 33/138, published in Bull. No. 24 dated 08/27/2001), including perforation of the casing in the blurred interval of the bottom-hole zone, creating a sandy permeable barrier by injecting quartz sand into the annulus through perforations of quartz sand in a carrier liquid with an aqueous solution of sodium silicate, followed by pumping an alcoholic solution of calcium chloride in the pore space of the created barrier, while before creation of the last injecting an aqueous solution of sodium silicate with a density of 1250-1300 kg / m ³ in an amount to provide complete filling of the pore annulus producing formation at a distance of 0.45-0.60 m from the wells and before pumping alcoholic solution of calcium chloride - emulsion solution of the following composition, wt.%:

flotation reagent - oxal T-80 40-60

Neonol AF 9-12 0.10-0.15

hydrocarbon fluid 39.85-59.90

in the pore space of the created sand permeable barrier, and as an aqueous solution of sodium silicate use liquid sodium glass with a density of 1400 kg / m ³ , which is treated before pumping at the wellhead quartz sand in a ratio of 0.20-0.30: 1.00 parts by weight respectively.

The disadvantages of this method are the long and laborious process of its implementation, as well as the inefficiency of fastening due to the low strength of the formed sand barrier and the reduction of capacitive and filtration characteristics of the bottomhole zone of the reservoir.

The closest in technical essence is the method of fastening the bottom-hole zone of the formation with unstable rocks (patent RU No. 2352764, IPC 8 ЕВВ 33/138, published in Bulletin No. 11 of 04/20/2009), including the creation of a filter by pumping a cured polymer composition into bottomhole zone, characterized in that as the curable polymer composition using an aqueous solution of urea resin, ammonium chloride and sodium nitrite in the following ratio, wt.%:

urea resin 80.0

ammonium chloride 1.0-3.0

sodium nitrite 1.0-3.0

water the rest

which is pumped into the bottom-hole zone of the well in an amount of 0.5 pore volume of the fixed rock, squeezed by one pore volume of hydrophobic fluid, and soak for reaction and curing during the day.

The disadvantages of this method is the low reliability of the filter in operation due to the fact that the partial filling of the intergranular space of the fixed rock with a cured resin solution occurs due to its smearing with a hydrophobic, squeezing liquid, and during the reaction of ammonium chloride and sodium nitrite under formation conditions, nitrogen is released, which provides the formation of a porous structure to the hardening mass, and the volume of nitrogen released is not controlled, therefore, the porous structure is not guaranteed verdeyuschey mass, and hence the reliability of the filter, and the filtering performance of the filter, with possibly as reduced well productivity and unobstructed sand from the well. In addition, the application of this method is ineffective in the presence of a higher productive formation (collector) of a non-reservoir (clay layer).

The objective of the invention is to create a reliable filter that allows you to filter the sand qualitatively, preventing its removal from the well, and increasing the efficiency of fastening the bottom-hole zone of the formation with unstable rocks in the presence of a non-reservoir above the productive formation with unstable rocks.

The problem is solved by the method of fastening the bottom-hole zone of the formation with unstable rocks, including a casing with perforations opposite the productive formation, composed of unstable rocks, creating a filter by injecting the polymer composition into the bottom-hole zone.

A method of attaching a bottom-hole formation zone with unstable rocks, including the creation of an anti-sand filter by injecting a polymer composition into the bottom-hole zone of a well formation through an open reservoir.

What is new is that before injecting the polymer composition, the bottom-hole zone of the formation is temporarily insulated with cement mortar in the form of wood sawdust, then the production layer is insulated to the roof by pouring in the well to the top of the productive formation in the form of a cement bridge, after which the casing is opened in different directions. columns 1-2 m above the productive layer of insulation with a total cross section of the perforations of at least 3000 mm ^2, more produce technical column descent insulated in the annular space, the packer is 10-15 m higher than the upper level of the perforation channels, hydraulic fracturing is performed (reservoir fracturing) - of the reservoir and the productive formation with inclined directional cracks with the injection of the polymer composition in the form of a polymer proppant, then the technical column with the packer is removed and production is carried out formation until the production rate decreases by more than 50% of the initial production rate, after which the insulation of the productive formation is broken with re-opening of the productive formation.

In figures 1, 2 and 3, the process of the proposed method for fastening the bottomhole formation zone with unstable rocks is sequentially shown.

It is known that during the operation of wells conducted on uncemented sandstones, there is a need to prevent the removal of sand from the well.

Sand is removed from the well, usually due to the destruction in the formation of natural cementitious material, which under normal conditions holds together individual grains of sand.

Cementing material is destroyed as a result of its dissolution in water (in wells that produce a large amount of produced water), as well as due to mechanical damage to the porous system caused by the filtration of formation fluids through rocks or by the action of a pressure drop near the wellbore.

In most known methods of preventing sand from being removed from wells, artificial barriers are created that are permeable to liquids but retaining solid particles.

The proposed method is as follows.

The method of fastening the bottom-hole zone of the formation with unstable rocks includes a well 1 (see Fig. 1), the casing 2 of which is equipped with perforations 3 that open the productive formation 4, folded by unstable rocks. During the operation of such a productive formation 4 from its perforation holes 3, sand is intensively removed from the bottomhole zone of the well (PZP) and lifted from the well along with the produced fluid. Due to the high sand content in the produced fluid, production equipment prematurely fails, in addition, sand removed from the formation is deposited on the bottom of the well, as a result of which the operation of the well ceases prematurely. After that, operational equipment is removed.

Before pumping the polymer composition by lowering the filling pipes (not shown in FIGS. 1, 2, 3) into the well 1 and through the perforations 3 of the casing 2 in the reservoir 4, temporary isolation 5 of the bottom zone of the reservoir 4 is made, for example, with cement mortar with filler in the form of wood sawdust.

Next, isolate the reservoir 4 to the roof 6, for example, by pouring in the well to the roof 6 of the reservoir 4 in the form of a cement bridge 7.

Then, a pipe string 8 with a perforator 9 is lowered into the casing 2 of the well 1. As a perforator 9, for example, a plastic perforator (manufactured by NEKKO LLC, Russian Federation, Yekaterinburg), which is equipped with two retractable cutting discs-milling cutters, located diametrically opposite to each other. In the same plane with the cutting discs there are two hydromonitor nozzles, which make the cavities in the bottomhole zone. The perforator is lowered into the well on the tubing pipes, the pump unit type CA-320 creates pressure in the tubing line, the disks of the perforator are brought into working position and create paired longitudinal slots in the production casing of the wells from 10 to 12 mm wide. Hydromonitor jets of a perforator through formed cracks under high pressure of 15 MPa erode the cement ring, adjacent rock, the remains of brown mud, asphalt-paraffin deposits, washing caverns with a depth of more than 0.5 m, that is, deep channels are formed for subsequent hydraulic fracturing.

A perforator 9 is placed opposite the non-reservoir 10, for example, a clay layer, L = 1 - 2 meters above the insulation (cement bridge 7) of the productive formation 4. Then, the casing 2 of the well 1 is opened in opposite directions against the non-reservoir 10 with oblique directions ( down) perforation channels 11, for example, at the same level, for example, with an angle of 60 ° around the circumference of the casing 1, perform six perforation channels 11, for example, 500 mm long and 10 mm wide and with a total section of perforation channels of at least 30,000 mm ² .

Next, the jet jets of the perforator through the perforation channels 11 formed obliquely directed downward (see FIG. 1) under high pressure of 15 MPa erode the cement ring adjacent to the rock, the remains of the brown mortar, asphalt-paraffin deposits, washing caverns with a depth of 0.5 m up to 1 m, that is, deep channels are formed in the reservoir non-reservoir 10 for subsequent hydraulic fracturing.

Next, from the casing string 2 of the well 1, the pipe string 8 with the perforation 9 is removed. Then, the casing string 2 (see FIG. 2) of the technical pipe 12 well 1 is isolated with the annulus 13 insulated by the packer 13 10-15 meters above the upper level of the perforation channels 11, and the lower end of the process string should be located opposite the perforation channels 11 made in the non-reservoir 10. As a packer 13, a passage packer of any known design is used, for example, a packer with a mechanical axial P-NMO installation (25 M Pa) (produced by the Packer research and production company, Oktyabrsky, Republic of Bashkortostan, Russian Federation).

Next, hydraulic fracturing (hydraulic fracturing) is carried out by any known methods using simultaneous injection of fracturing fluid with a crack fixer - proppant. As a fracturing fluid of a productive formation 4, composed of unstable rocks, and a non-reservoir 10, for example, a gel-like liquid is used.

As a gel-like liquid, known compositions are used, for example, those developed by Khimekogang CJSC with the trade names Khimeko-N (TU 2481-053-17197708), Khimeko-T (TU 2481-077-17197708-03), " Himeko-V "(TU 2499-038-17197708-98).

As an additional example of the use of a gel-like fluid, there may be a structured hydrocarbon gel-like composition for hydraulic fracturing described in patent No. 2043491, IPC 8 ЕВВ 43/26, publ. September 10, 1995

The volume of injected gel-like fracturing fluid is calculated by the formula;

V _g = k · (h _p + h _k ),

where V _g - the volume of the gel-like fluid rupture, m ³ ;

k = 1.4 ÷ 1.6 - conversion coefficient, m ³ / m;

h _p - the height of the reservoir 4, composed of unstable rocks;

h _to - the height of the reservoir-collector 10, m,

however, the weight volume of the polymer proppant added to the fracturing fluid is, for example, 1-1.5 tons per 1 m of the height of the productive formation 4, composed of unstable rocks, and non-reservoir 10.

Using a pumping unit (not shown in FIGS. 1, 2 and 3) through a technical column 12 through the perforation channels 11, a hydraulic fracturing of the non-reservoir 10 and producing formation 4 is carried out with oblique directional cracks formed as a result of pumping the fracturing fluid while fixing these cracks , with a polymer composition in the form of a polymer proppant, and a hydraulic connection is formed between the non-reservoir 10 and the reservoir 4, i.e. behind the casing 3 of the well 1 opposite the non-reservoir 10 and the productive formation 4, a filter 14 is formed from the polymer proppant layer, which fastens the bottom-hole zone of the formation with unstable rocks and prevents sand removal during subsequent operation of the well 1.

Suppliers of polymer proppant are LLC "Fores" (Russian Federation, Yekaterinburg). The production of polymer-coated proppant is also carried out by the company "Rezion" (St. Petersburg, Russian Federation). The polymer coating of proppant ensures the adhesion of proppant grains in reservoir conditions and the formation of a reliable filter that prevents sand removal.

The polymer proppant prevents the fracture crack from closing, providing free passage of oil and gas-saturated liquid (formation products 4) to the perforation channels 11 of the non-reservoir 10. The production of polymer-coated proppants involves the synthesis of several types of polymers and the application of a multilayer coating on a proppant base. The coating protects the proppant grain from destruction when exposed to aggressive environments and high cyclic loads. Under the influence of pressure and temperature, the coating forms a solid frame of the entire proppant pack, which allows you to create a reliable filter in the bottomhole formation zone of well 1.

After that, the packer 13 is unpacked and removed with the process column 12. Next, production equipment is lowered into the well 1 (not shown in FIGS. 1 and 2) and it is put into operation.

They produce products from the productive formation 4 of well 1 until the production rate decreases by more than 50% of the initial production rate, after which the insulation (cement bridge 7) is destroyed by drilling (see Fig. 3), i.e. the descent of the bit with a helical downhole motor (VZD) on the pipe string (figure 1, 2, 3 not shown) in the interval of the reservoir 4.

Then, perforation (any known, for example cumulative, hydromechanical or, as described above, a plastic perforator) re-open the reservoir 4 with the formation of perforation channels 15 (see FIGS. 2 and 3) through the time interval 5, hydraulically connecting the inner space 16 wells 1 with a reservoir 4 through a filter 14.

The proposed method, in the presence of a reservoir layer above the reservoir with unstable rocks, allows a reliable filter to be created behind the casing in the well opposite the reservoir, which allows high-quality filtering of sand and effectively prevents its removal from the well.

Due to the presence of a filter in the form of a polymer-coated proppant obtained as a result of hydraulic fracturing, the efficiency of fastening the bottomhole formation zone with unstable rocks is increased.

Claims (1)

A method of attaching a bottom-hole formation zone with unstable rocks, including creating an anti-sand filter by injecting a polymer composition into the bottom-hole zone of a well bore through an open reservoir, characterized in that before injecting the polymer composition, the bottom-hole zone of the formation is temporarily insulated with cement with a filler in the form of wood sawdust, after which the isolation of the reservoir to the roof by pouring in the well to the roof of the reservoir in the form of a cement bridge is carried out, after to produce multidirectional opening of the casing at 1-2 m above the productive layer of insulation with a total cross section of the perforations of at least 3000 mm ^2, more produce technical column descent insulated annulus above the packer 10-15 m the upper level of perforations, hydraulic fracturing produce formation - hydraulic fracturing - of a reservoir and a productive formation with inclined directional cracks with injection of a polymer composition in the form of a polymer proppant, then the technical column with the packer is removed and they produce production of the formation until the production rate decreases by more than 50% of the initial production rate, after which the isolation of the productive formation is destroyed with the re-opening of the productive formation.

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