RU2528805C1 - Method of increasing oil yield in inhomogeneous, highly-flooded, porous and fractured-porous, low- and high-temperature productive stratum - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed process comprises isolation of formation and bottom waters or annulus circulation. At insulation, water isolation polymer of loam-quartz system is injected into formation water saturated part while formation bottom zone and borehole are cemented by fast-setting plugging mix. In compliance with this invention, water isolation polymer of loam-quartz system is injected via tubing perforation below water-oil contact to create at extra shield in at least 20 mm from borehole. Said fast-setting plugging mix is injection via turning perforations above water-oil contact to make extra shield in at least 5 m from borehole. Productive bed oil-saturated interval is exposed by perforations in depth extending beyond contaminated zone boundaries. Said productive bed is re-exposed by hydrofrac or physical-chemical, wave, mechanical or acoustic effects.

EFFECT: higher reliability of formation water isolation at minimum capital costs.

4 dwg, 1 tbl

Description

The invention relates to the oil and gas industry and can be used in the development of oil and gas deposits with heterogeneous, highly watered, porous and fractured-porous, low and high temperature productive formations. It relates, in particular, to the field of increasing oil and gas recovery and stimulation of tributaries. It is known that in the process of exploitation of oil and gas deposits with heterogeneous, highly watered, porous and fractured-porous, low and high temperature productive formations, flooding occurs intensively for geological, technological and technical reasons.

A known method of stimulation of tributaries using hydraulic fracturing (hydraulic fracturing) in tightly cemented reservoir rocks. The disadvantage of this method is that in the presence of bottom water, the created fracture can connect to the water-saturated part of the formation, which requires significant additional costs for conducting waterproofing work in the well [G. Ovnatanov Opening and processing of the reservoir. - M.: Nedra, 1970. - S.233-238]. The temperature permissible range of its application is not defined.

There is a method of increasing oil recovery in fractured and porous formations with artificially created cracks after hydraulic fracturing [RF patent No. 2398102 C1, IPC E21B 43/22, 2010], which includes the selective injection of an aqueous solution of polyacrylamide with a crosslinker, a chromium compound, using an additive bentonite clay powder and silica sand. Modified bentonite clay powder is used, and in the form of a mixture of it with quartz sand, an aqueous solution is initially first injected containing 0.01-0.30 wt.% Of partially hydrolyzed polymer-polyacrylamide and 0.1-0.6 wt.% Of a crosslinker, a chromium-containing compound, selling water, then - injection of an aqueous solution of polyacrylamide (0.005 wt.%) with a viscosity (0.55 cP) of 10% higher viscosity of produced water (0.5 cP), in which 3-10 wt.% of a mixture of modified bentonite clay powder and silica sand with their initial ratio of 10: 1 at a subsequent increase in the concentration of sand to a ratio of 1: 2. The disadvantage of this method is that in production wells, cementing is carried out by cement grouting, which practically does not create an additional blocking screen in the bottomhole formation zone and clogs the oil-saturated and water-saturated interval of the formation, subsequently limiting the flow of oil. In addition, cement fixation is destroyed when using acidic compounds to cause inflow and the cement is damaged during perforation, and further significant additional costs are required for waterproofing the well.

There is a method of restoring productivity and putting into operation idle oil and gas wells, including repair and insulation work, opening a reservoir in the casing and putting the well into operation [application 98116654/33 of the Russian Federation, E21B 47/00, announced 04.09.98, published 06/20/00, bull. No. 17]. The disadvantage of this method when restoring the productivity of idle wells with complex reservoirs and low reservoir properties is the drilling of the second wellbore. Expected high costs of drilling the second wellbore and a low probability of it falling into the productive zone, especially in reservoirs with lenses and interlayers of rocks that have fairly good filtration-capacitive properties. Not determined temperature allowable range of application of the method.

The closest analogue to the proposed method is a method of restoring productivity and putting into operation idle oil and gas wells [RF patent No. 2231630, C17 E21B 43/00, 43/32, 2002]. The disadvantage of this method is that this method ensures the restoration of well productivity, preventing the influx of formation water, eliminating overflows only in reservoirs with low filtration-capacitive properties and close to water-oil contacts. The following disadvantages of the method: the temperature range of its application is not defined, fixing is carried out by cement slurry.

The main task when creating a new invention is to develop a reliable way to increase oil and gas recovery in heterogeneous, highly watered, fractured and porous reservoirs with temperatures from 20 to 100 degrees, for oil and gas deposits.

The aim of the invention is to increase the efficiency of the development of oil and gas deposits with heterogeneous, highly flooded, fractured and porous productive formations with temperatures from 20 to 100 degrees by eliminating the influx of formation, bottom water and conducting complex physico-chemical, wave, mechanical, acoustic methods of exposure or conducting fracturing at the oil saturated interval of the reservoir.

The technical result of the invention is to obtain additional oil production, increasing the efficiency of producing oil and gas reserves from wells by conducting complex physicochemical, wave, mechanical, acoustic methods of impact or hydraulic fracturing on the oil-saturated interval of the reservoir with the preliminary elimination of inflows of formation and bottom waters, annular flows with temperatures from 20 to 120 degrees.

The task and technical result are achieved by the fact that in the known method of increasing oil recovery of a productive formation, including conducting insulating work of formation, bottom water, or annular circulation, while performing insulating work into the water-saturated part of the formation, a water-insulating polymer-clay-quartz system is injected and, in addition, they fix the bottom-hole zone of the formation and the internal space of the wellbore with a fast-sealing grouting mixture, the peculiarity of It is Busy that water shutoff polymer-clay-silica system is pumped through the perforations of the column below the water contact - BHK - with the creation of the additional screen is not more than 20 m meters radially from the borehole; pressurized fast-setting cement slurry is pumped through the perforation holes of the column above the OWC with the creation of an additional screen of at least 5 m in radius from the wellbore; open the oil-saturated interval of the reservoir by perforations with a depth that extends beyond the contaminated zone; carry out re-opening of the reservoir with hydraulic fracturing - hydraulic fracturing - or physico-chemical, wave, mechanical, acoustic methods of exposure to the oil-saturated interval.

A water-insulating polymer-clay-quartz system (PGKS) is known according to the patent of the Russian Federation No. 2398102, C1 IPC E21B 43/22, 2010

The composition of the CCTS is protected by the copyright certificate (copyright certificate No. 1620610, publ. 1990) and the patent [RF patent 2439119, C2, IPC C09K 8/44, publ. 2010].

The whole process of applying the method is performed in the following order. Initially, based on the PGIS materials, the interval of water inflow through the reservoir or overflow behind the column, the position of the OWC or GOC in a specific production well, is established. For example, in FIG. 1, there is a certain perforation interval (4), an OWC is determined (3), an inflow of formation water (5) is detected by annular flow or by creating a cone from the lower water-saturated part of the formation (1), while the upper layer (2 ) oil saturated. To isolate formation water, the entire perforated interval is initially blocked by the cement bridge (6) of FIG. 2. After the cement is drilled in FIG. 3 to the lower perforation holes of the filter and the interval (1) is opened by perforation up to 4 meters below the BHA. Pickup should be at least 200 m ³ / day at a pressure of 10 MPa. Next, a selective injection of a water-insulating polymer-clay-quartz system is carried out with the creation of a blocking screen (2) along the flooded formation for at least 20 m and is forced through the squeezing fluid to the formation. Further, additional perforation (3) is carried out at a distance of 2 m above the oil and gas complex and the sealing composition is pumped on the basis of a quick setting grouting mixture (CCTS) with water being pushed deep into the formation (4). BSTS is sold with the creation of an additional block screen (4) within a radius of at least 5 m from the wellbore, while composition (5) is left inside the production casing, covering the newly formed upper and lower perforations. At the end of the supply fluid, the vendors (6) carry out a backwash with a calculated backpressure in the amount of two volumes of tubing, the well is closed and kept under pressure to undergo a polymerization reaction and harden the water-insulating and sealing components for 6 hours. After the specified period in FIG. 4, the face is normalized to an interval above the BHK of at least 3-4 meters (3). Repeated perforation (2) is sequentially performed along the oil-saturated interval of the reservoir with the depth of the perforations extending radially outside the contaminated zone. Then, hydraulic fracturing or other complex physicochemical, wave, mechanical, acoustic methods of impact (4) on the oil-saturated interval of the reservoir (2) with the development of jet pumps (6) and commissioning of the well are carried out.

One of the advantages of the method compared to the prototype is the advantage of the BCTS over traditional Portland cement, as determined by research and confirmed by patents. The following advantages of BCTS in use:

- regulation of the specific gravity from 1.1-2.2 g / cm ³ , the viscosity during the injection process is equivalent to the viscosity of the oil and is well filtered through the pores of the reservoir, fractures and leaks;

- regulation of the solidification time from 30 minutes to 6 hours;

- expansion in volume from 50 ° C to 100 ° C and more from 10-80%;

- resistance of the formed stone to underground aggressive environments, alkalis and acids;

- impact resistance and elasticity of hardened stone;

- strength up to 6 MPa.

When perforated by any charge, the stone from the BCST does not collapse, but an opening for the influx of oil forms. A distinctive feature of BSTS before traditional cement mortar is that, grasping the production casing, protects it from corrosion.

BSTS grouting mixture is used in two types, one for low-temperature wells from 20 to 60 ° C, the other from 60 to 100 ° C, depending on the hardener. The results of laboratory data on the study of the solidification of HFB, depending on the temperature are shown in table 1.

Table 1 The results of laboratory research Content, wt.% Temperature ° C Thickening time, h-min Setting time, h-min Bending Strength, MPa Extension% CF-F Barite NTF 2% water. solution APSM The proposed composition with hardener NTF fifty 49.0 2,5 - twenty 5-10 6-20 3.3 fifty 48,2 3,5 - twenty 3-15 4-15 3,7 fifty 47.7 4,5 - twenty 1-40 2-25 4.1 fifty 48,4 5.5 - twenty 0-52 1-20 4.4 fifty 47.0 1,5 - 55 4-20 5-10 5.2 fifty 45.3 2,5 - 55 3-05 3-55 5.8 fifty 42.35 3,5 - 60 2-05 3-00 7.1 fifty 40.8 4,5 - 60 1-10 1-45 8.2 The proposed composition with hardener APSM fifty 48.5 - 0.5 60 4-10 4-30 4.2 20.6 fifty 47.0 - 2.0 one hundred 0-40 0-45 8.6 79,4 Note: NTP - Nitrile trimethylorophosphonic acid. Barite - BaSO 4, APSM - adduct of polyethyleneimine and copper sulfate.

In the presence of annular crossflows of produced water in the producing well or under the influence of bottom water, isolation work is carried out without closing the oil-saturated filter and using bridge plugs, packer-retainers. The technological sequence remains the same as when eliminating the influx of water into the reservoir proposed above.

The proposed method of increasing oil recovery is more reliable compared to the prototype, the materials used are simple to prepare, are affordable, inexpensive, are produced by the domestic industry in sufficient quantities. The method can be used in formations with various reservoir properties, including primarily heterogeneous, highly watered, porous and fractured-porous, low and high temperature productive formations, effective oil recovery by complex methods is achieved, and, as a whole, increases oil recovery. It can be used in oil and gas deposits. Pilot work on testing the proposed method at the Samotlor field and other fields of the Nizhnevartovsk region showed high adaptability and efficiency.

Claims (1)

A method of increasing oil recovery in a productive formation, including insulating work of formation, bottom water, or annular circulation, while performing insulating work in the water-saturated part of the formation, injecting a water-insulating polymer-clay-quartz system and additionally securing the bottom-hole zone of the formation and the interior of the wellbore of a fast-sealing grouting mixture, characterized in that the water-insulating polymer-clay-quartz system is pumped through hole pockets of the column below the oil-water contact - VNK - with the creation of an additional screen of at least 20 m along the radius from the wellbore; pressurized fast-setting cement slurry is pumped through the perforation holes of the column above the OWC with the creation of an additional screen of at least 5 m along the radius from the wellbore; open the oil-saturated interval of the reservoir by perforations with a depth that extends beyond the contaminated zone; carry out re-opening of the reservoir with hydraulic fracturing - hydraulic fracturing - or physico-chemical, wave, mechanical, acoustic methods of exposure to the oil-saturated interval.

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