Method of filter cake removal of bottom hole area of low-permeable low-temperature terrigenous reservoir

FIELD: oil and gas industry.

SUBSTANCE: method of filter cake removal of bottom hole area of low-permeable low-temperature terrigenous reservoir located near the permafrost rocks comprises sequential injection through the column of oil-well tubing to the bottom hole area of mudded low-permeable low-temperature terrigenous reservoir of methanol in a volume of 1-2 m3 per 1 m of perforated thickness, phosphoric acid of 5-6% concentration with technological thermal equilibrium time of not more than 0.5 hours. Then aerated dispersed aqueous solution of hydrogen peroxide of low concentration of not more than 10-15 wt % is injected in the volume of 2-3 m3 per 1 m of the perforated thickness with forcing the orthophosphoric acid in a distal part of the reservoir. Then aerated dispersed aqueous solution of hydrogen peroxide is injected and forced again in the reservoir using the gas condensate with short-term technological thermal equilibrium time of not more than 0.5-1.0 h. Then removal and taking away of the remaining part of the aerated dispersed aqueous solution of hydrogen peroxide from the reservoir and the well to the surface is carried out. Then the well is developed by feeding to the well of inert gas, such as nitrogen, worked out, and the well is brought into production. At that injection of aerated dispersed aqueous solution of hydrogen peroxide is carried out by pulsed-cyclical method with alternate pumping the aqueous solution of hydrogen peroxide and inert gas, such as nitrogen.

EFFECT: increased permeability of dried bottom hole area of the reservoir, increase in the degree of filter cake removal of the bottom hole area and increase in productivity of the wells.

3 ex

 

The invention relates to the oil and gas industry, namely to the treatment of bottomhole formation zone (PPP), in particular to the clay cake removal PPP low-temperature low-permeability clastic sediments located near the permafrost).

Collectors of gas condensate wells in the fields of Western Siberia belong to the low-permeability clastic sediments, cemented clay with cement content to 10%, and some layers are located close to MSEs and low temperature rocks.

Usually to handle these collectors use acid solutions, in particular are used hydrochloric and hydrofluoric acid. However, acidic solutions have significant drawbacks, such as insufficient depth of penetration into the formation that does not provide the necessary coverage of the reagents of the PPP; the glut of the layer of reaction products, which complicates the process of their removal from the reservoir; the destruction of the skeleton of rock, which negatively affects the productivity of weakly cemented collector. It is therefore necessary to use alternative methods of bottomhole zone treatment (IPF), especially low-temperature low-permeability clastic sediments close to MSEs, providing deep penetration of reagents and great coverage of the PPP.

<> These methods include HMO various oxidants, such as hydrogen peroxide. Hydrogen peroxide upon interaction with clay minerals oxidizes and converts partially into forms that have less ability to adhesion processes, resulting in particles of clay minerals exfoliate and pass into the solution as a fine suspension. In this form of clay components, you can push in the depth of the layer where the concentration of clogging particles, the minimum, or to extract clay constituents from the formation into the borehole and then click delete on the surface. When you remove the clay constituents of the pore channels are expanding and the permeability of the rock increases.

In addition, the fields in Western Siberia are in the final stages of development, have abnormally low formation pressure (anpd) and a sufficiently large degree of water content of gas-bearing reservoir. Therefore, before carrying out works on PPP clay cake removal is necessary to conduct the drying of the interval of the productive formation. For this purpose the most suitable reagent is methanol or acetone. Pre-injection of these reagents leads to lower interfacial tension of the borehole fluid, the liberation of a large part of the "bound" water in small pores of the reservoir, to the drying of the PPP, and Zn�cheat, to improve formation permeability and increasing the efficiency of further reagent treatment.

Known clay cake removal method of bottom-hole zone of low-permeability Sandstone reservoir [RF Patent №2162146].

The disadvantage of this method is the low clay cake removal efficiency of bottom-hole zone of low-temperature low-permeability Sandstone reservoir in the conditions of abnormally low formation pressure (anpd), located close to MMP, is expressed in a weak removal of the reaction products from the pore space and the lack of complete coverage of the injected reagents the area of impact, there is insufficient depth of penetration of reagents into the reservoir, in addition, the deposition of reaction products to precipitate, clogging them pore channels and, as consequence, reduction of the permeability of the PPP.

Known clay cake removal method of bottom-hole zone of low-permeability Sandstone reservoir [RF Patent №2302522].

The disadvantage of this method is the low clay cake removal efficiency of bottom-hole zone of low-temperature low-permeability Sandstone reservoir in the conditions of abnormally low pressure near the MMP, the complex composition of the reagents, their great variety, which does not allow them control works, as well as large amounts of active acid solutions, which does not allow to extract the reaction products from PLA�that after neutralization. For reservoirs with low formation pressures and temperatures, especially close to MSEs, such solutions are not applicable because of the possible thawing MMP followed by the release of heat in the reaction of the injected reagents with the rock, the collapse of the borehole and the high probability of occurrence of an accident or outdoor fountain and gas fire. In addition, removal of the reaction products under conditions of abnormally low pressure is necessary to create a higher depression on the layer that leads to the destruction of the skeleton of the formation.

The challenge when creating the invention is to improve the efficiency of work on the effects on clogged bottom hole zone of the low-temperature low-permeability Sandstone reservoir, located near MSEs, in conditions of abnormally low pressure.

Achieved technical result, which is obtained as a result of the invention is to increase the permeability of the dried-PPP, increase the degree of clay cake removal of the bottomhole zone and, as a result, increasing the productivity of wells due to the complexity of ongoing operations.

The task and the technical result is achieved by the fact that raspisatsia bottom zone of low-temperature low-permeability Sandstone reservoir, located near permafrost, includes sequentially� injection through a column of tubing in the bottom zone clogged low-temperature low-permeability Sandstone reservoir of methanol in a volume of 1-2 m 3at 1 m perforated thickness, phosphoric acid 5-6% concentration with low process out, no more than 0.5 hours, after completion of the manufacturing of the self - aerated-dispersed aqueous solution of hydrogen peroxide of low concentration no more than 10-15 wt.% in the amount of 2-3 m3at 1 m perforated thickness bursting with phosphoric acid in a remote part of the reservoir, further injection and punching aerated-dispersed aqueous solution of hydrogen peroxide in the reservoir through a gas condensate with short-term technological out within 0.5-1.0 hours, removing and disposing of the remaining portion of the aerated-dispersed aqueous solution of hydrogen peroxide from the reservoir and the wellbore to the surface, develop well supplied into the bore of an inert gas, for example nitrogen, testing and putting the well into operation, thus, injection of aerated-dispersed aqueous solution of hydrogen peroxide is carried out pulse-cyclic method of alternating the injection of an aqueous solution of hydrogen peroxide and inert gas, for example nitrogen.

The method is implemented as follows.

In gas condensate well placed close to the MSE low-temperature low-permeability Sandstone reservoir, through a column of pump-compressor pipes (tubing) per�oncale pumped methanol, or acetone in a volume of 1-2 m3at 1 m perforated thickness to reduce the interfacial tension of the borehole fluid, to release a significant part of "bound" water in small pores of the low-temperature low-permeability clastic reservoir for draining the PPP, to increase the efficiency of the reaction subsequently injected with phosphoric acid and aerated-dispersed aqueous solution of hydrogen peroxide.

Then the tubing is pumped phosphoric acid 5-6% concentration for cleaning the column tubing from rust and other mechanical impurities to eliminate the interaction of an aqueous solution of hydrogen peroxide with metal pipes, which subsequently forced into the PPP to increase the effect of the destruction of the clay component of the rocks, forming the PPP. Leave orthophosphoric acid in the reservoir smaller process out, no more than 0.5 hours.

Then purified via the tubing string by setting the discharge gas (UNG) or booster pump installation aerated-dispersed aqueous solution of hydrogen peroxide in the amount of 2-3 m3at 1 m perforated thickness of the low concentration of 10-15 wt.%, push it in through the PPP gas condensate with short-term technological out within 0.5-1.0 hours for ocsla�of clay component from particles of rock, the outgoing PPP.

The injection is carried out pulse-cyclic method, periodically pumping aerated-dispersed aqueous solution, and then an inert gas such as nitrogen 9, and re-aerated-dispersed aqueous solution. Thus aerated-dispersed aqueous solution of hydrogen peroxide presses uploaded before orthophosphoric acid in a remote part of the formation.

Then carry out the deletion and removal of the remaining portion of aerated-dispersed aqueous solution of hydrogen peroxide from the PPP and the borehole to the surface.

In conclusion, carry out development wells feeding into the well of an inert gas, for example nitrogen, practicing and putting the well into operation.

Surface-active agent (surfactant) used in the creation of aerated-dispersed aqueous solution of hydrogen peroxide, for example, nonionic surfactants such as dissolved, cover the clay particles, prevents them from sticking together and facilitates their migration into the depth of the PPP when punching in or takeaway in the well under the drainage and removal from a well during its development.

Aerated-water dispersed aqueous hydrogen peroxide solution, passed through a disperser located after UNG before entering the well, greatly reduces the size of the individual bubble of inert gas, for example nitrogen, thereby�abilities and strengthens these bubbles, facilitating their penetration into the depth of the clogged PPP.

Hydrogen peroxide upon interaction with clay minerals oxidizes and converts partially into forms that have less ability to adhesion processes, resulting in particles of clay minerals exfoliate and pass into the solution as a fine suspension. In this form of clay components can be extracted from the reservoir into the well and then click delete on the surface. When you remove the clay formations of the pore channels are expanding and the permeability of the rock increases.

Aerated-water dispersed aqueous hydrogen peroxide solution allows you to deliver small volumes of reagent to a remote part of the reservoir increases the mobility of the reactant in the pore space of rocks and reduces the duration of well development.

Examples of implementation of the proposed method.

Example 1.

In gas condensate well with the production column with a diameter of 168 mm, which revealed a low-temperature low-permeability clastic formation with a thickness of 20 m with a temperature of 10°C and a formation pressure of 2 MPa below MMP 100 m3through the tubing 73 mm diameter is initially pumped methanol in a volume of 1 m3at 1 m perforated thickness, then phosphoric acid 5% concentration by punching her in the PPP, then AE�initialized-dispersed aqueous hydrogen peroxide solution in a volume of 2 m 3at 1 m perforated thickness concentration of 10 mass%, push it in through the PPP gas condensate pulse-cyclic method with short-term technological out for a period of not more than 0.5 hours, with a simultaneous burst of phosphoric acid in a remote part of the formation. The remainder of aerated-dispersed aqueous solution of hydrogen peroxide with the delaminated clay particles removed from the PPP and carried out of the borehole to the surface. The well is completed using an inert gas - nitrogen and put into operation.

Example 2.

In gas condensate well with the production column with a diameter of 146 mm, which revealed a low-temperature low-permeability clastic formation with a thickness of 10 m with a temperature of 12°C and a formation pressure of 4 MPa, below the MMP 200 m, through the drill pipe with a diameter of 73 mm initially pumped methanol in a volume of 1 m3at 1 m perforated thickness, then phosphoric acid 5% concentration by punching her in the PPP, then - aerated-dispersed aqueous hydrogen peroxide solution in a volume of 2 m3at 1 m perforated thickness of the concentration of 12 mass%, push it in through the PPP gas condensate pulse-cyclic method with short-term technological out for a period of not more than 0.5 h with simultaneous prodavlivanie�m phosphoric acid in a remote part of the formation. The remainder of aerated-dispersed aqueous solution of hydrogen peroxide with the delaminated clay particles removed from the PPP and carried out of the borehole to the surface. The well is completed using an inert gas - nitrogen and put into operation.

Example 3.

In gas condensate well with the production column with a diameter of 140 mm, which revealed a low-temperature low-permeability clastic formation with a thickness of 5 m with a temperature of 15°C and a formation pressure of 6 MPa, below the MSE for 300 meters, through the drill pipe with a diameter of 73 mm initially pumped methanol in a volume of 1 m3at 1 m perforated thickness, then phosphoric acid 6% concentration by punching her in the PPP, then - aerated-dispersed aqueous hydrogen peroxide solution in a volume of 2 m3at 1 m perforated thickness of the concentration 15 mass%, push it in through the PPP gas condensate pulse-cyclic method with short-term technological out for a period of not more than 0.5 h with a simultaneous burst of phosphoric acid in a remote part of the formation. The remainder of aerated-dispersed aqueous solution of hydrogen peroxide with the delaminated clay particles removed from the PPP and carried out of the borehole to the surface. The well is completed using an inert gas of nitrogen and injected into exploitation�.

The advantage of this method compared with similar ways of processing bottom-hole sahlinisternas zone is the complexity of all ongoing at the well of technological methods and operations, the present method uses a special selection of chemical reagents is not complex composition and operating of downloads in a certain sequence that allows to carry out work on the clay cake removal more efficiently and with less financial and time expenses. The increased efficiency is due to the preliminary drying of the PPP methanol, or acetone, after which the treated area is able better to respond with follow-up of the injected reagents. Injected followed by phosphoric acid slowly reacts with the rock than the other acids, for example hydrochloric or hydrofluoric, which gives it the ability, while remaining reactive to reach more remote parts of the PPP, having responsesyou and increased permeability of the near-borehole part of the PPP to prepare a more extended area of this part of the reservoir for subsequent processing. Injected behind the composition of hydrogen peroxide with a surfactant, aerated-water dispersed nitrogen, freely moving on a pre-phosphoric acid channels of the active layer interacts with clays�ple particle layer, flaking them from the rocks at the expense of the oxidation reaction and turning them into a fine slurry, facilitates the removal of the delaminated clay particles from the PPP in the final stage of the clay cake removal - the development wells.

The clay cake removal method of bottom-hole zone of low-temperature low-permeability Sandstone reservoir, located near permafrost, comprises the sequential injection through a column of tubing in the bottom zone clogged low-temperature low-permeability Sandstone reservoir of methanol in a volume of 1-2 m3at 1 m perforated thickness, phosphoric acid 5-6% concentration with low process out, not more than 0.5 h, after completion of the manufacturing of the self - aerated-dispersed aqueous solution of hydrogen peroxide of low concentration no more than 10-15 wt.% in the amount of 2-3 m3at 1 m perforated thickness bursting with phosphoric acid in a remote part of the reservoir, further injection and punching aerated-dispersed aqueous solution of hydrogen peroxide in the reservoir through a gas condensate with short-term technological out within 0.5 to 1.0 h, removing and disposing of the remaining portion of the aerated-dispersed aqueous solution of hydrogen peroxide from the reservoir and SLE�of the spring to the surface, the development of wells feeding into the well of an inert gas such as nitrogen, testing and commissioning of wells in operation, with the injection of aerated-dispersed aqueous solution of hydrogen peroxide is carried out pulse-cyclic method - alternating injection of an aqueous solution of hydrogen peroxide and an inert gas such as nitrogen.



 

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1 ex, 1 dwg

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the heavy oil extraction from underground field. Method of the heavy oil extraction from underground field includes: nanoemulsion (oil-in-water) injection to one or more injection wells, extraction of the specified heavy oil from one or more operation wells, where the specified nanoemulsion is produced using the method including: production of the uniform mixture (1) water/oil product with interfacial tension 1 mN/m maximum, containing water in quantity from 65% to 99.9% by weight, with a view to total mixture weight (1), and at least two surface-active substance (SAS) having different hydrophilic-lipophilic balance (HLB), selected from not-ionic, anionic, polymer SAS, preferably not0ionic; these SAS are in such quantity that to make the mixture (1) uniform mixture (1) dilution by the dispersion medium containing water with added at least one SAS selected from the specified SASs; this dispersion medium and SAS quantities are such that nanoemulsion is produced (oil-in-water) having HLB exceeding HLB of the mixture (1). Invention is developed in subclaims.

EFFECT: increased extraction efficiency.

34 cl, 1 dwg, 2 ex

FIELD: oil and gas industry.

SUBSTANCE: group of inventions is related to production of heavy hydrocarbons. In the in situ multistage solvent extraction method of heavy oil from oil pools at first liquids and gases are extracted from zones of contact with heavy oil in order to increase interfacial area of unextracted heavy oil subject to contact with solvent. Then solvent is injected in the form of steam to the above zones in order to increase pressure in the pool up to accumulation of sufficient quantity of solvent in the form of liquid to ensure contact with enlarged interfacial surface of heavy oil. Then the pool is isolated for the period sufficient to ensure diffusion of solvent to unextracted oil through the interfacial surface at ageing stage so that the mixture of solvent and oil with low viscosity is obtained. One or more parameters of the pool are measured to determine the degree of unextracted oil liquefaction in the pool by solvent. Oil extraction from the pool is commenced by gravity drainage when viscosity of oil becomes rather low to flow through the pool to the production well.

EFFECT: maximising liquefaction of heavy oil and maximising its extraction as a result.

19 cl, 11 dwg

FIELD: oil and gas industry.

SUBSTANCE: method involves displacement of the first fluid on a hydrocarbon basis, which is present at a non-cased interval of a well shaft, with the second fluid, contact of the second fluid to acid natural formation fluid so that the third fluid is formed, where the second fluid contains aqueous liquid dispersed as a disperse phase in oily liquid, and surface active substance (SAS) based on amine and chosen so that the above contact performs protonation of at least some part of SAS with formation of the third fluid included in an emulsion containing oily liquid reversely dispersed as a disperse phase in aqueous liquid, where at least 40 vol % of any solid substances that do not refer to a proppant and are present in the fluid are water-soluble at pH that is lower than or equal to 6.5, and SAS has the above said structure. An underground well treatment system. The fluid containing a reversible invert emulsion containing an aqueous liquid dispersed as a disperse phase in oily phase and the above SAS.

EFFECT: improving destruction efficiency of a filter cake.

20 cl, 6 dwg, 3 tbl, 2 ex

FIELD: oil and gas industry.

SUBSTANCE: under the method of development of oil deposits with nonuniform permeability comprising successive injection via the injection well of the water suspension containing polymer, mud powder and SAS solution, prior to the suspension injection in the deposit the initial intake of the injection well is determined under pressure in water line ands water mineralisation; in water with salinity level 0.15-40 g/l complex action SASs with pour point not exceeding minus 30°C and kinematical viscosity 35-50 sSt are used, i.e. water-alcohol solution of non-ionic SAS-monoalkyl esters of PEG at the following ratio wt %: specified SAS 0.001-1.0, specified water rest, suspension and SAS solution are injected in volume ratio (1-3):1 depending on initial intake of the injection well - at intake 200-400 m3/day - 1-2:1, 400-500 m3/day - 2-3:1, over 500 m3/d - 3:1, between suspension and SAS solution water with salinity level 0.15-40 g/l or water suspension of polyacrylimide with concentration 0.0001-0.1 wt % is injected. Under another option during this method in water with salinity level 40-300 g/l the complex SAS with pour point minus 40°C max is used, containing complex action SAS with pour point minus 30°C max. and kinematical viscosity 35-50 sSt - water-alcohol solution of non-ionic SAS - monoalkyl esters polyoxyethylene glycol 90 wt % and alkyldimethylbenzylammonium chloride 10 % at following ratio of components in wt %: specified SAS 0.001-1.0, specified water - rest, suspension and SA solution are injected to the deposit in volume ratio (1-3): 1 depending on initial intake of the injection well at water line pressure - at intake 200-400 m3/day - 1-2:1, 400-500 m3/day - 2-3:1, over 500 m3/day - 3:1, and between suspension and solution the water with salinity level 40-300 g/l or water suspension of polyacrylimide with concentration 0.0001 0.1 wt % are injected.

EFFECT: increased oil recovery of the deposit.

2 cl, 4 ex, 4 tbl

FIELD: oil and gas industry.

SUBSTANCE: under method of oil deposit development comprising determination of the injection well intake, oil recovery via the production wells, and injection via at least one injection well of the water dispersion of the water-soluble polymer and alkali metal hydroxide, this dispersion contains in wt %: water-soluble polymer 0.01-0.05, alkali 0.5-1.0, at definite intake values of the injection well the specified dispersion is injected until injection pressure increasing by 20-30%, its flushing in the deposit by the injected water in volume of tubing plus 1.0 m3, alkali composition in volume 10-30% of volume of injection of the specified dispersion is injected until specific intake decreasing by 10-20% and achievement of the injection pressure not exceeding the maximum permitted pressure on production string and production deposits, the specified compositions at specified water salinity under each of three options, and flush by water in volume 10-15 m3.

EFFECT: increased oil recovery of deposits and watercut reduction of production wells, spreading of process abilities.

3 cl, 1 ex, 2 tbl

FIELD: oil and gas production.

SUBSTANCE: invention provides a method of developing oil pool allowing production of oil from water-rich oil reservoir under difficult geological-tectonic conditions in the last development stage. In the method, neutral salt of carbonic acid and acid solution are forced into formation through injecting well with water generated in gas-liquid fringe created in formation. After pumping of neutral salt of carbonic acid, acid solution is pumped by portions alternating with water pumping. Before pumping of acid solution portions beginning by at least second portion, selective insulation of high-permeable formation intervals is performed. Aforesaid neutral salt of carbonic acid utilized is sodium carbonate aqueous solution or aqueous suspension of calcium carbonate and aforesaid acid solution is aqueous hydrochloric acid solution. Selective insulation of high-permeable formation intervals involves use of freshly prepared controllable viscoelastic composition containing water-soluble acrylic polymer, cross-linking agent, thermal stabilizer, surfactant, and water. Summary concentration of acid solution is determined from concentration of neutral salt of carbonic acid on the base of stoichiometric proportions.

EFFECT: increased efficiency of maintaining formation pressure and thereby oil recovery of formation due to leveled displacement front and reduced probability of the rupture of formation rock backbone, and simplified control of phase state of gas-liquid fringe by changing pressure of pumped acid solution portions.

8 cl

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