Evaluation of efficiency and control over carbonate seam acid processing

FIELD: oil-and-gas industry.

SUBSTANCE: proposed method comprises recovery of core, making of core specimens and their analysis at electronic scanning microscope. Chemical reagent is forced through prepared specimens and sections are made at entry and exit of said chemical reagent. X-ray tomography is used to analyse the core specimens after forcing though of said chemical reagent. Images are compared to isolate the most efficient forms of solution channels. Numerical value of acid processing efficiency is calculated by computer processing of characteristics of images produced with the help of tomographic scanner. Minimum numerical value of said efficiency is selected as a criterion of the highest efficiency of acid processing. Note here that magnitude of stimulation is used as the numerical value of acid processing efficiency. Note here that, first, software is used for automatic determination of bored hole propagation volume. Then, acid solution penetration depth is computed. Now, stimulation magnitude is calculated by mathematical formula.

EFFECT: higher accuracy of efficiency and control over acid processing, fast determination.

3 ex, 4 dwg

 

The invention relates to the development of oil and gas fields using acid methods of influence on the bottomhole formation zone and can be used to assess the effectiveness of acid treatment and improve the efficiency effects on the bottomhole zone of the reservoir.

A known way of extracting the borehole intervals for means of hydrochloric acid treatment, including selection of core samples, manufacture, extraction of the alcohol-benzol mixture, acid treatment, washing with distilled water, with subsequent calculation of the amount dissolved in the acid components of the rock collector, using data from magnetic logging (EN 2205951, IPC E21B 43/27, G01V 3/08, publ. 2003). However, the known method does not allow you to get complete information about the distribution of the reacted acid composition in space rock collector, the form and nature of the formed channels dissolution, as well as a detailed numerical calculation of the area and the depth of penetration of the acid composition. In addition, magnetic susceptibility dissolved in the acid components of the rocks associated with the presence in the composition of the rocks ferruginous chlorite, significantly limits the application of the method.

A known method of controlling the acid treatment of the reservoir, including coring, izgotovleniyu core for filtration research, pumping through the core samples of chemicals with different concentrations with different time intervals, thin sections of core samples, the selection sections with preserved structure of the rock, the definition of the relationship of the number of pores in the thin sections from the input of chemicals to the number of pores in the thin sections from the output of chemicals, determine the optimal concentration of chemical reagents for processing the productive formation by the maximum ratio of the number of pores in the thin sections. (EN 2057918, IPC E21B 43/27, publ. 1996). The known method is not effective enough due to the low visual informative about the effectiveness of the use of acidic composition and the duration of the counting, a large error in the calculation of the ratio of the number of pores in the thin sections from the input of chemicals to the number of pores in the thin sections from the output of chemicals.

Closest to the proposed invention is a method of evaluating the efficiency and control of acid carbonate reservoir, including coring, manufacture of core samples, the study of their scanning electron microscope, pumping through the core samples of the chemical reagent, the thin sections from the entrance and exit of the chemical, the study of x-ray tomography of core samples after pumping the product is, the image comparison and selection of the most effective forms of channels dissolution, the calculation of the coefficient of impactee method of computer processing units characteristics obtained using MRI images by placing images in graphic editor and selecting the minimum value of the coefficient of impactee as the criterion most effective acid treatment (RF patent for application No. 2012121869/03, priority 25.05.2012, IPC E21B 43/27). However, in this method there is the likelihood of inaccuracies in the calculation of the data, because you need to manually trace the outline is placed in the graphics editor image wormhole. This complicates the task requires a considerable investment of time.

The present invention is to improve the accuracy of estimation of efficiency and control acid treatment, and the acceleration of the process of calculation of the characteristics of the effects of the acidic composition.

The problem is solved so that the method of evaluating the efficiency and control of acid carbonate reservoir, including coring, manufacture of core samples, the study of their scanning electron microscope, pumping through the core samples of the chemical reagent, the thin sections from the entrance and exit of the chemical, the study of x-ray tomography of core samples after about acci chemical, the image comparison and selection of the most effective forms of channels dissolution, the calculation of numerical values of the efficiency of acid by the method of computer processing units characteristics of the images obtained by the imager, and select the minimum numerical value of efficiency as a criterion most effective acid treatment, as the numerical values of the efficiency of acid treatment is used amount of stimulation, and first using the software automatically determine the volume distribution of the wormhole, then the depth of penetration of the acid solution, and then calculate the magnitude of stimulation by the formula:

where St is the value of stimulation, mm2, V is the volume of distribution of wormholes, mm3g is the depth of penetration of the acid solution, mm.

The method is as follows.

Produce coring and manufacturing of core samples. Next, conduct a study of these samples by scanning electron microscope. Carry out pumping the chemical through the samples. Then the core samples after pumping the chemical examine x-ray tomography by comparing the images and produce the most effective forms of channels dissolution. To assess the effectiveness of the acid is processing, carry out the determination of the magnitude of stimulation by means of computer processing of the received data. The effective result of the use of acidic reagents is the formation of dominant wormholes. Calculate the volume of distribution of wormholes (V). Figure 3 shows the image volume wormholes.

Then determined automatically by the software Avizo Fire 7.1 the depth of penetration of the composition (g, Fig.4). Using these data, calculate the magnitude of stimulation of the St is the ratio of the values of V to g for each structural-genetic types of carbonate rocks. Then conduct the analysis of the results obtained and the minimum value of the magnitude of stimulation conclude most effective acid treatment.

Studies conducted on the core samples of the deposits of the Republic of Tatarstan. For processing samples of carbonate strata of the middle Carboniferous use the following acid compounds:

1. Hydrochloric acid + retarder snpch-A (10% hydrochloric acid by weight, THE 2458-314-05765670-2006 with ISM.1). Hydrochloric acid take concentration of 12%, GOST 3118-77. As retarder snpch-A use composition according to the patent of Russian Federation №2467164.

2. Hydrochloric acid (12%, GOST 3118-77);

3. Acetic acid (10%, GOST 19814-74).

Pumping acid compositions produced at the facility to filter fluid (in-depth interview is K-1M) through the rock specimen.

Here is an example of a specific implementation.

Example 1. Select the core, he made five core samples. Using a diamond circle cut samples from both end surfaces of the cores are then made transparent sections. Next, carry out a visual examination of scanning electron microscope to establish the characteristics of cavity-pore space, definitions of belonging to a certain structural-genetic type of carbonate rocks by studying the photos. The photographs (Fig.1A, IBS-1 - limestone bioclasts-zoogenic of the first type; 1B, IBS-2 - limestone bioclasts-zoogenic of the second type; 1B, IP - pelitomorphic; 1G, IP - stromatolites; 1D, IL - lithoclastic) difference in structural-genetic types of carbonate rocks, which implies the need for further research on the scanner.

Then spend pumping of 12% hydrochloric acid+inhibitor snpch-A in the ratio of 10:1 through selected core samples at the facility wipk-1M, with a working pressure Pslave=4-6 ATM pressure crimping of the Plife safety=8 ATM, the average download speed vZack=1 m/day. Next, the core is examined for x-ray tomography, studying the obtained images (tomograms) of the channels of dissolution (Fig.2). Repeat the same operation with the other samples.

Conduct sravneniyam each sample, visually distinguish the most effective channel of dissolution, after which they calculate the numerical values of the efficiency of acid treatment. To assess the effectiveness of acid treatment, use a method of computer processing units characteristics of the images obtained by MRI scanner - software Avizo Fire 7.1.

As the numerical values of the efficiency of acid treatment is used amount of stimulation. To do this, first determine the volume of distribution of wormholes (V), then the depth of penetration of the acid solution (g).

Calculation of the volume of the wormhole (V, Fig.3) and the determination of the depth of penetration of the acid solution g (Fig.4) hold on x-ray images automatically using software Avizo Fire 7.1. The calculation for limestone bioclasts-zoogenic of the first type. Figure 3, obtained on the scanner using the software Avizo Fire 7.1, visible:

the volume of distribution wormhole - V=319,7199 mm (Fig.3), the depth of penetration of the acid composition is g=30.0 mm (Fig.4). Calculate the magnitude of stimulation by the formula:

.

Similarly calculate all the indicators for the other four structural-genetic types of limestone after exposure to hydrochloric acid.

Example 2-3 performing analogously to example 1, changing the IP of the acid reagent. Composition No. 2 HCl + inhibitor snpch-A, composition No. 3 - acetic acid).

After pumping acid composition No. 2 through the core samples examined them on the x-ray scanner, compare images and assess the effectiveness of acid treatment using calculations by the method of computer image processing.

The calculation for composition No. 2:

The volume of distribution wormhole - V=1767,978 mm3,

The depth of penetration of the acid composition is g=11,0 mm

The magnitude of stimulation -,

The calculation for composition No. 3:

The volume of distribution wormhole - V=328,415 mm3,

The depth of penetration of the acid composition is g=28.0 mm,

The magnitude of stimulation -.

Acid composition according to the received data is considered optimal, if the minimum value of the magnitude of stimulation of the St.

Calculations of the magnitude of stimulation of the St for all structural-genetic types of limestone showed that the most effective acid is HCl+snpch-8903-A (composition No. 1).

The proposed method improves the accuracy of estimates of effectiveness and control of acid treatment of the carbonate reservoir and allows you to speed up the process of calculation of the characteristics of the effects of the acidic composition.

This invention allows for adequate visualization of the degree of change of the pore space of rocks to the lecturers, composing the productive part of the section in the zone of the acid exposure with the aim of increasing the productivity of wells. When comparing all of the research results, the ranking of the channels of the filter, get an objective visual and numerical characteristics of the distribution of acid composition in prokurennoy zone taking into account structural and genetic features of the productive reservoir.

The proposed method is the most appropriate non-destructive method for studying the structure of the core sample after acid exposure, solves the problem of increasing the accuracy of determination of solvent properties acid composition, its spatial distribution by conducting high-precision CT core samples, visually informative way and evaluate the effectiveness of acid treatment of the reservoir, allows greater certainty to establish the further tactics of treatment of bottomhole formation zone. The data obtained on core samples on the distribution of acid exposure in the pore space allow us to project them on the scale of the processing wellbore zone in which is received the largest increase oil output.

The method of evaluating the efficiency and control of acid carbonate reservoir, including coring, the fabrication of the samples of core, the study of their scanning electron microscope, pumping through the core samples of the chemical reagent, the thin sections from the entrance and exit of the chemical, the study of x-ray tomography of core samples after pumping the chemical, the image comparison and selection of the most effective forms of channels dissolution, the calculation of numerical values of the efficiency of acid by the method of computer processing units characteristics of the images obtained by the imager, and select the minimum numerical value of efficiency as a criterion most effective acid treatment, characterized in that, as the numerical values of the efficiency of acid treatment is used amount of stimulation, at first using the software automatically determine the volume distribution of the wormhole, then the depth of penetration of the acid solution, and then calculate the magnitude of stimulation by the formula:
,
where St is the value of stimulation, mm2,
V is the volume of distribution of wormholes, mm3,
g - depth of penetration of the acid solution, mm.



 

Same patents:

FIELD: oil-and-gas industry.

SUBSTANCE: proposed process comprises pre-flushing of the well with organic solvent. Then, organic solvent and film-forming anger are injected in the well. Film-forming agent represents 5-30% solution of boiler fuel in hydrocarbon solvent in amount of 0.5-2.5 m3/m of the bed perforated depth. Organic solvent buffer is used in amount of 3-6 m3 and aid solution in amount of 1-5 m3/m of perforated bed depth, injected fluids being injected thereafter in the bed.

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2 tbl, 4 ex

FIELD: oil and gas industry.

SUBSTANCE: method of oil formation treatment includes running of a string with a packer to the well, setting of the packer above the oil formation and subsequent injecting and flushing through the string to the oil formation of hydrocarbon solvent and acid agent in volumes exceeding filtration resistance in the formation zone remote from the well over the same value in the bottomhole zone, process withheld and removal of waste reaction products from the treated area by depression impact on the well. Then the pipe string at the well mouth below the packer is equipped with impulse liquid pulsator. At that a valve is mounted between the packer and liquid pulsator. An ejector pump with a feedthrough accessory is mounted above the packer. The string is run in to the well so that the packer is placed above the formation. Hydrocarbon solvent is injected to the string in pulsed mode, the packer is set, and hydrocarbon solvent is flushed to the formation by process fluid under pressure not exceeding the permitted pressure to the formation. The packer is released and the well remains under exposure. Then the well is washed out and acid solution is injected to the well, the packer is set, acid solution is flushed to the formation by process fluid under pressure not exceeding the permitted pressure to the formation. The packer is released and the well remains under exposure. After exposure period the valve is actuated and impulse liquid pulsator is cut off. The packer is released, the string is run in additionally so that radial openings of the valve are opposite the formation; the feedthrough accessory is removed from the ejector pump and a blind plus is installed instead. Then the packer is set, and reaction products are extracted by process fluid injecting along the string through the ejector pump and the well is completed through its tubing-casing annulus above the packer.

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4 dwg

FIELD: oil and gas industry.

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2 ex, 2 dwg

FIELD: oil-and-gas industry.

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3 ex, 1 dwg

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4 tbl, 1 dwg

FIELD: oil and gas production.

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25 cl, 1 tbl, 3 ex

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3 cl, 4 dwg, 1 tbl

FIELD: oil and gas production.

SUBSTANCE: invention relates to compositions used for intensifying wells owing to increasing permeability of rocks forming well bottom zones. Composition of invention contains 7.0 to 30.0% ethanol, 0.1 to 0.3% cupric chloride, 0.1 to 0.5% alkylbenzenesulfonate, and trichloroacetic acid (to 100%).

EFFECT: increased dissolving capacity of composition with respect to asphaltene-tar and paraffin deposits filling crack and pore space of rocks forming well bottom zones.

1 tbl

FIELD: oil and gas production.

SUBSTANCE: invention provides composition that can be used to intensify oil inflow and to develop well by means of acid treatment of terrigenous oil reservoir as well as to intensify oil inflow and to increase oil recovery of formations with the aid of hydraulic rupture of formation assisted by acid solutions. Composition contains borohydrofluoric acid needed to create borosilicate films prohibiting migration of particles during acid treatment. In addition, composition is characterized by lowered rate of reaction with rock at formation temperature in order to extend coverage of formation by treatment and to diminish deposit formation risk, low surface tension, low corrosion rate, and compatibility with inhibitors added to commercial acid, which will enhance efficiency of acid treatment using composition of invention. Composition is made up of, wt %: inhibited hydrochloric acid 8.0-15.0, fluorine-containing reagent (hydrofluoric acid, ammonium bifluoride, or ammonium fluoride) 1.5-10.0, boric acid 1.0-3.0, additionally isopropyl alcohol 5.0-10.0, and "Alkylfosfat-Khimeko" or "Efiroks-7", or "Fosfol-10" 0.5-2.0, and fresh water to 100%. In a method of acid treatment of the bottom area of terrigenous formation comprising consecutively pumping flushing fluid and acid composition into borehole, forcing the latter into formation by the aid of flushing fluid, giving time (up to 8 h) for reaction and subsequent removal of reaction products. Acid composition is used as it is or in the form of aqueous solution obtained by diluting composition with fresh water at water-to-composition ratio (1-5):1 in amount corresponding to 0.5-2.0 m3 per 1 m of perforated thickness of the formation. As flushing fluid, 1.5-3.0% ammonium chloride solution is used in amount 0.5-1.5 m3/m before pumping of acid composition or in amount 1.0-5.0 m3/m when used to force acid composition.

EFFECT: expanded useful possibilities of acid composition.

2 cl, 1 dwg, 2 tbl, 4 ex

FIELD: oil recovery industry, in particular buildup of reservoir recovery of low permeable, clay-containing beds.

SUBSTANCE: declaying composition contains clay dispersing reagent, peroxide compound and water, wherein as peroxide compound potassium fluoride peroxysolvate in activated form, comprising 1-3 mass % of oxalic or salicylic acid; and includes two sequential technological solutions. More specifically claimed composition contains (mass %): technological solutions 1: potassium fluoride peroxysolvate 1-2.5; hydrochloric acid as clay dispersing reagent 3-8.0; and balance: water; technological solutions 2: potassium fluoride peroxysolvate 1-2.5; sodium hydroxide as clay dispersing reagent 4-6.0; and balance: water. In addition said solution contain 0.1-1.0 mass % of water soluble surfactant. After treatment with disclosed solutions and well exposure dispersed reaction products are removed from bottom-hole formation zone.

EFFECT: bottom-hole formation zone of improved permeability due to effective removing of clayish and other mudding materials.

3 cl, 19 ex, 3 tbl

FIELD: oil and gas industry.

SUBSTANCE: method includes acidic treatment of bed, calculation of hardness decrease and pressure of rocks tearing and pressure for pressing working solution into bed, completion of well and the actual hydraulic tear. Pressure for pressing is determined from formula Pht=(2μ·Pm/(1-μ)+(1-3μ)·Pb/(1-μ), where Pht - rocks tear pressure, Pm - mountain pressure, Pb - bed pressure, μ - Poisson coefficient.

EFFECT: higher yields.

1 ex, 1 tbl

FIELD: oil industry.

SUBSTANCE: method includes treatment of face area of oil bed by hydrophobic powder in organic and pushing oil away from collector with following delivery of oil from face-adjacent area of extraction well for processing of oil-containing terrigenic bed into organic solvent additionally inserted is copolymer of ethylene with vinylacetate, well treatment is performed with relation of components in percents of mass: said powder 0.05-2, said copolymer 0,05-2, organic solvent - the rest.

EFFECT: higher efficiency.

2 tbl, 2 ex

FIELD: oil extractive industry.

SUBSTANCE: method includes determining porosity, penetrability and oil saturation level of shaft-adjacent area along whole length of deflected shaft. On basis of these ranges with low penetrability are detected, caverns presence level and diameters of shaft on ends thereof are determined. With consideration of characteristics of detected ranges at surface a pipe assembly is assembled, at end of which a ring saddle is mounted for locking ball, on both ends - hydraulic packers. Between these in assembly pipe a radial through calibrated channel is made. Pipe assembly is fixed at end of pipes column and these are lowered into chamber to level of deflected shaft mouth. With unpacked packers straight and backward washing of shaft is performed. After that acid is pumped into well in amount, equal to amount of first treatment range. Locking ball is dropped, first from the face shaft range with low penetrability is packed and concurrently acid is pressed therein, after that well is left for reaction. Then both packers are unpacked, backward washing of shaft is performed. By raising pipe column, pipe assembly with packers is transferred in backward, from face, direction into area of second, from face, range with low penetrability and above-mentioned operations are repeated. In turns, operations with each treatment range are performed.

EFFECT: higher efficiency.

2 cl, 6 dwg

FIELD: oil and gas industry.

SUBSTANCE: method includes serial pumping of film-forming hydrocarbon liquid and hydrochloric acid with adding of salt-acidic corrosion inhibitor to these, as said inhibitor a special paraffin deposits inhibitor is used, in form of composition of surfactants and aromatic solvents, while hydrochloric acid with addition of inhibitor before pumping is dispersed with gas to receive foam.

EFFECT: higher efficiency.

3 ex, 3 tbl

FIELD: oil and gas industry.

SUBSTANCE: method includes injection of processing liquid into bed, which liquid contains solved or dispersed in water complicated ether and polymer destructor, selected from oxidizing destructor and ferment destructor in such a way, that complicated ether is hydrolyzed with production of organic acid for solution of material soluble in acid, present in filtering layer or adjacent to it or in other damage in productive bed, and polymer destructor destroys polymer material, present in filtering layer or bio-film in productive bed.

EFFECT: higher efficiency, simplified method, higher productiveness, higher ecological safety.

31 cl, 1 tbl, 1 ex

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