HU206907B - Method for yielding petroleum under increased volumetric flushing efficiency - Google Patents

Abstract

The oil is displaced with CO2 and is collected on a gelling mixture. This gel viscous system for recovery of oil comprises (g/1) : 2-200 sodium silicate, 0.5-300 Na-K-, zirconium or ammonium salts, upto 200 surface active cpd, eg petroleum sulphonate and upto 200 alkaline metal hydroxide.

Description

The present invention relates to a method for operating oil tanks with water, gas and / or water vapor as a displacement medium, a mobility control plug system and a natural propulsion system, injected water and / or inert gas as propellant.

The economical operation of oil storage tanks can be significantly impaired by unfavorably low volumetric flooding. Often, due to the high microscopic displacement factor, the drug stopper and / or the naturally or artificially pressed propellant, viscous finger formation, and advancement into high permeability layers, will flood only a small fraction of the reservoir, resulting in an unfavorably low final oil.

In the case of reservoirs operated by water flooding and / or Enhanced Oil Recovery (EOR), the unfavorable volumetric efficiency is primarily due to the heterogeneity of the reservoir and is only secondarily due to viscosity and gravity problems.

There are some known methods for counteracting the resulting bulk volumetric overflow.

In order to reduce the adverse effects of, inter alia, reservoir heterogeneity, a so-called homogenizing plug is pressed in front of the oil mobilization plug, which is a viscous dispersion system consisting of oil, water, surfactant (s) and electrolytes.

For a similar purpose, surface-prepared macroemulsions are used in the processes described in U.S. Patent Nos. 3,149,669 and U.S. Patent 3,330,348.

However, the above-mentioned processes are not widespread in practice, partly because they are based on the use of expensive oil and / or surfactants derived therefrom, partly because of difficulties in moving the emulsions with water and injection problems, and partly because of the it cannot be solved at all.

The process of HU 186586 proposes to treat production wells and / or injection wells with crosslinkable polymer-silicate solution and crosslinking agent to reduce the adverse effects of early water breakage due to the inhomogeneity of the reservoirs and the unfavorable mobility rate and to improve the flooding profile. successive injection. The disadvantage of the process is that the treatment extends only to the zone around the well, and thus the effect achieved is limited in time and space.

With mixing and non-mixing EOR processes, such as in the case of flooding with liquid or gaseous hydrocarbons and CO ₂ or CO ₂ containing gases, ensuring proper volume efficiency is of paramount importance due to their low viscosity and density. In unfavorable cases, the economical implementation of the above procedures may also be questioned.

Several attempts have been made to increase the volumetric efficiency of CH gas and CO ₂ flooding. One of the most obvious and widely practiced methods is the alternating injection of gas and water (WAG, Candle, BH, AB: Trans. ALME 1958.213-31).

The advantage of the method is its simplicity, but the disadvantage is that it provides favorable flooding primarily for the water, ie it increases the water absorption capacity of the lower permeable layers, but the gas can only be injected sufficiently into the high permeability layers, so the process itself needs to be improved.

In US 3 342 256 and US 3 599 715 and many other patents, the mobility of CH gas and CO ₂ gas is reduced by injection of foaming agents. However, the widespread use of the method is hindered by the high cost of chemicals and many technological problems.

In the process of patent application HU 177703, it is desired to increase the efficiency of gas spraying by injection of foaming agents and dispersion systems. However, the process assumes the availability of special surfactants on an industrial scale, which makes operational implementation doubtful.

The process disclosed in HU 187730 proposes the combined use of alkaline silicates and CO ₂ for the efficient operation of petroleum depots using gels formed by the interaction of CO ₂ and silicates. Similar methods are described in US 2402588; U.S. Patent Nos. 3,285,388 and 3,261,400. However, practical experience has shown that injection of silicate solutions to the proper depth, transfer of the resulting gels to production wells is difficult due to high sorption, ion exchange and alkaline depletion, especially in the case of high bivalent ionic water and high acid oils, and / CO ₂ or of previously cultured azide / or containing CO ₂ and storage pools cent.

Based on the above, the known silicate processes are mainly suitable for the treatment of the zone around the well, and for the modification of injection and production profiles.

Steam and hot water processes also have volumetric flooding problems due to storage heterogeneity, unfavorable mobility rates, and gravity effects. Attempts have also been made to increase the efficiency of the procedures.

The use of solid crystals for mobility control and profile modifying is proposed by Heinemann et al., Heinemann Z, "Kratzer D. and Steiner P., Paper SPE (DOE 14903)" for steam and hot water flooding. The essence of the process is to use substances which, at high temperatures, sublimate in steam or are very soluble in water, but which, at storage temperature, form a practically insoluble precipitate. In this way, the special materials introduced with the heat transfer medium accumulate behind the heat front and have a countervailing effect. The use of the process in the plant is hindered by economic reasons and material selection problems.

It is an object of the present invention to provide a novel process

EN 206 907 B, which addresses the shortcomings of the known processes and broadens the range of applicable processes, is based on chemicals that are inexpensive and available in large quantities, can be prepared and are suitable for gas, water, improved water or heat injection methods, or to increase the volumetric flooding factor of a natural propulsion.

In order to achieve this goal, we have found that the water-soluble alkaline silicates in the CO ₂ storage medium and / or the presence of divalent (Ca ⁺⁺ , Mg ⁴⁴ ·) ions are favored, the behavior and mobility of the gels formed it can be influenced by humates (humic acids, various salts thereof, in particular Na, K, zirconium or ammonium salts). In this way, the alkaline silicate solution injected into the container can be made to move the container silicate gels with low sorption and to gel at the desired location in the container. Because the humates themselves can be gelled, complex gels can be formed which have better properties than the individual gels, so there is a wide variety of gels and gel combinations that best suit the storage properties. It has also been found that these gel systems can also positively influence the microscopic displacement factor.

Thus, in accordance with the present invention, a mobility control plug system which is 1-300 g / l alkaline silicate, is pressed into the container before, during, or alternately for 1 to 20, preferably 1 to 4, cycles of injection of the displacement medium. preferably 2200 g / l of Na-silicate and 0.5-300 g of Na, zirconium or ammonium humate, preferably 0.5-200 g / l of Na-humate, and 0-200 g / l of surfactant, preferably 1-100 g / l of petroleum sulfonate and / or Na, K, zirconium or ammonium salts of sulfonated humates, and finally 0 to 200 g / l, preferably 1-150 g / l of Na, K, ammonium hydroxide containing said mobility control plug system in an amount of 0.01 to 1.0, preferably 0.050.5 pore volume.

It has been found that the properties of the gel systems described above can be further improved by the surfactants used in the various EOR processes, and therefore certain surfactants (anionic, cationic, nonionic or mixtures thereof) may be considered as injectability, stability, mobility control ability, oil displacement, etc. repair additives. Preferred are, for example, Na, K or ammonium, zirconium salts of sulfonated humates prepared by sulfonation of petroleum sulfonates and / or humic acids.

The parameters of the mobility control systems described above (e.g., injectability, gelling) can also be improved by the addition of alkalis (e.g., NaOH, KOH, NH ₄ OH).

This is required when relatively high amounts of in situ gel-forming (alkaline consuming or pH-lowering) components (e.g., CO ₂ and / or divalent cations) are present in the reservoir.

Our investigations also covered the heat tolerance and thermal stability of silicate-humate systems. It has been found that alkali silicates and various humates and humate sulfonates have excellent heat resistance and heat stability and can be gelled at the application temperature of steam or hot water flooding.

According to a preferred embodiment of the present invention, the operation of crude oil storage tanks with carbon dioxide or gas containing at least 10% carbon dioxide as displacement medium and water or inert gas as propellant is effected with increased volumetric flooding effect. before or during injection of CO ₃ or CO ₂ -containing gases, a mobility control plug system is pressed into the reservoir which, upon exposure to CO ₂ , converts directly into a mobile gel-viscous system and increases the volumetric flooding of gas and water factor.

The mobility control plug system comprises 1-300 g / l alkaline silicate, preferably 2-200 g / l Nasilicate;

0.5300 g / l of Na, K, zirconium or ammonium humate, preferably 0.5-200 g / l of Na Humate;

0-200 g / l of surfactant, preferably petroleum sulfonate and / or Na, K, zirconium or ammonium salts of sulfonated humates at a concentration of 1100 g / l,

0-200 g / l Na, K-, NH 4 hydroxide, preferably at a concentration of 1150 g / l.

The mobility control plug size of 0.01-1.0, preferably 0.05-0.5 part of the pore volume of the container concerned, which be injected continuously, in a single plug, azide or _CO2 or _{CO2-containing} gas alternately from 1 to 20, preferably 2-5 cycles.

Alternatively, the mobility control plug may be opened for composition into an alkaline silicate-containing screw plug and a protective plug containing other materials, which may be partially or completely pressed before, partially or completely after the screw. In this case, the total volume of the protective and protective plug is 0.01 to 1.0, preferably 0.050.5, pore volume each, and the concentrations are the same as those described for the integrated plug.

In another preferred embodiment, the oil reservoirs in water or an improved water-flooding, or than 10% by volume cultivated at lower gázelárasztással and water by pressing, and hot water or gőzbesajtolással CO ₂ content can be carried out under increased volumetric flooding efficiency that preferably prior to the displacement fluids either alternately, pressurizing a mobility control plug system that is exposed to divalent and polyvalent cations by the divalent and polyvalent cations of the storage fluids, either externally, before, during or after the mobility control plug system, or mobile gels under the influence of other gelling agents

EN 206 907 B converts to a cosine system and increases the volumetric flooding factor of displacement media.

The mobility control plug system composition, closure size and the same application technology point of view, the _CO2 azide, or at least 10% by volume CO ₂ os administration is described in combination with natural gas.

The use of the process of the invention provides the following beneficial effects:

(a) Provides for the mobility control of the mobility control plug system to the extent necessary to completely flood the container.

b) Ensures the mobility of the mobility control gel system created in the reservoir from the injection rut or water body to the production wells, thereby extending mobility control to the entire reservoir.

c) By adjusting the flow resistance of the gel system according to the heterogeneity of the reservoir, a high volumetric flood factor can be achieved.

d) Increases the volumetric flooding factor for steam and hot water injection, stabilizes clay minerals, and prevents dispersal of storage rock, thereby greatly increasing the feasibility and cost effectiveness of these cultivation processes.

The following examples illustrate the practice of the invention without limiting the scope of the claim to the embodiments.

Example 1

By sandwiching two sandstone storage models of different permeability, a heterogeneous system was created. On the injection side, the proportion of fluid flowing into each layer was measured separately using high-pressure liquid and gas flow meters, and the liquid products were captured for each of the two models in a high-pressure, communicating gas space. The gas produced was not measured.

The parameters of the above models were: length: 198 cm cross section 5.6 cm ² permeability to water: 225 and 50 mD porosity: 22 and 18% initial water saturation: 25 and 28% layer pressure: 100 bar layer temperature: 64 ° C oil dissolved gas content: 52 m ³ / m ³ oil density: 820 kg / m ³ (20 ° C) oil viscosity: 3.2 mPa.s (at 20 ° C)

The above system was first flooded. With an initial water saturation, the oil permeabilities were 160 and 40 mD. Water breakthrough occurred in the higher permeability layer at a total pore volume of 0.28, while in the lower permeable layer only after about 1.3 V _p .

The aqueous oil yields in the higher permeability layer were 60% and 54% respectively, the residual oil saturations were 30% and 33%, respectively, and the aqueous effective permeabilities were 59 and 10 mD, respectively.

At the beginning of the water flood, 20% of the injected water flowed into the lower permeability layer, which initially increased to 25%, then decreased after the water permeability in the higher permeability layer and finally reached 14%. This condition corresponds to a secondary post-flood situation.

Further, 0.3 pore volumes of natural gas containing 80% CO ₂ + continuous water flooding were performed. Only 11% of the CO ₂ gas stream flowed into the lower permeable layer, but in the event of a flood, the water share reached 30% and then dropped to 25%.

The extra oil yield was 12% in the higher permeability layer and only 3% in the lower permeability layer. This condition represents a post-immiscible carbon dioxide plug + water flood.

At the end of the production period, according to one embodiment of the process of the invention, a mobility control plug was pressed in an amount of 0.15 parts of pore volume and having the following composition:

g / l Na-Humate g / 1 Na-Silicate g / 1 NaOH g / l Petroleum Sulfonate (M = 450)

To the above mobility control plug was added 4 g / l NaOH to prevent the early gelling effect of pre-flooding with CO ₂ . After inserting the above plug, 0.05 pore volume of pressurized water was pressed and the model was sealed for 48 hours. Approximately 80% of the injected drug and the subsequent water plug flowed into a higher permeability layer.

After 48 hours, 0.3% pore volume of 80% CO ₂ gas + continuous water spray was used. More than 60% of the gas flowed into the low-permeability layer, and after an initial 60% amount of water, this value stabilized at 50%.

During the above operation, further significant oil yields were achieved. The excess oil in the higher permeability layer was an additional 10% of the original oil supply and in the lower permeability layer 16%. In this way, the excess oil after flooding increased to 22% in the higher permeability layer and 19% in the lower permeability layer.

Example 2

In the model of Example 1, a possible variation of the patent process was used immediately after the water flood. A mobility control plug was pressed in an amount of 0.15 parts of pore volume and had the following composition:

g / l Na-Humate 20 g / l Na-silicate g / l Petroleum sulphonate (M = 450).

After inserting the Mobility Plug, 0.05

HU 206 907 Β pore volume pressurized water was pressed and the model was sealed for 48 hours.

85% of the injected drug and water flowed into the higher permeability layer. After 48 hours, 0.3 pore volume of 80% CO ₂ gas was injected, followed by continuous water separation. Approximately 50-50% of both the gas and the water flowed into the high and low permeability layers. The excess oil yield was 28% in the higher permeability layer and 21% in the lower permeability layer based on the original oil supply.

Example 3

In the model apparatus of Example 1, a mobility control plug was pressed in just before the water was flooded, amounting to 0.3 parts of pore volume and having the following composition:

g / l Na-Humate 16 g / l SiO ₂

Nearly 80% of the injected drug flowed into the higher permeability layer.

After the plug, the treated system was subjected to water flooding, whereby 50-50% of the water flowed into the higher and lower permeability layers.

The aqueous oil yield was 65% from the higher permeability layer and 60% from the lower permeable one.

The water breakthrough occurred in both layers after 0.45 V _p , thus reducing the amount of water needed to reach the final oil yield from 2 V _p to 0.8 V _p .

Example 4

In the model apparatus of Example 1, a 15 g / l solution of petroleum sulfonate, 0.3% of the pore volume, was pressed after the water flood, followed by a water spray.

75% of the petroleum sulphonate plug was in the higher permeability layer and 30% was added to the original oil supply.

The lower permeability layer is virtually non-produced oil.

Example J.

In the model of Example 1, the following mobility control plug was pressed in front of the petroleum sulfonate screw plug of Example 4 in an amount of 0.15 pore volume and having the following composition:

g / l Na-Humate 16 g / l SiO ₂ .

After the mobility control medium, 0.2 V _p water and then 0.3 V _p 15 g / l petroleum sulfonate solution were injected into the model followed by continuous displacement water. About 80% of the Mobility Plug flowed into the higher permeability layer. Approximately 50-50% of the petroleum sulfonate plug and the subsequent water flowed into the various permeability layers.

The excess oil yield in the high permeability layer was 24% and in the lower permeability layer 22% relative to the original oil supply.

Example 6

A mobility control plug system was pressed into the model apparatus of Example 1 prior to flooding, having the following composition:

g / l Na-Humate 100 g / l Na-Silicate 10 g / l NaOH

The plug system of the above composition was cyclically pressed as a 3x0.02 pore volume plug, between and after which 0.01 pore volume water plugs were pressed and the model was sealed for 48 hours.

After the standstill, 0.05 pore volume of surfactant solution was injected as displacement medium having the following composition:

g / l sulfonated human Na salt 30 g / l petroleum sulfonate (M = 450)

Finally, 1.2 pore volumes of water were injected as a propellant. As a result of the mobility control plug system, both the displacement medium and the propellant medium flowed to the two layers of different permeability in a nearly 1: 1 ratio. The final oil yield was 95% in the higher permeability layer and 92% in the lower permeability layer, resulting in values of 35% and 38%, respectively, for excess oil yields relative to water flooding.

Claims (2)

PATIENT INDIVIDUAL POINTS 1. A process for extracting oil at an increased volumetric effluent efficiency with oil, water and / or water vapor as a displacement medium, with a mobility regulating plug system and a natural water drive, injected water and / or an inert gas as propellant, characterized in that the displacement medium is injected. before or during, or alternatively, 1-20, preferably 1-4 cycles, a mobility control plug is pressed into the reservoir containing from 1 to 300 g / l of alkali silicate, preferably 2200 g / l of Na silicate, and 0.5- 300 g / l Na, zirconium or ammonium humate, preferably 0.5200 g / l Na-humate, and 0-200 g / l surfactant, preferably 1-100 g / l petroleum sulphonate and / or sulfonate Na, K, Zirconium or Ammonium salts of humans, finally containing 0-200 g / l, preferably 1-150 g / l of Na, K, ammonium hydroxide, also referred to as mobility regulation Plug system employed 0.01 to 1.0, preferably 0.05 to 0.5 pore volumes of quantities. A method according to claim 1, characterized in that the mobility control plug system is formed by forming a six-pin plug containing from 1 to 300 g / l of alkali silicate, preferably from 2 to 200 g / l of Na silicate, and a protective plug of 0.5-300 g / l of Na, K, zirconium or NH ₄ , preferably 0.5-200 g / l EN 206 907 Sodium humate, and 0-200 g / 1 of surfactant, preferably from 1 to 100 g / 1 petroleum sulfonate and / or sulfonated huniatok Na, K or NH ₄ salts of, and finally 0200 g / 1, one eló'nyösen -150 g / l of Na-, K-, NH ₄ -hydroxide, where the size of the six-pin and the protective plug is 0.1 to 1.0, preferably 0.05 to 0.5 pore size, and the plug is partially or completely pressed before the six-pin or after the six-pin. Published by the National Bureau of Invention, Budapest Responsible for the publication: dr. Gabriella Szvoboda Head of Department ARCANUM Bt.-BUDAPEST