阅读说明：本技术 一种同井注采提高采收率的增产方法 (Yield increasing method for increasing recovery ratio by injection and production in same well ) 是由 刘顺 李勇 于 2020-05-18 设计创作，主要内容包括：本发明提供了一种同井注采提高采收率的增产方法,其中,所述同井注采提高采收率的增产方法包括：当生产井产量明显降低后,以交替注入形式对生产井进行若干轮次的断塞注气、断塞注微乳体系,使油水充分渗吸置换,进而实现生产井增产的目的。本发明所提供的注天然气-注微乳体系-渗吸置换-若干轮次循环注入生产的工艺不仅可以提高采出程度,而且能增大流体流通通道的渗透率,是一种经济、实用、简单、易操作、环保的新增产措施。(The invention provides a production increasing method for increasing recovery efficiency by injection and production in the same well, wherein the production increasing method for increasing recovery efficiency by injection and production in the same well comprises the following steps: after the production well yield is obviously reduced, a micro-emulsion system of plug breaking gas injection and plug breaking injection is carried out on the production well for a plurality of times in an alternative injection mode, so that oil and water are fully imbibed and replaced, and the purpose of production well yield increase is further achieved. The process of injecting natural gas, injecting a micro-emulsion system, imbibition replacement and circulating injection for a plurality of times provided by the invention can not only improve the extraction degree, but also increase the permeability of a fluid circulation channel, and is a new production increasing measure which is economic, practical, simple, easy to operate and environment-friendly.)

1. The production increasing method for increasing the recovery factor by injection and production in the same well is characterized by comprising the following steps of:

after the production well yield is obviously reduced, a micro-emulsion system of plug breaking gas injection and plug breaking injection is carried out on the production well for a plurality of times in an alternative injection mode, so that oil and water are fully imbibed and replaced, and the purpose of production well yield increase is further achieved.

2. The method according to claim 1, characterized in that it comprises: when the output of the production well is obviously reduced, (1) closing the well after performing slug gas injection on the production well, and closing the well after performing slug gas injection on the production well;

(2) and (3) repeating the step (1), and performing a slug gas injection and slug micro-emulsion injection system for a plurality of rounds on the production well to ensure that oil and water are fully imbibed and replaced, thereby achieving the purpose of increasing the production of the production well.

3. The method of claim 1 or 2, wherein the gas injected by plug-break gas injection is natural gas.

4. The method according to claim 1 or 2, wherein the microemulsion system comprises 0.1-2 wt% of petroleum sulfonate surfactant, 0.1-3 wt% of surface hydroxylated nanosilica, and the balance water, based on 100% of the total weight of the microemulsion system.

5. The method of claim 4, wherein the surface hydroxylated nanosilica has a particle size of 7-15 nm.

6. The method of claim 1 or 2, wherein the slug is insufflated for 5 hours per round.

7. The method of claim 1 or 2, wherein the well is blind 24h after slug injection.

8. The method according to claim 1 or 2, wherein the time for slug injection of the microemulsion system is 10 hours per run.

9. The method of claim 1 or 2, wherein the well is plugged 24 hours after the microemulsion system is slug injected.

10. The method of claim 2, wherein in the step (2), the step (1) is repeated, and three rounds of slug gas injection and slug micro-emulsion injection systems are performed on the production well, so that oil and water are fully imbibed and replaced, and the purpose of increasing the production of the production well is achieved.

Technical Field

The invention relates to a production increasing method for improving recovery efficiency by injection and production in the same well, belonging to the technical field of oil extraction.

Background

When the oil well is extracted, because pressure difference exists between the matrix and the fractures and between the matrix and the shaft, oil in the matrix and the natural fractures can flow into the bottom of the well through the wide fractures. During oil flow, when the resistance created by the matrix and the pores of the natural fractures is large, oil is retained, thereby reducing the production of the oil well. I.e. over a period of production (typically several months, some as short as 2 months), the production of the well decreases very quickly, or there is little production. For the condition, the stimulation measure usually adopted is to drill a certain number of injection wells around the oil well by a certain well spacing and a geometric well pattern shape to perform water injection or gas injection in advance, and the water or gas injected by the water injection well pattern can displace the retained oil to flow into the bottom of the well again; or some other stimulation means such as secondary fracturing, acid fracturing, repeated fracturing, etc., is performed on the production well, with the purpose of increasing the fluid flow channels and increasing the oil flow capacity, thereby restoring the production rate of the well. Although the methods have certain effect and are also the current common production increasing mode, the method has the problems of very high construction cost, and certain uncertainty of the overall benefit based on the reality of poor physical properties of the reservoir developed in China.

Therefore, providing a novel production increasing method for improving the recovery efficiency by injection and production in the same well has become a technical problem to be solved in the field.

Disclosure of Invention

In order to solve the defects and shortcomings, the invention aims to provide a production increasing method for increasing the recovery efficiency by injecting and producing oil from the same well. The method provided by the invention realizes production increase in a gas-liquid alternative injection mode, wherein the liquid phase is a microemulsion system containing a surfactant, so that the oil-water interfacial tension can be reduced, and the oil displacement efficiency can be improved.

In order to achieve the above object, the present invention provides a production increasing method for increasing recovery efficiency by injection and production in the same well, wherein the production increasing method for increasing recovery efficiency by injection and production in the same well comprises:

after the production well yield is obviously reduced, a micro-emulsion system of plug breaking gas injection and plug breaking injection is carried out on the production well for a plurality of times in an alternative injection mode, so that oil and water are fully imbibed and replaced, and the purpose of production well yield increase is further achieved.

Preferably, the method comprises: when the output of the production well is obviously reduced, (1) closing the well after performing slug gas injection on the production well, and closing the well after performing slug gas injection on the production well;

(2) and (3) repeating the step (1), and performing a slug gas injection and slug micro-emulsion injection system for a plurality of rounds on the production well to ensure that oil and water are fully imbibed and replaced, thereby achieving the purpose of increasing the production of the production well.

In the above-described method, preferably, the gas injected by the plug-breaking gas injection is natural gas.

In the above method, preferably, the microemulsion system comprises 0.1-2 wt% of petroleum sulfonate surfactant, 0.1-3 wt% of surface hydroxylated nano-silica and the balance water, based on 100% of the total weight of the microemulsion system.

The petroleum sulfonate surfactant and the surface hydroxylated nano-silica are conventional substances and can be obtained by commercial purchase or self-made purchase.

In the above method, preferably, the particle size of the surface hydroxylated nano silica is 7 to 15 nm.

In the above-described method, preferably, the slug is insufflated for a period of 5 hours per round.

In the above described method, the well is preferably blind 24h after slug injection.

In the above-described method, preferably, the time for the slug injection of the microemulsion system is 10 hours per one round.

In the above-described method, the well is preferably plugged 24 hours after the microemulsion system is slug-injected.

In the method, preferably, in the step (2), the step (1) is repeated, and three rounds of slug gas injection and slug micro-emulsion injection systems are performed on the production well, so that oil and water are sufficiently imbibed and replaced, and the purpose of increasing the production of the production well is further achieved.

When the production well yield is obviously reduced, the physical yield increasing method of a slug gas injection (such as natural gas) + slug injection microemulsion system is carried out on the production well, and the core of the theory of the method is not the traditional method for increasing fracture or displacing oil drop flow at high pressure, and the method does not completely change the wettability, capillary pressure and the like in a chemical mode. The core thought of the method provided by the invention is as follows: after the oil well is produced for a certain period (the yield is obviously reduced), the pores and natural cracks of the matrix 2 can be closed due to the existence of the pressure difference between the formation stress and the production well 1, and the flowing difficulty of the oil drops 3 is increased. When the substrate and the natural fracture 5 are closed, the flow micro-channels are changed, the resistance of pore throats is greatly increased, oil hardly passes through the pore throats of the flow channels, oil drops are sporadically or in small strands at the large channels of the substrate and the natural fracture, more oil gas (shown in figure 1) is remained in the substrate and the fracture (including the natural fracture 5 and the hydraulic fracture 4) due to the blockage of the narrow flow channels or the blockage of certain flow channels, and at the moment, high-cost production increasing measures are blindly adopted, and the effect is not necessarily obvious.

The technical scheme provided by the invention is that after the production well yield is obviously reduced, the production well is subjected to slug gas injection and slug oil and gas injection replacement for a plurality of times in an alternate injection mode, so that oil and water are fully imbibed and replaced, and the purpose of production well yield increase is further realized; the injection system injects gas, such as natural gas, into the reservoir, and the injection system takes the principle of not damaging the physical properties of the reservoir of the oil reservoir, and the technical scheme has the following three functions:

the first is that: the air pressure of injected natural gas can force the substrate and the natural crack channel to be slightly enlarged, the constraint pressure of oil drops is directly changed, the adhesion force of the oil drops is reduced, the oil drops are easy to flow, oil drops of a plurality of micro-channels can pass through narrow channels, and most of the oil drops which are easy to flow are concentrated in a gathering area with a larger storage space according to the principle of minimum resistance; and the flow of the air flow 6 will flush the flow channel, making the oil droplets flow and concentrate more easily, as shown in fig. 2.

Secondly, the following steps: the injected microemulsion system not only enlarges and flushes the flow channel, but also aims to reduce the oil-water interfacial tension of the microemulsion system in the pressure building stage so as to fully generate the oil-gas replacement imbibition process.

Thirdly, the method comprises the following steps: the injected natural gas-microemulsion system increases the formation pressure, and forces the imbibition process to accelerate, namely, the liquid remained in the reservoir has more low-salinity liquid flowing into the matrix under the action of the imbibition force, and according to the mass conservation principle, more oil drops are necessarily replaced, and the oil drops are also necessarily concentrated in an easily-stored aggregation area, which is shown in figure 3. At this time, the oil droplets are distributed somewhere in easy storage, or sporadically, or in line, or even in flakes.

When the production well is normally produced, the process of releasing pressure of the matrix to the bottom of the well is adopted, at the moment, natural airflow (namely the oil-gas flowing direction 7) drives part of the matrix and oil drops of natural cracks to be more concentrated, and meanwhile, a flowing channel flowing to the bottom of the well is smoother, so that the oil drops can more easily flow into the bottom of the well, and the dual purposes of improving the imbibition efficiency and improving the flowing efficiency of a flowing channel are achieved, as shown in fig. 4; the process of injecting natural gas, injecting a micro-emulsion system, imbibition replacement, injecting for a plurality of times and production can not only displace more oil drops, but also increase the permeability of a fluid circulation channel, thus being a new production increasing measure which is economical, practical, simple, easy to operate and environment-friendly.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic diagram of the fracture and oil droplet distribution (oil droplets are blocked in the flow path) under the production conditions of the oil well according to the present invention.

Fig. 2 is a schematic diagram of the fracture and oil droplet distribution (fracture micro-tensioning, flushing flow channels) under the oil well injection conditions of the present invention.

Fig. 3 is a schematic diagram of oil drop imbibition and concentration in the pressure-holding stage of the present invention.

FIG. 4 is a schematic diagram of the micro-closure of the crack, the flushing of the flow channel with air and water, and the flow of oil droplets driven by the air flow in the production process of the present invention.

The main reference numbers illustrate:

1. a production well;

2. a substrate;

3. oil droplets;

4. hydraulic fracture;

5. natural fractures;

6. a gas stream;

7. the direction of oil and gas flow.

Detailed Description

In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.

Experimental example 1

The embodiment provides a production increasing method for improving recovery efficiency by injection and production in the same well, which comprises the following steps:

the microemulsion system prepared in the embodiment comprises 1 part by weight of petroleum sulfonate surfactant, 1.5 parts by weight of surface hydroxylated nano silicon dioxide and 97.5 parts by weight of water, and the adopted permeability is 50 multiplied by 10^-3μm²The core is saturated with oil and then is displaced by water, then natural gas is injected into a slug for 5 hours, a simulated blank well is injected for 24 hours, the microemulsion system is injected into the slug for 10 hours, the simulated blank well is injected for 24 hours, and the slug gas injection-slug injection microemulsion system is alternately injected for three times and then water injection is carried out, and the obtained experimental results are shown in the following table 1.

TABLE 1 slug gas injection-slug injection microemulsion system for improving recovery efficiency

As can be seen from Table 1, the total recovery ratio is increased by 16.23% compared with the water flooding recovery ratio after the slug gas injection-slug injection microemulsion system is alternately injected by adopting the yield increasing method for increasing the recovery ratio by injecting and extracting in the same well.

Experimental example 2

In the embodiment, a natural core of a tight reservoir of a Changqing oil field is selected to carry out a displacement experiment so as to evaluate the pressure reduction and injection increase effects of the production increasing method for injecting and extracting the oil recovery from the same well.

The microemulsion system prepared in the embodiment comprises 1 part by weight of petroleum sulfonate surfactant, 1.5 parts by weight of surface hydroxylated nano-silica and 97.5 parts by weight of water, water flooding is carried out at a constant flow rate of 0.5mL/min, after the pressure is stabilized, natural gas is injected into a slug for 5 hours, a well is blocked for 24 hours in a simulated mode, the microemulsion system is injected into the slug for 10 hours, the well is blocked for 24 hours in a simulated mode, and the slug gas injection-slug injection microemulsion system is injected alternately for three times, and water flooding is carried out, and the obtained experimental results are shown in the following table 2.

TABLE 2 slug gas injection-slug injection microemulsion system pressure-reducing and injection-increasing effect

From the table 2, it can be seen that the injection pressure is reduced by 24.3% after the slug gas injection-slug injection microemulsion system is alternately injected by the production increasing method for increasing the recovery ratio by injection and production in the same well, which indicates that the method has better pressure reduction and injection increase effects.

In conclusion, the yield increasing method for increasing the recovery rate by injection and production in the same well provided by the embodiment of the invention can increase the recovery rate and has better pressure reduction and injection increase effects.

The above description is only exemplary of the invention and should not be taken as limiting the scope of the invention, so that the invention is intended to cover all modifications and equivalents of the embodiments described herein. In addition, the technical features and the technical inventions of the present invention, the technical features and the technical inventions, and the technical inventions can be freely combined and used.