Horizontal well large-dose deep profile control injection method

Abstract

The application discloses a large-dose deep profile control injection method for a horizontal well, and according to the permeability of a stratum where a horizontal well to be injected is located, when the permeability distribution of two ends of the horizontal well to be injected is uneven, a stratum is positively injected to be blocked at the horizontal well section with the largest permeability, and then the blocked stratum is removed by reversely injecting from the horizontal well section with the smallest permeability; the positive injection and the reverse injection are repeated, the high-permeability area is blocked by using injection materials, and when the permeability of the two ends of the horizontal well to be injected is uniform, the positive injection and the reverse injection are alternately injected from the two ends of the horizontal well section until a preset injection amount is reached, so that the large-dose deep profile control injection of the horizontal well is completed, the uniformity of the distribution of the profile control agent in the stratum is obviously improved, the profile control operation effect is improved, and the effective period of the profile control is prolonged; meanwhile, the profile control agent entering amount of different areas of the horizontal section can be adjusted by adjusting the injection time of the positive injection and the reverse injection, and the high-permeability area can be controlled.

Description

Technical Field

[0001] This invention belongs to the field of oil production engineering and relates to a horizontal well profile control injection method, and more particularly to a horizontal well deep profile control injection method with large doses. Background Technology

[0002] Compared to vertical wells, horizontal wells have a larger drainage area, thus offering better development results. However, due to well structure and reservoir edge and bottom water inrush issues, horizontal wells are also more prone to water encounters, which can easily develop into water flooding of the entire well. For such water-flooded wells, oilfields typically convert them into water injection wells, i.e., horizontal well water injection. Similar to vertical well water injection, due to the presence of fractures and high-permeability zones, horizontal well water injection development is also highly susceptible to water channeling in low-resistance, high-permeability zones, rendering the crude oil in low-permeability areas unusable and severely impacting the effectiveness of water injection development.

[0003] Therefore, proper profile control is particularly important for water injection in horizontal wells. Near-wellbore profile control is prone to backflow at deeper formation depths, causing water to re-enter high-permeability layers, resulting in poor profile control effectiveness. This has led to the development of deep profile control. The commonly used deep profile control agent for horizontal wells is a pre-crosslinked gel particle type. This type of agent is characterized by its ability to absorb water and swell, exhibiting elasticity, strength, and water retention capacity. Through its three-dimensional structure, the particles block pore throats in the formation and undergo reversible deformation and movement under external forces, achieving deep profile control. Furthermore, the temperature and salt resistance of granular profile control agents is far superior to that of polymer gel profile control agents.

[0004] When injecting granular profile control agents (hereinafter referred to as profile control agents) using conventional injection methods, the agent is injected into the well through the tubing, migrates within the tubing to the horizontal well toe, and then flows back from the annulus to the horizontal well root. During this backflow process, the agent continuously enters the formation through the casing perforations. This process presents the following drawbacks:

[0005] Firstly, due to gravity, particles tend to accumulate more easily in the lower part of the horizontal well. When the amount of accumulated particles exceeds the outflow from the casing perforation hole, the particles will accumulate in the annulus, leading to a significant loss of profile control agent. At the same time, it can also cause the tubing to become stuck and unable to be retrieved, resulting in engineering and economic losses.

[0006] CN109339735A proposes adding 0.1-0.15% polymer to the injection solution to maintain the suspension of bulk-swelling particles by increasing the viscosity of the carrier solution; others have improved particle suspension by adding salt to the carrier solution to increase the solution density and reduce the density difference between the solution and the particles. However, both of these methods are slightly more expensive and have not been very effective in practical applications.

[0007] Secondly, since the profile control agent enters the formation during the process of flowing back from the toe to the root, the amount of profile control agent entering the formation decreases from the toe to the root throughout the injection process. This results in uneven distribution of the amount of profile control agent entering the formation and is prone to damaging the medium and low permeability layers, making it more difficult for subsequent water injection to enter the medium and low permeability layers and utilize the crude oil therein. At the same time, it is also impossible to adjust the injection volume of profile control agent in each layer around the horizontal well according to various formation parameters near the horizontal section. Summary of the Invention

[0008] The purpose of this invention is to provide a method for injecting large doses of deep profile control agents into horizontal wells, so as to overcome the problems of uneven distribution of profile control agents and large-scale deposition of particles between the casing and tubing when injecting large doses of particulate profile control agents into horizontal wells.

[0009] A method for high-dose deep profile control injection in horizontal wells includes the following steps:

[0010] S1, detect the permeability of the formation where the horizontal well to be injected is located;

[0011] S2, when the permeability distribution at both ends of the horizontal well section to be injected is uneven, first inject forward into the horizontal well section with the highest permeability to plug the formation, inject according to the preset injection time, and after the forward injection is completed, inject backward into the horizontal well section with the lowest permeability to remove the blockage; repeat the forward injection and reverse injection until the preset injection volume is reached;

[0012] When the permeability at both ends of the horizontal well section to be injected is uniform, injection is carried out alternately from both ends of the horizontal well section until the preset injection volume is reached, thereby completing the large-dose deep profile control injection of the horizontal well.

[0013] Geological and logging data are used to determine the properties of the formation near the horizontal well, such as permeability. Based on the permeability distribution of the formation in the horizontal section of the horizontal well, the injection and reverse injection times are designed.

[0014] When the permeability of the toe of a horizontal well is high, forward injection through the tubing is used to seal the formation, supplemented by reverse injection through the annulus to remove the blockage.

[0015] When the permeability of the horizontal well base is high, reverse injection into the annulus of the casing is used to seal the formation, supplemented by forward injection into the tubing to clean the casing blockage.

[0016] When the formation permeability near the horizontal section of a horizontal well is relatively uniform, alternating forward and reverse injections are adopted, with an equal amount of profile control agent injected in each round. This allows the profile control agent to enter the formation evenly while achieving the purpose of well washing.

[0017] Preferably, a casing and tubing are nested inside the horizontal well to be injected, with the tubing inside the casing, forming an annulus between the casing and the tubing.

[0018] Preferably, the length of the tubing is greater than the length of the casing, and the tubing is used to inject into the horizontal well section with higher permeability over a long distance, while the annulus of the tubing and casing is used to inject into the horizontal well section with higher permeability over a short distance.

[0019] Preferably, the permeability of the formation where the horizontal well to be injected is located is determined by geological and well logging data, and the time for forward and reverse injection is set according to the permeability distribution of the formation in the horizontal section of the horizontal well.

[0020] Preferably, when the permeability distribution at both ends of the horizontal well section to be injected is uneven, the forward injection time is 20-30 hours and the reverse injection time is 10-15 hours.

[0021] Preferably, when the permeability is uniform at both ends of the horizontal well section to be injected, the forward injection time and the reverse injection time are the same.

[0022] Preferably, both the forward injection time and the reverse injection time are 20-30 hours.

[0023] Preferably, when the permeability distribution at both ends of the horizontal well section to be injected is uneven, clean water is injected in reverse from the horizontal well section with the lowest permeability to remove the blockage.

[0024] Preferably, when the permeability at both ends of the horizontal well section to be injected is uniform, the amount of profile control agent injected alternately from both ends of the horizontal well section is the same.

[0025] Preferably, after the number of alternating injections of the profile control agent reaches a set threshold, clean water is injected into the horizontal section of the horizontal well through the annulus, and then the alternating injection of the profile control agent is repeated from both ends of the horizontal well section.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] This invention discloses a method for high-dose deep profile control injection in horizontal wells. Based on the measured permeability of the formation where the horizontal well is to be injected, when the permeability distribution at both ends of the horizontal well section is uneven, forward injection is performed to seal the formation in the section with the highest permeability, followed by reverse injection to remove the blockage in the section with the lowest permeability. This forward and reverse injection process is repeated to seal high-permeability areas using the injected material. Conversely, when the permeability at both ends of the horizontal well section is uniform, forward and reverse injection is performed alternately from both ends until a preset injection volume is reached. This completes the high-dose deep profile control injection in the horizontal well, significantly improving the uniformity of profile control agent distribution in the formation, enhancing the effectiveness of profile control operations, and extending the effective period of profile control. Furthermore, the injection time for forward and reverse injections can be adjusted to regulate the amount of profile control agent entering different areas of the horizontal section, enabling targeted control of high-permeability areas.

[0028] Preferably, the profile control agent is injected alternately through the tubing and annulus. When the fluid in the annulus flows through the particle deposition zone, the deposited particles are washed away by the water flow, which can unblock the horizontal section of the horizontal well and eliminate the biggest problem of injecting particulate profile control agents into horizontal wells. At the same time, the activated profile control agent can continue to enter the formation, which greatly saves profile control costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the formation in the horizontal section of the horizontal well in Embodiment 1 of the present invention.

[0030] Figure 2 This is a schematic diagram of the formation in the horizontal section of the horizontal well in Embodiment 2 of the present invention.

[0031] Figure 3 This is a schematic diagram of the formation in the horizontal section of the horizontal well in Embodiment 3 of the present invention.

[0032] In the picture:

[0033] 1 is a sleeve;

[0034] 2 is the oil pipe;

[0035] 3 represents the annulus of the oil sleeve. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] This invention provides a method for high-dose deep profile control injection in horizontal wells, employing different schemes based on the permeability distribution of different formations;

[0040] Regarding the distribution of formation permeability in horizontal wells:

[0041] The permeability distribution in horizontal well sections may be relatively uniform or uneven.

[0042] The permeability of the horizontal well section is relatively uniform, meaning the difference in permeability between the two ends of the horizontal well section is less than 5%. High-permeability layers are distributed at both ends of the horizontal well section. Figure 3 In the illustrated embodiment, the high-permeability layer is distributed throughout the entire horizontal well;

[0043] The permeability distribution at both ends of the horizontal well section is uneven, meaning that the high-permeability layer of the horizontal well section is located at one end of the horizontal well, or the permeability difference between the two ends of the horizontal well section to be injected is greater than 20%.

[0044] like Figure 1 or Figure 2 As shown, the high-permeability layer is located at the root or toe of the horizontal well. The high-permeability layer, medium-permeability layer, and low-permeability layer are distributed from one end of the horizontal well to the other end, with the high-permeability layer concentrated in one area.

[0045] Specifically, the following steps are included:

[0046] S1, detect the permeability of the formation where the horizontal well to be injected is located;

[0047] S2. First, inject profile control agent into the horizontal well section with the highest permeability to seal the formation. Inject profile control agent according to the preset injection time. After the forward injection is completed, inject in reverse from the horizontal well section with the lowest permeability to remove the blockage. Repeat the forward and reverse injection until the preset injection volume is reached, thereby completing the large-dose deep profile control injection in the horizontal well.

[0048] Specifically, casing and tubing are nested inside the horizontal well to be injected, with the tubing inside the casing, forming an annulus between the casing and tubing; the insertion length of the tubing is greater than the insertion length of the casing, and the tubing is used to inject into the horizontal well section with higher permeability at a longer distance (the toe of the horizontal well), while the annulus is used to inject into the horizontal well section with higher permeability at a shorter distance (the heel of the horizontal well).

[0049] The permeability of the formation where the horizontal well to be injected is located is determined by geological and well logging data. Based on the permeability distribution of the formation in the horizontal section of the horizontal well, the timing of forward and reverse injection is set.

[0050] The specific injection time is set according to the formation permeability distribution.

[0051] When the permeability distribution at both ends of the horizontal well section to be injected is uneven, the forward injection time is 20-30 hours and the reverse injection time is 10-15 hours.

[0052] Specifically, when the permeability of the horizontal well toe is high, the formation is sealed by forward injection through the tubing, and the blockage is cleared by reverse injection through the annulus of the auxiliary oil casing. Forward and reverse injections are repeated until the set injection volume is reached and then stopped.

[0053] When the permeability of the horizontal well base is high, reverse injection through the annulus of the casing is used to seal the formation, supplemented by forward injection through the tubing to clean the casing blockage. Reverse and forward injections are repeated until the set injection volume is reached and then stopped.

[0054] When the formation permeability near the horizontal section of a horizontal well is relatively uniform, alternating forward and reverse injections are adopted, with an equal amount of profile control agent injected in each round until the set injection volume is reached and then stopped. This allows the profile control agent to enter the formation evenly while achieving the purpose of well washing.

[0055] This invention provides a novel injection method that significantly improves the uniformity of profile control agent distribution in the formation, enhances the effectiveness of profile control operations, and extends the effective period of profile control. Furthermore, this invention allows for the adjustment of the amount of profile control agent entering different areas of the horizontal section by regulating the injection time of forward and reverse injections, enabling targeted control of high-permeability areas.

[0056] This invention employs alternating injection of profile control agents through tubing and annulus. When fluid flows through the particle deposition zone in the annulus, the deposited particles are washed away and moved by the water flow, which can unblock the horizontal section of the horizontal well. This eliminates the biggest problem of injecting particulate profile control agents into horizontal wells. At the same time, the activated profile control agent can continue to enter the formation, greatly saving profile control costs.

[0057] Example 1

[0058] When the permeability distribution at both ends of the horizontal well section to be injected is uneven, that is, when the high-permeability layer of the horizontal well section to be injected is located at one end of the horizontal well, or when the permeability difference between the two ends of the horizontal well section to be injected is greater than 20 percent.

[0059] like Figure 1 As shown, there is a horizontal injection well in the formation. The permeability of the formation near the horizontal section of the well shows a trend of high permeability at the root (point A) and low permeability at the toe (point B). It is necessary to carry out deep profile adjustment of the formation near the root (high permeability layer at point A) to ensure that subsequent water injection can flow into the medium and low permeability layers and start the crude oil in them.

[0060] First, a particulate suspension is injected into the formation through the annulus of the casing over a period of 24 hours. The suspension begins to contact the formation at the root region of the horizontal well and flows directly into it. Because the suspension flows from the root to the toe, the particles preferentially enter the high-permeability layer at the root, thus blocking it. In the subsequent well sections, the particle concentration decreases significantly, reducing damage to the medium and low-permeability layers.

[0061] The outlet of the oil sleeve annulus is located at the root (point A);

[0062] After continuous injection, some particles may settle under the influence of gravity. The settled particles gradually accumulate at the bottom of the casing, forming a blockage. Therefore, after the set injection time is reached, clean water is injected into the horizontal section of the horizontal well through the tubing for 12 hours.

[0063] The tubing outlet is located at the low toe (point B). The clean water injected into the tubing will flow into the horizontal well casing at the toe of the horizontal well and move towards the root of the horizontal well. During this process, the clean water can flush away the particles that remain and accumulate in the casing, achieving the purpose of washing the well, unblocking, and preventing the tubing from getting stuck and unable to be pulled out. In addition, the water flow will also drive the previously injected bulky particles, causing the particles to move further into the deeper formation.

[0064] Repeat the above steps of injecting particulate suspension into the formation through the annulus and injecting clean water into the horizontal section of the horizontal well through the tubing until the designed injection volume is reached, then end the injection.

[0065] Example 2

[0066] like Figure 2 As shown, there is a horizontal injection well in the formation. The permeability of the formation near the horizontal section of the well shows a trend of high permeability at the toe (point B) and low permeability at the root (point A), gradually decreasing from the toe to the root. It is necessary to carry out deep profile modification of the formation near the toe (point B) to ensure that subsequent water injection can flow into the medium and low permeability layers and start the crude oil in them.

[0067] First, a particulate suspension is injected into the formation through the tubing over a period of 20 hours. The tubing outlet is located at the toe (point B). After the suspension flows into the casing in the toe area of ​​the horizontal well, it begins to contact the formation and flows into the formation. Since the suspension flows from the toe to the root, the particles will preferentially enter the high-permeability layer in the toe, thus blocking the high-permeability layer.

[0068] After continuous injection, some particles may settle under the influence of gravity. The settled particles gradually accumulate at the bottom of the casing, forming a blockage. At this time, clean water is injected into the horizontal section of the horizontal well through the annulus for 10 hours. The outlet of the annulus is located at the root (point A). The clean water injected into the annulus will move from the root of the horizontal well to the toe.

[0069] During this process, clean water can flush away residual particles accumulated in the casing, achieving the purpose of well cleaning, unblocking, and preventing the tubing from getting stuck and unable to be retrieved. In addition, the water flow will also drive the previously injected bulky particles, causing the particles to move further into the deeper formation.

[0070] Repeat the steps described above: injecting particulate suspension into the formation through the tubing and injecting clean water into the horizontal section of the horizontal well through the annulus until the designed injection volume is reached.

[0071] Example 3

[0072] like Figure 3 As shown, the permeability of the horizontal well section to be injected is relatively uniform, that is, the permeability difference between the two ends of the horizontal well section is less than 5%.

[0073] There is a horizontal injection well in the formation. The formation permeability near the horizontal section of the well is relatively uniform. The permeability of the toe (point B) and the root (point A) is roughly the same. It is necessary to perform deep profile modification on the formation near the wellbore to ensure that subsequent water injection can flow into the medium and low permeability layers and start the crude oil in them.

[0074] First, a particulate suspension is injected into the formation through the tubing over a period of 20 hours. After flowing into the casing in the horizontal well toe area, the suspension begins to contact the formation and then flows into it.

[0075] The suspension flows from the toe to the root, and the particles preferentially enter the strata near the toe, blocking the strata near the toe.

[0076] Then, a particulate suspension is injected into the formation through the annulus of the casing and tubing over a period of 20 hours. The suspension begins to contact the formation in the root region of the horizontal well and flows directly into the formation. The suspension flows from the root to the toe, and the particles preferentially enter the root formation, thus sealing it.

[0077] The two steps described above, by alternately injecting the profile control agent in both directions, can ensure that the profile control agent enters the formation evenly and improve the sealing effect.

[0078] After continuous injection, some particles may settle under the influence of gravity. The settled particles gradually accumulate at the bottom of the casing, forming a blockage. When the number of alternating injections of the profile control agent reaches the set threshold, this application sets the number of alternating injections of the profile control agent to 4 times. At this time, clean water is injected into the horizontal section of the horizontal well through the annulus of the casing, and the injection time is 12 hours.

[0079] The water injected into the annulus of the casing will move from the root to the toe of the horizontal well. During this process, the water can flush away the particles that remain and accumulate in the casing, achieving the purpose of washing the well, unblocking, and preventing the tubing from getting stuck and unable to be pulled out. In addition, the water flow will also drive the previously injected bulky particles, causing the particles to move further into the deeper formation.

[0080] Repeat the above steps until the designed injection volume is reached.

[0081] This invention employs alternating injection of profile control agents through tubing and annulus. When fluid flows through the particle deposition zone in the annulus, the deposited particles are washed away and moved by the water flow, which can unblock the horizontal section of the horizontal well. This eliminates the biggest problem of injecting particulate profile control agents into horizontal wells. At the same time, the activated profile control agent can continue to enter the formation, greatly saving profile control costs.

[0082] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0083] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0084] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for large-dose deep profile control injection of horizontal wells, characterized in that, The method comprises the following steps: S1, detecting the permeability of the formation where the horizontal well to be injected is located; S2, when the permeability distribution of the two ends of the horizontal well section to be injected is uneven, first injecting the plugging formation in the positive direction of the horizontal well section with the largest permeability, injecting for a preset injection time, after the positive injection is completed, injecting in the reverse direction from the horizontal well section with the smallest permeability to clean the blockage; repeating the positive injection and the reverse injection until the preset injection amount is reached; When the permeability of the two ends of the horizontal well section to be injected is uniform, the positive and reverse injection is alternately performed from the two ends of the horizontal well section until the preset injection amount is reached, thereby completing the large-dose deep profile control injection of the horizontal well; The casing and the tubing are nested in the horizontal well to be injected, the tubing is nested in the casing, and the oil-casing annulus is formed between the casing and the tubing; The placement length of the tubing is greater than the placement length of the casing, the tubing is used to inject the horizontal well section with a large permeability at a long distance, and the oil-casing annulus is used to inject the horizontal well section with a large permeability at a short distance; When the permeability of the two ends of the horizontal well section to be injected is uniform, the positive injection time and the reverse injection time are the same; the positive injection time and the reverse injection time are both 20-30h.

2. The method according to claim 1, wherein, The permeability of the formation where the horizontal well to be injected is located is determined through geological and logging data, and the positive injection time and the reverse injection time are set according to the permeability distribution of the horizontal section of the horizontal well.

3. The method according to claim 1, wherein, When the permeability distribution of the two ends of the horizontal well section to be injected is uneven, the positive injection time is 20-30h, and the reverse injection time is 10-15h.

4. The method according to claim 1, wherein, When the permeability distribution of the two ends of the horizontal well section to be injected is uneven, the reverse injection of clean water is performed from the horizontal well section with the smallest permeability to clean the blockage.

5. The method according to claim 1, wherein, When the permeability of the two ends of the horizontal well section to be injected is uniform, the use amount of the profile control agent for the alternate injection from the two ends of the horizontal well section is the same.

6. The method according to claim 5, wherein, When the number of times of the positive and reverse alternate injection of the profile control agent reaches a set threshold, clean water is injected into the horizontal section of the horizontal well through the oil-casing annulus, and then the positive and reverse alternate injection of the profile control agent from the two ends of the horizontal well section is repeated.

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