Resin well cementation method for carbon dioxide injection well

Abstract

The invention discloses a resin well cementation method for a carbon dioxide injection well, which comprises the following steps of: calculating the annulus volume between a small-diameter casing string and an original well casing according to the specification parameters of the casing; a well killing hydraulic well is used, and after well killing is completed, the small-diameter casing string is lowered to the preset depth, and then a well mouth is installed; the method comprises the following steps: injecting a first solution into an annulus between a small-diameter casing string and an original well casing until well killing fluid in the annulus and the small-diameter casing is completely replaced by the first solution; after well killing fluid replacement is completed, a second solution with the same volume as the annulus volume is injected into the small-diameter casing string, the density of the second solution and the density of the first solution are close and both smaller than the density of the well killing fluid, the second solution and the first solution are different in color, and a high-strength carbon dioxide corrosion resistant resin slug is injected into the annulus pump; the technical problem of resin well cementation in the overflow state of the carbon dioxide injection well is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of well cementing, and relates to a carbon dioxide injection well resin cementing method. BACKGROUND

[0002] Carbon dioxide injection into the underground to enhance oil production is one of the important ways of carbon capture, utilization and storage (CCUS) and is also a key technology for improving the recovery of ultra-low permeability oil reservoirs. The lithology of the Chang 8 oil reservoir in Huang 3 area of Changqing Oilfield is dense, and the recovery rate is low by water injection. The average production of oil wells in the carbon dioxide flooding test area can be increased by more than 37%, the production of central wells is doubled, and the ultimate recovery rate is more than 34%. Under the guidance of the previous national CCUS demonstration project, Changqing Oilfield gradually expanded the carbon dioxide flooding industrial test in the old water injection wells, and adjusted the development mode from water flooding to carbon dioxide flooding. However, due to the service of the old water injection wells for many years, the casing is perforated and lost under the corrosion, and the wellbore integrity is poor, which seriously affects the enhanced oil production effect of carbon dioxide flooding. Therefore, before converting to carbon dioxide injection, wellbore reconstruction needs to be performed by using small casing cementing.

[0003] Since the traditional silicate cement has poor carbon dioxide corrosion resistance, in order to ensure the interlayer sealing effect during long-term carbon dioxide injection, a high-strength resin system with carbon dioxide corrosion resistance needs to be used instead of the G-grade cement slurry system. However, when the resin cementing is performed by using the positive circulation in the carbon dioxide injection well, the following four problems mainly exist.

[0004] 1. High-density kill fluid makes resin system slip up

[0005] Long-term water injection development and reservoir heterogeneity cause part of the reservoir to become a high-pressure water layer, and the formation pressure coefficient is generally high. The wellhead pressure relief is slow and the period is long, and usually, well killing needs to be performed before resin cementing. The density of the kill fluid is 1.3-1.5 g / cm 3 , which is higher than the density of the high-strength carbon dioxide corrosion-resistant resin system. When the resin system returns to the external annulus from the small-diameter casing shoe during conventional positive circulation cementing, the resin system slips up and migrates under the action of the density difference between the resin system and the kill fluid, causing the small casing bottom to be empty, which is difficult to meet the cementing requirements during long-term carbon dioxide injection.

[0006] 2. Low success rate, complex process, and high cost of plugging high-pressure water layer

[0007] After the well is killed by using the kill fluid, the high-pressure water layer is plugged and set by using the plugging agent, and then the plug is drilled, the pressure is tested, and the wellbore is not overflowed. If the original casing has multiple loss positions, multiple plugging, setting, drilling, and pressure testing processes are usually required, and the success rate of the high-pressure water layer plugging process is low, which easily causes a long well occupation period and a sharp increase in operation cost.

[0008] 3. Wellbore upper resin system super-retarding

[0009] Due to the depth of 2800-3000m of the 8th long section, the longitudinal difference of wellbore temperature is large, the upper temperature is 30-40℃, and the wellbore temperature near the reservoir is 85-95℃. When the conventional positive circulation resin cementing is used, in order to prolong the curing time of the resin under high temperature conditions and ensure the safety of field construction, a high-temperature curing agent and resin are compounded to form a cementing fluid, and two different resin systems with different curing temperatures cannot be used, and the high-temperature curing agent needs to be used to adjust the curing time of the resin system. When the plug is displaced to the position, the high-temperature curing agent and resin compound cementing fluid returns to the upper well section, because the temperature of the upper formation is low, the cementing fluid system appears super-retarding, and even does not cure.

[0010] 4. The conventional resin system is prone to sedimentation replacement during injection

[0011] The high-strength carbon dioxide corrosion-resistant resin system used in the prior art is usually not soluble in water, not miscible with water, and the density is 1.1-1.2g / cm 3 When the wellbore is filled with high-density kill fluid (higher than 1.2g / cm 3 ), during the plug displacement of the positive circulation cementing, due to the overflow of the high-pressure water layer and the "floating" ability of the resin, the upward slipping and replacement speed of the resin in the annulus between the small casing and the original well casing is accelerated, so that the actual resin amount in the annulus is reduced; at the same time, after the plug is displaced to the position, the high-density kill fluid in the annulus is replaced by the resin and a small amount of formation water, and the liquid column pressure in the annulus between the small casing and the original well casing is obviously reduced. Even in the case of casing gate closed, the liquid in the formation will still invade the annulus. During the setting process, the resin in the lower part of the annulus between the small casing and the original well casing will be replaced by the high-density kill fluid in the upper part, so that the cementing quality of the bottom of the wellbore or the formation near the reservoir is poor, and even the empty casing phenomenon occurs, which cannot effectively solve the long-term sealing problem between layers.

[0012] Therefore, it is urgent to develop a resin cementing method suitable for carbon dioxide injection wells to improve the cementing quality of the wellbore and improve the sealing effect of the formation. SUMMARY

[0013] The purpose of the present application is to provide a carbon dioxide injection well resin cementing method, which solves the empty casing phenomenon at the bottom of the small casing by replacing the kill fluid; by using the resin which can be partially miscible with water, pumping the high-temperature curing resin in the annulus first, and then pumping the high-temperature curing resin in the annulus, the super-retarding problem of the high-strength carbon dioxide corrosion-resistant resin system in the upper well section is avoided, and the cementing effect of the small-diameter casing is effectively improved.

[0014] In order to achieve the above purpose, the present application provides the following technical scheme:

[0015] A resin cementing method for carbon dioxide injection well, comprising the following steps:

[0016] Determination of parameters: according to the casing specification parameters, the annular volume between the small diameter casing string and the original well casing is calculated;

[0017] Installation of wellhead: the well is pressureed with kill fluid, and after the well is pressureed, the small diameter casing string is lowered to the predetermined depth, and then the wellhead is installed;

[0018] Kill fluid replacement: after the installation of the wellhead is completed, the first solution is injected into the annulus between the small diameter casing string and the original well casing until the kill fluid in the annulus and the small diameter casing is completely replaced by the first solution;

[0019] Pumping resin: after the kill fluid replacement is completed, the second solution with the same volume as the annular volume is injected into the small diameter casing string, the density of the second solution is close to and less than the density of the kill fluid, the second solution is different in color from the first solution, and the high-strength carbon dioxide corrosion-resistant resin plug is pumped into the annulus until the second solution is completely discharged;

[0020] Cementing: after the resin pumping is completed, the squeeze pressure holding is stopped, and the cementing is completed.

[0021] Further, when the well is pressureed with kill fluid, the kill fluid density is obtained according to the maximum shut-in pressure, and the wellhead is not overflowed after the well is pressureed, and the well pressure is completed.

[0022] Further, the small diameter casing string structure comprises a float shoe and a small diameter casing from bottom to top, and the float shoe is not provided with a one-way valve.

[0023] Further, the first solution is clear water; and the second solution is a mixture of clear water and pigment.

[0024] The second solution can directly add ordinary red or blue pigment to clear water and stir uniformly, can be miscible with the clear water in the wellbore before cementing, and a certain miscible plug will be generated at the interface during the actual displacement process, but the density difference between the two is very small, and the length of the miscible plug is almost negligible.

[0025] Further, the high-strength carbon dioxide corrosion-resistant resin plug has a density of 1.03-1.05 g / cm 3 , and is miscible with clear water.

[0026] Further, the high-strength carbon dioxide corrosion-resistant resin is obtained by mixing a soluble resin emulsion and a curing agent, and the preparation of the soluble resin emulsion comprises: an epoxy resin, polyethylene glycol and a boron trifluoride ether solution, a non-ionic emulsifier is obtained by warming reaction; then the epoxy resin is taken and added to the above non-ionic emulsifier, mixed and stirred uniformly to obtain a mixed solution, then distilled water is added to the mixed solution, and continues to be stirred to obtain a soluble resin emulsion.

[0027] Further, the water-soluble resin emulsion

[0028] In a three-necked flask, add epoxy resin (E-51) and polyethylene glycol and a catalytic amount of boron trifluoride ether solution, and heat to 80°C for 2h to obtain a non-ionic emulsifier; then take a certain amount of epoxy resin, add it to the above non-ionic emulsifier, mix and stir uniformly. Then add distilled water to the mixed solution, continue to stir for 0.5h to prepare.

[0029] Further, the high-strength carbon dioxide corrosion resistant resin plug comprises a low-temperature curing resin and a high-temperature curing resin, the high-temperature curing resin is pumped into the annulus first, and then the low-temperature curing resin is pumped into the annulus, the curing temperature of the low-temperature curing resin is 30-40°C, and the curing temperature of the high-temperature curing resin is 80-95°C.

[0030] The low-temperature curing resin and the high-temperature curing resin differ in that different curing agents with different curing temperatures are used.

[0031] Further, the injection amount of the high-temperature curing resin is the product of the annular area between the bottom boundary of the low-temperature curing resin plug and the well bottom and the original well casing and small casing, plus an additional 5% volume; the injection amount of the low-temperature curing resin is the annular volume between the wellhead and the bottom boundary of the low-temperature curing resin plug and the original well casing, plus an additional 5% volume, and the bottom boundary of the low-temperature curing resin plug is 300-600m from the wellhead.

[0032] Further, the high-strength carbon dioxide corrosion resistant resin front is pumped into the casing float shoe before pumping, and the resin pumping is completed.

[0033] Further, after the resin pumping is completed, the squeeze pressure holding is stopped and the cementing is completed after 48h.

[0034] The application also provides a resin cementing method for carbon dioxide injection wells,

[0035] S1 According to the maximum shut-in pressure, the kill fluid density is converted, and the wellhead is circulated after killing without overflow;

[0036] S2 Open the wellhead, lower the small-diameter casing string to the designed depth, and then install the wellhead; use the pump truck to squeeze clean water, and circulate and replace the kill fluid in the wellbore;

[0037] S3 Calculate the annular volume between the small-diameter casing and the original well casing, and inject the same volume of colored clean water into the small-diameter casing;

[0038] S4 Two high-strength carbon dioxide corrosion resistant resin systems are squeezed from the annulus between the small-diameter casing and the original well casing until the front of the resin system reaches the casing float shoe position, that is, the colored clean water completely returns to the wellhead, and the squeezing is stopped.

[0039] S5 hold pressure for 48h.

[0040] As optimization, in step S1, the equivalent density of the well control fluid is converted according to the maximum shut-in pressure.

[0041] As optimization, in step S2, the casing string structure comprises a float shoe and a small-diameter casing from bottom to top, and the float shoe is without built-in check valve, and the wellhead can realize forward and reverse squeeze.

[0042] As optimization, in step S3, the volume of the annulus between the small-diameter casing and the original well casing needs to be accurately calculated, and the same volume of colored clean water is pumped into the small-diameter casing.

[0043] As optimization, in step S3, when the high-strength carbon dioxide corrosion resistant resin system flows down in the annulus between the small-diameter casing and the original well casing, the colored clean water in the small-diameter casing returns from the wellhead, and the displacement during pumping is basically equal to the displacement during return.

[0044] As optimization, in step S4, the high-strength carbon dioxide corrosion resistant resin system can be partially miscible with clean water, and the density is 1.03-1.05g / cm 3 .

[0045] As optimization, in step S4, the first injected resin system is cured at a high temperature of 80-95℃, and the second injected resin system can be cured at a low temperature of 30-40℃.

[0046] As optimization, in step S4, when the colored clean water is completely returned, pumping is immediately stopped, so that the front edge of the high-strength carbon dioxide corrosion resistant resin system in the annulus between the small-diameter casing and the original well casing just reaches the position of the casing float shoe, and the plug face in the small-diameter casing is prevented from being too high.

[0047] As optimization, in step S4, after the high-strength carbon dioxide corrosion resistant resin system is pumped into place, clean water displacement is not needed.

[0048] Beneficial effects:

[0049] The well injection method is suitable for the working conditions of small-diameter casing cementing of high-pressure water layer overflow and large longitudinal difference of wellbore temperature, avoids complex treatment procedures caused by high-pressure water layer plugging before cementing, and improves the construction efficiency.

[0050] The application solves the problem of empty casing at the bottom of the small casing by replacing the kill fluid; solves the problem of causing the cementing fluid system to appear super-retarding setting or even not setting by first pumping the high-temperature curing resin in the annulus and then pumping the high-temperature curing resin in the annulus; solves the problem of the resin at the lower part of the annulus between the small casing and the original well casing being replaced by the high-density kill fluid at the upper part during the setting process, which causes the cementing quality of the wellbore bottom or the formation near the reservoir to be poor, even the empty casing phenomenon occurs, and the long-term sealing problem between layers cannot be effectively solved.

[0051] The resin cementing fluid system disclosed in the application has a density of 1.03-1.05 g / cm 3 , can be partially miscible with clear water, and slows down the settlement and replacement during the pumping and shut-in setting stages; the application adopts a two-section resin system with different curing temperatures to avoid the super-retarding setting problem of the resin system at the upper well section. The resin cementing method for carbon dioxide injection wells disclosed in the application can significantly improve the construction efficiency of small-diameter casing cementing in overflow wells of water-pressured layers, avoid the super-retarding setting problem of the high-strength carbon dioxide corrosion-resistant resin system at the upper well section, effectively improve the cementing effect of small-diameter casings, and realize long-term management of formation sealing. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0053] Figure 1 A schematic diagram for pumping colored clear water into the small-diameter casing.

[0054] Figure 2 A schematic diagram for the front edge of the high-strength carbon dioxide corrosion-resistant resin system reaching the casing float shoe position.

[0055] In the figure, ① is colored clear water; ② is clear water; and ③ is a high-strength carbon dioxide corrosion-resistant resin system. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0057] Embodiment 1

[0058] A resin cementing method for carbon dioxide injection well, the specific steps are:

[0059] S1 According to the highest shut-in pressure P0, the circulating pressure control fluid density is calculated, and the wellhead is overflow-free after circulating.

[0060] S2 Open the wellhead, pull out the pressure control pipe column, lower the φ114.3mm direct connection type casing column to the designed depth, install the wellhead, and shut in the well. Pump clean water between the φ114.3mm direct connection type casing and the original well casing annulus, circulate and replace the pressure control fluid in the wellbore, control the displacement of 200-300L / min during the pumping process, and adjust the throttle valve opening of the wellhead return pipeline in real time, so that the pumping displacement and the return displacement are basically equal.

[0061] S3 Close the casing gate, and inject the same volume of colored clean water into the φ114.3mm direct connection type casing, and then shut in the well.

[0062] S4 While adjusting the throttle valve opening of the wellhead return pipeline, extrude the high-strength corrosion-resistant resin system between the φ114.3mm direct connection type casing and the original well casing, control the pumping displacement not to exceed 300L / min, control the extrusion pressure not to exceed 25MPa, until the front edge of the high-strength carbon dioxide corrosion-resistant resin system reaches the casing float shoe position, that is, the colored liquid is completely returned to the wellhead, and the extrusion is stopped.

[0063] S5 Shut in and wait for pressure and condensation.

[0064] In step S4, during the process of extruding the high-strength carbon dioxide corrosion-resistant resin between the small-diameter casing and the original well casing annulus, in order to ensure that the high-pressure water layer does not overflow into the wellbore and does not affect the volume of the returned colored clean water, a certain back pressure needs to be applied to the return and discharge outlet inside the small-diameter casing, that is, the wellhead return pressure is maintained at (P0+0.5)MPa, until the front edge of the high-strength carbon dioxide corrosion-resistant resin system reaches the casing float shoe position.

[0065] Example 2

[0066] Based on the above-mentioned embodiments, in this embodiment, the high-strength carbon dioxide corrosion-resistant resin system in step S4 is a high molecular compound, which is modified by introducing hydrophilic groups into the epoxy resin structure to have certain solubility in water. At the same time, a proper amount of graphite filler is added to reduce the density to 1.03-1.05 g / cm3. Then, according to the longitudinal distribution characteristics of the wellbore temperature, two different temperature curing agents are adjusted, so that the curing time at 30-40℃ and 80-95℃ is 3-4h, and the compressive strength after 48h curing is 60-70MPa, which better adapts to the longitudinal distribution of the wellbore temperature and meets the requirements of field construction and cementing quality.

[0067] The application innovatively proposes a carbon dioxide injection well resin cementing method, which can be used for cementing construction under the condition of high-pressure water layer overflow, avoiding complex procedures and reservoir pollution caused by high-pressure water layer plugging. The use of two different curing temperature high-strength carbon dioxide corrosion-resistant resin system slugs can better adapt to the well conditions with large longitudinal difference of wellbore temperature. According to the return of colored clear water, the pumping parameters of high-strength carbon dioxide corrosion-resistant resin are optimized, the position of resin front in the annulus of small-diameter casing and original well casing is accurately controlled, and the problem of high plug face in small-diameter casing is effectively prevented.

[0068] The above is a specific description of the application by means of embodiments. It is necessary to point out that the embodiments are only preferred embodiments of the application, and do not limit the application in any way. Any simple modification or change of the embodiments according to the technical essence of the application still belongs to the protection scope of the technical solution of the application. The methods not described in detail in the embodiments are all prior art, and the application will not be described one by one.

Claims

1. A resin cementing method for a carbon dioxide injection well, characterized by, The method comprises the following steps: Determination of parameters: according to the casing specification parameters, the annular volume between the small-diameter casing string and the original well casing is calculated; Wellhead installation: the well is pressed using the kill fluid, and after the well is pressed, the small-diameter casing string is lowered to a predetermined depth, and then the wellhead is installed; Kill fluid replacement: after the wellhead is installed, the first solution is injected into the annulus between the small-diameter casing string and the original well casing until the kill fluid in the annulus and the small-diameter casing is completely replaced by the first solution; Resin pumping: after the kill fluid replacement is completed, the second solution with a volume equal to the annular volume is injected into the small-diameter casing string, the density of the second solution is close to and smaller than the density of the kill fluid, the second solution is different in color from the first solution, and the high-strength carbon dioxide corrosion-resistant resin plug is pumped into the annulus until the second solution is completely discharged; Cementing: after the resin pumping is completed, the squeezing is stopped, the pressure is held, and the cementing is completed.

2. The method of cementing a well as defined in claim 1, characterized in that, When the well is pressed using the kill fluid, the kill fluid density is obtained according to the maximum shut-in pressure, the wellhead is not overflowed after the well is pressed, and the well pressing is completed.

3. The method of cementing a well as defined in claim 1, characterized in that, The small-diameter casing string structure comprises a float shoe and a small-diameter casing from bottom to top, and the float shoe is not provided with a one-way valve.

4. The method of claim 1, wherein, The first solution is clear water, and the second solution is a mixture of clear water and pigment.

5. The method of claim 1, wherein, The resin plug has a density of 1.03-1.05 g / cm 3 are partially miscible with water.

6. The method of cementing a well as defined in claim 5, characterized in that, The high-strength carbon dioxide corrosion-resistant resin is obtained by mixing a soluble resin emulsion and a curing agent, and the preparation of the soluble resin emulsion comprises: an epoxy resin, polyethylene glycol, and a boron trifluoride ether solution, a non-ionic emulsifier is obtained by warming reaction; then the epoxy resin is taken and added to the above non-ionic emulsifier, mixed and stirred uniformly to obtain a mixed solution, then distilled water is added to the mixed solution, and continuous stirring is carried out to obtain a soluble resin emulsion.

7. The method of claim 1, wherein, The high-strength carbon dioxide corrosion-resistant resin plug comprises a low-temperature curing resin and a high-temperature curing resin, the high-temperature curing resin is first pumped into the annulus, and then the high-temperature curing resin is pumped into the annulus, the curing temperature of the low-temperature curing resin is 30-40℃, and the curing temperature of the high-temperature curing resin is 80-95℃.

8. The method of claim 6, wherein, The injection amount of the high-temperature curing resin is the product of the annular area between the bottom boundary of the low-temperature curing resin plug and the well bottom and the original well casing and the small casing, and an additional volume of 5%; the injection amount of the low-temperature curing resin is the annular volume between the wellhead and the bottom boundary of the low-temperature curing resin plug and the original well casing, and an additional volume of 5%, and the bottom boundary of the low-temperature curing resin plug is at a depth of 300-600m underground.

9. The method of claim 3, wherein, The front edge of the high-strength carbon dioxide corrosion-resistant resin is pumped into the annulus to the casing float shoe, and the resin pumping is completed.

10. The method of claim 1, wherein, After the resin pumping is completed, the squeezing is stopped, the pressure is held for 48h, and the cementing is completed.

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