Disclosure of Invention
The invention aims to provide a gel water shutoff agent suitable for water shutoff of a high-salinity ultrahigh-temperature oil reservoir, which can be well suitable for water shutoff construction of a high-salinity fracture-cavity oil reservoir ultra-deep well in a high-temperature high-salinity oil field.
In order to achieve the purpose, the invention provides a gel water shutoff agent, wherein the gel water shutoff agent comprises the following raw materials:
negative non-ionic polyacrylamide, anionic polyacrylamide, a cross-linking agent A, a cross-linking agent B, an antacid stabilizer, a metal cation stabilizer, an inorganic salt nano-stabilizer and water; wherein, the cross-linking agent A is one or the combination of more than two of aldehyde cross-linking agents and aldehyde derivative cross-linking agents; the crosslinking agent B is one or the combination of more than two of phenol crosslinking agents; wherein the metal cation stabilizer is a nickel cation stabilizer;
based on the mass of the raw materials of the gel water plugging agent, the mass percentage of the negative non-ionic polyacrylamide is 0.5-0.7%, the mass percentage of the cross-linking agent A is 0.9-1.1%, the mass percentage of the cross-linking agent B is 0.9-1.1%, the mass percentage of the antacid stabilizer is 0.1-0.3%, the mass percentage of the metal cation stabilizer is 0.1-0.3%, and the mass percentage of the inorganic salt nano stabilizer is 0.1-0.3%.
The gel water shutoff agent provided by the invention realizes the improvement of the strength, the salt resistance, the temperature resistance and the stability of a polymer gel system by utilizing a high-content organic phenolic aldehyde crosslinking system and simultaneously using three types of stabilizers. The high-content cross-linking agent A and the high-content cross-linking agent B enhance the thermal stability of a high-temperature polymer gel system and reduce the separation effect of a polymer main agent and the cross-linking agent; on the basis, the acid-resistant stabilizer, the metal cation stabilizer and the inorganic salt nano stabilizer are added into the high-temperature polymer gel system at the same time, so that more water locking points are provided for the three-dimensional grid-shaped cross-linked polymer solution, the thermal stability is improved, meanwhile, the hypersalinity water corrosion is effectively inhibited, and a more stable structure is formed (as shown in figure 1).
In the above gel plugging agent, preferably, the raw material composition of the gel plugging agent further comprises 0.7-0.9% of an oxygen scavenger based on the raw material mass of the gel plugging agent; more preferably, the oxygen scavenger is selected from urea and/or thiourea;
in a specific embodiment, the gel water shutoff agent comprises the following raw materials in percentage by mass:
0.5-0.7% of negative non-ionic polyacrylamide, 0.5-0.7% of anionic polyacrylamide, 0.9-1.1% of cross-linking agent A, 0.9-1.1% of cross-linking agent B, 0.7-0.9% of deoxidant, 0.1-0.3% of antacid stabilizer, 0.1-0.3% of metal cation stabilizer, 0.1-0.3% of inorganic salt nano stabilizer and the balance of water;
wherein, the cross-linking agent A is one or the combination of more than two of aldehyde cross-linking agents and aldehyde derivative cross-linking agents; the crosslinking agent B is one or the combination of more than two of phenol crosslinking agents; wherein the metal cation stabilizer is a nickel cation stabilizer.
In the above gel blocking agent, preferably, the average molecular weight of the anionic or nonionic polyacrylamide is 700000-800000 daltons.
In the above gel blocking agent, preferably, the average molecular weight of the anionic polyacrylamide is 400000-500000 daltons.
In the above gel water shutoff agent, preferably, the crosslinking agent a is formaldehyde and/or urotropine. When urotropine is used as the crosslinking agent A, the urotropine slowly releases formaldehyde and ammonia gas at the formation temperature, the formaldehyde reacts with the crosslinking agent B to form a phenolic aldehyde pre-polymerization crosslinking body, the gelling time of a polymer gel system is prolonged, the thermal stability of the polymer gel system is further improved, and the separation effect of a polymer main agent and the crosslinking agent is effectively reduced.
In the above gel water shutoff agent, preferably, the crosslinking agent B is catechol, hydroquinone and/or resorcinol.
In the above gel water shutoff agent, preferably, the antacid stabilizer is scleroglucan.
In the above gel blocking agent, preferably, the metal cation stabilizer is nickel chloride.
In the above gel water shutoff agent, preferably, the inorganic salt nano stabilizer is selected from nano silica.
In the above gel water shutoff agent, the water may be distilled water or saline water (e.g., formation water, simulated formation water, etc.); preferably, the degree of mineralization of said water does not exceed 25 x 104mg/L。
The invention also provides a preparation method of the gel water shutoff agent, wherein the method comprises the following steps:
adding an antacid stabilizer to water to obtain a first solution;
respectively dissolving anionic polyacrylamide and anionic polyacrylamide in the first solution to obtain an anionic polyacrylamide solution and an anionic polyacrylamide solution;
mixing a negative non-ionic polyacrylamide solution and an anionic polyacrylamide solution, and adding a cross-linking agent A and a cross-linking agent B to obtain a second solution;
and dissolving inorganic salt nano stabilizer and metal cation stabilizer in the second solution in sequence to prepare the gel water shutoff agent.
In the above preparation method, preferably, when the raw material composition of the gel water shutoff agent contains an oxygen scavenger, the oxygen scavenger is added simultaneously with the crosslinking agent a and the crosslinking agent B.
In one embodiment, the preparation method of the gel water shutoff agent comprises the following steps:
the method comprises the following steps: taking a certain amount of water, adding an antacid stabilizer into the water, and stirring the mixture for at least 0.5h at the stirring speed of 800-;
step two: taking part of the first solution, slowly adding the anionic and nonionic polyacrylamide under the stirring condition of 200-300rpm, and continuously stirring for 1-1.5h at the stirring speed of 200-300rpm until the anionic and nonionic polyacrylamide is completely dissolved to obtain an anionic and nonionic polyacrylamide solution; the obtained anionic and nonionic polyacrylamide solution is a homogeneous solution which is as transparent as possible and has no fish eye blocking substances;
step three: taking the other part of the first solution, slowly adding the anionic polyacrylamide under the stirring condition of 200-300rpm, and continuously stirring at the stirring speed of 200-300rpm for 1-1.5h until the anionic polyacrylamide is completely dissolved to obtain an anionic polyacrylamide solution; the obtained anionic polyacrylamide solution is as transparent as possible and is a homogeneous solution without fish eye blocking substances;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully dissolved;
step five: on the basis of the fourth step, adding a cross-linking agent A, a cross-linking agent B and an oxygen scavenger into the mixed solution, and stirring at the stirring speed of 200-300rpm for 20-30min until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, adding the inorganic salt nano stabilizer into the second solution, and stirring for 30-45min at the stirring speed of 200-300rpm until all the powder is completely dissolved; then, continuing to add the metal cation stabilizer, and stirring for 5-10min at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain the gel water plugging agent.
The gel water shutoff agent provided by the invention is a self-repairing pre-crosslinked gel system, and the shear stress is basically kept unchanged at a constant shear rate. Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
1. can be directly used with a mineralization value lower than 25 × 104Preparation of mg/L formation water, greatly reducingThe construction cost of the mine field is low, and the final gelling performance of the rubber composition comprises a stable period and the colloid strength and the like are not influenced.
2. The gel can tolerate the high temperature of not less than 170 ℃, has good thermal stability, can still effectively gel under the conditions of ultrahigh temperature and high salt, has low dehydration rate after gelling, and can be suitable for the water plugging requirement of high-temperature and high-salt oil fields (such as Tahe oil fields) with well depth of more than 6000m and ultrahigh reservoir temperature.
3. After being gelatinized, the colloid has high strength and good plugging performance.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and completely with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the embodiment of the invention, the dehydration rate is determined by the following formula:
wherein S is dehydration rate,%; v is the gel volume at the onset of the gel; vt is the gel volume after the aging time t.
Example 1
The embodiment provides a gel plugging agent SPG1, wherein the gel plugging agent is prepared by:
the method comprises the following steps: taking 100mL of simulated saltWater (16 g NaCl, 7g CaCl per 100ml deionized water)2And 1g of MgCl2Prepared to obtain the product with the total mineralization degree of 24 multiplied by 104mg/L) is put into a beaker, 0.2g of acid-fast stabilizer scleroglucan is added into the simulated saline under the stirring condition of a magnetic stirrer (the stirring speed is 800-;
step two: taking part of the first solution, stirring by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step three: taking the other part of the first solution, stirring the first solution by a magnetic stirrer, slowly adding 0.6g of anionic polyacrylamide (with the average molecular weight of 400000-;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h by using a magnetic stirrer at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully mutually soluble;
step five: on the basis of the fourth step, adding 1.0g of urotropine, 1.0g of hydroquinone and 0.8g of thiourea into the mixed solution, and stirring for 20-30min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, 0.2g of nano silicon dioxide is added into the second solution, and a magnetic stirrer is used for stirring for 30-45min at the stirring speed of 200-300rpm until all the powder is completely dissolved; then, 0.2g of nickel chloride is continuously added, and the mixture is stirred for 5-10min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved, so as to obtain the gel water plugging agent.
The gel water shutoff agent prepared in the embodiment is kept stand in a high-temperature oven at 170 ℃ for about 2-4H to gelatinize, the colloid strength of the formed colloid reaches H-I grade through evaluation by a visual code method, and the dehydration rate of 120 days at 170 ℃ is less than 30%.
Example 2
The embodiment provides a gel plugging agent SPG2, wherein the gel plugging agent is prepared by:
the method comprises the following steps: taking 100mL of formation water (a water sample is provided by a Tahe oilfield oil extraction second factory, the mineralization degree is 240g/L), putting the formation water into a beaker, adding 0.2g of acid-resistant stabilizer scleroglucan into the simulated saline water under the stirring condition of a magnetic stirrer (the stirring speed is 900rpm), and continuing stirring for 0.5h until the acid-resistant stabilizer scleroglucan is completely dissolved to obtain a first solution;
step two: taking part of the first solution, stirring by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step three: taking the other part of the first solution, stirring the first solution by a magnetic stirrer, slowly adding 0.6g of anionic polyacrylamide (with the average molecular weight of 400000-;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h by using a magnetic stirrer at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully mutually soluble;
step five: on the basis of the fourth step, adding 1.0g of urotropine, 1.0g of hydroquinone and 0.8g of thiourea into the mixed solution, and stirring for 20-30min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, 0.2g of nano silicon dioxide is added into the second solution, and a magnetic stirrer is used for stirring for 30-45min at the stirring speed of 200-300rpm until all the powder is completely dissolved; then, 0.2g of nickel chloride is continuously added, and the mixture is stirred for 5-10min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved, so as to obtain the gel water plugging agent.
The gel water shutoff agent prepared in the embodiment is kept stand in a high-temperature oven at 170 ℃ for about 2-4H to gelatinize (as shown in fig. 2A and fig. 2B), the colloid strength of the formed colloid reaches H-I grade by adopting a visual code method, and the dehydration rate of 105 days at 170 ℃ is less than 30%.
Experimental example 1
The experimental example provides a series of gel water shutoff agent performance tests, wherein the gel water shutoff agents are only different in that the addition amounts of the metal cation stabilizer nickel chloride are respectively as follows: 0%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1%. The preparation method of the gel specifically comprises the following steps:
the method comprises the following steps: 100mL of simulated saline (16 g NaCl, 7g CaCl per 100mL of deionized water)2And 1g of MgCl2Prepared to obtain the product with the total mineralization degree of 24 multiplied by 104mg/L) is put into a beaker, 0.2g of acid-fast stabilizer scleroglucan is added into the simulated saline under the stirring condition of a magnetic stirrer (the stirring speed is 800-;
step two: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step three: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h by using a magnetic stirrer at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully mutually soluble;
step five: on the basis of the fourth step, adding 1.0g of urotropine, 1.0g of hydroquinone and 0.8g of thiourea into the mixed solution, and stirring for 20-30min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, 0.2g of nano silicon dioxide is added into the second solution, and a magnetic stirrer is used for stirring for 30-45min at the stirring speed of 200-300rpm until all the powder is completely dissolved; and then, continuously adding nickel chloride according to the addition amount of the metal cation stabilizer nickel chloride, and stirring for 5-10min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain the gel water plugging agent.
The properties of these gel water-blocking agents are shown in Table 1.
TABLE 1
Experimental example 2
The experimental example is used for testing the plugging capability of the gel plugging agent provided in example 1, and a one-dimensional core plugging experiment under different crack opening degrees is performed by specifically adopting the following method:
1. preparing three one-dimensional fracture simulation rock cores F1, F2 and F3 with different fracture openness, wherein the fracture openness is 1mm, 3mm and 5mm respectively;
selecting two marble plates A, B with the same size, cutting the marble A into 3 blocks with the same size, namely A1, A2 and A3, and cutting the marble B into 3 blocks with the same size, namely B1, B2 and B3; bonding A1 and B1 by using epoxy resin, drilling holes at the outlet end and the inlet end, cleaning, connecting pipelines, and manufacturing a one-dimensional fracture simulation rock core F1 with the fracture size of 30cm in length, 4.5cm in width and 1mm in opening degree; bonding A2 and B2 by using epoxy resin, drilling holes at the outlet end and the inlet end, cleaning, connecting pipelines, and manufacturing a one-dimensional fracture simulation rock core F2 with the fracture size of 30cm in length, 4.5cm in width and 3mm in opening degree; bonding A3 and B3 by using epoxy resin, drilling holes at the outlet end and the inlet end, cleaning, connecting pipelines, and manufacturing a one-dimensional fracture simulation rock core F3 with the fracture size of 30cm in length, 4.5cm in width and 5mm in opening degree;
2. in an oven, 2PV formation water injection (outlet end is driven by water) is carried out at the speed of 0.5ml/min on one-dimensional fracture simulation cores F1, F2 and F3 respectively to record the injection pressure delta p1Then, the injection pressure Δ p of the gel blocking agent SPG1 of 0.52PV was recorded at a rate of 0.5ml/min2Adjusting the temperature of the oven to 150 ℃, standing for 3 hours, injecting water again to record the injection pressure delta p3And calculating the plugging rate. The results are shown in Table 2.
TABLE 2
Core numbering
|
Core opening (mm)
|
Δp1(kPa)
|
Δp2(kPa)
|
Δp3(kPa)
|
Plugging rate
|
F1
|
1
|
0.81
|
100.82
|
103.85
|
82.46%
|
F2
|
3
|
0.46
|
96.42
|
96.86
|
90.27%
|
F3
|
5
|
0.21
|
92.05
|
96.17
|
87.69% |
Experimental example 3
The experimental example provides the field application verification of the gel water shutoff agent provided by the invention.
Before the gel water shutoff agent system is used for water shutoff, a certain oil well of the Tahe oil field is subjected to water shutoff for many times, and the oil increment for 3 months is difficult to achieve. The well belongs to a typical high-salt high-temperature fracture-cave carbonate reservoir well, the reservoir body of the oil well develops in a fracture mode, the well depth is 5703m, the salinity of saline water is 207608mg/L, and the formation temperature is as high as 125-. Injecting 50m from 6 months, 20 days to 24 days in 20203After the gel water shutoff agent provided by the invention is used for stewing for one week, under the condition of not changing the liquid production amount, the well water content is reduced from 90 percent to 50 percent, the crude oil yield is increased from 5t/d to 15t/d, the later record shows that the oil well stably produces for 3 months, and the accumulated yield is increased by 1000 t. As shown in fig. 3.
In the experimental example, the gel plugging agent provided by the invention is prepared in the following manner:
adding oil field water into an on-site stirring tank, adding 0.2 wt% of scleroglucan into the oil field water, then adding 0.6 wt% of polyacrylamide A and 0.6 wt% of polyacrylamide B according to the percentage, then adding 1.0 wt% of hydroquinone, 1.0 wt% of urotropine, 0.8 wt% of thiourea, 0.2 wt% of nano silicon dioxide and 0.1 wt% of metal cation stabilizer, and fully stirring and dissolving.
Experimental example 4
The experimental example provides a series of gel water shutoff agent performance tests, wherein the gel water shutoff agents are only different in the addition amount of the acid-resistant stabilizer concentration: 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%. The preparation method of the gel specifically comprises the following steps:
the method comprises the following steps: 100mL of simulated saline (16 g NaCl, 7g CaCl per 100mL of deionized water)2And 1g of MgCl2Prepared to obtain the product with the total mineralization degree of 24 multiplied by 104mg/L) is put into a beaker, the acid-resistant stabilizer scleroglucan is added into the simulated saline according to the addition amount of the acid-resistant stabilizer under the stirring condition of a magnetic stirrer (the stirring speed is 800-;
step two: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step three: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h by using a magnetic stirrer at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully mutually soluble;
step five: on the basis of the fourth step, adding 1.0g of urotropine, 1.0g of hydroquinone and 0.8g of thiourea into the mixed solution, and stirring for 20-30min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, 0.2g of nano silicon dioxide is added into the second solution, and a magnetic stirrer is used for stirring for 30-45min at the stirring speed of 200-300rpm until all the powder is completely dissolved; then, 0.2g of nickel chloride is added continuously, and the mixture is stirred for 5-10min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved, so as to obtain the gel water plugging agent.
The properties of these gel water-blocking agents are shown in Table 3.
TABLE 3
Experimental example 5
The experimental example provides a series of gel water shutoff agent performance tests, wherein the gel water shutoff agents are only different in the addition amount of the inorganic salt nano stabilizer, and the addition amount is respectively as follows: 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%. The preparation method of the gel specifically comprises the following steps:
the method comprises the following steps: 100mL of simulated saline (16 g NaCl, 7g CaCl per 100mL of deionized water)2And 1g of MgCl2Prepared to obtain the product with the total mineralization degree of 24 multiplied by 104mg/L) is put into a beaker, 0.2g of acid-fast stabilizer scleroglucan is added into the simulated saline under the stirring condition of a magnetic stirrer (the stirring speed is 800-;
step two: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step three: taking 50mL of the first solution, stirring the first solution by a magnetic stirrer under the stirring condition of the magnetic stirrer (the stirring speed is 200-;
step four: mixing the anionic polyacrylamide solution and the nonionic polyacrylamide solution prepared in the second step and the third step, and stirring for 0.5-1h by using a magnetic stirrer at a stirring speed of not more than 200rpm to ensure that the anionic polyacrylamide solution and the nonionic polyacrylamide solution are fully mutually soluble;
step five: on the basis of the fourth step, adding 1.0g of urotropine, 1.0g of hydroquinone and 0.8g of thiourea into the mixed solution, and stirring for 20-30min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved to obtain a second solution;
step six: on the basis of the fifth step, adding nano silicon dioxide into the second solution according to the addition of the inorganic salt nano stabilizer, and stirring for 30-45min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved; then, 0.2g of nickel chloride is added continuously, and the mixture is stirred for 5-10min by using a magnetic stirrer at the stirring speed of 200-300rpm until all the powder is completely dissolved, so as to obtain the gel water plugging agent.
The properties of these gel water-blocking agents are shown in Table 4.
TABLE 4
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.