High-pressure salt water layer cementing back-slurry column cement slurry system and preparation method thereof

Abstract

The application discloses a high-pressure salt water layer cementing reverse slurry column cement slurry system and a preparation method thereof. The reverse slurry column cement slurry system is composed of a leading slurry and a tail slurry. The leading slurry is a cement slurry system with a density in the range of 2.2g / cm 3 ~2.45g / cm 3 , and the tail slurry is a cement slurry system with a density in the range of 1.9g / cm 3 ~2.0g / cm 3 . The preparation method of the reverse slurry column cement slurry system comprises the following steps: preparing a cement slurry system with a density in the range of 2.2g / cm 3 ~2.45g / cm 3 as the leading slurry of the high-pressure salt water layer cementing reverse slurry column cement slurry system; and preparing a cement slurry system with a density in the range of 1.9g / cm 3 ~2.0g / cm 3 . The cement slurry system disclosed by the application is easy to mix on site, and can well solve the problem of high-pressure salt water layer cementing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of salt water layer cementing. Specifically, it is a high-pressure salt water layer cementing reverse column cement slurry system and a preparation method thereof. BACKGROUND

[0002] High-pressure salt-gypsum layer cementing has been a worldwide technical problem. This is because of the high water solubility, plasticity and high salinity of salt rock. During cementing, salt and metal ions such as Ca 2+ , Mg 2+ , etc. in the salt-gypsum layer and salt water layer will dissolve into the cement slurry, resulting in changes in properties such as flash setting, accelerated setting, density increase, delayed setting or thickening without setting, etc., which brings risks to cementing construction and affects cementing quality.

[0003] Annular air channeling after high-pressure well cementing can lead to interlayer channeling, directly affecting the testing and evaluation of oil and gas layers, polluting the oil and gas layers, and reducing the recovery rate. Annular air channeling also has adverse effects on subsequent operations such as water injection, acidizing and fracturing, and separate layer production in oilfield development. In addition, the occurrence of annular air channeling can greatly shorten the service life of oil and gas wells, and in severe cases, oil and gas can spew out at the wellhead, or even cause cementing blowout accidents after cementing. Once a blowout accident occurs, even if remedial techniques such as cement squeezing are used, it is difficult to achieve the desired effect. Therefore, preventing annular air channeling after cementing is not only a requirement for cementing quality work, but also a necessary condition for correct evaluation of exploration and development results, protection of oil and gas layers, and improvement of recovery rate. Good annular isolation can achieve the purpose of separate layer production, avoid environmental pollution, and unnecessary resource waste.

[0004] For high-pressure well cementing, the common practice is to use a high-density cement slurry system to balance the formation pressure. High-density cement slurry is usually weighted with barite, iron ore powder, etc. These weighting materials are inert and cannot participate in hydration, which leads to slow development of cement stone strength during the waiting-on-cement process, and in severe cases, causes annular channeling and leads to interlayer isolation failure. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a high-pressure salt water layer cementing reverse column cement slurry system and a preparation method thereof, to solve the problem of effective interlayer isolation in high-pressure salt wells. The reverse column cement slurry system can provide static column pressure to stabilize the formation, and has the advantages of short transition time, salt resistance and channeling prevention, etc.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] A high-pressure salt water layer cementing reverse column cement slurry system, which is composed of a leading slurry and a trailing slurry. The leading slurry has a density of 2.2g / cm 3 ~ 2.45g / cm 3cement slurry system with density in the range of 1.9g / cm 3 ~2.0g / cm 3 cement slurry system with density in the range of 1.9g / cm

[0008] The high-pressure salt water layer cementing backflow column cement slurry system has the following components: 40-55 parts by weight of water, 100 parts by weight of cement, 40-110 parts by weight of weighting agent, 2-4 parts by weight of fluid loss additive, 2-5 parts by weight of filler, 2-4 parts by weight of expansion agent, 0.5-1.0 parts by weight of dispersant, 0.1-1.0 parts by weight of multifunctional additive, 5-10 parts by weight of salt, and 0.3-0.5 parts by weight of defoaming agent.

[0009] If the addition amount of the fluid loss additive in the lead slurry is less than 2 parts by weight, the water loss control cannot meet the requirements, and if the addition amount is greater than 4 parts by weight, it will cause the cement slurry consistency to increase, which is not conducive to pumping, and the cost increases; the filler has two functions: on the one hand, according to the close packing theory, the filler and other components are particle graded to improve the density of the formed cement stone; on the other hand, the filler has a suspending stabilizing effect, which can reduce the settling of the weighting material in the high-density system. Due to the natural shrinkage characteristics of Portland cement, the addition of the expansion agent can resist the shrinkage of the cement stone, otherwise, once the cement stone shrinks, micro-gaps will occur, resulting in cement sealing failure. The multifunctional additive has a suspending stabilizing effect, and because a large amount of weighting material is added to the high-density cement slurry system, if the suspending stability is not good, settling will easily occur, affecting the overall performance of the cement slurry; in addition, the multifunctional additive also has a channeling prevention effect. In high-pressure salt water layer cementing, the chloride ion content in the formation is very high, when the cement slurry reaches the formation with high chloride ion content, ion exchange is easily caused, which can cause significant changes in the performance of the cement slurry, and in severe cases, safety accidents can occur, so salt needs to be added to make the chloride ion content in the cement slurry equivalent to that in the formation, thereby effectively avoiding ion exchange with the formation. In addition, when the content of salt is less than 10wt%, it has a setting accelerating effect, when the content is 10wt%-15wt%, it neither retards nor accelerates setting, and when the content is greater than 15wt%, it has a setting retarding effect.

[0010] The tail slurry has the following components: 40-55 parts by weight of water, 100 parts by weight of cement, 2-4 parts by weight of fluid loss additive, 2-4 parts by weight of filler, 2-4 parts by weight of expansion agent, 5-10 parts by weight of salt, and 0.2-0.5 parts by weight of defoaming agent.

[0011] The cement of the cement slurry system for cementing high-pressure salt water layer reverse column is G-class cement selected according to API 10A standard; the fluid loss additive is AMPS terpolymer fluid loss additive; the filler is micro-silicon powder with a particle size of 0.1-0.5 μm; the expanding agent is calcium-aluminum oxide

the calcium-aluminum oxide is aluminum powder wrapped with an aluminum oxide corrosion layer, one or both of active magnesium oxide or calcium oxide and a mixture of two or more thereof

[0012] The cement of the cement slurry system for cementing high-pressure salt water layer reverse column is composed of the following components in weight parts: calcium silicate 46-56 parts by weight, tricalcium aluminate 2-8 parts by weight, tetracalcium aluminoferrite 8-24 parts by weight, magnesium oxide 2-6 parts by weight, and sulfur trioxide 1-3 parts by weight.

[0013] The preparation method of the AMPS terpolymer fluid loss additive of the cement slurry system for cementing high-pressure salt water layer reverse column comprises the following steps:

[0014] Step (1-1), the terpolymer monomer is added into distilled water to obtain dispersion A;

[0015] Step (1-2), sodium hydroxide solution is added dropwise into the dispersion A to adjust the pH of the dispersion A, and after the pH is adjusted, dispersion B is obtained;

[0016] Step (1-3), the dispersion B is transferred into a four-necked flask and heated, and when the temperature of the dispersion B is raised to the polymerization temperature, ammonium persulfate solution is added to initiate the polymerization reaction, and after the reaction is completed, the dispersion B is naturally cooled to room temperature, and the AMPS terpolymer fluid loss additive is obtained. There are many kinds of commercially available fluid loss additives, which are suitable for different well conditions. The fluid loss additive prepared by the method of aqueous solution free radical polymerization in the present application has good salt resistance, strong stability and strong control over fluid loss, and is suitable for salt-resistant cement slurry system.

[0017] In step (1-1) of the cement slurry system for cementing high-pressure salt water layer reverse column, the terpolymer monomer is composed of 35-45 parts by weight of 2-acrylamido-2-methylpropane sulfonic acid, 25-35 parts by weight of acrylamide and 15-25 parts by weight of acrylic acid; and the mass concentration of the terpolymer monomer in the dispersion A is 240 g / L.

[0018] In step (1-2) of the cement slurry system for cementing high-pressure salt water layer reverse column, the mass concentration of sodium hydroxide in the sodium hydroxide solution is 20 g / L; and the pH of the dispersion B is 6-9.

[0019] In step (1-3), the mass fraction of ammonium persulfate in the ammonium persulfate solution is 20 wt%, and the addition amount of the ammonium persulfate solution is determined according to the mass ratio of ammonium persulfate to the ternary polymer monomer in step (1-1) being 0.5% to 1%; the polymerization reaction temperature is 60 to 80 DEG C; and the reaction time is 4 to 6 hours.

[0020] The high-pressure salt water layer cementing reverse-slurry-column cement slurry system has a multifunctional additive which is a polymer settling stabilizer, and the multifunctional additive is commercially available and has a trade name of multipurpose cement additive, BJ UltraMax TM L, and a manufacturer is Baker Hughes; a dispersing agent is an aldehyde ketone polymer (including USZ, SAF, DRS, etc.); and a weighting agent is composed of iron ore powder A and iron ore powder B, and the densities of the iron ore powder A and the iron ore powder B are both in a range of 5.0 to 5.1 g / cm 3 ; the average particle size of the iron ore powder A is 130 to 160 mu m, the average particle size of the iron ore powder B is 20 to 30 mu m, and the mass ratio of the iron ore powder A to the iron ore powder B is 4:1 to 3:1, so that the particle grading effect of the leading slurry is good, the solid content in a unit volume is high, and the weighting effect is good.

[0021] The high-pressure salt water layer cementing reverse-slurry-column cement slurry system has the densities of the iron ore powder A and the iron ore powder B both being 5.05 g / cm 3 ; the average particle size of the iron ore powder A is 150 mu m, the average particle size of the iron ore powder B is 25 mu m, and the mass ratio of the iron ore powder A to the iron ore powder B is 4:1.

[0022] A preparation method of a high-pressure salt water layer cementing reverse-slurry-column cement slurry system, which comprises the following steps: preparing a cement slurry system with a density in a range of 2.2 g / cm 3 ~ 2.45 g / cm 3 as leading slurry of the high-pressure salt water layer cementing reverse-slurry-column cement slurry system; and preparing a cement slurry system with a density in a range of 1.9 g / cm 3 ~ 2.0 g / cm 3 as tail slurry of the high-pressure salt water layer cementing reverse-slurry-column cement slurry system.

[0023] The preparation method of the high-pressure salt water layer cementing reverse-slurry-column cement slurry system comprises the following steps in the preparation method of the leading slurry:

[0024] Step (2-1) prepares the following raw materials: 100 parts by weight of cement, 40-110 parts by weight of weighting agent, 2-4 parts by weight of fluid loss agent, 2-5 parts by weight of filler, 2-4 parts by weight of expanding agent, 0.5-1.0 parts by weight of dispersing agent, and 0.1-1.0 parts by weight of multifunctional additive;

[0025] Step (2-2) uniformly mixes the raw materials prepared in step (2-1) at room temperature to obtain dry ash mixture A.

[0026] Step (2-3) adds 40-55 parts by weight of water, 5-10 parts by weight of salt, and 0.3-0.5 parts by weight of defoaming agent into the stirring cup of the constant-speed stirrer, turns on the constant-speed stirrer, stirs at 1500 rpm for 3 min to completely dissolve the salt, then uniformly pours the dry ash mixture A into the rotating stirring cup at 4000 rpm within 15 seconds, and then stirs at 12000 rpm for 35 seconds to obtain the lead slurry.

[0027] The preparation method of the tail slurry comprises the following steps:

[0028] Step (3-1) prepares the following raw materials according to the following weight parts: 100 parts by weight of cement, 2-4 parts by weight of fluid loss agent, 2-4 parts by weight of filler, and 2-4 parts by weight of expanding agent.

[0029] Step (3-2) uniformly mixes the raw materials prepared in step (3-1) at room temperature to obtain dry ash mixture B.

[0030] Step (3-3) adds 40-55 parts by weight of water, 5-10 parts by weight of salt, and 0.2-0.5 parts by weight of defoaming agent into the stirring cup of the constant-speed stirrer, turns on the constant-speed stirrer, stirs at 1500 rpm for 3 min to completely dissolve the salt, then uniformly pours the dry ash mixture B into the rotating stirring cup at 4000 rpm within 15 seconds, and then stirs at 12000 rpm for 35 seconds to obtain the tail slurry.

[0031] The technical scheme of the present application achieves the following beneficial technical effects:

[0032] This invention utilizes a high-density cement slurry prepared with a self-made dewatering agent and a particle size distribution of the weighting agent. This slurry is easily mixed on-site, resulting in a cement stone with high strength and low permeability. The high-pressure brine well cementing system of this invention, with its dual-setting system formed by the synergistic combination of high-density and conventional density slurries, provides sufficient hydrostatic pressure to stabilize the formation. It also exhibits short initial and final setting times, rapid strength development, and high final strength, effectively sealing key formations and minimizing annular flow. This cement slurry system is easy to mix on-site and effectively solves the problem of sealing high-pressure brine formations.

[0033] The method of this invention for preparing a cement slurry system for high-pressure brine well cementing columns features short mixing times during the preparation of the lead and tail slurries, enabling continuous pumping using a four-machine Sewa dual-machine pump truck. The high-density lead slurry prepared by this invention has a density of 2.2 g / cm³. 3 ~2.45g / cm 3 The dynamic cutting force / initial cut / final cut were all below 1.9 g / cm. 3 ~2.0g / cm 3 High-density tail slurry effectively avoids instability during the slurry replacement process after cement injection and severe cross-mixing of tail slurry, thus ensuring the overall performance of the cement slurry; and the high-density tail slurry is 2.2 g / cm³. 3 ~2.45g / cm 3 The thickening time was higher than 1.9 g / cm³. 3 ~2.0g / cm 3 The thickening time of the tailings is more than 2 hours. In the cementing industry, the shorter the thickening time of the tailings, the faster its solidification time. During the transformation of the tailings from liquid to solid, a gelation weight loss phenomenon will occur, which will cause the generated hydrostatic column pressure to gradually decrease to the hydrostatic column pressure of water. At this time, the tailings have not yet formed a gel structure, which can fully ensure that sufficient hydrostatic column pressure is provided during the waiting solidification period to ensure effective pressure stabilization until the tailings solidify and form strength to achieve interlayer sealing, thereby improving the cementing quality.

[0034] The method of this invention produces a dual-setting system for the lead slurry and tail slurry. When used together, they form a slurry column structure, fully meeting the formation requirements of high-pressure salt-gypsum layers. This system exhibits high salt resistance, with water loss within 50 mL and free fluid of 0 mL, ensuring the final cement stone does not shrink and has a slight expansion effect. However, even with a dual-setting system, using only high-density cement slurry in the lower active salt-gypsum layer still results in unsatisfactory cementing quality. This invention addresses the need for interlayer sealing in cementing by utilizing a low-density (i.e., conventional density) tail slurry with short setting time and rapid strength development, providing excellent sealing for salt-gypsum layers. Combined with a high-density lead slurry, it ensures effective pressure stabilization during the lead slurry's setting period. The slurry column dual-setting system effectively solves the problem of poor sealing of salt-gypsum layers by existing cement slurries, achieving excellent application results. Attached Figure Description

[0035] Figure 1 A schematic diagram of the static gelation curve of the collar slurry prepared in Example 2 of this invention;

[0036] Figure 2 A schematic diagram of the cementing quality evaluation CBL-VDL-RBT in Embodiment 2 of the present invention. Detailed Implementation

[0037] Example 1

[0038] In this embodiment, the cement slurry system for cementing high-pressure brine formations consists of a lead slurry and a tail slurry; the lead slurry has a density of 2.2 g / cm³. 3 The cement slurry system; the tailings slurry has a density of 1.9 g / cm³. 3 Cement grout system within the scope.

[0039] The density is 2.2 g / cm³. 3 The preparation method of the collar paste includes the following steps:

[0040] Step (2-1) Prepare raw materials: 100kg cement, 50kg weighting agent, 2.5kg water loss reducing agent, 5kg filler, 3kg expansion agent, 0.8kg dispersant and 1.0kg multifunctional additive;

[0041] Step (2-2): Under normal temperature conditions, mix the raw materials prepared in step (2-1) evenly to obtain dry ash mixture A;

[0042] Steps (2-3): Add 47 kg of water to the mixing bowl of a constant-speed mixer, along with 5 kg of salt and 0.3 kg of defoamer. Turn on the constant-speed mixer and stir at 1500 rpm for 3 minutes to completely dissolve the salt. Then, pour the dry ash mixture A evenly into the rotating mixing bowl at 4000 rpm over 15 seconds. Finally, stir at 12000 rpm for 35 seconds to obtain a density of 2.2 g / cm³. 3 The collar padding;

[0043] The density is 1.9 g / cm³. 3 The preparation method of tailings includes the following steps:

[0044] Step (3-1) Prepare raw materials: 100kg cement, 2kg water loss reducer, 3kg filler and 3kg expansion agent;

[0045] Step (3-2) Under normal temperature conditions, the raw materials prepared in step (3-1) are mixed evenly to obtain dry ash mixture B;

[0046] Step (3-3) 48 kg of water was added into the stirring slurry cup of constant speed stirrer, 5 kg of salt and 0.2 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture B was uniformly poured into the rotating stirring slurry cup at 4000 rpm for 15 seconds; then it was stirred at 12000 rpm for 35 seconds to obtain the tail slurry with a density of 1.9 g / cm 3 .

[0047] In this embodiment, the cement is commercially available G-grade cement

in other embodiments, the cement is composed of the following components by weight: calcium silicate 46-56 parts by weight, tricalcium aluminate 2-8 parts by weight, tetracalcium aluminoferrite 8-24 parts by weight, magnesium oxide 2-6 parts by weight, sulfur trioxide 1-3 parts by weight

[0048] Step (1-1), the terpolymer monomer was stirred in distilled water to obtain dispersion A; the terpolymer monomer was composed of 45 parts by weight of 2-acrylamido-2-methylpropane sulfonic acid, 35 parts by weight of acrylamide and 25 parts by weight of acrylic acid; the mass concentration of the terpolymer monomer in dispersion A was 240 g / L;

[0049] Step (1-2), sodium hydroxide solution was added dropwise to dispersion A to adjust the pH of dispersion A, and dispersion B was obtained after adjusting the pH; the mass concentration of sodium hydroxide in the sodium hydroxide solution was 20 g / L; the pH of dispersion B was 8;

[0050] Step (1-3), the dispersion B is transferred to a four-necked flask and heated, and when the temperature of the dispersion B is raised to the polymerization temperature, the ammonium persulfate solution is added to initiate the polymerization reaction, the mass fraction of ammonium persulfate in the ammonium persulfate solution is 20wt%, the addition amount of the ammonium persulfate solution is determined according to the standard that the mass of ammonium persulfate is 1% of the mass of the terpolymer monomer in step (1-1); the polymerization temperature is 80℃; the reaction time is 5 hours; and after the reaction is completed, the system is naturally cooled to room temperature, thereby obtaining the AMPS terpolymer anti-fluid loss agent.

[0051] Example 2

[0052] The cement slurry system for high-pressure salt water layer cementing and back-mud column in this example is composed of a lead slurry and a tail slurry; the lead slurry is a cement slurry system with a density in the range of 2.25g / cm 3 ; and the tail slurry is a cement slurry system with a density in the range of 1.95g / cm 3 .

[0053] The preparation method of the lead slurry with a density of 2.25g / cm 3 includes the following steps:

[0054] Step (2-1), preparing raw materials: 100kg of cement, 60kg of weighting agent, 2.5kg of fluid loss additive, 5kg of filler, 3kg of expansion agent, 0.8kg of dispersant and 1.0kg of multifunctional additive;

[0055] Step (2-2), uniformly mixing the raw materials prepared in step (2-1) at room temperature to obtain dry ash mixture A;

[0056] Step (2-3), adding 47kg of water into the stirring cup of the constant-speed stirrer, adding 5kg of salt and 0.3kg of defoaming agent; starting the constant-speed stirrer to stir at a speed of 1500rpm for 3min to make the salt completely dissolved; then uniformly pouring the dry ash mixture A into the rotating stirring cup at a speed of 4000rpm within 15s; and then stirring at a speed of 12000rpm for 35s, thereby obtaining the lead slurry with a density of 2.25g / cm 3 ;

[0057] The preparation method of the tail slurry with a density of 1.95g / cm 3 includes the following steps:

[0058] Step (3-1), preparing raw materials: 100kg of cement, 2kg of fluid loss additive, 3kg of filler and 3kg of expansion agent;

[0059] Step (3-2), uniformly mixing the raw materials prepared in step (3-1) at room temperature to obtain dry ash mixture B;

[0060] Step (3-3) 45 kg of water was added into the stirring cup of constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture B was uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then it was stirred at 12000 rpm for 35 seconds, to obtain the tail slurry with a density of 1.95 g / cm 3 .

[0061] In this embodiment, the cement is commercially available G-grade cement; the filler is microsilica with a particle size of 0.1-0.5 μm; the expanding agent is calcium-aluminum oxide-active magnesium oxide; the salt is sodium chloride; the defoaming agent is a polyether defoaming agent; the multifunctional additive is a polymer sedimentation stabilizer, which is commercially available in this embodiment, and the trade name is multipurpose cement additive, BJ UltraMax TM L, and the manufacturer is Baker Hughes; the dispersing agent is aldehyde ketone polymer SAF (sulfonated acetone formaldehyde condensate); the weighting agent is composed of iron ore powder A and iron ore powder B; the densities of the iron ore powder A and the iron ore powder B are both 5.05 g / cm 3 ; the average particle size of the iron ore powder A is 150 μm, and the average particle size of the iron ore powder B is 25 μm; the mass ratio of the iron ore powder A to the iron ore powder B is 3:1; the fluid loss reducers in the lead slurry and the tail slurry are both self-made AMPS terpolymer fluid loss reducers, and the preparation method is the same as that in Example 1.

[0062] Example 3

[0063] The cement slurry system for high-pressure salt water layer cementing in this embodiment is composed of a lead slurry and a tail slurry; the lead slurry is a cement slurry system with a density of 2.3 g / cm 3 ; and the tail slurry is a cement slurry system with a density in the range of 2.0 g / cm 3 .

[0064] The preparation method of the lead slurry with a density of 2.3 g / cm 3 includes the following steps:

[0065] Step (2-1) Preparation of raw materials: 100 kg of cement, 75 kg of weighting agent, 3 kg of fluid loss reducer, 5 kg of filler, 3 kg of expanding agent, 1.0 kg of dispersing agent and 1.0 kg of multifunctional additive;

[0066] Step (2-2) The raw materials prepared in step (2-1) were uniformly mixed and stirred at room temperature to obtain a dry ash mixture A;

[0067] Step (2-3) 50 kg of water was added into the stirring cup of constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture A was uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then the stirring was carried out at 12000 rpm for 35 seconds, and the slurry with a density of 2.3 g / cm 3 was obtained.

[0068] The preparation method of the tail slurry with a density of 2.0 g / cm 3 includes the following steps:

[0069] Step (3-1) the raw materials were prepared: 100 kg of cement, 2 kg of fluid loss additive, 3 kg of filler and 3 kg of expanding agent;

[0070] Step (3-2) the raw materials prepared in step (3-1) were uniformly mixed at room temperature to obtain dry ash mixture B;

[0071] Step (3-3) 42 kg of water was added into the stirring cup of constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture B was uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then the stirring was carried out at 12000 rpm for 35 seconds, and the tail slurry with a density of 1.95 g / cm 3 was obtained.

[0072] In this embodiment, the cement is commercially available G-grade cement; the fluid loss additives are all self-made AMPS ternary copolymer fluid loss additives, and the preparation method is the same as that of Example 1; the filler is micro-silica powder with a particle size of 0.1-0.5 μm; the expanding agent is calcium-aluminum oxide-calcium oxide; the salt is sodium chloride; the defoaming agent is a polyether defoaming agent; the multifunctional additive is a polymer sedimentation stabilizer, and in this embodiment, the multifunctional additive is commercially available, and the trade name is multipurpose cement additive, BJ UltraMax TM L, and the manufacturer is Baker Hughes; the dispersing agent is aldehyde ketone polymer SAF (sulfonated acetone formaldehyde condensate); the weighting agent is composed of iron ore powder A and iron ore powder B; the densities of the iron ore powder A and the iron ore powder B are both 5.05 g / cm 3 ; the average particle size of the iron ore powder A is 150 μm, and the average particle size of the iron ore powder B is 25 μm; the mass ratio of the iron ore powder A to the iron ore powder B is 4:1.

[0073] Example 4

[0074] The cement slurry system for cementing high-pressure salt water layer in this embodiment is composed of a leading slurry and a trailing slurry; the leading slurry is a cement slurry system with a density of 2.35 g / cm 3 The trailing slurry is a cement slurry system with a density in the range of 1.9 g / cm 3 .

[0075] The preparation method of the leading slurry with a density of 2.35 g / cm 3 includes the following steps:

[0076] Step (2-1) prepares raw materials: 100 kg of cement, 90 kg of weighting agent, 3 kg of fluid loss additive, 5 kg of filler, 2 kg of expansion agent, 1.0 kg of dispersant and 1.0 kg of multifunctional additive;

[0077] Step (2-2) uniformly mixes the raw materials prepared in step (2-1) at room temperature to obtain dry ash mixture A;

[0078] Step (2-3) adds 52 kg of water into the stirring cup of the constant-speed stirrer, adds 5 kg of salt and 0.3 kg of defoaming agent; starts the constant-speed stirrer, stirs at a speed of 1500 rpm for 3 min to completely dissolve the salt; then uniformly pours the dry ash mixture A into the rotating stirring cup at a speed of 4000 rpm within 15 seconds; then stirs at a speed of 12000 rpm for 35 seconds to obtain the leading slurry with a density of 2.35 g / cm 3 .

[0079] The preparation method of the trailing slurry with a density of 1.9 g / cm 3 includes the following steps:

[0080] Step (3-1) prepares raw materials: 100 kg of cement, 2 kg of fluid loss additive, 3 kg of filler and 3 kg of expansion agent;

[0081] Step (3-2) uniformly mixes the raw materials prepared in step (3-1) at room temperature to obtain dry ash mixture B;

[0082] Step (3-3) adds 48 kg of water into the stirring cup of the constant-speed stirrer, adds 5 kg of salt and 0.2 kg of defoaming agent; starts the constant-speed stirrer, stirs at a speed of 1500 rpm for 3 min to completely dissolve the salt; then uniformly pours the dry ash mixture B into the rotating stirring cup at a speed of 4000 rpm within 15 seconds; then stirs at a speed of 12000 rpm for 35 seconds to obtain the trailing slurry with a density of 1.9 g / cm 3 .

[0083] In this embodiment, the cement is commercially available G-grade cement; the fluid loss additive is commercially available AMPS terpolymer fluid loss additive; the filler is micro-silica powder with a particle size of 0.1-0.5 μm; the expansive agent is calcium-aluminum oxide-activated magnesium oxide; the salt is potassium chloride; the defoaming agent is polyether defoaming agent; and the multifunctional additive is polymer sedimentation stabilizer, which is commercially available in this embodiment and has a trade name of multipurpose cement additive, BJ UltraMax TM L, the manufacturer is Baker Hughes; the dispersant is aldehyde ketone polymer SAF (sulfonated acetone formaldehyde condensate); and the weighting agent is iron ore powder with an average particle size of 120 μm and a density of 5.05 g / cm 3 .

[0084] Example 5

[0085] The high-pressure salt water layer cementing backspurt cement slurry system in this embodiment is composed of a lead slurry and a tail slurry; the lead slurry is a cement slurry system with a density of 2.4 g / cm 3 ; and the tail slurry is a cement slurry system with a density in the range of 2.0 g / cm 3 .

[0086] The preparation method of the lead slurry with a density of 2.4 g / cm 3 includes the following steps:

[0087] Step (2-1) prepares raw materials: 100 kg of cement, 100 kg of weighting agent, 3 kg of fluid loss additive, 5 kg of filler, 2 kg of expansive agent, 1.0 kg of dispersant, and 1.0 kg of multifunctional additive;

[0088] Step (2-2) uniformly mixes the raw materials prepared in step (2-1) at room temperature to obtain dry ash mixture A;

[0089] Step (2-3) adds 50 kg of water into a stirring cup of a constant-speed stirrer, adds 5 kg of salt and 0.3 kg of defoaming agent, starts the constant-speed stirrer, stirs at a speed of 1500 rpm for 3 min to completely dissolve the salt, then uniformly pours the dry ash mixture A into the rotating stirring cup at a speed of 4000 rpm within 15 seconds, and then stirs at a speed of 12000 rpm for 35 seconds to obtain the lead slurry with a density of 2.4 g / cm 3 .

[0090] The preparation method of the tail slurry with a density of 1.95 g / cm 3 includes the following steps:

[0091] Step (3-1) prepares raw materials: 100 kg of cement, 2 kg of fluid loss additive, 3 kg of filler, and 3 kg of expansive agent;

[0092] Step (3-2) The raw materials prepared in step (3-1) are mixed uniformly at room temperature to obtain dry ash mixture B.

[0093] Step (3-3) 45 kg of water is added to the stirring cup of the constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent are added; the constant speed stirrer is started, and the salt is completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture B is uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then it is stirred at 12000 rpm for 35 seconds to obtain the tail slurry with a density of 2.0 g / cm 3 .

[0094] In this embodiment, the cement is commercially available G-grade cement; the fluid loss additive of the leading slurry is a commercially available AMPS terpolymer fluid loss additive, and the fluid loss additive of the tail slurry is a self-made AMPS terpolymer fluid loss additive, which is prepared by the same method as in Example 1; the filler is microsilica with a particle size of 0.1-0.5 μm; the expanding agent is calcium aluminum oxide; the salt is potassium chloride; the defoaming agent is a polyether defoaming agent; the multifunctional additive is a polymer sedimentation stabilizer, which is commercially available in this embodiment, and the trade name is multipurpose cement additive, BJ UltraMax TM L, and the manufacturer is Baker Hughes; the dispersing agent is aldehyde ketone polymer SAF (sulfonated acetone formaldehyde condensate); the weighting agent is composed of iron ore powder A and iron ore powder B; the densities of iron ore powder A and iron ore powder B are both 5.05 g / cm 3 ; the average particle size of iron ore powder A is 150 μm, and the average particle size of iron ore powder B is 25 μm; the mass ratio of iron ore powder A to iron ore powder B is 4:1.

[0095] Example 6

[0096] The high-pressure salt water layer cementing back-slurry column cement slurry system in this embodiment is composed of a leading slurry and a tail slurry; the leading slurry is a cement slurry system with a density of 2.45 g / cm 3 ; and the tail slurry is a cement slurry system with a density in the range of 2.0 g / cm 3 .

[0097] The preparation method of the leading slurry with a density of 2.45 g / cm 3 includes the following steps:

[0098] Step (2-1) Preparation of raw materials: 100 kg of cement, 110 kg of weighting agent, 2 kg of fluid loss additive, 5 kg of filler, 2 kg of expanding agent, 1.0 kg of dispersing agent and 1.0 kg of multifunctional additive;

[0099] Step (2-2) The raw materials prepared in step (2-1) are mixed uniformly at room temperature to obtain dry ash mixture A;

[0100] Step (2-3) 50 kg of water was added into the stirring cup of constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture A was uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then the stirring was carried out at 12000 rpm for 35 seconds, and the leading slurry with a density of 2.45 g / cm 3 was obtained.

[0101] The preparation method of the tail slurry with a density of 2.0 g / cm 3 includes the following steps:

[0102] Step (3-1) the raw materials were prepared: 100 kg of cement, 2 kg of fluid loss additive, 3 kg of filler and 3 kg of expanding agent;

[0103] Step (3-2) the raw materials prepared in step (3-1) were uniformly mixed at room temperature to obtain dry ash mixture B;

[0104] Step (3-3) 42 kg of water was added into the stirring cup of constant speed stirrer, 5 kg of salt and 0.3 kg of defoaming agent were added; the constant speed stirrer was started, and the salt was completely dissolved by stirring at 1500 rpm for 3 min; then the dry ash mixture B was uniformly poured into the rotating stirring cup at 4000 rpm for 15 seconds; then the stirring was carried out at 12000 rpm for 35 seconds, and the tail slurry with a density of 2.0 g / cm 3 was obtained.

[0105] In this embodiment, the cement is commercially available G-grade cement; the fluid loss additive of the leading slurry is commercially available AMPS terpolymer fluid loss additive, and the fluid loss additive of the tail slurry is self-made AMPS terpolymer fluid loss additive, which is prepared by the same method as in Example 1; the filler is microsilica with a particle size of 0.1-0.5 μm; the expanding agent is calcium aluminum oxide; the salt is sodium chloride; the defoaming agent is polyether defoaming agent; the multifunctional additive is polymer sedimentation stabilizer, which is commercially available in this embodiment, and the trade name is multipurpose cement additive, BJ UltraMax TM L, and the manufacturer is Baker Hughes; the dispersing agent is aldehyde ketone polymer SAF (sulfonated acetone formaldehyde condensate); and the weighting agent is iron ore powder with an average particle size of 60 μm, and the density of the iron ore powder is 5.05 g / cm 3 .

[0106] In the preparation of the leading slurry and the tail slurry in Examples 1-6, the slurry mixing time is short, and the continuous pumping can be realized by using four-mechanism double-pump truck. The high-density leading slurry has a density of 2.2 g / cm 3~2.45g / cm 3 < 1.9g / cm 3 ~2.0g / cm 3 2.2g / cm 3 ~2.45g / cm 3 > 1.9g / cm 3 ~2.0g / cm 3 > 2hThe lead slurry and tail slurry prepared by the method of Embodiment 1 to Embodiment 6 can form a reverse slurry column structure when used together, can fully meet the requirements of high-pressure salt-gypsum layer formation, has high salt resistance, and the fluid loss is within 50 mL, the free fluid is 0 mL, so that the final cement stone does not shrink, but has a slight expansion effect. The comprehensive performance test results of the lead slurry and tail slurry prepared by Embodiment 1 to Embodiment 6 are shown in Table 1.

[0107] Table 1

[0108]

[0109] The high-pressure salt water layer cementing reverse slurry column cement slurry system prepared by Embodiment 1 to Embodiment 6 was applied to the engineering test of BD block in Iraq; the tested well depth is 4500-5050 meters, and the bottom hole temperature is 110-125℃. The application test results are shown in Table 2.

[0110] Table 2

[0111]

[0112]

[0113] Figure 1 The static gelation curve of the lead slurry prepared in Embodiment 2 is shown in FIG. 1, from which it can be seen that the designed cement slurry has a short transition time, fast strength development, and good anti-channeling performance; Figure 1

[0114] The quality evaluation CBL-VDL-RBT of the high-pressure salt water layer cementing reverse slurry column cement slurry system prepared by Embodiment 2 is shown in FIG. 2, from which it can be seen that the cementing quality is 100% qualified, the high-quality rate is more than 90%, and has very good economic benefits and application prospects. Figure 2 Figure 2

[0115] ​Obviously, the above embodiments are only examples for clearly illustrating the present application and are not intended to limit the present application. Based on the above description, one of ordinary skill in the art can make other different forms of changes or modifications. Here, it is not necessary or possible to enumerate all the embodiments. The obvious changes or modifications derived from the above should be covered in the protection scope of the present application.

Claims

1. A high pressure salt water layer cementing backspurt cementing system, characterized in that, consists of a lead slurry and a tail slurry; the lead slurry is a cement slurry system having a density in the range of 2.2 g / cm 3 ~ 2.45 g / cm 3 ; the tail slurry is a cement slurry system having a density in the range of 1.9 g / cm 3 ~ 2.0 g / cm 3 ; The lead slurry is composed of the following components by weight: 40-55 parts by weight of water, 100 parts by weight of cement, 40-110 parts by weight of weighting agent, 2-4 parts by weight of fluid loss additive, 2-5 parts by weight of filler, 2-4 parts by weight of expanding agent, 0.5-1.0 parts by weight of dispersant, 0.1-1.0 parts by weight of multifunctional additive, 5-10 parts by weight of salt and 0.3-0.5 parts by weight of defoaming agent; The tail slurry is composed of the following components by weight: 40-55 parts by weight of water, 100 parts by weight of cement, 2-4 parts by weight of fluid loss additive, 2-4 parts by weight of filler, 2-4 parts by weight of expanding agent, 5-10 parts by weight of salt and 0.2-0.5 parts by weight of defoaming agent; The cement is G-grade cement; the fluid loss additive is an AMPS terpolymer fluid loss additive; the filler is microsilica with a particle size of 0.1-0.5 μm; the expanding agent is calcium aluminate oxide; the defoaming agent is a polyether defoaming agent; and the salt is sodium chloride and / or potassium chloride; The multifunctional aid is a polymer settlement stabilizer; the dispersant is an aldehyde ketone polymer; the weighting agent is composed of iron ore powder A and iron ore powder B, the densities of the iron ore powder A and the iron ore powder B are both within the range of 5.0-5.1 g / cm 3 The average particle size of the iron ore powder A is 130-160 μm, the average particle size of the iron ore powder B is 20-30 μm, and the mass ratio of the iron ore powder A to the iron ore powder B is 4:1-3:

1.

2. The high-pressure saltwater zone cementing backspurt cement slurry system of claim 1, wherein, The cement is composed of the following components by weight: 46-56 parts by weight of calcium silicate, 2-8 parts by weight of tricalcium aluminate, 8-24 parts by weight of tetracalcium aluminoferrite, 2-6 parts by weight of magnesium oxide and 1.0-3 parts by weight of sulfur trioxide.

3. The high-pressure saltwater zone cementing backspurt cement slurry system of claim 1, wherein, The preparation method of the AMPS terpolymer fluid loss additive comprises the following steps: Step (1-1), adding the terpolymer monomer into distilled water and stirring to obtain dispersion A; Step (1-2), adding sodium hydroxide solution into the dispersion A to adjust the pH of the dispersion A, and obtaining dispersion B after adjusting the pH; Step (1-3), transferring the dispersion B into a four-necked flask and heating, adding ammonium persulfate solution to initiate the polymerization reaction when the temperature of the dispersion B reaches the polymerization temperature, and obtaining the AMPS terpolymer fluid loss additive after the reaction is completed and the temperature is naturally cooled to room temperature.

4. The high-pressure saltwater zone cementing backspurt cement slurry system of claim 3, wherein, In step (1-1), the terpolymer monomer is composed of 35-45 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 25-35 parts by weight of acrylamide and 15-25 parts by weight of acrylic acid; and the mass concentration of the terpolymer monomer in the dispersion A is 240 g / L; In step (1-2), the mass concentration of sodium hydroxide in the sodium hydroxide solution is 20 g / L; and the pH of the dispersion B is 6-9; In step (1-3), the mass fraction of ammonium persulfate in the ammonium persulfate solution is 20 wt%, the amount of the ammonium persulfate solution is added according to the standard that the mass of ammonium persulfate is 0.5-1% of the mass of the terpolymer monomer in step (1-1); the polymerization temperature is 60-80°C; and the reaction time is 4-6 hours.

5. The high-pressure saltwater zone cementing backspurt cement slurry system of claim 1, wherein, The density of the iron ore fines A and the iron ore fines B was 5.05 g / cm 3 The average particle size of the iron ore fines A was 150 μm and the average particle size of the iron ore fines B was 25 μm. The mass ratio of the iron ore fines A to the iron ore fines B was 4:

1.

6. A method of preparing a high pressure salt water layer cementing backspurt cement slurry system as claimed in any one of claims 1 to 5, characterised in that, cement slurries with densities in the range of 2.2 g / cm 3 ~ 2.45 g / cm 3 are prepared as a lead slurry for high pressure salt water zone cementing back-reaming string cement slurries; cement slurries with densities in the range of 1.9 g / cm 3 ~ 2.0 g / cm 3 are prepared as a tail slurry for high pressure salt water zone cementing back-reaming string cement slurries.

7. The method of preparing a high pressure salt water layer cementing backspurt cement slurry system of claim 6, wherein, The preparation method of the lead slurry comprises the following steps: Step (2-1), preparing the following raw materials: 100 parts by weight of cement, 40-110 parts by weight of weighting agent, 2-4 parts by weight of fluid loss additive, 2-5 parts by weight of filler, 2-4 parts by weight of expanding agent, 0.5-1.0 parts by weight of dispersant and 0.1-1.0 parts by weight of multifunctional additive; Step (2-2), mixing and stirring the raw materials prepared in step (2-1) at room temperature to obtain dry ash mixture A; Step (2-3) 40-55 parts by weight of water is added into the stirring cup of constant speed stirrer, 5-10 parts by weight of salt and 0.3-0.5 parts by weight of defoaming agent are added; the constant speed stirrer is started, and the stirring is carried out at 1500 rpm for 3 min to make the salt completely dissolved; then the dry ash mixture A is uniformly poured into the rotating stirring cup at 4000 rpm within 15 seconds; then the stirring is carried out at 12000 rpm for 35 seconds, and the slurry is obtained; The preparation method of the tail slurry comprises the following steps: Step (3-1) raw materials are prepared according to the following parts by weight: 100 parts by weight of cement, 2-4 parts by weight of a fluid loss additive, 2-4 parts by weight of a filler and 2-4 parts by weight of an expanding agent; Step (3-2) the raw materials prepared in step (3-1) are uniformly mixed and stirred at room temperature to obtain a dry ash mixture B; Step (3-3) 40-55 parts by weight of water is added into the stirring cup of constant speed stirrer, 5-10 parts by weight of salt and 0.2-0.5 parts by weight of defoaming agent are added; the constant speed stirrer is started, and the stirring is carried out at 1500 rpm for 3 min to make the salt completely dissolved; then the dry ash mixture B is uniformly poured into the rotating stirring cup at 4000 rpm within 15 seconds; then the stirring is carried out at 12000 rpm for 35 seconds, and the tail slurry is obtained.

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