Foamed cement slurry and its applications

Abstract

The application relates to the technical field of oil drilling, and discloses a foamed cement slurry and application thereof, wherein the foamed cement slurry comprises the following components in parts by weight: 100 parts of cement, 0.1-40 parts of toughening particles, 0.1-40 parts of an elastic agent, 1-30 parts of a fluid loss reducer, 0.1-20 parts of a retarder, 1-30 parts of a filler, 0.1-20 parts of a foaming agent-I, 0.1-20 parts of a foaming agent-II, 0.1-20 parts of a foam stabilizer, 0.1-20 parts of a dispersing agent and 10-80 parts of water. The foamed cement slurry has the characteristics of a wide density adjustment range, high compressive strength, short thickening time and a wide temperature application range, can be applied in shale gas well slimming well cementing engineering under the condition of being lower than or equal to 95 DEG C, and has good applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil drilling technology, in particular to a foamed cement slurry and application thereof. BACKGROUND

[0002] With the increasing demand for energy and the deepening of oil and gas exploration, unconventional oil and gas such as shale gas has been regarded as a focus, and the exploration and development efforts have been increased. Shale gas has very good resource potential and exploration and development prospect. With the continuous advancement of shale gas exploration and development, the contradiction between high cost and economic benefit will gradually become prominent in the future, and the demand for cost reduction and efficiency improvement is becoming more and more intense. Under this background, the well profile is optimized, the hole diameter is reduced under the premise of ensuring the smooth implementation of drilling technology, the wellbore is slimmed down, the drilling cost is reduced, the mechanical drilling speed and time efficiency are improved, and the shale gas development is promoted to a low-cost and high-efficiency mode.

[0003] Due to the use of small size hole and casing, the annular space on one side is small, the annular pressure consumption is high under the same upflowing velocity during the replacement process, and then the high construction pump pressure brings great risk to the leakage and channeling prevention. In addition, large-scale hydraulic fracturing has a great impact on the thin cement ring interface, and the sealing integrity of the cement ring is difficult to guarantee, which is easy to cause the annular pressure of the shale gas well.

[0004] Therefore, it is necessary to develop a high-toughness and high-strength foamed cement slurry suitable for shale gas slim-hole wells to meet the needs of future shale gas slim-hole well cementing engineering. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the cement ring of the shale gas slim-hole well cementing slurry in the prior art is narrow, resulting in insufficient compressive strength and low toughness, and easy to cause annular pressure. A foamed cement slurry and application thereof are provided, which has the characteristics of wide density adjustment range, high compressive strength, short thickening time and wide temperature application range, and can be applied in shale gas slim-hole well cementing engineering under the condition of less than or equal to 95℃, having good applicability.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a foamed cement slurry, wherein the foamed cement slurry comprises the following components in parts by weight: 100 parts of cement, 0.1-40 parts of toughening particles, 0.1-40 parts of elastic agent, 1-30 parts of fluid loss reducer, 0.1-20 parts of retarder, 1-30 parts of filler, 0.1-20 parts of foaming agent-I, 0.1-20 parts of foaming agent-II, 0.1-20 parts of foam stabilizer, 0.1-20 parts of dispersant and 10-80 parts of water.

[0007] The second aspect of the present application provides the application of the aforementioned foamed cement slurry in shale gas slim-hole well.

[0008] The beneficial effects achieved by the technical solution are as follows:

[0009] (1) The foamed cement slurry in the application can be used as a low-density cement slurry, with a density of 1.2 g / cm 3 -1.7 g / cm 3 The cement slurry system can be applied to a wide temperature range of 50-95℃.

[0010] (2) In the foamed cement slurry in the application, the elastic agent and the toughening particles synergistically act to greatly reduce the elastic modulus of the cement slurry, prevent annulus pressure after fracturing of a slim-hole shale gas well, and the temperature-sensitive shape memory polymer exists in the form of particles at normal temperature, which is conducive to pumping, and the temperature-sensitive shape memory polymer will slowly stretch under the action of high temperature downhole, which plays a good role in improving the toughness of the cement stone, especially in reducing the elastic modulus of the thin cement ring in the slim-hole well and preventing annulus pressure.

[0011] (3) The foaming agent-I in the application adopts a chemical foaming method, and the foaming agent-II is added to form a foaming system during cementing, which has strong foaming capacity and can produce gas microfoam. In combination with animal protein complex foam stabilizer, nano filler and the like, the slurry is uniform and stable, has good flowability, rapid development of compressive strength, short thickening transition time and the like, has emulsifying and dispersing effect on the invading gas, prevents the formation of channels, and is conducive to the prevention of channeling in the shale gas well. DETAILED DESCRIPTION

[0012] The endpoints of the ranges and any values disclosed in this document are not limited to the precise values recited as the exact dimensions are not critical to the application. Each integer value within the range is to be considered to have been specified in this document. The endpoints of the ranges and any value between the recited values in a range can each be combined with one or more of the recited values to achieve a new range or a new value. All new ranges and values are to be considered disclosed in this document.

[0013] The first aspect of the application provides a foamed cement slurry, wherein the foamed cement slurry comprises the following components in parts by weight: 100 parts of cement, 0.1-40 parts of toughening particles, 0.1-40 parts of an elastic agent, 0.1-30 parts of a fluid loss reducer, 0.1-20 parts of a retarder, 1-30 parts of a filler, 0.1-20 parts of foaming agent-I, 0.1-20 parts of foaming agent-II, 0.1-20 parts of a foam stabilizer, 0.1-20 parts of a dispersant, and 10-80 parts of water.

[0014] In the application, when the foamed cement slurry is prepared by selecting each component according to the above specific parts by weight, the density of the foamed cement slurry under the condition of 20℃ standard atmospheric pressure is 1.2-1.7 g / cm 3The foam cement slurry can be used as a low-density cement slurry, is suitable for shale gas slim hole wells at 50-95 DEG C, and has the advantages of high compressive strength and short thickening transition time.

[0015] According to the present application, the foam cement slurry comprises the following components in parts by weight: 100 parts of cement, 5-20 parts of toughening particles, 1-20 parts of an elastic agent, 1-20 parts of a fluid loss reducer, 0.2-15 parts of a retarder, 5-20 parts of a filler, 1-15 parts of a foaming agent-I, 1-15 parts of a foaming agent-II, 1-15 parts of a foam stabilizer, 1-12 parts of a dispersant, and 20-60 parts of water.

[0016] In the present application, the cement is not particularly limited, and can be selected by those skilled in the art as needed, preferably, the cement is oil well cement.

[0017] According to the present application, the toughening particles comprise a temperature-sensitive shape memory polymer and fibers, preferably, the weight ratio of the temperature-sensitive shape memory polymer to the fibers is 0.6-2:1, preferably 0.8-1.2:1.

[0018] In the present application, the toughening particles can be prepared by a method comprising the following steps: low-temperature freezing and crushing the temperature-sensitive shape memory polymer; then adding fibers and uniformly mixing to obtain the toughening particles.

[0019] In the present application, the step of low-temperature freezing and crushing the temperature-sensitive shape memory polymer is to freeze the temperature-sensitive shape memory polymer to -10 DEG C to -30 DEG C using liquid nitrogen, and then crush the temperature-sensitive shape memory polymer to 20 mesh-80 mesh.

[0020] In the present application, the temperature for the extrusion granulation is set to 55-80 DEG C, and the size of the extrusion granulation is controlled to be 0-5 mm in diameter and length, preferably 2-5 mm.

[0021] According to the present application, preferably, the contact angle of the temperature-sensitive shape memory polymer is 20 DEG -65 DEG, preferably 20 DEG -50 DEG. The temperature-sensitive shape memory polymer is a product obtained by plasma modification of a temperature-sensitive swelling material selected from at least one of styrene-butadiene copolymer, styrene-butyl acrylate copolymer, polyvinyl acetal gel and polyurethane.

[0022] According to the present application, preferably, the modification process comprises: under an inert atmosphere, plasma treating the temperature-sensitive swelling material, the plasma being argon with a purity of 98%-99.999%, the flow rate of the plasma being 1-100 sccm, the discharge power being 10-400 W, and the treatment time being 2-10 min.

[0023] Preferably, the inert gas is argon with a purity of >99.999%.

[0024] In the application, the plasma modification adopts a plasma treatment instrument, mainly including a discharge system, a reaction chamber, an air inlet system, an electromagnetic shield, a vacuum pumping system and a gas discharge system, the discharge frequency is 13.56 MHz, and the maximum power is 400 W.

[0025] In the application, the surface of the temperature-sensitive swelling material is treated by the plasma, so that the surface of the temperature-sensitive swelling material is modified, a large number of free radicals are formed on the surface of the polymer, a large number of original hydroxyl groups, carboxyl groups and other functional groups are opened, and the hydrophilicity and the plugging capacity are effectively improved.

[0026] In the application, the surface activity of the temperature-sensitive swelling material before and after modification is determined by using a contact angle equipment CA500S, a whole inclination full-automatic optical contact angle measuring instrument is used to measure the contact angle of a sample surface and a liquid drop (deionized water) in an atmospheric environment, a standard method for testing the surface wettability and absorbability of a sheet material by using an automatic contact angle tester is executed, and the surface wettability and aging of the temperature-sensitive shape memory polymer before and after modification is characterized.

[0027] According to the application, preferably, the fiber is a polypropylene fiber and / or a polyvinyl chloride fiber.

[0028] In some embodiments, the fiber is a polypropylene fiber and a polyvinyl chloride fiber. Further, the polypropylene fiber accounts for 30-70% of the total weight of the fiber, preferably 40-60%. The polyvinyl chloride fiber accounts for 30-70% of the total weight of the fiber, preferably 40-60%.

[0029] Preferably, the weight of the toughening particles is 0.1-40 parts, for example 0.1 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range formed by any two of the above values, preferably 5-20 parts.

[0030] In the application, the shape memory deformation temperature of the temperature-sensitive shape memory polymer is 50-95 DEG C, the temperature-sensitive shape memory polymer is in a granular form in order to facilitate pumping in a construction process, but under the action of high temperature in a well, the temperature-sensitive shape memory polymer will slowly expand, and the temperature-sensitive shape memory polymer plays a good role in improving the toughness of the cement slurry.

[0031] In the present application, the toughening particles prepared by the above method contain the temperature-sensitive shape memory polymer with a defined contact angle and the fiber (specific fiber and composition), and the amount relationship, which can effectively improve the compressive strength of the foamed cement slurry, shorten the thickening time, and is suitable for shale gas wells, especially for reducing the modulus of elasticity of the slim hole well, preventing the annular pressure and playing a good role.

[0032] According to the present application, preferably, the foaming agent-I is a solid compound soluble in water, which contains an anion group of chlorine, oxygen, bromine or nitrogen and a cation group containing potassium, sodium, ammonium, lithium, magnesium, calcium or aluminum.

[0033] In some embodiments, the foaming agent-I is selected from at least one of potassium chlorate, magnesium chlorate, sodium chlorate, sodium perchlorate, ammonium perchlorate, calcium chlorate, calcium nitrate, sodium nitrate, potassium nitrate, aluminum nitrate, potassium chlorate, potassium bromate, potassium perchlorate, lithium perchlorate, sodium bromate, magnesium perchlorate.

[0034] In the present application, the weight fraction of the foaming agent-I is 0.1-20 parts, such as 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, and any value in the range between any two of the above-mentioned values, preferably 1-15 parts.

[0035] According to the present application, preferably, the foaming agent-II is a nitrogen-containing compound solution.

[0036] In some embodiments, the nitrogen-containing compound is selected from at least one of ammonium chloride, hydrochloric acid ammonium, ammonium nitrite, ethylenediamine, ammonium nitrate, methylthionamide, ammonium sulfate, ethylthionamide, ammonium bisulfate and methyl hydrochloric acid hydrogen amine.

[0037] In the present application, the foaming agent-I and the foaming agent-II are used in the way of chemical foaming, which has the characteristics of high gas evolution rate, high displacement efficiency, and basically no effect on the thickening time and compressive strength of the cement slurry.

[0038] In the present application, the foaming agent-I is used in the way of chemical foaming, and the foaming agent-II is added during the cementing process to form a foaming system, which has strong foaming capacity and can produce gas microfoam. Combined with animal protein complex foam stabilizer, nano filler, etc., the slurry is uniform and stable, has good flowability, rapid development of compressive strength, short thickening transition time, etc., has emulsifying and dispersing effect on the invading gas, prevents the formation of channels, and is beneficial to the anti-channeling of shale gas wells.

[0039] In the present application, the compressive strength of the foamed cement slurry develops rapidly, and the cement slurry can be quickly thickened and has compressive strength, and the time from the beginning of strength to a certain strength is short.

[0040] According to the present application, the concentration of the nitrogen-containing compound in the foaming agent-II is 0.5-4 mol / L, preferably 1-2.5 mol / L.

[0041] In the present application, the weight fraction of the foaming agent-II is 0.1-20 parts, for example 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, and any value in the range consisting of any two of the above values, preferably 1-15 parts.

[0042] According to the present application, the filler is a nano-silica emulsion.

[0043] In the present application, the weight fraction of the filler is 1-30 parts, for example 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 25 parts, 30 parts, and any value in the range consisting of any two of the above values, preferably 5-20 parts.

[0044] In the present application, the silica particles contained in the filler have strong sphericity, micro-aggregate filling effect and crystal nucleus effect, which can increase the compressive strength of the cement sheath.

[0045] According to the present application, the elastic agent is selected from at least one of styrene-butadiene rubber, cis-butadiene rubber, isoprene rubber, nitrile rubber, chloroprene rubber and ethylene-propylene rubber.

[0046] In the present application, preferably, the elastic agent is a powder, and the powder has a diameter of 10-500 mesh, preferably 70-90 mesh.

[0047] In the present application, preferably, the weight fraction of the elastic agent is 0.1-40 parts, for example 0.1 parts, 0.5 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range consisting of any two of the above values, preferably 1-20 parts.

[0048] In the present application, the elastic agent and the toughening particles synergistically act, which can greatly reduce the elastic modulus of the cement slurry, prevent annulus pressure after slim-hole fracturing, and not affect the thickening time and late strength development of the cement slurry.

[0049] According to the present application, preferably, the foam stabilizer is at least one selected from the group consisting of cocamide diethanol, sodium fatty alcohol polyoxyethylene ether sulfate, triethanolamine, fatty alcohol diethanol amide and cetyl alcohol.

[0050] In the present application, the weight fraction of the foam stabilizer is 0.1-20 parts, such as 0.1, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts, and any value in the range between any two of the above-mentioned values, preferably 1-15 parts.

[0051] In the present application, during the mixing process of preparing the foamed cement slurry, the foaming agent-I and the foaming agent-II are in contact and chemically react to produce gas in the cement slurry, and under the stabilizing effect of the foam stabilizer, the purpose of filling gas in the cement slurry can be achieved, and the foamed cement slurry is prepared.

[0052] According to the present application, the dispersant is at least one selected from the group consisting of sulfonated formaldehyde-acetone polycondensate dispersant, polynaphthalene sulfonate dispersant and lignin sulfonate dispersant.

[0053] In the present application, the weight fraction of the dispersant is 0.1-20 parts, such as 0.1, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts, and any value in the range between any two of the above-mentioned values, preferably 1-12 parts.

[0054] According to the present application, the retarder is at least one selected from the group consisting of tartaric acid, citric acid, boric acid, sodium borate, sodium gluconate, 2-acrylamide-2-methylpropane sulfonic acid and acrylic acid copolymer, 2-acrylamide-2-methylpropane sulfonic acid and itaconic acid copolymer.

[0055] In the present application, the weight fraction of the retarder is 0.1-20 parts, such as 0.1, 0.2, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts, and any value in the range between any two of the above-mentioned values, preferably 0.2-15 parts.

[0056] In the present application, the retarder functions to adjust the thickening time of the cement slurry. The adsorption group is adsorbed on the surface of the cement particles to form a dense protective layer to prevent water molecules from freely entering and leaving the surface layer of the cement particles, reducing the hydration speed, while the retarder molecules can also reduce the Ca 2+It has strong chelating ability, hinders the growth of hydration product micro-nucleus, and achieves the purpose of inhibiting hydration, so as to have the effect of retarding and adjusting the thickening time.

[0057] According to the present application, the fluid loss additive is selected from at least one of polyvinyl alcohol fluid loss additive, cellulose ether fluid loss additive, latex fluid loss additive, propylene amide and 2-propylene amide-2-methyl propyl sulfonic acid polymer fluid loss additive.

[0058] In some embodiments, the cellulose ether fluid loss additive is selected from at least one of hydroxyethyl cellulose fluid loss additive, carboxymethyl cellulose fluid loss additive and carboxymethyl hydroxyethyl cellulose fluid loss additive.

[0059] In some embodiments, the latex fluid loss additive is butadiene-styrene latex fluid loss additive.

[0060] In the present application, the weight fraction of the fluid loss additive is 0.1-30 parts, for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30 parts, and any value in the range between any two of the above-mentioned values, preferably 1-20 parts.

[0061] In the present application, the fluid loss additive acts by adsorbing cement particles and water molecules to form a reinforced hydration film around the cement particles, promoting the stability of the cement slurry and the rubber protection effect, thereby facilitating the formation of a dense mud cake and reducing the fluid loss of the cement slurry.

[0062] In the present application, preferably, the weight fraction of water is 10-80 parts, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 parts, and any value in the range between any two of the above-mentioned values, preferably 20-60 parts.

[0063] The second aspect of the present application provides an application of the aforementioned foamed cement slurry in shale gas slim hole wells.

[0064] According to a particularly preferred embodiment of the present application, the foamed cement slurry comprises the following components in parts by weight: 100 parts of cement, 5-10 parts of toughening particles, 2-10 parts of elastic agent, 2-10 parts of fluid loss additive, 0.3-5 parts of retarder, 5-20 parts of filler, 1-10 parts of foaming agent-I, 1-10 parts of foaming agent-II, 1-10 parts of foam stabilizer, 5-10 parts of dispersant and 30-50 parts of water.

[0065] The application will be described in detail below by examples. The specific conditions not indicated in the following examples and comparative examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer.

[0066] The raw materials used: nano-silica emulsion is a commercially available product of Texas Continental Shelf Petroleum Engineering Co., Ltd., which meets the technical solution disclosed in CN201410538428.1;

[0067] Styrene-butadiene temperature-sensitive swelling material is a commercially available product of Texas Continental Shelf Co., with the brand SCR-TD;

[0068] The contact angle is measured by CA500S whole-body inclined full-automatic optical contact angle measuring instrument;

[0069] The plasma treatment instrument is VP-R series plasma treatment instrument of Guangzhou Shanzhun Technology Co., Ltd.;

[0070] The reagents or instruments used without indicating the manufacturer are conventional products that can be obtained through market purchase.

[0071] In the following examples and comparative examples,

[0072] The density of the foamed cement slurry is measured by hydrostatic weighing method;

[0073] The thickening performance, API fluid loss, compressive strength, and rheological parameters are measured according to GB / T19139-2012 Oil Well Cement Test Methods;

[0074] Elastic modulus: measured according to the method in High Temperature and High Pressure Resistant Ultra-high Density Cement Stone Mechanical Properties (Song He, Yang Wei, and Tang Junfeng, et al. [J]. Drilling Fluids and Completion Fluids, 2021 (038-006)).

[0075] Toughening particle preparation example A1

[0076] (1) Plasma modification: using a plasma treatment instrument, the styrene-butadiene temperature-sensitive swelling material is placed on the lower electrode of the reaction chamber, vacuumed to 2 Pa, argon gas is introduced by opening the inlet, the flow rate of the plasma is controlled to 10 sccm by using a rotameter, the discharge power is 100 W, and the treatment time is 2 min, to obtain a temperature-sensitive shape memory polymer.

[0077] (2) The temperature-sensitive shape memory polymer is frozen at -10°C to low temperature using liquid nitrogen, and then crushed into powder with a size of 20-80 mesh.

[0078] (3) Polypropylene fiber (polypropylene) and polyvinyl chloride fiber (polyvinyl chloride) are mixed in a weight ratio of 1:1 to obtain the fiber.

[0079] (4) The fiber and the warm-sensitive shape memory polymer powder are mixed at a weight ratio of 1:1 at high speed, and the mixed material is granulated at 75°C by using an extrusion granulator, and the size of the extrusion granulation is controlled to be less than or equal to 5mm in diameter and length.

[0080] Toughening particle preparation example A2

[0081] (1) The styrene-butadiene warm-sensitive expansion material is frozen at a low temperature of-10°C by using liquid nitrogen, and is crushed into a powder with a size of 20-80 mesh.

[0082] (2) The polypropylene fiber (polyamide fiber) and the polyvinyl chloride fiber (chlorofiber) are mixed at a weight ratio of 1:1 to obtain the fiber.

[0083] (3) The fiber and the warm-sensitive expansion material powder are mixed at a weight ratio of 1:1 at high speed, and the mixed material is granulated at 75°C by using an extrusion granulator, and the size of the extrusion granulation is controlled to be less than or equal to 5mm in diameter and length.

[0084] Test example 1

[0085] The surface activity of the warm-sensitive shape memory polymer and the styrene-butadiene warm-sensitive expansion material is measured by using a contact angle device CA500S, which is a whole body tilting full-automatic optical contact angle measuring instrument, to measure the contact angle between the sample surface and the liquid drop (deionized water) in the atmospheric environment, and the standard method for testing the surface wettability and absorption of sheet material by using an automatic contact angle tester is executed to characterize the surface wettability and aging of the warm-sensitive shape memory polymer and the styrene-butadiene warm-sensitive expansion material, and the contact angle is measured three times, respectively, and the results are shown in Table 3.

[0086] Table 3

[0087] Temperature-sensitive shape memory polymer Styrene-butadiene temperature-sensitive expanding material Contact angle (°) 31 / 39 / 34 65 / 54 / 51

[0088] The water contact angle of the surface of the styrene-butadiene warm-sensitive expansion material is 65 / 54 / 51°, and the contact angle of the warm-sensitive shape memory polymer obtained by the plasma treatment can be seen that the plasma treatment obviously improves the surface wettability of the warm-sensitive shape memory polymer, and the water contact angle is reduced to below 31 / 39 / 34°, and the hydrophilicity of the warm-sensitive shape memory polymer is greatly improved.

[0089] Example 1

[0090] The foam cement slurry is prepared according to the standard API10B-4-2004.

[0091] The basic composition of the slurry dry ash is: 100 parts of G-grade oil well cement, 0.5 parts of magnesium chlorate, 5 parts of butadiene rubber, and 5 parts of toughening particle A1.

[0092] The basic composition of the slurry liquid is as follows: 0.5 parts of 2.2 mol / L ammonium nitrite, 0.5 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 3 parts of butadiene-styrene latex water loss reducer, 8 parts of nano silica emulsion, 0.3 parts of sodium gluconate, 10 parts of sulfonated formaldehyde-acetone condensate dispersant, and 48 parts of water.

[0093] First, weigh and mix the solid dry ash component and liquid component of the slurry. Then, add the mixed liquid component to the mixer and stir at 4000 rpm for 15 seconds. Continue stirring at 12000 rpm for 35 seconds to obtain foamed cement slurry.

[0094] Example 2

[0095] Foamed cement slurry was prepared according to standard API10B-4-2004, and the foamed cement slurry was prepared according to the formulation in Table 1 and the preparation method of Example 1.

[0096] Example 3

[0097] Foamed cement slurry was prepared according to standard API10B-4-2004, and the foamed cement slurry was prepared according to the formulation in Table 1 and the preparation method of Example 1.

[0098] Example 4

[0099] Foamed cement slurry was prepared according to standard API10B-4-2004, and the foamed cement slurry was prepared according to the formulation in Table 1 and the preparation method of Example 1.

[0100] Example 5

[0101] Foamed cement slurry was prepared according to standard API10B-4-2004, and the foamed cement slurry was prepared according to the formulation in Table 1 and the preparation method of Example 1.

[0102] Example 6

[0103] Foamed cement slurry was prepared according to the method in Example 4, except that the toughening particles A1 were 10 parts by weight. The specific formula is shown in Table 1.

[0104] Example 7

[0105] Foamed cement slurry was prepared according to the method in Example 4, except that the dispersant was 5 parts by weight. The specific formula is shown in Table 1.

[0106] Prepare foamed cement slurry according to the formula in Table 1.

[0107] Example 8

[0108] Foamed cement slurry was prepared according to the method in Example 4, except that 5 parts by weight of toughening particles A2 were used. The specific formula is shown in Table 1.

[0109] Comparative Example 1

[0110] The foamed cement slurry was prepared according to the method of Example 4, except that the foaming agent-I, foaming agent-II, foam stabilizer and dispersant were not added, and the specific formulation is shown in Table 2.

[0111] Comparative Example 2

[0112] The foamed cement slurry was prepared according to the method of Example 4, except that the toughening particles were not added, and the specific formulation is shown in Table 2.

[0113] Comparative Example 3

[0114] The foamed cement slurry was prepared according to the method of Example 4, except that the dispersant was not added, and the specific formulation is shown in Table 2.

[0115] Table 1

[0116]

[0117]

[0118] Table 1 (continued)

[0119]

[0120] Table 2

[0121]

[0122] Test Example 2

[0123] The density of the foamed cement slurry was tested under the condition of 20℃ and standard atmospheric pressure, and the density of the foamed cement slurry after heating and pressurizing was measured by hydrostatic weighing method. The foamed cement slurry was poured into a circular pressure-resistant steel mold with a diameter of 8cm and a height of 10cm, the inside of which was coated with polytetrafluoroethylene, and the lower part was sealed with a threaded cap, and the middle of the upper sealing threaded cap had a small hole with a diameter of 0.5cm for pressure transmission. Then, the circular pressure-resistant steel mold filled with the foamed cement slurry was placed into a high-temperature and high-pressure curing kettle, and water was used as the heat and pressure transmission medium for heating and pressurizing curing. After 48 hours, the cement stone was taken out, and the specific results are shown in Table 4.

[0124] Table 4

[0125]

[0126]

[0127] As can be seen from the results in Table 4, the density of the foamed cement slurry of Examples 1-8 of the present application is 1.2-1.7g / cm 3The density of the foam cement slurry is lower than that of the foam cement slurry of Comparative Examples 1-3, and the foam cement slurry can be used as a low-density cement slurry.

[0128] The API fluid loss of the foam cement slurry is lower than 50 mL / 30 min, and meets the API standard requirement.

[0129] The thickening performance test results of the foam cement slurry with different amounts of retarder are shown in Table 5.

[0130] Table 5

[0131]

[0132]

[0133] It can be seen from the results in Table 5 that the thickening performance is greater than 200 min at 95 ℃ / 45 MPa, and the thickening time can be linearly adjusted by the amount of the retarder, which proves that the amount of the retarder has obvious adaptability to the foam cement slurry system.

[0134] The compressive strength test results of the foam cement slurry are shown in Table 6.

[0135] Table 6

[0136] Compressive strength (48 h, 95°C), MPa Elastic modulus, GPa Example 1 30.3 8.1 Example 2 27.1 6.9 Example 3 20.2 5.8 Example 4 19.7 5.0 Example 5 15.2 4.1 Example 6 19.8 4.6 Example 7 20.1 4.7 Example 8 18.5 5.2 Comparative Example 1 40.2 11.4 Comparative Example 2 36.6 12.7 Comparative Example 3 41.3 10.45

[0137] It can be seen from the results in Table 6 that the foam cement slurry of the present application Examples 1-8 has a lower elastic modulus and a significantly increased compressive strength at 48 h and 95 ℃, compared with the foam cement slurry of Comparative Examples 1-3, and the elastic modulus of the foam cement slurry of Comparative Examples 1-3 is greater than 9 GPa, which cannot meet the requirement of low elastic modulus and high toughness.

[0138] Test Example 3

[0139] The rheological parameters of the foam cement slurry of the present application Examples and Comparative Examples at different temperatures are tested, and the specific results are shown in Table 7.

[0140] Table 7

[0141] Room temperature (25°C rheological parameters) High temperature (95°C rheological parameters) Example 1 300+ / 213 / 162 / 88 / 12 / 10 235 / 156 / 85 / 43 / 10 / 8 Example 2 300+ / 220 / 150 / 80 / 10 / 8 246 / 142 / 80 / 40 / 10 / 8 Example 3 300+ / 215 / 167 / 83 / 13 / 11 237 / 151 / 82 / 42 / 10 / 8 Example 4 300+ / 218 / 169 / 86 / 11 / 10 237 / 150 / 80 / 40 / 10 / 8 Example 5 300+ / 234 / 131 / 85 / 11 / 9 238 / 136 / 75 / 39 / 7 / 5 Example 6 300+ / 228 / 158 / 88 / 12 / 9 249 / 149 / 89 / 49 / 11 / 8 Example 7 300+ / 216 / 162 / 87 / 12 / 9 235 / 159 / 85 / 43 / 9 / 7 Example 8 300+ / 223 / 151 / 82 / 10 / 8 249 / 141 / 81 / 40 / 9 / 7 Comparative Example 1 300+ / 300+ / 300+ / 182 / 45 / 38 300+ / 252 / 161 / 100 / 25 / 23 Comparative Example 2 300+ / 203 / 142 / 68 / 7 / 5 215 / 126 / 65 / 23 / 3 / 1 Comparative Example 3 300+ / 300+ / 181 / 108 / 28 / 25 300+ / 215 / 143 / 80 / 15 / 14

[0142] It can be seen from the results in Table 7 that all the present application Examples have good rheological properties, and the friction generated in the construction process is low, which has a better effect on reducing the construction pump pressure and reducing the risk of leakage in the construction. Compared with the present application Examples, the apparent density of Comparative Example 1 and Comparative Example 3 is significantly increased, which will generate high friction in the construction, the construction pump pressure is high, and the formation is easy to be pressed to leak. Since no toughening particles are added in Comparative Example 2, the rheological property of the slurry is too thin, which is not conducive to the settlement stability of the cement slurry, and the stratification phenomenon is easy to occur, which does not meet the construction requirement.

[0143] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A foamed cement slurry, characterized in that, The foam cement slurry comprises the following components in parts by weight: 100 parts of cement, 5-20 parts of toughening particles, 1-20 parts of an elastic agent, 1-20 parts of a fluid loss agent, 0.2-15 parts of a retarder, 5-20 parts of a filler, 1-15 parts of a foaming agent-I, 1-15 parts of a foaming agent-II, 1-15 parts of a foam stabilizer, 1-12 parts of a dispersant, and 20-60 parts of water; The toughening particles comprise a temperature-sensitive shape memory polymer and fibers; The temperature-sensitive shape memory polymer has a contact angle of 20°-50°; the temperature-sensitive shape memory polymer is a product obtained by plasma modification of a temperature-sensitive swelling material; The filler is a nano-silica emulsion.

2. The foamed cement slurry of claim 1, wherein, The weight ratio of the temperature-sensitive shape memory polymer to the fibers is 0.6-2:

1.

3. The foamed cement slurry of claim 2, wherein, The weight ratio of the temperature-sensitive shape memory polymer to the fibers is 0.8-1.2:

1.

4. The foamed cement slurry of claim 1, wherein, The temperature-sensitive swelling material is selected from at least one of styrene-butadiene copolymer, styrene-butyl acrylate copolymer, polyvinyl acetal gel, and polyurethane; And / or, the fibers are polypropylene fibers and / or polyvinyl chloride fibers.

5. The foamed cement slurry of claim 4, wherein, The fibers are polypropylene fibers and polyvinyl chloride fibers.

6. The foamed cement slurry of claim 5, wherein, The amount of the polypropylene fibers is 30-70% of the total weight of the fibers.

7. The foamed cement slurry of claim 6, wherein, The amount of the polypropylene fibers is 40-60% of the total weight of the fibers.

8. The foamed cement slurry of any of claims 1-7, wherein, The foaming agent-I is a water-soluble solid compound containing an anion group of chlorine, oxygen, bromine, or nitrogen and a cation group containing potassium, sodium, ammonium, lithium, magnesium, calcium, or aluminum.

9. The foamed cement slurry of claim 8, wherein, The foaming agent-I is selected from at least one of potassium chlorate, magnesium chlorate, sodium chlorate, sodium perchlorate, ammonium perchlorate, calcium chlorate, calcium nitrate, sodium nitrate, potassium nitrate, aluminum nitrate, potassium chlorate, potassium bromate, potassium perchlorate, lithium perchlorate, sodium bromate, and magnesium perchlorate.

10. The foamed cement slurry of any of claims 1-7, wherein, The foaming agent-II is a nitrogen-containing compound solution.

11. The foamed cement slurry of claim 10, wherein, The nitrogen-containing compound is selected from at least one of ammonium chloride, hydroammonium chloride, ammonium nitrite, ethylenediamine, ammonium nitrate, methylthionamide, ammonium sulfate, ethylthionamide, ammonium bisulfate, and methylhydrogen bisulfate.

12. The foamed cement slurry of claim 10, wherein, In the foaming agent-II, the concentration of the nitrogen-containing compound is 0.5-4 mol / L.

13. The foamed cement slurry of claim 12, wherein, In the foaming agent-II, the concentration of the nitrogen-containing compound is 1-2.5 mol / L.

14. The foamed cement slurry of any of claims 1-7, wherein, The elastic agent is selected from at least one of styrene-butadiene rubber, cis-butadiene rubber, isoprene rubber, nitrile-butadiene rubber, chloroprene rubber, and ethylene-propylene rubber.

15. The foamed cement slurry of any of claims 1-7, wherein, The foam stabilizer is selected from at least one of coconut oil diethanolamide, sodium fatty alcohol polyoxyethylene ether sulfate, triethanolamine, fatty alcohol diethanolamide, and cetyl alcohol.

16. The foamed cement slurry of any of claims 1-7, wherein, The dispersant is selected from at least one of sulfonated formaldehyde-acetone polycondensate dispersant, polynaphthalene sulfonate dispersant, and lignosulfonate dispersant.

17. The foamed cement slurry of any of claims 1-7, wherein, The retarder is selected from at least one of tartaric acid, citric acid, boric acid, sodium borate, sodium gluconate, 2-acrylamide-2-methylpropane sulfonic acid and acrylic acid copolymer, and 2-acrylamide-2-methylpropane sulfonic acid and itaconic acid copolymer.

18. The foamed cement slurry of any of claims 1-7, wherein, The fluid loss agent is selected from at least one of a polyvinyl alcohol-based fluid loss agent, a cellulose ether-based fluid loss agent, a latex-based fluid loss agent, and a propenylamide and 2-propenamide-2-methylpropane sulfonic acid polymer-based fluid loss agent.

19. The foamed cement slurry of claim 18, wherein, The cellulose ether-based fluid loss agent is selected from at least one of a hydroxyethyl cellulose fluid loss agent, a carboxymethyl cellulose fluid loss agent, and a carboxymethyl hydroxyethyl cellulose fluid loss agent.

20. The foamed cement slurry of claim 18, wherein, The latex-based fluid loss agent is selected from a butadiene-styrene latex fluid loss agent.

21. Use of the foamed cement slurry of any one of claims 1-20 in a shale gas slim hole well.

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