阅读说明：本技术 一种复合絮凝剂、水基钻井液及其应用 (Composite flocculant, water-based drilling fluid and application of water-based drilling fluid ) 是由 李子杰 赵波 李文明 刘均一 丁海峰 宋彦波 刘全江 路峰 薛立国 盖涛 张宗耀 于 2019-10-21 设计创作，主要内容包括：本发明涉及石油钻井液技术领域,具体涉及一种复合絮凝剂、水基钻井液及其应用。本发明所述复合絮凝剂由以下成分及其重量份组成：聚丙烯酰胺0.05份-0.3份、无机盐2份-20份和聚胺类抑制剂1份-10份。本发明复合絮凝剂主要是利用高分子聚丙烯酰胺与聚胺类抑制的协同作用,提高复合絮凝剂的絮凝效果。本发明复合絮凝剂能够降低粘土水化和加速固相颗粒絮凝沉降,用于上部地层快速钻进,同时提高絮凝程度,实现有效地固相控制。(The invention relates to the technical field of petroleum drilling fluid, and particularly relates to a composite flocculant, a water-based drilling fluid and application thereof. The composite flocculant comprises the following components in parts by weight: 0.05 to 0.3 portion of polyacrylamide, 2 to 20 portions of inorganic salt and 1 to 10 portions of polyamine inhibitor. The composite flocculant of the invention mainly utilizes the synergistic effect of inhibition of the high-molecular polyacrylamide and the polyamine to improve the flocculation effect of the composite flocculant. The composite flocculant can reduce clay hydration and accelerate flocculation and sedimentation of solid phase particles, is used for rapid drilling of upper strata, simultaneously improves flocculation degree and realizes effective solid phase control.)

1. The composite flocculant is characterized by comprising the following components: polyacrylamide, inorganic salts and polyamine inhibitors.

2. The composite flocculant according to claim 1, which is characterized by comprising the following components in parts by weight: 0.05 to 0.3 portion of polyacrylamide, 2 to 20 portions of inorganic salt and 1 to 10 portions of polyamine inhibitor.

3. The composite flocculant according to claim 1, which is characterized by comprising the following components in parts by weight: 0.1-0.2 part of polyacrylamide, 5-15 parts of inorganic salt and 3-7 parts of polyamine inhibitor; preferably, the composition comprises the following components in parts by weight: 0.12 to 0.18 portion of polyacrylamide, 8 to 12 portions of inorganic salt and 5 portions of polyamine inhibitor.

4. The composite flocculant according to any one of claims 1 to 3, wherein the polyacrylamide is selected from one or more of nonionic polyacrylamide, anionic polyacrylamide or cationic polyacrylamide, preferably anionic polyacrylamide; the average molecular weight of the nonionic polyacrylamide is (6-10) multiplied by 10⁶(ii) a The anionic polyacrylamide has hydrolysis degree of 20-40%, and average molecular weight of 3-20 x 10⁶(ii) a The cationic polyacrylamide has cationic degree of 20-50%, and average molecular weight of (1-2) × 10⁷。

5. The composite flocculant according to any one of claims 1 to 3, wherein the inorganic salt is selected from one or more of calcium chloride, sodium chloride or potassium chloride, preferably calcium chloride.

6. The composite flocculant according to any one of claims 1 to 3, wherein the polyamine-based inhibitor is selected from one or more of an amine-based polyol, an amine-based silanol or a polyether amine, preferably an amine-based polyol; preferably, the aminopolyol has an average molecular weight of 800-1000.

7. A water-based drilling fluid comprising the composite flocculant of any one of claims 1 to 6.

8. The drilling fluid of claim 7, wherein the composite flocculant is 0.5-2.0% by weight of the water-based drilling fluid.

9. Use of a composite flocculant according to any one of claims 1 to 6 and a drilling fluid according to claim 7 or 8 for flocculation-assisted separation of solids phase control.

10. The use according to claim 9, wherein the composite flocculant is added at the time of application.

Technical Field

The invention relates to the technical field of petroleum drilling fluid, and particularly relates to a composite flocculant, a water-based drilling fluid and application thereof.

Background

The polyamine shale inhibitor is one of important components of amino drilling fluid, and plays a key role in inhibiting borehole instability, drill bit balling, borehole purification and the like caused by hydration expansion and dispersion of shale. The polar group on the molecular chain of the high molecular weight polyamine shale inhibitor is adsorbed with clay, so that an adsorption layer is formed, and the adsorption layer has the function of retarding the permeation of water molecules into shale; the low molecular weight amine polymer shale inhibitor can enter the middle of a clay layer, and clay layer sheets are bound together by means of electrostatic adsorption and hydrogen bond action of protonated amine, so that the inter-layer distance of clay minerals in shale is reduced, and an inhibiting effect is achieved.

The stalactite and the like construct the polyamine high-performance water-based drilling fluid according to the hydration characteristics of shale and the multi-element synergistic inhibition thought. The system mainly comprises polyamine shale inhibitor SDJA, coating inhibitor SDB, aluminum salt plugging anti-collapse agent HA-1, clean lubricant SD-505, flow pattern regulator, filtrate reducer and the like. The results show that: the polyamine shale inhibitor can reduce the hydration interlamellar spacing of the clay to the maximum extent under low concentration, and effectively inhibit the hydration expansion of the clay; after being compounded, the polyamine shale inhibitor and the aluminum salt plugging anti-collapse agent can obviously retard the pore pressure transmission (Zhonghanyi, Qizhengsong, Huangweian, et al. evaluation and application of characteristics of polyamine high-performance water-based drilling fluid [ J ]. scientific technology and engineering, 2013,13(10):2803 and 2807.).

The Wangqiao discovers in the research that the aminopolyol has strong inhibition, can effectively inhibit the hydration dispersion of clay, and has strong inhibition even under the condition of very low concentration; the aminopolyols have a certain influence on the rheology of the clay dispersion, but this influence is not so great; has little effect on fluid loss (Wangqiao seawater amino drilling fluid research and application [ D ]. 2014.). The amido polyalcohol not only has the advantages of strong cation adsorption, strong inhibition, long action time and the like, but also overcomes the defects of serious flocculation of cations on drilling fluid, increased filter loss and the like, and is an excellent shale inhibitor (Wangjinsong, Gangde peak, Lanqiang. bispolysulfanyl polyalcohol drilling fluid in low-permeability oil fields in Bohai south [ J ] drilling fluid and completion fluid, 2010,27 (3)).

From the above analysis, at present, most of polyamine substances are used as inhibitors in drilling fluids, and other applications of polyamine inhibitors in oil field production are rarely reported.

In recent years, the development of composite flocculants has become a hot spot. The composite flocculant is divided into three major categories of inorganic composite type, organic composite type and organic-inorganic composite type according to chemical components. The inorganic composite flocculant has more components, and the main raw materials comprise aluminum salt, ferric salt and silicate. The organic-inorganic composite flocculant is mainly characterized by variety and diversified performance. The action mechanism is mainly related to the synergistic effect, and the inorganic high molecular components adsorb impurities and suspended particles to promote the formation of particles and increase gradually; the organic high molecular components are subjected to the self-bridging action, and the surface charges of pollutants are neutralized by the existence of inorganic salts, so that the flocculation effect of the organic high molecules is promoted.

Chinese patent application (CN109021941A) discloses a coating flocculant for drilling fluid, which comprises, by mass, 20-50 parts of potassium chloride, 10-18 parts of sodium carbonate, 5-15 parts of 2-acrylamide-2-methylpropanesulfonic acid, 0-10 parts of acrylamide, 60-150 parts of vinyl acetate, 80-120 parts of water-soluble silicone oil and 1-5 parts of sodium polyacrylate. The product has very high dissolution speed, a neutral aqueous solution, strong clay and drilling cuttings dispersion inhibiting capability, good salt and temperature resistance, and super-strong anti-collapse effect, and is beneficial to the protection of oil and gas layers; overcomes the defects that the viscosity of a system is increased and the phenomenon of over flocculation is easy to occur when high molecular weight polyacrylamide (with the higher molecular weight of 600-1400 ten thousand) is used, so that the filtration loss of slurry is increased, the stability of the slurry is insufficient, and particles or powdery coating agents are easy to be mutually agglomerated into lumps which are difficult to dissolve due to the high molecular weight, so that the complete dissolution consumes long time and has low speed.

Chinese patent application (CN106830245A) discloses a desulfurization wastewater flocculant, which comprises the following components in percentage by weight: 0.01% -2% of polyacrylamide; 0.01 to 15 percent of polyamine salt; 1% -40% of poly aluminum iron; 0.001% -5% of surfactant; 50 to 90 percent of water. The composite flocculant is prepared by compounding a water-soluble high-molecular compound flocculant and an inorganic salt flocculant, and the high positive charge density of the inorganic flocculant and the bridging effect of the organic high-molecular compound flocculant generate a synergistic effect to improve the flocculation treatment capacity.

At present, aiming at the strong slurry making in the drilling process, when the drilling cuttings pass through a sedimentation basin during the conventional large-cycle operation, the flow velocity is reduced, and after the drilling cuttings are subjected to coagulation and separation under the action of a flocculating agent, the upper clear liquid returns to a circulating system, so that the normal drilling fluid construction is realized; the problems that the rheological property of the drilling fluid is difficult to control and a well hole is not smooth are solved, but the problems that a large circulation pool occupies a large area and easily pollutes the environment are also caused. In addition, the second well of part of high deflecting point wells and cluster well groups or subsequent construction wells can not be subjected to large circulation, so that the problems that the rheological property of the drilling fluid is difficult to control and the well hole is not smooth are prominent, and complex accidents such as partial well tripping, meeting resistance, electric resistance card, drilling to form new holes and even drilling tool burying are caused. However, in the small circulation drilling process, the drill cuttings are subjected to extrusion grinding of a drill string, hydration dispersion and the like, the surfaces of clay particles are negatively charged, and the clay particles repel each other, are not easy to coalesce and sink and are difficult to remove.

However, the problem of low solid control efficiency of the solid control equipment in the rapid drilling process of the upper stratum is not solved.

Disclosure of Invention

The invention mainly aims to provide a composite flocculant and a water-based drilling fluid which can improve flocculation effect, realize effective solid-phase control in the process of quickly drilling an upper stratum and assist in improving solid-phase control efficiency. The composite flocculant of the invention mainly utilizes the synergistic effect of inhibition of the high-molecular polyacrylamide and the polyamine to improve the flocculation effect of the composite flocculant.

The technical scheme of the invention is as follows:

the invention aims to provide a composite flocculant, which consists of the following components: polyacrylamide, inorganic salts and polyamine inhibitors.

Preferably, the composite flocculant comprises the following components in parts by weight: 0.05 to 0.3 portion of polyacrylamide, 2 to 20 portions of inorganic salt and 1 to 10 portions of polyamine inhibitor.

In another aspect, the present invention provides a water-based drilling fluid, which comprises the above composite flocculant.

The invention also provides the application of the composite flocculant and the drilling fluid in flocculation-assisted separation solid phase control.

The composite flocculant provided by the invention comprises polyacrylamide, inorganic salt and polyamine inhibitor, and the three components interact with each other to exert the synergistic effect of coating-flocculation-inhibition: firstly, polyacrylamide can be bridged and coated on the surface of clay particles to accelerate the aggregation and the sinking of the clay particles; inorganic salt makes the colloid system unstable and accelerates flocculation under the action of a compressed double electric layer of cations; the amine inhibitor can penetrate through a clay layer, and binds clay wafers together through electrostatic adsorption, hydrogen bond action, dipole action and the like, so that water molecules are prevented from entering and an inhibiting effect is exerted.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention unexpectedly discovers that the polyacrylamide and the polyamine inhibitor play an obvious synergistic effect in the flocculation process, can obviously improve the flocculation speed and the flocculation effect, and has sufficient solid-liquid separation; the method is used for quickly drilling the upper stratum, simultaneously improves the flocculation degree and realizes effective solid phase control.

(2) When the composite flocculant provided by the invention is applied to water-based drilling fluid, the flocculation efficiency and effect of solid-phase particles in the drilling fluid can be improved, the rock stratum clay is prevented from swelling and dispersing, the pulping inhibition rate is effectively improved, and the rheological property of the drilling fluid is controlled. Compared with the existing drilling fluid, the composite flocculant provided by the invention can reduce the apparent viscosity of the water-based drilling fluid by more than 20%, improve the median value of solid phase particle size by more than 20%, and improve the density by less than 1.10g/cm³。

(3) The composite flocculant can reduce the hydration of clay, accelerate the flocculation and sedimentation of solid-phase particles, improve the solid control efficiency of solid control equipment, further convert the traditional drilling fluid circulation mode, and achieve the aims of reducing the occupied land and reducing the environmental pollution.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In a first aspect of the invention, a composite flocculant is provided, which consists of the following components: polyacrylamide, inorganic salts and polyamine inhibitors.

Preferably, the composite flocculant comprises the following components in parts by weight: 0.05 to 0.3 portion of polyacrylamide, 2 to 20 portions of inorganic salt and 1 to 10 portions of polyamine inhibitor. In order to further improve the flocculation effect and the pulping inhibition rate of the composite flocculant, preferably, the composite flocculant comprises the following components in parts by weight: 0.1-0.2 part of polyacrylamide, 5-15 parts of inorganic salt and 3-7 parts of polyamine inhibitor. More preferably, the composite flocculant comprises the following components in parts by weight: 0.12 to 0.18 portion of polyacrylamide, 8 to 12 portions of inorganic salt and 5 portions of polyamine inhibitor.

In the invention, the polyacrylamide forms long-chain macromolecules after being dissolved in water, and adsorbs a plurality of clay particles through bridging action to form aggregated large particles, so that the sedimentation speed is high, and the turbidity of a precipitation liquid is low. When the concentration of polyacrylamide is too low, flocculation is incomplete; at too high a concentration, the polyacrylamide and clay particles may form a network structure that is detrimental to flocculation. Within the dosage range of the invention, the flocculation effect and the pulping inhibition rate of the composite flocculant are better.

Preferably, the polyacrylamide is selected from one or more of non-ionic Polyacrylamide (PAM), anionic polyacrylamide (HPAM) or Cationic Polyacrylamide (CPAM). In order to further enhance the flocculation effect of the polyacrylamide, preferably, the polyacrylamide is anionic polyacrylamide. The electrical repulsion between the negatively charged links (-COO-) of HPAM allows it to dissolve and spread out in water, passing through the adsorption groups (-CONH)₂) Simultaneously adsorb on the surface of two or more clay particles, bridge them, and flocculate the particles by the twist of molecular chains.

Based on the flocculation effect of nonionic polypropylene, the nonionic polyacrylamide preferably has an average molecular weight of (6-10). times.10⁶(ii) a Further preferably, the average molecular weight of the nonionic polyacrylamide is 1 × 10⁷。

Preferably, the anionic polyacrylamide has a degree of hydrolysis of 20-40%, preferably 30%; average molecular weight of 3-20 x 10⁶Preferably 1.5X 10⁷. When the hydrolysis degree of HPAM is too low, the extension of molecular chains is influenced, and the flocculation effect is reduced; too high a degree of hydrolysis affects the adsorption of HPAM on the clay surface and also reduces flocculation.

Preferably, the cationic polyacrylamide has a cationicity of 20-50%, preferably 25%; average molecular weight of (1-2). times.10⁷Preferably 1X 10⁷. When the cation degree of the CPAM is too low, the adsorption of the CPAM on the clay surface is influenced, and the flocculation effect is reduced; too high a cationicity affects the stretching of the molecular chains and also reduces flocculation.

In the present invention, the inorganic salt destabilizes the colloidal system by the effect of the compressed double electric layers of the cations, thereby accelerating flocculation. Preferably, the inorganic salt is selected from one or more of calcium chloride, sodium chloride or potassium chloride, preferably calcium chloride. CaCl₂By ionized Ca²⁺The thickness of a double electric layer diffused on the surface of clay particles is compressed, and zeta potential is reduced, so that the effects of inhibiting hydration, expansion and dispersion of clay are achieved; CaCl₂Ca produced after ionization²⁺Can be mixed with Na in clay mineral⁺Ion exchange occurs to change the sodium soil into calcium soil, thereby reducing the hydration, expansion and dispersion capability of the clay.

Preferably, the polyamine inhibitor is selected from one or more of amino polyalcohol, amino silanol or polyether amine, preferably amino polyalcohol; preferably, the aminopolyol has an average molecular weight of 800-1000. In the present invention, the aminopolyol abstracts protons from water when dissolved, and forms positively charged ammonium ions. The ammonium ions with low molecular weight penetrate into the interlayer of the clay particles, and the positively charged ammonium ions are adsorbed on the clay particles through static electricity, so that the zeta negative potential of the clay is rapidly reduced and becomes positive, thereby performing 'passivation' treatment on the clay and reducing the hydration and dispersion capacity of the clay.

The invention provides a water-based drilling fluid which comprises the composite flocculant.

Preferably, the composite flocculant comprises from 0.5 to 2.0% by weight of the water-based drilling fluid, such as 0.5%, 1%, 2%, and any value within the range of any two of these points. When the weight fraction of the composite flocculant is lower than 0.5 percent or the weight fraction of the composite flocculant is higher than 2 percent, the water-based drilling fluid cannot reach the following indexes: apparent viscosity reduction is more than 20%, median value of solid phase particle size is improved more than 20%, and density is less than 1.10g/cm³. Preferably, the drilling fluid comprises 0.5-2.0 wt% flocculant.

In a third aspect, the invention provides the composite flocculant and the application of the drilling fluid in flocculation-assisted separation and solid phase control.

In order to timely remove the flocculation and precipitation in the water-based drilling fluid, the separation solid phase control is carried out in a solid control device, so that solid phase particles are prevented from becoming finer and finer along with the prolonging of time, and the difficulty of removal is increased. Therefore, the composite flocculant is combined with centrifugal separation, low-density solid phases such as clay and the like are separated from the drilling fluid, and the purpose of realizing more thorough solid-liquid separation and controlling slurry making by drilling the upper bottom layer is achieved.

According to the invention, the solid phase control is carried out in a solid control device.

According to the invention, preferably, the solid control equipment is selected from a four-stage solid control system consisting of a vibrating screen-desander-deslimer-centrifuge. The four-stage solid control system can better meet the requirements of the small-circulation drilling fluid process technology in the whole drilling process, and can reduce the difficulty of field operation.

In the invention, the vibrating screen is used as first-stage solid control equipment to remove useless solid phase in the first time, preferably, the vibrating screen is a linear vibrating screen or a translational elliptical screen, and the aim of removing finer solid phase particles by using small-aperture screen cloth is fulfilled by increasing the number of the vibrating screen. The flow of the drilling fluid can also be changed, the drilling fluid returned from the wellhead is firstly cleaned of large-particle solid phase by a large-aperture screen cloth (80-120 meshes) vibrating screen, the screen is prevented from being pasted and the damage of the screen cloth is relieved, and then the treated drilling fluid is supplied to another ultra-fine-aperture screen cloth (more than 180 meshes) vibrating screen by a slurry supply pump so as to clean the fine-particle solid phase, so that the burden of the next several stages of solid control equipment can be greatly relieved, the stages of the solid control equipment can be reduced, and the maintenance cost of the equipment is reduced.

According to the specific implementation mode of the invention, in the drilling construction of the upper strong slurrying stratum, on one hand, the water-based drilling fluid containing the composite flocculant is adopted for drilling operation, so that solid-phase particles are fully flocculated; the ground solid control treatment is convenient; on the other hand, during the stratum solid control treatment, the sieve of the vibrating screen is 120-180 meshes, and the solid phase particles which are as fine as possible are removed in the first-stage solid control equipment to the greatest extent. In order to use finer screen cloth, 2-3 vibrating screens can be used simultaneously, and the sand remover and the centrifuge are all started. The centrifuge can rotate at 1600-3200r/min to prepare 1200 million of water-based drilling fluid, wherein the weight fraction of the composite flocculant is 2.0 percent, the water-based drilling fluid is injected into the working centrifuge through a pump, a gate valve is adjusted, and clear water overflows from the centrifuge.

Preferably, the composite flocculant is added firstly during application. The inventor of the invention finds that the addition sequence of the composite flocculant has very obvious influence on the flocculation effect, and the flocculation effect when the composite flocculant is added firstly is obviously better than that when the composite flocculant is added later. Because the composite flocculant is added firstly, the water precipitation speed is obviously accelerated, and the water precipitation volume is obviously increased. Therefore, the composite flocculant solution is prepared in advance for drilling during field construction, and newly broken drill cuttings are flocculated as soon as possible.

In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

In the following examples, the six-speed viscosity of the test slurry was measured by a six-speed rotational viscometer, with specific reference to the oil and gas industry drilling fluid field test part 1: water-based drilling fluids (GB/T16783.1-20061).

The particle size and the particle size distribution of the test slurry are measured by a laser particle size distribution instrument.

Calculation of apparent viscosity (AV/mPa.s): AV is 0.5 phi₆₀₀

Calculation of the plastic viscosity (PV/mPa.s): PV ═ phi₆₀₀－Φ₃₀₀

Calculation method of dynamic shear force (YP/Pa): YP ═ AV-PV

Anionic polyacrylamide (HPAM, Mr ═ 1.5X 10)⁷α ═ 30%) was purchased from commercially available product sold under the trademark HPAM-30 by yoxin chemical ltd, shandong; cationic polyacrylamide (CPAM, Mr ═ 1.0X 10)⁷25% cationic degree) was purchased from Shandong Polyxin chemical Co., Ltd under the name of CPAM-25; nonionic polyacrylamide (PAM, Mr ═ 1.0 × 10)⁷) A commercial product which is purchased from Shandong Juxin chemical Co Ltd and has the brand number of PAM-1; calcium chloride (CaCl)₂) The product is a commercial product with the brand number of CC-1 from Boyou mud technology Limited liability company in the Shengli oil field; the aminopolyol (AP-1) is a commercial product with the trade name of AP-1 from Shandong Shunyuan petroleum science and technology Limited company; the evaluation soil (main component kaolinite) is a commercial product which is purchased from Boyou mud technology Limited liability company of the Shengli oil field and has the brand number PJT-1; the sodium soil is purchased from a commercial product of a Shengli oil field Boyou slurry technology Limited liability company under the brand ZJNT; untreated bentonite (calcium montmorillonite as the main component) is purchased from a commercial product with the brand number PRT-1 of Boyou mud technology of Shengli oil field; soda ash is purchased from a commercial product of a Shengli oil field Boyou slurry technology Limited liability company under the brand name ZJCJ; is provided withThe inorganic-inorganic flocculant (XNJ-1) is a commercial product with the trademark XNJ-1 of Boyou mud technology of Shengli oil field.

Example 1A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.05 part of nonionic polyacrylamide, 2 parts of sodium chloride and 1 part of aminopolyol.

The average molecular weight of the nonionic polyacrylamide is 6 multiplied by 10⁶The aminopolyol has an average molecular weight of 800.

Example 2 composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.3 part of nonionic polyacrylamide, 20 parts of calcium chloride and 10 parts of aminopolyol.

The average molecular weight of the nonionic polyacrylamide is 10 multiplied by 10⁶The aminopolyol has an average molecular weight of 1000.

Example 3A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.12 part of anionic polyacrylamide, 5 parts of calcium chloride and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 20% and an average molecular weight of 3 × 10⁶The aminopolyol has an average molecular weight of 900.

Example 4A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.2 part of anionic polyacrylamide, 15 parts of calcium chloride and 7 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 20% and an average molecular weight of 3 × 10⁶The aminopolyol has an average molecular weight of 800.

Example 5A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.12 part of anionic polyacrylamide, 8 parts of calcium chloride and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 40% and an average molecular weight of 2 x 10⁷The aminopolyol has an average molecular weight of 1000.

Example 6A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide, 10 parts of calcium chloride and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The aminopolyol has an average molecular weight of 800.

Example 7A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.25 part of cationic polyacrylamide, 15 parts of potassium chloride and 7 parts of aminopolyol.

The cationic polyacrylamide has a cationic degree of 25% and an average molecular weight of 2X 10⁷The aminopolyol has an average molecular weight of 1000.

Example 8A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.18 part of cationic polyacrylamide, 12 parts of calcium chloride and 5 parts of aminopolyol.

The cationic degree of the cationic polyacrylamide is 30 percent, and the average molecular weight is 1.5 multiplied by 10⁷The aminopolyol has an average molecular weight of 800.

Example 9A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide, 10 parts of calcium chloride and 5 parts of amino silanol.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The average molecular weight of the amino silanol is 1000.

Example 10A composite flocculant

The composite flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide, 10 parts of calcium chloride and 5 parts of polyether amine.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The polyetheramine has an average molecular weight of 900.

Comparative example 1a flocculating agent

The flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide and 10 parts of calcium chloride.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷。

Comparative example 2 a flocculating agent

The flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The aminopolyol has an average molecular weight of 800.

Comparative example 3A flocculating agent

The flocculant comprises the following components in parts by weight: 10 parts of calcium chloride and 5 parts of aminopolyol.

The aminopolyol has an average molecular weight of 800.

Comparative example 4 a flocculating agent

The flocculant comprises the following components in parts by weight: 0.5 part of anionic polyacrylamide, 10 parts of calcium chloride and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The aminopolyol has an average molecular weight of 800.

Comparative example 5A flocculating agent

The flocculant comprises the following components in parts by weight: 0.5 part of anionic polyacrylamide, 25 parts of calcium chloride and 5 parts of aminopolyol.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷The aminopolyol has an average molecular weight of 800.

Comparative example 6A flocculating agent

The flocculant comprises the following components in parts by weight: 0.15 part of anionic polyacrylamide, 10 parts of calcium chloride and 5 parts of octadecyl amine.

The anionic polyacrylamide has a hydrolysis degree of 30% and an average molecular weight of 1.5 × 10⁷。

Comparative example 7A flocculating agent

The flocculant is an organic-inorganic flocculant (XNJ-1) and is a commercial product with a trademark of XNJ-1 from Boyou mud technology Limited liability company in Shengli oil fields.

Test examples

(first) flocculation evaluation experiment

Firstly, adding a composite flocculant: pouring 20ml of water into a 25ml measuring cylinder with a plug, adding 1.5 wt% of composite flocculant (composite flocculant of examples 1-10 and comparative examples 1-6) and 10 wt% of evaluation soil, shaking up and down, standing, and reading the water separation volume V at different times_{Water (W)}。

Adding a composite flocculant: placing 20ml of 10% evaluation soil suspension into a 25ml measuring cylinder, adding 1.5 wt% of composite flocculant (composite flocculant of examples 1-10 and comparative examples 1-6), shaking up and down, standing, and reading water separation volume V at different times_{Water (W)}The experimental results are shown in table 1 below.

TABLE 1 flocculation evaluation results for different flocculants

As can be seen from the flocculation experimental data in Table 2, the composite flocculant of the invention can obviously improve the volume of the separated water and has stronger flocculation capacity. The flocculation effect is obviously influenced by the adding sequence of the composite flocculant, when the composite flocculant is added firstly, the water separating speed is obviously accelerated, the water separating volume is obviously increased, and the effect is obviously higher than that of adding the composite flocculant later. The composite flocculant provided by the embodiment of the invention has strong flocculation effect and is beneficial to solid phase separation.

(II) evaluation of slurry formation

Adding 1.5 wt% of composite flocculant (composite flocculant of examples 1-10 and comparative examples 1-6) into 400ml of water, stirring for 30min, then adding 5 wt% of sodium soil and 10 wt% of evaluation soil, stirring for 30min to obtain test slurry I, standing for 24h, measuring six-speed viscosity of the test slurry I, pouring the residual slurry into an aging tank, and measuring six-speed viscosity after hot rolling at 50 ℃/16 h. The rheological parameters were measured as shown in Table 2 below.

TABLE 2 different flocculating agent rheology parameters

From the rheological parameters of Table 2, it is clear that the apparent viscosity reduction with the composite flocculant of the invention is > 20%. The composite flocculant of the invention can obviously reduce the apparent viscosity, plastic viscosity and dynamic shear force of the test pulp I and has stronger ability of inhibiting the pulping of clay, namely the composite flocculant of the invention has higher pulping inhibition rate.

(III) evaluation test of particle size analysis

400ml of water was taken and added with 1.5 wt% of composite flocculant (composite flocculant of examples 1-10 and comparative examples 1-6) respectively, stirred for 20min, then added with 8 wt% of untreated bentonite and soda ash accounting for 7 wt% of untreated bentonite, and stirred for 30min to obtain experiment slurry II. The measured particle size analysis data are shown in Table 3.

TABLE 3 results of particle size analysis evaluation of different flocculants

As can be seen by comparing the particle size distribution data in Table 3, the median particle size of the solid phase using the composite flocculant of the present invention was improved by > 20%. The composite flocculant provided by the invention can obviously improve the particle size of the test pulp II, has higher particle size distribution and stronger flocculation capacity, namely, the composite flocculant provided by the invention can improve the flocculation efficiency of solid-phase particles.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.