CN115975609A - Preparation method and application of high-density solid-free weighting agent - Google Patents

Preparation method and application of high-density solid-free weighting agent Download PDF

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CN115975609A
CN115975609A CN202111205514.7A CN202111205514A CN115975609A CN 115975609 A CN115975609 A CN 115975609A CN 202111205514 A CN202111205514 A CN 202111205514A CN 115975609 A CN115975609 A CN 115975609A
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solution
weighting agent
free
solid
density
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CN115975609B (en
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李秀灵
赵怀珍
蓝强
李琼
杨倩云
王莉萍
张守文
乔姝文
向术芳
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Drilling Fluid Technology Service Center Of Sinopec Shengli Petroleum Engineering Co ltd
Sinopec Oilfield Service Corp
Sinopec Shengli Petroleum Engineering Corp
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Drilling Fluid Technology Service Center Of Sinopec Shengli Petroleum Engineering Co ltd
Sinopec Oilfield Service Corp
Sinopec Shengli Petroleum Engineering Corp
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Abstract

The invention provides a preparation method and application of a high-density solid-free weighting agent, wherein the preparation method comprises the following steps of S1, dissolving a first soluble weighting material and a second soluble weighting material in a solvent, preferably water, to obtain a solution A; s2, adding a pH regulator into the solution A to obtain a solution B with a pH value of 8-9.5; s3, carrying out first heat treatment on the solution B to obtain a solution C; s4, cooling the solution C, and adding a tackifier, an oxygen scavenger and a chelating agent into the cooled solution C to obtain a solution D; s5, carrying out second heat treatment on the solution D to obtain a solution E; s6, heating the solution E to remove a liquid phase to obtain a solid phase; and S7, drying and granulating the solid phase in sequence to obtain the high-density solid-free weighting agent. The density of the obtained weighting agent can reach 1.715g/cm 3 (ii) a The temperature resistance reaches 180 ℃, the shielding effect is low, and the influence on the extension of polymer molecular chains is small; has the performances of high density, no solid phase, high temperature resistance, low shielding effect, low cost and the like, and is suitable for the requirements of deep well drilling.

Description

Preparation method and application of high-density solid-free weighting agent
Technical Field
The invention relates to the field of drilling fluid of oil and gas fields, in particular to a preparation method and application of a high-density solid-free weighting agent.
Background
With the development of oil field exploration and development, the horizon of a drilling oil reservoir is continuously deepened, the temperature and the pressure of the reservoir are improved, the requirement on drilling fluid in the exploitation process of an oil-gas well is higher and higher, and the density of the currently common solid-free drilling fluid is generally lower than 1.50g/cm 3 The temperature resistance is not more than 150 ℃, the requirement of high-temperature and high-pressure gas reservoir exploration and development is difficult to meet, the high-temperature and high-density solid-free drilling fluid needs to be developed urgently, and a solid-free weighting agent is one of the core treating agents.
In the field of oil and gas field drilling, solid-free weighting agents are generally inorganic salts and organic salts. Wherein the inorganic salt weighting agent is mainly chloride, and is commonly NaCl, KCl and CaCl 2 、MgCl 2 And ZnCl 2 The organic salt is mainly formate, and common sodium formate, potassium formate, cesium formate and the like are used. Inorganic substanceThe salt weighting agent has high requirements on other treating agents in the drilling fluid, has high rheological property regulation difficulty in the construction process, and has strong corrosivity on underground pipes and poor environmental protection. Wherein monovalent inorganic salts are typically used to formulate density of less than 1.30g/cm 3 When the density is higher than 1.30g/cm 3 In the process, a divalent salt or organic salt weighting agent is usually adopted, but divalent salts such as calcium salt and zinc salt are easy to react with formation water to form scale and generate precipitate, thus seriously blocking pores of a reservoir stratum, and the weighting agent is expensive, seriously corroded, toxic to environment and people and not suitable for wide application. Sodium formate is easy to agglomerate and crystallize when the temperature is lower than 11 ℃. The saturated solubility of potassium formate is 1.58g/cm 3 However, the addition amount of the water is 3 times of that of water, and the addition amount is large, so that the price is high. Although the density of the cesium formate can be prepared to be 2.4g/cm 3 The drilling fluid on the left and right, but the raw material is as high as 40 more than ten thousand per ton, so the popularization and the application of the drilling fluid are greatly limited.
At the same time, in high concentration of solid-free weighting agent, due to K + 、Na + 、Ca 2+ When the polymer treating agent is dissolved by using a high-salt concentration solution, the inorganic ions are easily combined with side groups on polymer molecules, so that charge repulsion inside the molecules is shielded, the extension degree of polymer molecular chains is reduced, the mobility of the polymer molecules is weakened, the macroscopic viscosity of the polymer solution is correspondingly reduced, and the viscosity of the prepared drilling fluid is lower. In order to meet the drilling requirement, technicians often increase the addition of the tackifier, but after high-temperature aging or underground circulation, the electrostatic shielding effect is weakened, polymer molecular chains are stretched, and the drilling fluid is excessively viscous and poor in performance.
Therefore, a solid-free weighting agent which is resistant to high temperature, high in density, low in cost and shielding effect and small in influence on polymer treatment agents is needed to be developed, so that the safety and the high efficiency of an oil-gas reservoir and the storage and production increase of a later-period reservoir stratum are guaranteed.
Chinese patent CN 104610937A discloses an environment-friendly high-density solid-free weighting agent and a preparation method thereof. The weighting agent has the highest density of 1.828g/cm 3 The proportion is as follows: 0.02-0.05 part of dispersant, 0.3-1 part of tackifier and 0.5-1.2 parts of chelating agent0.6 to 2 portions of corrosion inhibitor and the balance of soluble weighting material, wherein the soluble weighting material is one or more of potassium formate, potassium citrate, potassium acetate, potassium silicate and potassium sulfate. The process comprises the following steps: mixing the raw materials according to the weight ratio, and uniformly stirring; adding water to dissolve at high temperature (70-80 deg.C); evaporating to dryness to obtain a solid; and crushing the obtained solid into powder to prepare the solid weighting agent.
Chinese patent CN 107987806A discloses a monovalent salt weighting agent and a preparation method and application thereof. The weighting agent is used for preparing the well killing fluid, and the density is 1.40-1.65g/cm 3 The range of the temperature-resistant agent is adjustable, the temperature resistance reaches 180 ℃, and the temperature-resistant agent comprises the following components in parts by weight: 28-48 parts of monovalent organic salt, 4-6 parts of industrial salt, 20-33 parts of sodium dihydrogen phosphate, 19-32 parts of disodium hydrogen phosphate and 3-5 parts of potassium phosphate, wherein the organic salt is selected from at least one of sodium formate, potassium formate and sodium acetate. The preparation method comprises the following steps: according to the weight parts of the components, monovalent organic salt, industrial salt, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium phosphate and an optional anticorrosive agent are mixed and stirred uniformly to obtain the monovalent salt weighting agent.
Chinese patent CN 107642357A discloses a temperature-resistant low-corrosion high-density solid-free test solution and a preparation method thereof. The density of the test solution can reach 1.82g/cm at most 3 And can keep stable performance at 180 ℃, and mainly comprises 0.02-0.05wt% of oxygen scavenger and 10-70wt% of phosphate. The preparation method comprises the following steps: dissolving the raw materials by using water, uniformly mixing to obtain a mixed solution, and cooling the mixed solution to room temperature.
Chinese patent CN 107033863A discloses a solid-free, pollution-free, low-damage and high-density completion fluid and a preparation method thereof. The density of the completion fluid is 1.7-1.9 g/cm 3 The temperature resistance is 160 ℃, and the temperature resistance is 1-5% of potassium hydroxide, 5-10% of monopotassium phosphate, 15-40% of monopotassium phosphate, 1-5% of potassium formate, 10-30% of potassium pyrophosphate, 5-12% of cesium formate, 0.2-0.8% of tackifier, 1-2% of filtrate reducer and the balance of water. The preparation method comprises the following steps: adding potassium monohydrogen phosphate, potassium dihydrogen phosphate, potassium formate, potassium pyrophosphate and formic acid into the reclaimed waterStirring the cesium until the cesium is completely dissolved, and preparing a base solution; adding the tackifier into the base liquid, stirring, uniformly mixing, then adding the filtrate reducer, stirring, and uniformly mixing; finally, adding potassium hydroxide to ensure that the pH value of the solution is between 10 and 12, and continuously stirring until the solution is uniformly mixed.
Chinese patent CN107603578A discloses a heavy salt for a high-density low-pH value completion fluid and a preparation method thereof. The density of the weighting agent saturated aqueous solution at 20 ℃ is 1.32-1.726 g/cm 3 The method comprises the following steps: (1) Adding the component A into distilled water, stirring for dissolving, and adjusting the pH value of the solution to 4-7; (2) Heating the solution to 93-125 ℃, and refluxing and preserving heat for 10-120 min; (3) adding the component B, and adjusting the pH value of the solution to 7.5-8.5; (4) Heating the solution to 105-125 ℃, and carrying out reflux and heat preservation for 10-120 min; (5) Heating and concentrating the solution obtained in the step (4) at a temperature of less than or equal to 105 ℃, and drying and granulating; wherein the component A is selected from one or more of bromomalonic acid, phosphoric acid, potassium dihydrogen phosphate, dipotassium hydrogen phosphate and potassium phosphate; the component B is one or more selected from potassium pyrophosphate, potassium tripolyphosphate and potassium formate.
The analysis of the above solid-free weighting agent, test fluid or completion fluid shows that the known prior art does not clearly indicate how to solve the shielding effect on the polymer under high salt concentration, and the adopted solid-free weighting agent has the defects of large addition, high cost and the like.
Disclosure of Invention
In view of the above problems in the prior art, it is an object of the present invention to provide a method for preparing a high density solid-free weighting agent, so as to solve the problem that the density of the currently common solid-free drilling fluid is generally lower than 1.50g/cm 3 The problems of difficult control of sticking and cutting, high cost and the like. The density of the weighting agent prepared by the preparation method can reach 1.715g/cm at most 3 (ii) a The temperature resistance reaches 180 ℃, the shielding effect is low, and the influence on the extension of polymer molecular chains is small; has high density, no solid phase, high temperature resistance, low shielding effect andlow cost and the like, and is suitable for the requirements of deep well drilling.
The second purpose of the present invention is to provide a high-density solid-free weighting agent corresponding to the first purpose.
It is a further object of the present invention to provide a high density solid-free weighting agent solution that meets the above objects.
The fourth object of the present invention is to provide a dense solid-free weighting agent and the use of a high-density solid-free weighting agent solution that correspond to the above objects.
In order to achieve one of the purposes, the technical scheme adopted by the invention is as follows:
a method of making a high density, solid-free weighting agent, comprising:
s1, dissolving a first soluble weighting material and a second soluble weighting material in a solvent to obtain a solution A;
s2, adding a pH regulator into the solution A to obtain a solution B with a pH value of 8-9.5;
s3, carrying out first heat treatment on the solution B to obtain a solution C;
s4, cooling the solution C, and adding a tackifier, an oxygen scavenger and a chelating agent into the cooled solution C to obtain a solution D;
s5, carrying out second heat treatment on the solution D to obtain a solution E;
s6, heating the solution E to remove a liquid phase to obtain a solid phase; and
s7, drying and granulating the solid phase in sequence to obtain the high-density solid-free weighting agent,
wherein, in step S1, the first soluble weighting material is selected from phosphates, preferably at least one of potassium phosphate, dipotassium hydrogen phosphate, potassium tripolyphosphate and potassium pyrophosphate, and the second soluble weighting material is selected from formates, preferably at least one of sodium formate and potassium formate.
In some preferred embodiments of the present invention, in step S1, the solvent is water.
According to the present invention, the water may be distilled water or deionized water.
In some preferred embodiments of the present invention, the components are used in amounts of, by weight:
Figure BDA0003306721780000041
in some preferred embodiments of the present invention, the total amount of the first soluble weighting material and the second soluble weighting material is 55 to 200 parts, preferably 100 to 200 parts, and more preferably 120 to 180 parts.
In some preferred embodiments of the present invention, the first soluble weight material is used in an amount of 25 to 30 parts and the second soluble weight material is used in an amount of 100 to 130 parts.
According to the invention, the pH regulator is used in such an amount that the pH of the solution reaches a predetermined value.
In some preferred embodiments of the present invention, the pH adjusting agent is selected from at least one of sodium hydroxide and potassium hydroxide; and/or the viscosifier is selected from at least one of low viscosity carboxymethyl cellulose (LV-CMC), high viscosity carboxymethyl cellulose (HV-CMC), low polyanion cellulose (LV-PAC), high polyanion cellulose (HV-PAC), xanthan gum (XC), hydroxyethyl cellulose (HEC) and sulfonate copolymer (DSP); and/or the oxygen scavenger is selected from at least one of thiourea, sodium thiosulfate and sodium sulfite; and/or the chelating agent is at least one selected from sodium gluconate, disodium ethylene diamine tetraacetate, sodium tartrate and sodium citrate.
According to the invention, the low-viscosity carboxymethylcellulose (LV-CMC) can be any commercially available product of any type, with an exemplary viscosity ranging from 0.2 to 0.5 Pa.s in a 2% aqueous solution.
According to the invention, the highly viscous carboxymethylcellulose (HV-CMC) may be any commercially available brand, with exemplary viscosities ranging from 0.8 to 1.0 Pa.s for a 2% aqueous solution.
According to the invention, the low polyanionic cellulose (LV-PAC)) may be any commercially available brand of product, illustratively having a viscosity in the range of 80 to 100mpa.s in a 2% aqueous solution.
According to the invention, the highly polyanionic cellulose (HV-PAC) may be any commercially available brand of product, illustratively having a viscosity in the 2% aqueous solution range of 1600mPa.s.
According to the present invention, the kind of the tackifier is not particularly limited, and any commercially known one of the above kinds can be applied to the present application to obtain the same technical effect.
In some preferred embodiments of the present invention, in step S3, the conditions of the first heat treatment include: the temperature is 70-110 ℃, and the time is 1-6 h, preferably 2-4 h.
According to the invention, the first heat treatment is carried out under reflux conditions.
According to the invention, the beneficial effects obtained by the treatment of the solution B in the manner defined by the first heat treatment at least comprise: firstly, phosphate is hydrolyzed slowly in an alkali solution, and the temperature is raised, so that the phosphate and formate dissolution is accelerated. Secondly, after the phosphate and the formate are completely dissolved, the aqueous solution of the phosphate and the formate has viscosity, and has stable dispersibility after rolling at high temperature, and the experimental result is obtained, particularly, other treating agents are continuously added under the state of being close to a saturated solution, so that crystals are not easy to precipitate.
In some preferred embodiments of the present invention, in the step S4, the target temperature of the cooling is 20 ℃ to 40 ℃.
In some preferred embodiments of the present invention, in step S5, the conditions of the second heat treatment include: the temperature is 70-100 ℃, and the time is 1-8 h, preferably 2-6 h.
According to the invention, the beneficial effects obtained by the treatment of the solution D in the manner defined by the second heat treatment at least comprise: firstly, molecules generate violent movement at high temperature, the acting force among the molecules of the tackifier is greater than the shielding effect of salt, molecular chains are stretched, and the tackifier shows better viscosity. After the molecular chain of the tackifier is stretched, the intermolecular acting force is stronger, and the chelating agent is cooperated, so that the shielding effect of inorganic ions is greatly reduced, and the subsequent drilling fluid is favorably added with other treating agents, such as the tackifier, the flow pattern regulator and the like, and the dosage is controlled. And secondly, the deoxidizing is facilitated, the temperature resistance and the stability of the treating agent are improved, and the formed solid-free weighting agent is more stable.
In some preferred embodiments of the present invention, the heating conditions in step S6 include a temperature of 90 ℃ to 100 ℃.
According to the invention, in step S6, the heating is carried out in order to concentrate the solution E.
In some preferred embodiments of the present invention, in step S7, the drying conditions include: the temperature is 100-150 ℃ and the time is 2-12 h.
According to the present invention, in step S7, granulation is a conventional operation in the art, and the present invention is not intended to be limited thereto too much, and the operation may be performed according to any granulation process commonly used in the art, even known.
In order to achieve the second purpose, the invention adopts the following technical scheme:
a high density solids free weighting agent made according to the method of making any of the above embodiments.
In order to achieve the third purpose, the technical scheme adopted by the invention is as follows:
a high density solids-free weighting agent solution comprising the high density solids-free weighting agent of any of the above embodiments and water.
In some preferred embodiments of the invention, the high density solid phase-free weighting agent solution has a density of 1.317g/cm at 30 ℃ 3 ~1.715g/cm 3 Preferably 1.534g/cm 3 ~1.715g/cm 3
In some preferred embodiments of the present invention, the high density solid-free weighting agent solution has a pH of 8.0 to 9.0.
In order to achieve the fourth purpose, the technical scheme adopted by the invention is as follows:
use of a high density solids-free weighting agent according to any of the above embodiments or a solution of a high density solids-free weighting agent according to any of the above embodiments in a drilling fluid.
In some preferred embodiments of the invention, the use is as a drilling fluid additive.
According to the present invention, the drilling fluid may be any drilling fluid known in the art.
The invention has the advantages that at least the following aspects are achieved:
firstly, the weighting agent without solid phase prepared according to the scheme of the invention is prepared into a weighting agent aqueous solution with water, and the density of the unsaturated aqueous solution ranges from 1.317 to 1.715g/cm 3 The highest density of the solution reaches 1.715g/cm 3 Is much higher than the density (1.57 g/cm) of the prior common solid-free weighting agent 3 )。
Secondly, the introduced phosphate has the effect of a corrosion inhibitor, so that the corrosion strength to the downhole tool can be reduced, and the downhole drilling tool is effectively protected.
Thirdly, the adhesion promoter and the chelating agent are adopted, so that the shielding effect of inorganic ions is reduced, and the control of the dosage of a subsequent treating agent is facilitated.
And fourthly, monovalent salt is adopted for compounding, so that carbonate, sulfate radical and the like in the formation water are not easy to generate precipitates, the reservoir is not blocked, and the pollution to the reservoir is small.
Fifthly, compared with the prior art, the phosphate weighting material is adopted, the price is low, and the cost of the high-density weighting agent is greatly reduced.
Detailed Description
The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.
The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available from commercial sources.
In the following embodiments, xanthan gum (XC) was used from north river, ninja dun peng chemical ltd; high viscosity carboxymethyl cellulose (HV-CMC) was purchased from witt drilling aids, ltd, nunxiang; high polyanionic cellulose (HV-PAC) was purchased from Hebei Haisi chemical Co., ltd; low viscosity carboxymethyl cellulose (LV-CMC) was purchased from witt drilling aid ltd, nunxiang; low polyanionic cellulose (LV-PAC) was purchased from Shandong Dongyngsheng large cellulose factory; hydroxyethyl cellulose (HEC) was purchased from zibo hai billows chemical co; sulfonate copolymer (DSP) was purchased from Dongying cis-sourced Petroleum technologies.
Example 1
Adding 100g of distilled water into a glass reaction bottle, then adding 25g of sodium formate and 30g of potassium tripolyphosphate, stirring for dissolving, and adjusting the pH value to 8 by using potassium hydroxide; heating the solution to 70 ℃ and carrying out reflux heat preservation for 1h; cooling the solution to 20 ℃, adding 0.3gXC,0.1gHV-CMC,0.02g thiourea and 0.3g disodium ethylene diamine tetraacetate, and stirring for dissolving; heating the solution to 70 ℃ and carrying out reflux heat preservation for 2 hours; and heating, concentrating and drying the solution at 95 ℃ for 4 hours, and granulating.
Example 2
Adding 100g of distilled water into a glass reaction bottle, then adding 30g of sodium formate and 50g of potassium phosphate, stirring for dissolving, and adjusting the pH value to 8.5 by using sodium hydroxide; heating the solution to 80 ℃ and carrying out reflux heat preservation for 4 hours; cooling the solution to 30 ℃, adding 0.2gXC,0.1gHV-PAC,0.03g of sodium thiosulfate and 0.4g of sodium gluconate, and stirring for dissolving; heating the solution to 90 ℃ and carrying out reflux heat preservation for 1h; heating, concentrating and drying the solution for 4 hours at 100 ℃, and granulating.
Example 3
Adding 100g of distilled water into a glass reaction bottle, then adding 60g of sodium formate and 70g of potassium pyrophosphate, stirring for dissolving, and adjusting the pH value to 8.5 by using sodium hydroxide; heating the solution to 90 ℃ and carrying out reflux heat preservation for 3 hours; cooling the solution to 30 ℃, adding 0.1gXC,0.5gLV-CMC,0.05g sodium sulfite and 0.1g sodium citrate, and stirring for dissolving; heating the solution to 80 ℃ and carrying out reflux heat preservation for 2 hours; the solution is heated, concentrated and dried for 4 hours at the temperature of 97 ℃ for granulation.
Example 4
Adding 100g of distilled water into a glass reaction bottle, then adding 100g of potassium formate and 30g of dipotassium hydrogen phosphate, stirring for dissolving, and adjusting the pH value to 9.5 by using potassium hydroxide; heating the solution to 110 ℃ and carrying out reflux heat preservation for 6 hours; cooling the solution to 20 ℃, adding 0.3g HEC,0.5g LV-PAC,0.02g sodium sulfite and 0.3g sodium tartrate, and stirring for dissolving; heating the solution to 90 ℃ and carrying out reflux heat preservation for 5 hours; heating and concentrating the solution at 95 ℃, drying for 4h, and granulating.
Example 5
Adding 100g of distilled water into a glass reaction bottle, then adding 66.7g of potassium formate and 50g of potassium tripolyphosphate, stirring for dissolving, and adjusting the pH value to 9 by using sodium hydroxide; heating the solution to 110 ℃ and carrying out reflux heat preservation for 2 hours; cooling the solution to 30 ℃, adding 0.2g of HEC, 0.1g of DSP,0.03g of sodium thiosulfate and 0.2g of sodium gluconate, and stirring for dissolving; heating the solution to 80 ℃ and carrying out reflux heat preservation for 6 hours; heating and concentrating the solution at 95 ℃, drying for 4h, and granulating.
Example 6
Adding 100g of distilled water into a glass reaction bottle, then adding 40g of potassium formate and 70g of potassium pyrophosphate, stirring for dissolving, and adjusting the pH value to 8.5 by using sodium hydroxide; heating the solution to 110 ℃ and carrying out reflux heat preservation for 4 hours; cooling the solution to 30 ℃, adding 0.2g of HEC, 0.2g of DSP,0.04g of sodium sulfite and 0.3g of disodium ethylene diamine tetraacetate, and stirring for dissolving; heating the solution to 80 ℃ and carrying out reflux heat preservation for 6 hours; heating and concentrating the solution at 100 ℃, drying for 4h, and granulating.
Example 7
Adding 100g of distilled water into a glass reaction bottle, then adding 30g of potassium formate and 100g of potassium pyrophosphate, stirring for dissolving, and adjusting the pH value to 9 by using potassium hydroxide; heating the solution to 110 ℃ and carrying out reflux heat preservation for 4 hours; cooling the solution to 40 ℃, adding 0.3g of HEC, 0.2g of DSP,0.05g of thiourea and 0.5g of sodium gluconate, and stirring for dissolving; heating the solution to 100 ℃ and carrying out reflux heat preservation for 4 hours; heating and concentrating the solution at 100 ℃, drying for 4h, and granulating.
Example 8
Adding 100g of distilled water into a glass reaction bottle, then adding 25g of potassium formate and 130g of potassium pyrophosphate, stirring for dissolving, and adjusting the pH value to 9 by using sodium hydroxide; heating the solution to 110 ℃ and carrying out reflux heat preservation for 4 hours; cooling the solution to 40 ℃, adding 0.1g of DSP and 0.2gLV-CMC,0.04g of sodium sulfite and 0.4g of sodium tartrate, and stirring for dissolving; heating the solution to 100 ℃ and carrying out reflux heat preservation for 8 hours; heating, concentrating and drying the solution for 4 hours at 100 ℃, and granulating.
Example 9
This example differs from example 8 only in that the pH was adjusted to 8.5 using sodium hydroxide and the weighting agent was obtained under otherwise identical conditions.
Example 10
This example differs from example 8 only in that the pH was adjusted to 9.5 using sodium hydroxide and the weighting agent was obtained under otherwise identical conditions.
Comparative example 1
The weighting agent was prepared according to the method shown in example 2 in CN 107603578A.
Comparative example 2
The weighting agent was prepared according to the method shown in example 6 in CN 107642357A.
Test example 1
The solid weighting agents prepared in the above embodiments were subjected to dissolution tests, and the solutions were dissolved in 100mL of distilled water to prepare weighting agent aqueous solutions, all of which were completely dissolved without precipitation, and the solution densities were as shown in the following table (the densities were measured at 30 ℃).
Figure BDA0003306721780000101
The dissolution experiment described above shows that: the density of the weighting agent aqueous solution prepared by the invention can reach 1.715g/cm 3 The density is in the range of 1.317-1.715g/cm 3 . The weighting agent aqueous solution is in an unsaturated state.
Test example 2
The weighting agents of examples 1 to 10 and comparative examples 1 to 2 were dissolved in 100mL of distilled water, and a tackifier was added to examine the effect of the inorganic ion shielding effect on the polymer tackifier, and the specific test results are shown in the following table.
Figure BDA0003306721780000102
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Figure BDA0003306721780000111
The data of examples 1-10 show that the viscosity of the system increases significantly when other polymer-based treating agents are added to the weighting agent aqueous solution at room temperature and pressure. The comparative data of examples 8-10 show that when the pH of the solution is 9 in preparation method S2, the shielding effect of salt ions in the solution is minimal, and the viscosity of the solution is increased relatively greatly. Comparative example 1 and comparative example 2 continued to add tackifier, the viscosity of the solution did not rise but dropped, have verified that the weighting agent prepared by conventional preparation method, prepared into high concentration salt solution, very apt to limit the molecular extension of tackifier. Meanwhile, as can be seen from the data of example 6 and example 9 in table 3 of the comparison document CN 107642357A, the density difference between the two examples is not large, but the viscosity difference is large, example 9 is a salt solution with a viscosity higher than that of example 6, example 6 is a polymer tackifier with 2.5% of xanthan gum and 2.5% of polyacrylamide added, and the viscosity of the two tackifiers is obviously increased at such a high addition amount, especially polyacrylamide, but the test data of example 6 is not so, which further verifies that the high-concentration salt solution can limit the molecular extension of the tackifier.
Therefore, the inorganic ion shielding effect of the weighting agent aqueous solution prepared by the invention is reduced, the influence on the extension of polymer molecules is less, and the technical personnel can control the addition amount of the weighting agent aqueous solution.
Test example 3
The weighting agents of examples 1 to 10 were dissolved in 100mL of distilled water, and subjected to a hot rolling test at a temperature of 180 ℃ for 16 hours, and no crystal was precipitated, and changes in density and apparent viscosity of the weighting agent solution before and after aging were measured at 30 ℃ by using a densimeter and a six-speed rotary viscometer, as can be seen from the data in the following table, and the density and apparent viscosity thereof did not change significantly before and after hot rolling. Therefore, the high-density solid-free weighting agent prepared by the embodiment of the invention can resist the temperature of 180 ℃.
Figure BDA0003306721780000121
Test example 4
The weighting agents of examples 1 to 10 and comparative examples 1 to 2 were dissolved in 100mL of distilled water, and the polymer-based tackifier was continuously added, and the mixture was subjected to a hot rolling test at 150 ℃ for 16 hours, cooled to 30 ℃, and the change in viscosity was measured using a six-speed rotational viscometer, and the effect of the tackifier on the performance of the weighting agent solution was examined at high temperature and high salt concentration.
Figure BDA0003306721780000122
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Figure BDA0003306721780000131
The data from examples 1-10 above show that at 150 ℃, when the weighting agent prepared according to the present invention is added to the formulated high salt solution, the viscosity shear of the system is not high and no flocculent material is formed. The viscosity is increased by continuously adding the tackifier in comparative examples 1 and 2, particularly in comparative example 2, the increase is obvious, and the reasonable selection of the addition range of the polymer tackifier by a person skilled in the art is greatly influenced. This is mainly because the polymer tackifier of comparative example 2 containing 2.5% xanthan gum and 2.5% polyacrylamide (at 300 to 600 ten thousand), the polymer is restricted by a large amount of salt ions to have low molecular extension at normal temperature and pressure, macroscopically, the viscosity is low, but under the action of high-temperature and high-salt solution, the molecular thermal motion effect is greater than the shielding effect of salt, the molecular structure of the polymer tackifier is extended, and the viscosity is greatly increased. In high-temperature high-salt solution, part of polymer tackifier is broken to generate small molecular substances, and a large amount of small molecules are clustered to form cotton flocculent substances. Therefore, the weighting agent is prepared by adopting a general preparation method, and when the polymer treating agent is continuously added, the overall performance of the solution is greatly influenced, the subsequent reasonable determination of the addition range of the polymer tackifier by a person skilled in the art is not utilized, and sometimes, the performance of the whole drilling fluid is also damaged.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined within the scope of the claims and modifications may be made without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims (10)

1. A method of making a high density solids-free weighting agent, comprising:
s1, dissolving a first soluble weighting material and a second soluble weighting material in a solvent, preferably water, to obtain a solution A;
s2, adding a pH regulator into the solution A to obtain a solution B with a pH value of 8-9.5;
s3, carrying out first heat treatment on the solution B to obtain a solution C;
s4, cooling the solution C, and adding a tackifier, an oxygen scavenger and a chelating agent into the cooled solution C to obtain a solution D;
s5, carrying out second heat treatment on the solution D to obtain a solution E;
s6, heating the solution E to remove a liquid phase to obtain a solid phase; and
s7, drying and granulating the solid phase in sequence to obtain the high-density solid-free weighting agent,
wherein, in step S1, the first soluble weighting material is selected from phosphates, preferably at least one of potassium phosphate, dipotassium hydrogen phosphate, potassium tripolyphosphate and potassium pyrophosphate, and the second soluble weighting material is selected from formates, preferably at least one of sodium formate and potassium formate.
2. The preparation method according to claim 1, wherein the components are used in the following amounts in parts by weight:
Figure FDA0003306721770000011
preferably, the total amount of the first soluble weighting material and the second soluble weighting material is 55 to 200 parts, preferably 100 to 200 parts, and more preferably 120 to 180 parts.
3. The production method according to claim 1 or 2, characterized in that the pH adjuster is selected from at least one of sodium hydroxide and potassium hydroxide; and/or the viscosifier is selected from at least one of low viscosity carboxymethyl cellulose (LV-CMC), high viscosity carboxymethyl cellulose (HV-CMC), low polyanion cellulose (LV-PAC), high polyanion cellulose (HV-PAC), xanthan gum (XC), hydroxyethyl cellulose (HEC) and sulfonate copolymer (DSP); and/or the oxygen scavenger is selected from at least one of thiourea, sodium thiosulfate and sodium sulfite; and/or the chelating agent is at least one selected from sodium gluconate, disodium ethylene diamine tetraacetate, sodium tartrate and sodium citrate.
4. The production method according to any one of claims 1 to 3, wherein in step S3, the conditions of the first heat treatment include: the temperature is 70-110 ℃, and the time is 1-6 h, preferably 2-4 h.
5. The production method according to any one of claims 1 to 4, wherein in step S5, the conditions of the second heat treatment include: the temperature is 70-100 ℃, and the time is 1-8 h, preferably 2-6 h.
6. A high-density solid-free weighting agent produced by the production method according to any one of claims 1 to 5.
7. A high density solids-free weighting agent solution comprising the high density solids-free weighting agent of claim 6 and water.
8. The high density solid free weighting agent solution of claim 7 wherein the high density solid free weighting agent solution has a density of 1.317g/cm at 30 ℃ 3 ~1.715g/cm 3 Preferably 1.534g/cm 3 ~1.715g/cm 3
9. The high density solid free weighting agent solution according to claim 7 or 8, wherein the high density solid free weighting agent solution has a pH of 8.0 to 9.0.
10. Use of a high density solids free weighting agent according to claim 6 or a high density solids free weighting agent solution according to any of claims 7 to 9 in a drilling fluid, preferably as a drilling fluid additive.
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