Synthetic base drilling fluid and preparation method thereof
阅读说明：本技术 一种合成基钻井液及其制备方法 (Synthetic base drilling fluid and preparation method thereof ) 是由 王磊磊 黄达全 张坤 郭剑梅 闫晓婷 陈庭贵 田增艳 谷艳峰 王红芳 单春雨 张 于 2019-11-15 设计创作，主要内容包括：本发明公开了一种合成基钻井液,60％～95％的合成基础油和5％～40％盐水,二者质量分数总计为100％；以及以合成基础油和盐水总重量计的2％～6％的乳化剂、0％～3％的氧化钙、1％～3％的有机土、2％～3％的降滤失剂和50％～500％的惰性加重材料；所述的乳化剂由烷基葡萄糖酰胺、阴离子表面活性剂、极性溶剂和非极性溶剂制备而成。该钻井液具有良好的环保特性,无毒、可降解,尤其适合海洋以及陆地环境敏感地区的勘探开发。(The invention discloses a synthetic base drilling fluid, 60-95% of synthetic base oil and 5-40% of brine, wherein the mass fractions of the synthetic base oil and the brine are 100% in total; 2 to 6 percent of emulsifier, 0 to 3 percent of calcium oxide, 1 to 3 percent of organic soil, 2 to 3 percent of filtrate reducer and 50 to 500 percent of inert weighting material based on the total weight of the synthetic base oil and the salt water; the emulsifier is prepared from alkyl glucose amide, an anionic surfactant, a polar solvent and a non-polar solvent. The drilling fluid has good environmental protection characteristic, is nontoxic and degradable, and is particularly suitable for exploration and development of oceans and land environment sensitive areas.)
1. The synthetic base drilling fluid is characterized by comprising 60-95% of synthetic base oil and 5-40% of brine by mass, wherein the mass fractions of the synthetic base oil and the brine are 100%; 2 to 6 percent of emulsifier, 0 to 3 percent of calcium oxide, 1 to 3 percent of organic soil, 2 to 3 percent of filtrate reducer and 50 to 500 percent of inert weighting material based on the total weight of the synthetic base oil and the salt water;
the saline water is a sodium chloride solution, a calcium chloride solution, a potassium chloride solution, a sodium formate solution, a potassium formate solution or a cesium formate solution with the mass fraction of 20-25%;
the emulsifier is compounded by alkyl glucose amide, anionic surfactant and nonpolar solvent; the alkyl glucose amide is prepared from 27-50 parts by weight of glucose methylamine, 29-43 parts by weight of fatty acid or fatty acid ester, 9-27 parts by weight of polar solvent and 0.12-0.16 part by weight of sodium alkoxide, and the molecular structural formula is as follows:
wherein n is any integer of 5-17, and n is an odd number; the polar solvent is C1～C4The small molecule monohydric or dihydric alcohol of (a); the anionic surfactant is 1-3 parts by weight of sulfate salt type anionic surfactant; 7-9 parts by weight of a non-polar solvent, and the synthetic base oil has a kinematic viscosity of 2-6 mm at 40 DEG C2A synthetic base oil per second.
2. The synthetic-based drilling fluid of claim 1, wherein the synthetic base oil is a gas oil-based synthetic base oil, a poly α -olefin-based synthetic base oil, a synthetic ester-based synthetic base oil, an internal olefin-based synthetic base oil, or a polyether-based synthetic base oil.
3. The synthetic based drilling fluid of claim 1, wherein the organo-soil is a quaternary ammonium salt of montmorillonite or a quaternary ammonium salt of sepiolite.
4. The synthetic based drilling fluid of claim 1, wherein the inert weighting material is at least one of limestone, barite, hematite.
5. The synthetic based drilling fluid of claim 1, wherein the fluid loss additive is at least one of lignite resin, oxidized bitumen.
6. The synthetic based drilling fluid of claim 1, wherein the sulfate salt type anionic surfactant is a fatty alcohol sulfate, a fatty alcohol polyoxyethylene ether sulfate, a glycerol fatty acid ester sulfate, or a sulfated sodium ricinoleate.
7. The synthetic based drilling fluid of claim 1 wherein the polar solvent is at least one of ethanol, propanol, butanol, propylene glycol.
8. The synthetic based drilling fluid of claim 1, wherein the fatty acid is a saturated fatty acid with a carbon chain length of 6-18, and the fatty acid ester is a methyl ester of a saturated fatty acid with a carbon chain length of 6-18.
9. The preparation method of the synthetic-based drilling fluid according to any one of claims 1 to 8, which is characterized by comprising the following specific steps: adding glucose methylamine and fatty acid or glucose methylamine and fatty acid ester into a polar solvent, heating to 120-130 ℃ under the action of a sodium alkoxide catalyst, carrying out reflux reaction for 2-5 h to generate an alkyl glucosamide solution, then adding a non-polar solvent and an anionic surfactant while the solution is hot, and stirring uniformly to obtain an emulsifier product; then, weighing the synthetic base oil, the brine, the emulsifier, the calcium oxide, the organic soil, the filtrate reducer and the inert weighting material in proportion, and uniformly mixing and stirring to obtain a solution with the density of 1.2-2.8 g/cm3The synthetic base drilling fluid.
Technical Field
The invention relates to the technical field of petroleum and natural gas exploration, in particular to synthetic base drilling fluid and a preparation method thereof.
Background
The oil-based drilling fluid is a drilling fluid system which is composed of oil serving as a continuous phase, water serving as a dispersed phase, and an emulsifier, a shear enhancing agent, a plugging agent, a filtrate loss reducer, alkali and other chemical agents. Compared with water-based drilling fluid, the drilling fluid has the advantages of good lubrication, pollution resistance, high temperature resistance, strong inhibition, oil-gas layer protection and the like, so that the drilling fluid is more and more widely applied to difficult wells such as deep wells, ultra-deep wells, wells with complex structures, special stratum wells, large-displacement horizontal wells and the like.
However, with the increasing number of complex wells and the stricter environmental regulations, higher demands are made on the performance of the drilling fluid. The synthetic base drilling fluid is produced under the condition that the water base drilling fluid can not meet the performance requirements of complex conditions under the well and the traditional mineral oil base (diesel oil and white oil) drilling fluid can not meet the environmental protection requirements. The synthetic base drilling fluid has the advantages of low toxicity, biodegradability, no fluorescence and the like on the basis of the advantages of excellent temperature resistance, strong inhibition, good lubricity and the like of the traditional mineral oil drilling fluid, and is widely used in ocean deep water and environment sensitive areas.
Disclosure of Invention
The invention aims to provide a synthetic base drilling fluid which has the advantages of strong emulsion stability, low biological toxicity and simple preparation.
The invention also aims to provide a preparation method for preparing the synthetic base drilling fluid.
Therefore, the technical scheme of the invention is as follows:
a synthetic base drilling fluid comprises 60-95% of synthetic base oil and 5-40% of brine by mass, wherein the mass percentages of the synthetic base oil and the brine are 100%; 2 to 6 percent of emulsifier, 0 to 3 percent of calcium oxide, 1 to 3 percent of organic soil, 2 to 3 percent of filtrate reducer and 50 to 500 percent of inert weighting material based on the total weight of the synthetic base oil and the salt water; wherein the content of the first and second substances,
the saline water is a sodium chloride solution, a calcium chloride solution, a potassium chloride solution, a sodium formate solution, a potassium formate solution or a cesium formate solution with the mass fraction of 20-25%;
the alkyl glucose amide is prepared from 27-50 parts by weight of glucose methylamine, 29-43 parts by weight of fatty acid or fatty acid ester, 9-27 parts by weight of polar solvent and 0.12-0.16 part by weight of sodium alkoxide, and the molecular structural formula is as follows:
wherein n is any integer of 5-17, and n is an odd number; the polar solvent is C1～C4The small molecule monohydric or dihydric alcohol of (a); the anionic surfactant is 1-3 parts by weight of sulfate salt type anionic surfactant; 7-9 parts by weight of a non-polar solvent, and the synthetic base oil has a kinematic viscosity of 2-6 mm at 40 DEG C2A synthetic base oil per second.
In the formula components of the synthetic base drilling fluid, the emulsifier takes alkyl glucose amide as a main component, the alkyl glucose amide belongs to a non-ionic surfactant, the toxicity is low, the alkyl glucose amide is biodegradable, starch and grease are main raw materials used in the preparation process of the synthetic base drilling fluid, the starch and the grease exist in large quantities in nature, belong to renewable resources, and have the characteristics of raw material acquisition and low cost; meanwhile, a glucose chain segment in the alkyl glucose amide molecular chain has a large amount of hydroxyl groups and strong hydrophilicity, and has strong surface activity after forming an amide molecular chain with an aliphatic hydrophobic chain segment with a certain length, and the emulsification stability can be realized at a lower concentration, so that the alkyl glucose amide molecular chain is used as an emulsifier in the synthetic base drilling fluid, and the disadvantage of poor environmental protection of the traditional emulsifier can be avoided while the emulsification effect is realized. The purpose of introducing the nonpolar solvent is to improve the fluidity of the product and facilitate the field charging construction; the anionic surfactant is added to moderately break up intermolecular association formed by the alkyl glucamide due to polyhydroxy, so that the fluidity of the product is increased, and the nonionic/anionic composite surfactant is formed with the alkyl glucamide to achieve the purpose of synergy.
Preferably, the kinematic viscosity of the synthetic base oil is 2-6 mm measured at 40 DEG C2The synthetic base oil is prepared by chemical synthesis or refining, removes toxic and harmful substances such as aromatic hydrocarbon and the like, has the properties of environmental protection, good fluidity, no fluorescence, low freezing point and the like, can be purchased from commercial products, and can be prepared from Saraline185V type gas oil or Sarapar147 type gas oil produced by Shell company.
Preferably, the organic soil is a quaternary ammonium compound of montmorillonite or a quaternary ammonium compound of sepiolite.
Preferably, the inert weighting material is at least one of limestone, barite and hematite.
Preferably, the fluid loss additive is at least one of lignite resin and oxidized asphalt.
Preferably, the sulfate anionic surfactant is fatty alcohol sulfate, fatty alcohol-polyoxyethylene ether sulfate, glycerin fatty acid ester sulfate or sulfated sodium ricinoleate. Wherein the fatty alcohol sulfate is fatty alcohol sulfate with carbon number of 12-16, such as sodium dodecyl sulfate; the chemical structural formula of the fatty alcohol-polyoxyethylene ether sulfate is as follows: RO (CH)2CH2O)n-SO3Na, wherein n is 2 or 3, and R is an alkyl group having 12 to 15 carbon atoms; the glycerin fatty acid monoester sulfate is glycerin fatty acid ester sulfate with 12-14 carbon atoms, such as glycerin fatty acid ester sulfateSodium monolaurate sulfate.
Preferably, the polar solvent is at least one of ethanol, propanol, butanol and propylene glycol.
Preferably, the sodium alkoxide is sodium methoxide or sodium ethoxide.
Preferably, the fatty acid is a saturated fatty acid with a carbon chain length of 6-18, and the fatty acid ester is a methyl ester of a saturated fatty acid with a carbon chain length of 6-18. More preferably, the fatty acid is caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid or stearic acid; the fatty acid ester is methyl caproate, methyl caprylate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate or methyl stearate.
A preparation method of a synthetic base drilling fluid comprises the following steps: adding glucose methylamine and fatty acid or glucose methylamine and fatty acid ester into a polar solvent, heating to 120-130 ℃ under the catalysis of sodium alkoxide, performing reflux reaction for 2-5 hours to generate an alkyl glucosamide solution, then adding a non-polar solvent and an anionic surfactant while the solution is hot, and uniformly stirring to obtain an emulsifier product; then weighing the synthetic base oil, the brine, the emulsifier, the calcium oxide, the organic soil, the filtrate reducer and the inert weighting material in proportion, and uniformly mixing and stirring to obtain a solution with the density of 1.2-2.8 g/cm3The synthetic base drilling fluid.
Preferably, in step S1, the feeding molar ratio of the glucosamine to the fatty acid is 1: 0.8-1.22; the feeding molar ratio of the glucose methylamine to the fatty acid ester is 1: 1.02-1.10.
Compared with the prior art, the emulsifier used in the invention takes the alkyl glucosamide as a main component, and glucose units are arranged on the molecular chain of the alkyl glucosamide, so that on one hand, a large amount of hydroxyl groups are introduced into the molecular chain, the hydrophilic capability is enhanced, the emulsifying and wetting capabilities of the emulsifier are enhanced, the emulsifier has wetting and emulsifying effects, one agent has multiple effects, and the formula of the drilling fluid is simplified; on the other hand, the glucose unit has the characteristic of environmental protection, so that the product has the characteristics of low toxicity and easy degradation, and can be used together with environment-friendly synthetic base oil to overcome the environmental protection problem of the traditional mineral oil-based drilling fluid caused by the base oil and a treating agent; in addition, the synthetic base drilling fluid is simple in preparation method, high in yield, suitable for industrial production and application and good in popularization and application prospect.
Detailed Description
The present invention will be further described with reference to the following examples, which are not intended to limit the scope of the invention in any way, in examples 1 to 6 and comparative examples, each component is commercially available, wherein the amount of each component added is specifically referred to parts by weight, and each of the gas oil-based synthetic base oil, poly α -olefin-based synthetic base oil, synthetic ester-based synthetic base oil, internal olefin-based synthetic base oil and polyether-based synthetic base oil has a kinematic viscosity (40 ℃) of 2 to 6mm2A commercial synthetic base oil per second.