High-performance brine drilling fluid for potassium salt drilling

Abstract

The invention relates to the technical field of brine drilling fluids, in particular to a high-performance brine drilling fluid for potassium salt drilling, which is prepared from the following raw materials in percentage by weight: 2-3% of sepiolite, 1-2% of rice hull powder, 2-5% of macromolecular hydrophilic colloid, 1.5-3% of water-soluble alcohol, 0.2-1% of inorganic salt recrystallization inhibitor and the balance of composite brine, the composite brine is composed of water, sodium chloride, magnesium chloride, potassium chloride, lithium chloride, calcium bicarbonate and boric oxide, and the composite brine drilling fluid further comprises at least one of a salt-resistant filtrate reducer, a salt-resistant anti-collapse agent, a salt-resistant plugging agent and a salt recrystallization inhibitor. The sepiolite, the rice hull powder, the macromolecular hydrophilic colloid, the water-soluble alcohol 1, the inorganic salt recrystallization inhibitor and the composite salt water adopted by the drilling fluid are low in raw material cost, low in price, easy to obtain and high in environmental protection property, the drilling fluid prepared from the raw material components is moderate in density and proper in viscosity, the drilling tool jamming phenomenon can be effectively improved in the process of preparing ores of a potassium salt ore bed, and the drilling efficiency is improved. And the drilling and coring quality is high.

Description

Technical Field

[0001] The invention relates to the technical field of brine drilling fluid, in particular to a high-performance brine drilling fluid for potash drilling. Background Art

[0002] Salt drilling projects may encounter strata such as mudstone, mud conglomerate, silty mudstone, sandstone, potassium salt, rock salt and carnallite, such as the potassium salt survey wells constructed in Jiangcheng County, Yunnan and Jinggu County, Yunnan. Among them, potassium salt and rock salt strata are easily dissolved in water, resulting in problems such as poor quality of salt core sampling and expansion of well diameter; mudstone and mud conglomerate strata swell or disperse in water, and mudstone rock powder is suspended and dispersed in the drilling fluid, resulting in increased solid content of the drilling fluid and the occurrence of drill bit mud packing. The potassium salt deep hole rope coring drilling process requires that the brine drilling fluid has excellent ability to inhibit the dissolution of potassium salt and other salt cores, rock powder carrying performance and lubrication performance, as well as low viscosity and filtration loss.

[0003] At present, potash drilling projects mainly use brine drilling fluid, saturated magnesium chloride brine drilling fluid, composite saturated brine drilling fluid and oil-based drilling fluid. However, when using brine or brine-prepared drilling fluid for construction, there are generally problems such as poor lubrication performance, poor rock powder carrying capacity, and large filtration loss. The saturated brine drilling fluid prepared with magnesium chloride also has a significant increase in viscosity after aging, which will cause the pump pressure to increase during drilling and affect the drilling efficiency.

[0004] Therefore, it is necessary to provide a high-performance brine drilling fluid for potash drilling to solve the above technical problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-performance brine drilling fluid for potash drilling.

[0006] The invention provides a high-performance brine drilling fluid for potassium salt drilling, which is prepared from the following raw materials in weight ratio: 2-3% of sepiolite, 1-2% of rice husk powder, 2-5% of macromolecular hydrophilic colloid, 1.5-3% of water-soluble alcohol, 0.2-1% of inorganic salt recrystallization inhibitor and the rest is composite brine.

[0007] Preferably, the composite brine consists of the following components: water, sodium chloride, magnesium chloride, potassium chloride, lithium chloride, calcium bicarbonate and boron oxide, and the pH value of the composite brine is 7.

[0008] Sepiolite is a long-fiber hydrothermal sepiolite, i.e., α-type sepiolite, which is composed of silicon-oxygen tetrahedron and magnesium-oxygen octahedron. Sepiolite has a unique pore structure, which can carry the rock cuttings and sand particles produced during the drilling process, remove some harmful solids, improve the downhole conditions, and reduce the occurrence of drill sticking. Sepiolite has good slurrying performance during use.

[0009] Rice husk powder can improve the structural strength of the mud in the whole system to facilitate drilling and coring. Rice husk powder has excellent porosity and can cover and carry sand and cuttings produced during the drilling process, and cooperate with sepiolite to remove harmful solids and reduce drill sticking.

[0010] Water-soluble alcohol has good hydrophilicity and water solubility, and has excellent wetting power. It can effectively reduce the friction resistance between solid particles, between solid particles and liquid molecules, and between liquid molecules, play a good lubricating role, reduce the occurrence of drill sticking, and at the same time adjust the viscosity of the system, stabilize the well wall, and improve the coring effect.

[0011] Macromolecular hydrophilic colloids can not only adjust the viscosity of the entire system, but also bind a large amount of free water, reduce the free water in the drilling fluid, play a good role in reducing water loss, and at the same time weaken the penetration of water into drill cuttings and formations, reduce shale hydration expansion, and play a good role in preventing collapse.

[0012] Inorganic salt recrystallization inhibitors are used to improve the recrystallization and salt precipitation of saturated brine drilling fluids caused by temperature differences on the ground and at the bottom of the well.

[0013] The composite brine can effectively inhibit the dissolution of salt minerals in the ore, improve the quality of coring, and ensure the integrity of the coring.

[0014] Preferably, the raw material also includes 1-2% by weight of borax.

[0015] Preferably, the macromolecular hydrophilic colloid is selected from at least one of gelatin and gum arabic.

[0016] Preferably, the water-soluble alcohol is a mixture of ethylene glycol, polyethylene glycol and polyvinyl alcohol.

[0017] Preferably, the weight ratio of ethylene glycol, polyethylene glycol and polyvinyl alcohol is 1:(0.3-1):(0.2-1).

[0018] Preferably, the composite brine drilling fluid also includes at least one of a salt-resistant fluid loss reducer, a salt-resistant collapse preventer, a salt-resistant plugging agent and a salt recrystallization inhibitor.

[0019] Preferably, the salt-resistant fluid loss reducer comprises at least one of lignite resin, sulfonated phenolic resin, sulfonated lignite, lignite tannin special resin, fluid loss reducer KJAN, and humic acid propanesulfonic acid amide multipolymer;

[0020] The anti-salt and anti-collapse agent comprises at least one of sulfonated asphalt, modified asphalt and organosilicon humic acid;

[0021] The salt-resistant plugging agent comprises at least one of plugging agent GFD-1, calcium carbonate powder QS-2, nano silicon dioxide NS-1, and ultrafine calcium carbonate powder;

[0022] The salt recrystallization inhibitor comprises at least one of a salt recrystallization inhibitor NTA and a salt recrystallization inhibitor II for drilling fluid.

[0023] Compared with the related art, the high-performance brine drilling fluid for potash drilling provided by the present invention has the following beneficial effects:

[0024] 1. The drilling fluid of the present invention adopts sepiolite, rice husk powder, macromolecular hydrophilic colloid, water-soluble alcohol inorganic salt recrystallization inhibitor and composite brine, which has low raw material cost, is cheap and easy to obtain, and is highly environmentally friendly. The drilling fluid obtained by configuring the raw material components has moderate density and appropriate viscosity. In the preparation of ore from potassium salt ore layers, it can effectively improve the drill sticking phenomenon and has high drilling and coring quality;

[0025] 2. The present invention uses borax, which can be used as a pH buffer in the system after being dissolved in water, to improve the change of pH value during drilling, so as to facilitate drilling and coring. At the same time, borax forms a network structure by cross-linking the hydroxyl groups of water-soluble alcohols, which can not only adjust the viscosity of the system, but also inhibit shale dispersion, reduce the loss of drilling fluid, and further improve the quality of coring;

[0026] 3. The present invention adopts gelatin and gum arabic. The gelatin and gum arabic are mixed in an aqueous solution. Due to opposite charges, a complex is formed, and microcapsules are condensed and precipitated. During the flow of drilling fluid, the microcapsules are squeezed into shale pores, cracks and the like, playing a certain filling and blocking role, preventing free water from entering, improving the adhesion to the cracks, effectively reducing the damage to the ore layer, and playing a role in stabilizing the well wall.

[0027] 4. The present invention obtains water-soluble alcohol by compounding ethylene glycol, polyethylene glycol and polyvinyl alcohol, which can modify the surface properties of solid particles and liquid molecules, improve the surface properties between solid particles, between solid particles and liquid molecules, and between liquid molecules, thereby improving the coring effect. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The specific implementation of a high-performance brine drilling fluid for potash drilling is described in detail below in conjunction with specific embodiments.

[0030] The invention provides a high-performance brine drilling fluid for potash drilling, comprising: 2-3% of sepiolite, 1-2% of rice husk powder, 2-5% of macromolecular hydrophilic colloid, 1.5-3% of water-soluble alcohol, 0.2-1% of inorganic salt recrystallization inhibitor, and the rest of composite brine,

[0031] In an embodiment of the present invention, the composite brine is composed of the following components: water, sodium chloride, magnesium chloride, potassium chloride, lithium chloride, calcium bicarbonate and boron oxide, and the pH value of the composite brine is 7, and the mass concentration and other parameters of the composite brine are shown in the following table:

[0032]

[0033] It should be noted that sepiolite is a long-fiber hydrothermal sepiolite, i.e., α-type sepiolite, and its structure is composed of silicon-oxygen tetrahedron and magnesium-oxygen octahedron. Sepiolite has a unique internal pore structure, which can carry the rock cuttings and sand particles generated during the drilling process, remove some harmful solids, improve the downhole conditions, and reduce the occurrence of drill sticking. Sepiolite has good slurrying performance during use.

[0034] Rice husk powder can improve the structural strength of the mud in the whole system to facilitate drilling and coring. Rice husk powder has excellent porosity and can cover and carry sand and cuttings produced during the drilling process, and cooperate with sepiolite to remove harmful solids and reduce drill sticking.

[0035] Water-soluble alcohol has good hydrophilicity and water solubility, and has excellent wetting power. It can effectively reduce the friction resistance between solid particles, between solid particles and liquid molecules, and between liquid molecules, play a good lubricating role, reduce the occurrence of drill sticking, and at the same time adjust the viscosity of the system, stabilize the well wall, and improve the coring effect.

[0036] Macromolecular hydrophilic colloids can not only adjust the viscosity of the entire system, but also bind a large amount of free water, reduce the free water in the drilling fluid, play a good role in reducing water loss, and at the same time weaken the penetration of water into drill cuttings and formations, reduce shale hydration expansion, and play a good role in preventing collapse.

[0037] Inorganic salt recrystallization inhibitors are used to improve the recrystallization and salt precipitation of saturated brine drilling fluids caused by temperature differences on the ground and at the bottom of the well.

[0038] The composite brine can effectively inhibit the dissolution of salt minerals in the ore, improve the quality of coring, and ensure the integrity of the coring.

[0039] In an embodiment of the present invention, the raw material further comprises 1-2% by weight of borax.

[0040] It should be noted that: by using borax, borax can be used as a pH buffer in the system after being dissolved in water, improving the change of pH value during drilling, so as to facilitate drilling and coring. At the same time, borax forms a network structure by cross-linking the hydroxyl groups of water-soluble alcohols, which can not only adjust the viscosity of the system, but also inhibit shale dispersion, reduce drilling fluid loss, and further improve the quality of coring.

[0041] In an embodiment of the present invention, the macromolecular hydrophilic colloid is selected from at least one of gelatin and gum arabic.

[0042] It should be noted that: by adopting the above technical solution, gelatin and gum arabic are mixed in an aqueous solution, and a complex is formed due to opposite charges, which is condensed into microcapsules and precipitated. During the flow of drilling fluid, they are squeezed into shale pores, cracks and other locations, playing a certain filling and sealing role, preventing free water from entering, improving the adhesion to the cracks, effectively reducing damage to the ore layer, and playing a role in stabilizing the well wall.

[0043] In an embodiment of the present invention, the water-soluble alcohol is a mixture of ethylene glycol, polyethylene glycol, and polyvinyl alcohol.

[0044] It should be noted that: since the particles in the drilling fluid are very irregular in shape and the surface properties are extremely uneven, the particles are easily bonded to each other to form a flocculated grid structure. After ethylene glycol, polyethylene glycol and polyvinyl alcohol are compounded, the surface properties of solid particles and liquid molecules can be modified, and the surface properties between solid particles, between solid particles and liquid molecules, and between liquid molecules can be improved, thereby improving the coring effect.

[0045] In an embodiment of the present invention, the weight ratio of ethylene glycol, polyethylene glycol and polyvinyl alcohol is 1:(0.3-1):(0.2-1).

[0046] By adopting the above technical solution, the ratio of ethylene glycol, polyethylene glycol and polyvinyl alcohol is optimized so as to form an adsorption hydration layer on the surface of clay particles, which is beneficial for subsequent drilling and coring.

[0047] In an embodiment of the present invention, the composite brine drilling fluid further comprises at least one of a salt-resistant fluid loss reducer, a salt-resistant collapse preventer, a salt-resistant plugging agent and a salt recrystallization inhibitor.

[0048] In an embodiment of the present invention, the salt-resistant fluid loss reducer comprises at least one of lignite resin, sulfonated phenolic resin, sulfonated lignite, lignite tannin special resin, fluid loss reducer KJAN, and humic acid propanesulfonic acid amide multi-polymer;

[0049] The anti-salt and anti-collapse agent comprises at least one of sulfonated asphalt, modified asphalt and organosilicon humic acid;

[0050] The salt-resistant plugging agent comprises at least one of plugging agent GFD-1, calcium carbonate powder QS-2, nano silicon dioxide NS-1, and ultrafine calcium carbonate powder;

[0051] The salt recrystallization inhibitor comprises at least one of a salt recrystallization inhibitor NTA and a salt recrystallization inhibitor II for drilling fluid.

[0052] The working principle of a high-performance brine drilling fluid for potash drilling provided by the present invention is as follows:

[0053] Sepiolite has a unique pore structure, which can carry the rock cuttings and sand particles produced during the drilling process, remove some harmful solids, improve the downhole conditions, and reduce the phenomenon of drill sticking. Sepiolite has good slurrying performance during use.

[0054] Rice husk powder can improve the structural strength of the mud in the whole system to facilitate drilling and coring. Rice husk powder has excellent porosity and can cover and carry sand and cuttings produced during the drilling process, and cooperate with sepiolite to remove harmful solids and reduce drill sticking.

[0055] Water-soluble alcohol has good hydrophilicity and water solubility, and has excellent wetting power. It can effectively reduce the friction resistance between solid particles, between solid particles and liquid molecules, and between liquid molecules, play a good lubricating role, reduce the occurrence of drill sticking, and at the same time adjust the viscosity of the system, stabilize the well wall, and improve the coring effect.

[0056] Macromolecular hydrophilic colloids can not only adjust the viscosity of the entire system, but also bind a large amount of free water, reduce the free water in the drilling fluid, play a good role in reducing water loss, and at the same time weaken the penetration of water into drill cuttings and formations, reduce shale hydration expansion, and play a good role in preventing collapse.

[0057] Inorganic salt recrystallization inhibitors are used to improve the recrystallization and salt precipitation of saturated brine drilling fluids caused by temperature differences on the ground and at the bottom of the well.

[0058] The composite brine can effectively inhibit the dissolution of salt minerals in the ore, improve the quality of coring, and ensure the integrity of the coring.

[0059] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high performance brine drilling fluid for potash drilling, characterized in that: The invention is prepared from raw materials in the following weight proportion: 2-3% of sepiolite, 1-2% of rice husk powder, 2-5% of macromolecular hydrophilic colloid, 1.5-3% of water-soluble alcohol, 0.2-1% of inorganic salt recrystallization inhibitor and the rest of the composite salt water.

2. The high performance brine drilling fluid for potash drilling according to claim 1, characterized in that: The composite brine is composed of the following components: water, sodium chloride, magnesium chloride, potassium chloride, lithium chloride, calcium bicarbonate and boron oxide, and the pH value of the composite brine is 7.

3. A high performance brine drilling fluid for potash drilling according to claim 2, characterized in that: It also includes 1-2% by weight of borax.

4. The high performance brine drilling fluid for potash drilling according to claim 1, characterized in that: The macromolecular hydrophilic colloid is selected from at least one of gelatin and gum arabic.

5. The high performance brine drilling fluid for potash drilling according to claim 4, characterized in that: The water-soluble alcohol is a mixture of ethylene glycol, polyethylene glycol and polyvinyl alcohol.

6. The high performance brine drilling fluid for potash drilling according to claim 5, characterized in that: The weight ratio of the ethylene glycol, polyethylene glycol and polyvinyl alcohol is 1:(0.3-1):(0.2-1).

7. A high performance brine drilling fluid for potash drilling according to claim 6, characterized in that: The composite salt water drilling fluid also includes at least one of a salt-resistant fluid loss reducer, a salt-resistant collapse preventer, a salt-resistant plugging agent and a salt recrystallization inhibitor.

8. The high performance brine drilling fluid for potash drilling according to claim 7, characterized in that: The salt-resistant fluid loss reducer comprises at least one of lignite resin, sulfonated phenolic resin, sulfonated lignite, lignite tannin special resin, fluid loss reducer KJAN, and humic acid propanesulfonic acid amide multi-polymer; The anti-salt and anti-collapse agent comprises at least one of sulfonated asphalt, modified asphalt and organosilicon humic acid; The salt-resistant plugging agent comprises at least one of plugging agent GFD-1, calcium carbonate powder QS-2, nano silicon dioxide NS-1, and ultrafine calcium carbonate powder; The salt recrystallization inhibitor comprises at least one of a salt recrystallization inhibitor NTA and a salt recrystallization inhibitor II for drilling fluid.

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