Anti-mud ball drilling fluid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of petroleum drilling engineering, and particularly relates to anti-mud ball drilling fluid as well as a preparation method and application thereof. The anti-mud-ball drilling fluid provided by the invention adopts the components with specific contents, so that the anti-mud-ball drilling fluid has good inhibition and anti-mud-ball performance, can meet the high-speed drilling requirements of offshore oil fields, effectively inhibits hydration expansion and dispersion of mud rock drilling cuttings in a high-mud-rock-content stratum, maintains stable rheological properties of the drilling fluid in the high-speed drilling process, and has good anti-mud-ball performance. A low ECD additional value is controlled, underground safety is guaranteed, the well drilling period is shortened, and production efficiency is improved. In addition, the mud ball prevention drilling fluid provided by the invention can effectively prevent the problems of mud ball discharge and bit balling in the rapid drilling process of a high-mudstone-content stratum, assist borehole cleaning and improve the stroke drilling speed. In addition, the anti-mud-ball drilling fluid provided by the invention can effectively reduce the friction torque of a drilling tool in the rapid drilling process of a high-mud-rock-content stratum, release effective drilling pressure and improve the drilling time efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum drilling engineering, and in particular relates to an anti-mud ball drilling fluid and a preparation method and application thereof. Background Art

[0002] Unlike onshore oil and gas wells, offshore oil and gas well platforms are expensive, and drilling cycle control is the key to cost control, which requires a significant increase in drilling speed to shorten the drilling cycle. However, when the drilling speed is increased in offshore oil and gas fields, the phenomenon of mud balls often occurs due to the failure to carry cuttings in time. In severe cases, it will lead to poor annular space and increase pump pressure, which will cause various complex downhole problems. In addition, during high mechanical drilling speed drilling in mudstone sections, the drill bit is easily absorbed and wrapped by hydrated mudstone cuttings when breaking the rock formation at high speed, thereby reducing the rock breaking efficiency and causing a decrease in mechanical drilling speed.

[0003] The document "Drilling Fluid Technology for Fast Drilling in the Upper Section of Moshixi-Gaoshiti" (Petroleum & Natural Gas Chemical Industry, January 2020) discloses a dual salt-hydrophobic polymer drilling fluid system. This drilling fluid system has good water loss and wall-building properties, strong inhibition and plugging properties, medium-pressure water loss of 3.2 mL, a rolling recovery rate of 99.46%, and resistance to mudstone pollution of 15% (w), creating the fastest mechanical drilling speed record of 8.46 m / h in a 311.2 mm wellbore in the Gaoshi 001 block.

[0004] The document "Excellent and Fast Drilling Drilling Fluid Technology in the Tabei Area of ​​Xinjiang" (Drilling Fluid and Completion Fluid, March 2014) discloses an excellent and fast drilling drilling fluid technology, which emphasizes the strong coating, strong inhibition and strong plugging and anti-collapse properties of the drilling fluid. It has achieved good application results in the Lungu 7-18 well, with an average mechanical drilling speed of 13.53m / h for the entire well.

[0005] The document "Excellent and Fast Drilling Fluid Technology in the Junxi Wusu Block" (Journal of Ludong University (Natural Science Edition), April 2021) discloses a polyamine micro-nano plugging and anti-collapse drilling fluid system with the characteristics of good inhibition and strong plugging properties. It was applied on-site in 10 wells in the Junxi Wusu block. The drilling and completion operations were smooth, with an average mechanical drilling speed of 12.84m / h.

[0006] However, compared with the mechanical drilling speed of offshore drilling, the mechanical drilling speed of superior and fast drilling mentioned in the above study is still not high. The mechanical drilling speed of offshore drilling is basically above 50m / h, and some well sections even exceed 150m / h. The above drilling fluid still cannot meet the requirements of high-speed offshore drilling. Summary of the invention

[0007] The object of the present invention is to provide an anti-mud ball drilling fluid and a preparation method and application thereof. The anti-mud ball drilling fluid provided by the present invention meets the requirements of high-speed marine drilling on drilling fluid.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The invention provides an anti-mud ball agent, comprising the following components: a polyether-siloxane copolymer, fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol; the mass ratio of the polyether-siloxane copolymer to the fatty amine polyoxyethylene ether is 40-60:10-20; the mass ratio of the polyether-siloxane copolymer to the fatty alcohol polyoxyethylene ether is 40-60:10-20; the mass ratio of the polyether-siloxane copolymer to the acetylene glycol is 40-60:20-30.

[0010] Preferably, the fatty amine polyoxyethylene ether includes one or both of dodecylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether; the fatty alcohol polyoxyethylene ether includes one or more of lauryl alcohol polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether; the acetylene glycol includes one or more of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol.

[0011] The present invention also provides a method for preparing the anti-mud ball agent described in the above scheme, comprising the following steps:

[0012] Unsaturated polyether, unsaturated organosiloxane, initiator and water are mixed for free radical polymerization to obtain polyether-siloxane copolymer; the polyether-siloxane copolymer is fourthly mixed with fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol to obtain an anti-mud ball agent.

[0013] Preferably, the mass ratio of the unsaturated polyether to the unsaturated organosiloxane is 30-50:1-5; the unsaturated polyether includes one or more of polyethylene glycol methyl allyl ether, polyoxyalkyl methyl allyl ether, polypropylene glycol allyl ether and polyethylene glycol diallyl ether; the unsaturated organosiloxane includes one or more of 3-(methacryloyloxy)propyltrimethoxysilane, vinyltriethoxysilane, 3-(methacryloyloxy)propylmethyldimethoxysilane and 3-(acryloyloxy)propyltrimethoxysilane.

[0014] The present invention also provides an anti-mudball drilling fluid, comprising a drilling fluid gel and a weighting material; the drilling fluid gel comprises water and components accounting for the following mass percentages of the water:

[0015] pH regulator 0.6%-1.0%, filtration reducer 0.8%-1.2%, plugging agent 2.0%-4.0%, coating agent 0.3%-0.6%, inhibitor 3.0%-5.0%, anti-mud ball agent 3.0%-5.0%, anti-wear and drag reducer 2.0%-3.0%, viscosity enhancer 0.3%-0.5%, inorganic salt 8%-15%; the anti-mud ball agent is the anti-mud ball agent described in the above scheme or the anti-mud ball agent obtained by the preparation method described in the above scheme; the amount of the weighting material is determined according to the density requirement.

[0016] Preferably, the preparation method of the inhibitor comprises the following steps: first mixing an organic carboxylic acid, a first organic amine and an azeotropic agent for a condensation reaction to obtain an amide, and second mixing the amide with a second organic amine and water to obtain the inhibitor.

[0017] Preferably, the mass ratio of the organic carboxylic acid to the first organic amine is 10-30:40-60; the mass ratio of the organic carboxylic acid to the entrainer is 10-30:5-10; the organic carboxylic acid includes one or more of tartaric acid, succinic acid, malic acid, lauric acid and 4-methyl-4-phenyl-2-pentenoic acid; the first organic amine includes one or more of ethylenediamine, diethylenediamine, 2-propyleneamine, 1,2-dimethylpropylamine, hexamethylenediamine and hexamethylenetetramine.

[0018] Preferably, the second organic amine includes one or more of tetramethylammonium chloride, dimethyldialkylammonium chloride, choline chloride, polyethyleneimine and polyetherdiamine; and the mass ratio of the amide to the second organic amine is 40-50:20-30.

[0019] The present invention also provides a method for preparing the anti-mud ball drilling fluid described in the above scheme, comprising the following steps:

[0020] (1) mixing a pH regulator, a fluid loss reducer, a plugging agent, a coating agent, an inhibitor, an anti-mud ball agent, an anti-wear drag reducer, a tackifier, an inorganic salt and water to obtain a drilling fluid gel;

[0021] (2) The drilling fluid gel and the weighting material are mixed to a target density to obtain the anti-mud ball drilling fluid.

[0022] The present invention also provides the use of the anti-mudball drilling fluid described in the above scheme or the anti-mudball drilling fluid obtained by the preparation method described in the above scheme in high-speed drilling of high-mudstone formations in offshore oil fields.

[0023] The present invention provides an anti-mud ball agent. The anti-mud ball agent provided by the present invention is adsorbed on the surface of drill cuttings through the hydrophilic ether bonds and hydroxyl groups in the molecules, and forms a hydrophobic film using the hydrophobic alkyl and siloxy groups to play a water-isolating role, thereby preventing mudstone drill cuttings from agglomerating into balls and preventing mud packing of the drill bit.

[0024] The present invention also provides a method for preparing the anti-mud ball agent of the above scheme. The preparation method provided by the present invention has simple steps, convenient operation and high feasibility.

[0025] The invention also provides an anti-mud ball drilling fluid. In the anti-mudball drilling fluid provided by the present invention, the pH value regulator is used to adjust the pH value of the drilling fluid; the filtrate reducer plays a role in reducing the filtrate loss of the drilling fluid, so as to reduce the penetration of the filtrate into the formation pores; the plugging agent is used to improve the quality of the drilling fluid filter cake and enhance the wall protection performance; the coating agent is mainly used to prevent the hydration and dispersion of mudstone cuttings and ensure the integrity of the cuttings; the inhibitor mainly forms hydrogen bonds with the six-membered silicon-oxygen ring in the clay through the amine group to form hydrogen bonds for adsorption, thereby preventing water molecules from entering the crystal layer, thereby inhibiting the hydration and expansion of the clay and preventing the hydration and slurrying of the clay; the anti-mudball agent is adsorbed on the surface of the cuttings through the hydrophilic ether bonds and hydroxyl groups in the molecule, and forms a hydrophobic film with the hydrophobic alkyl and siloxy groups to play a water-isolating role, thereby preventing the mudstone cuttings from agglomerating into balls and preventing the drill bit from mud-balling; the anti-wear and drag reducing agent is used to reduce the friction torque of the drill tool; the viscosity enhancer can effectively increase the viscosity and dynamic shear force of the drilling fluid; the inorganic salt has two functions, one is to play an auxiliary inhibition role, and the other is to be used to increase the density of the drilling fluid to reduce the use of solid phase weighting materials.

[0026] The anti-mudball drilling fluid provided by the present invention adopts the above-mentioned components, so that it has good inhibitory and anti-mudball properties, can meet the requirements of high-speed drilling in offshore oil fields, effectively inhibit the hydration expansion and dispersion of mudstone cuttings in high-mudstone formations, and maintain the stability of the rheological properties of the drilling fluid during high-speed drilling to control the lower ECD added value, ensure downhole safety, and thus shorten the drilling cycle and improve production efficiency. In addition, the anti-mudball drilling fluid provided by the present invention can effectively prevent the problems of mud balls and drill bit mud packing during rapid drilling in high-mudstone formations, help clean the wellbore, and increase the stroke drilling speed. In addition, the anti-mudball drilling fluid provided by the present invention can effectively reduce the friction torque of the drill tool during rapid drilling in high-mudstone formations, release the effective drilling pressure, and improve the drilling time efficiency.

[0027] The present invention also provides a method for preparing the anti-mudball drilling fluid of the above scheme. The preparation method provided by the present invention has simple steps, good safety, high feasibility, and can be applied in large-scale industrialization.

[0028] The present invention also provides the use of the anti-mudball drilling fluid described in the above scheme or the anti-mudball drilling fluid obtained by the preparation method described in the above scheme in high-speed drilling of high-mudstone formations in offshore oil fields. The anti-mudball drilling fluid provided by the present invention has good inhibition and anti-mudball performance, can be used for high-speed drilling of high-mudstone formations in offshore oil fields, and has significant economic benefits. DETAILED DESCRIPTION

[0029] The invention provides an anti-mud ball agent, comprising the following components: a polyether-siloxane copolymer, fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol; the mass ratio of the polyether-siloxane copolymer to the fatty amine polyoxyethylene ether is 40-60:10-20; the mass ratio of the polyether-siloxane copolymer to the fatty alcohol polyoxyethylene ether is 40-60:10-20; the mass ratio of the polyether-siloxane copolymer to the acetylene glycol is 40-60:20-30.

[0030] The anti-mud ball agent provided by the present invention comprises fatty amine polyoxyethylene ether; the fatty amine polyoxyethylene ether preferably comprises one or two of dodecylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether.

[0031] In the present invention, the mass ratio of the polyether-siloxane copolymer to the fatty amine polyoxyethylene ether is preferably 42-60:10-20, more preferably 44-56:12-18, further preferably 48-52:14-16, and further preferably 50:15.

[0032] The anti-mud ball agent provided by the present invention comprises fatty alcohol polyoxyethylene ether; the fatty alcohol polyoxyethylene ether preferably comprises one or more of lauryl alcohol polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether.

[0033] In the present invention, the mass ratio of the polyether-siloxane copolymer to the fatty alcohol polyoxyethylene ether is preferably 42-60:10-20, more preferably 44-56:12-18, further preferably 48-52:14-16, and further preferably 50:15.

[0034] The anti-mud ball agent provided by the present invention comprises acetylene glycol; the acetylene glycol preferably comprises one or more of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol.

[0035] In the present invention, the mass ratio of the polyether-siloxane copolymer to the acetylene glycol is preferably 42-60:20-30, more preferably 43-56:22-28, further preferably 47-54:24-28, and further preferably 49-51:24-26.

[0036] The present invention also provides a method for preparing the anti-mud ball agent described in the above scheme, comprising the following steps:

[0037] The unsaturated polyether, unsaturated organosiloxane, initiator and water are mixed (referred to as the third mixing) to carry out free radical polymerization reaction to obtain a polyether-siloxane copolymer; the polyether-siloxane copolymer is fourthly mixed with fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol to obtain an anti-mud ball agent.

[0038] In the present invention, the unsaturated polyether preferably includes one or more of polyethylene glycol methyl allyl ether, polyoxyalkyl methyl allyl ether, polypropylene glycol allyl ether and polyethylene glycol diallyl ether.

[0039] In the present invention, the unsaturated organosiloxane preferably includes one or more of 3-(methacryloyloxy)propyltrimethoxysilane, vinyltriethoxysilane, 3-(methacryloyloxy)propylmethyldimethoxysilane and 3-(acryloyloxy)propyltrimethoxysilane.

[0040] In the present invention, the mass ratio of the unsaturated polyether to the unsaturated organosiloxane is preferably 30-50:1-5, more preferably 34-47:2-4, further preferably 37-43:2-4, and further preferably 40:3.

[0041] In the present invention, the initiator preferably includes one or more of potassium persulfate, ammonium persulfate and azobisisobutylamidine hydrochloride.

[0042] In the present invention, the mass ratio of the unsaturated polyether to the initiator is preferably 30-50:0.06-0.30, more preferably 35-46:0.10-0.22, further preferably 38-43:0.15-0.18, and further preferably 40:0.15-0.16.

[0043] In the present invention, the water preferably includes one or more of distilled water and deionized water.

[0044] In the present invention, the mass ratio of the unsaturated polyether to water is preferably 30 to 50:100, more preferably 33 to 46:100, further preferably 36 to 43:100, and further preferably 39 to 40:100.

[0045] In the present invention, the third mixing is preferably: unsaturated polyether and water are mixed to obtain a third mixture, and then the third mixture is mixed with unsaturated organosiloxane while stirring to obtain a reaction liquid, and then the reaction liquid and initiator are heated and mixed (recorded as the second heating mixing).

[0046] In the present invention, the temperature of the second heating and mixing is preferably 60 to 90° C., more preferably 64 to 85° C., further preferably 70 to 80° C., and further preferably 74 to 77° C.; the second heating and mixing is preferably stirring and mixing.

[0047] In the present invention, the temperature of the free radical polymerization reaction is preferably the same as that of the second heating and mixing, which will not be repeated here; the insulation time of the free radical polymerization reaction is preferably 3 to 5 hours, more preferably 3.5 to 4.5 hours, and further preferably 4 hours.

[0048] In the present invention, the free radical polymerization reaction preferably further comprises cooling the obtained reaction product; the final temperature of the cooling is preferably room temperature.

[0049] The present invention also provides an anti-mudball drilling fluid, comprising a drilling fluid gel and a weighting material; the drilling fluid gel comprises water and components accounting for the following mass percentages of the water:

[0050] pH regulator 0.6%-1.0%, filtration reducer 0.8%-1.2%, plugging agent 2.0%-4.0%, coating agent 0.3%-0.6%, inhibitor 3.0%-5.0%, anti-mud ball agent 3.0%-5.0%, anti-wear and drag reducer 2.0%-3.0%, viscosity enhancer 0.3%-0.5%, inorganic salt 8%-15%; the anti-mud ball agent is the anti-mud ball agent described in the above scheme or the anti-mud ball agent obtained by the preparation method described in the above scheme; the amount of the weighting material is determined according to the density requirement.

[0051] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention comprises a pH value regulator; the mass percentage of the pH value regulator to the water is 0.6% to 1.0%, preferably 0.7% to 0.9%, and more preferably 0.8%.

[0052] In the present invention, the pH adjuster preferably includes sodium carbonate and hydroxide; the hydroxide preferably includes one or more of sodium hydroxide and potassium hydroxide; the mass ratio of the hydroxide to sodium carbonate is preferably (1-2):1, more preferably (1.2-1.8):1, and further preferably 1.5:1. In a specific embodiment of the present invention, the pH adjuster is sodium hydroxide and sodium carbonate in a mass ratio of 1:1.

[0053] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention comprises a fluid loss reducer; the mass percentage of the fluid loss reducer to the water is 0.8% to 1.2%, preferably 0.9% to 1.1%, and more preferably 1%.

[0054] In the present invention, the fluid loss reducer preferably includes one or more of carboxymethyl starch, cross-linked carboxymethyl starch and cross-linked hydroxypropyl starch, and more preferably cross-linked carboxymethyl starch.

[0055] The drilling fluid glue in the anti-mudball drilling fluid provided by the present invention includes a plugging agent; the mass percentage of the plugging agent to the water is 2.0% to 4.0%, preferably 2.5% to 3.5%, more preferably 2.8% to 3.2%, and further preferably 3%.

[0056] In the present invention, the plugging agent preferably includes one or both of humic acid resin and sulfonated lignite, and more preferably humic acid resin.

[0057] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention comprises a coating agent; the mass percentage of the coating agent to the water is 0.3% to 0.6%, preferably 0.4% to 0.5%, and more preferably 0.45%.

[0058] In the present invention, the coating agent is preferably partially hydrolyzed polyacrylamide.

[0059] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention includes an inhibitor; the mass percentage of the inhibitor to the water is 3.0% to 5.0%, preferably 3.4% to 4.6%, more preferably 3.7% to 4.2%, and further preferably 4%.

[0060] In the present invention, the preparation method of the inhibitor preferably comprises the following steps: first mixing an organic carboxylic acid, a first organic amine and an azeotropic agent for condensation reaction to obtain an amide, and second mixing the amide with a second organic amine and water to obtain the inhibitor.

[0061] In the present invention, the organic carboxylic acid preferably includes one or more of tartaric acid, succinic acid, malic acid, lauric acid and 4-methyl-4-phenyl-2-pentenoic acid.

[0062] In the present invention, the first organic amine preferably includes one or more of ethylenediamine, diethylenediamine, 2-propyleneamine, 1,2-dimethylpropylamine, hexamethylenediamine and hexamethylenetetramine.

[0063] In the present invention, the mass ratio of the organic carboxylic acid to the first organic amine is preferably 10-30:40-60, more preferably 15-25:45-55, and further preferably 18-22:47-51.

[0064] In the present invention, the azeotropic agent preferably includes one or more of benzene, toluene and xylene.

[0065] In the present invention, the mass ratio of the organic carboxylic acid to the entrainer is preferably 10-30:5-10, more preferably 15-25:6-9, and further preferably 20:7-8.

[0066] In the present invention, the temperature of the first mixing is preferably the same as the temperature of the condensation reaction; the first mixing is preferably: the organic carboxylic acid and the entrainer are heated and mixed (referred to as the first heated mixing) to obtain a first mixture, and then the first mixture and the first organic amine are mixed while stirring.

[0067] In the present invention, the temperature of the condensation reaction is preferably 80-90°C, more preferably 82-88°C, and further preferably 84-85°C, and the holding time is preferably 4-8h, more preferably 5-7h, and further preferably 6h. When the condensation reaction is carried out in the present invention, the generated water, excess reactants and entrainer are evaporated simultaneously.

[0068] In the present invention, the condensation reaction preferably further comprises cooling the obtained product; the final temperature of the cooling is preferably room temperature.

[0069] In the present invention, the second organic amine preferably includes one or more of tetramethylammonium chloride, dimethyldialkylammonium chloride, choline chloride, polyethyleneimine and polyetherdiamine.

[0070] In the present invention, the mass ratio of the amide to the second organic amine is preferably 40-50:20-30, more preferably 42-48:22-28, and further preferably 44-46:24-26.

[0071] In the present invention, the water preferably includes one or more of distilled water and deionized water.

[0072] In the present invention, the mass ratio of the amide to water is preferably 40-50:20-30, more preferably 42-48:22-28, and further preferably 44-46:24-26.

[0073] The drilling fluid glue in the anti-mudball drilling fluid provided by the present invention includes an anti-mudball agent; the mass percentage of the anti-mudball agent to the water is 3.0% to 5.0%, preferably 3.4% to 4.6%, more preferably 3.7% to 4.2%, and further preferably 4%.

[0074] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention comprises an anti-wear and drag reducing agent; the mass percentage of the anti-wear and drag reducing agent to the water is 2.0% to 3.0%, preferably 2.2% to 2.8%, and more preferably 2.4% to 2.5%.

[0075] In the present invention, the anti-wear and drag reducing agent is preferably the anti-wear and drag reducing agent CX300-A produced by Shenzhen LiTe Energy Technology Co., Ltd.

[0076] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention includes a viscosity enhancer; the mass percentage of the viscosity enhancer to the water is 0.3% to 0.5%, preferably 0.35% to 0.45%, more preferably 0.37% to 0.42%, and further preferably 0.40%.

[0077] In the present invention, the viscosity increasing agent is preferably xanthan gum.

[0078] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention includes inorganic salts; the mass percentage of the inorganic salts to the water is 8% to 15%, preferably 9% to 14%, more preferably 10% to 13%, and further preferably 11% to 12%.

[0079] In the present invention, the inorganic salt preferably includes sodium chloride and potassium chloride; the mass ratio of sodium chloride to potassium chloride is preferably 1:(1-2), more preferably 1:(1.2-1.8), and further preferably 1:(1.4-1.6).

[0080] The drilling fluid gel in the anti-mudball drilling fluid provided by the present invention comprises water; the water preferably comprises one or more of well site water, oil field water and tap water.

[0081] The anti-mudball drilling fluid provided by the present invention comprises a weighting material; the weighting material is preferably barite; the density of the barite is preferably 4.2-4.4 g / cm 3 , more preferably 4.25 to 4.35 g / cm 3 , more preferably 4.3 g / cm 3 The present invention determines the amount of weighting material based on the known relationship between density requirement and weighting material, and the relationship between density requirement and weighting material is shown in Formula A:

[0082] Amount of weighting material = ρ B ×V 1 ×{(ρ B -ρ 1 ) / (ρ B -ρ 2 )-1} formula A;

[0083] In formula A, ρ B is the density of barite, ρ 1 is the density of the drilling fluid before adding weighting materials, ρ 2 is the density of the drilling fluid after adding weighting materials, V 1 The volume of a drilling fluid before weighting material is added.

[0084] The present invention also provides a method for preparing the anti-mud ball drilling fluid described in the above scheme, comprising the following steps:

[0085] (1) mixing a pH regulator, a fluid loss reducer, a plugging agent, a coating agent, an inhibitor, an anti-mud ball agent, an anti-wear drag reducer, a tackifier, an inorganic salt and water to obtain a drilling fluid gel;

[0086] (2) The drilling fluid gel and the weighting material are mixed to a target density to obtain the anti-mud ball drilling fluid.

[0087] The present invention mixes a pH value regulator, a fluid loss agent, a plugging agent, a coating agent, an inhibitor, an anti-mud ball agent, an anti-wear and drag reducing agent, a tackifier, an inorganic salt and water to obtain a drilling fluid glue. In the present invention, the pH value regulator, a fluid loss agent, a plugging agent, a coating agent, an inhibitor, an anti-mud ball agent, an anti-wear and drag reducing agent, a tackifier, an inorganic salt and water are preferably mixed by stirring.

[0088] After obtaining the drilling fluid glue, the present invention mixes the drilling fluid glue and the weighting material to a target density to obtain the anti-mudball drilling fluid. In the present invention, the mixing of the drilling fluid glue and the weighting material is preferably stirred.

[0089] The present invention also provides the use of the anti-mudball drilling fluid described in the above scheme or the anti-mudball drilling fluid obtained by the preparation method described in the above scheme in high-speed drilling of high-mudstone formations in offshore oil fields.

[0090] The anti-mudball drilling fluid provided by the invention has good inhibition and anti-mudball performance, can be used for high-speed drilling in high-mudstone formations in offshore oil fields, and has significant economic benefits.

[0091] In order to further illustrate the present invention, the scheme of the present invention is described in detail below in conjunction with embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0092] Example 1

[0093] The steps of the preparation method of the anti-mud ball drilling fluid in this embodiment are as follows:

[0094] (1) Preparation of inhibitors:

[0095] Taking tartaric acid as a reference, 10 parts by mass of tartaric acid and 5 parts by mass of benzene are mixed and heated to 90°C, 40 parts by mass of ethylenediamine are added with stirring, and a condensation reaction occurs at 90°C for 4 hours, during which the generated water, excess reactants and benzene are evaporated; the product after cooling to room temperature is uniformly mixed with tetramethylammonium chloride and deionized water in a mass ratio of 4:2:2 to obtain an inhibitor.

[0096] (2) Preparation of anti-mud ball agent:

[0097] Taking polyethylene glycol methyl allyl ether as a benchmark, 30 parts by mass of polyethylene glycol methyl allyl ether was dissolved in 100 parts by mass of deionized water, 1 part by mass of 3-(methacryloyloxy)propyltrimethoxysilane was added with stirring, the temperature was raised to 60°C, 0.06 parts by mass of initiator potassium persulfate was added with stirring, and a free radical polymerization reaction occurred at 60°C for 3 hours. The product after being cooled to room temperature was uniformly mixed with dodecylamine polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and 2,4,7,9-tetramethyl-5-decyne-4,7-diol in a mass ratio of 4:1:1:2 to obtain an anti-mud ball agent.

[0098] (3) Formula of anti-mud ball drilling fluid:

[0099] Taking 400g of well site water as the calculation basis, the anti-mud ball drilling fluid of this embodiment includes the following components according to the mass percentage of the well site water:

[0100] pH adjuster (0.4% sodium hydroxide + 0.2% sodium carbonate);

[0101] Fluid loss reducer (cross-linked carboxymethyl starch): 0.8%;

[0102] Sealing agent (humic acid resin): 2.0%;

[0103] Coating agent (partially hydrolyzed polyacrylamide): 0.3%;

[0104] Inhibitors: 3.0%;

[0105] Anti-mud ball agent: 3.0%;

[0106] Anti-wear and drag reducing agent (anti-wear and drag reducing agent CX300-A): 2.0%;

[0107] Thickener (xanthan gum): 0.3%

[0108] Inorganic salt (4% sodium chloride + 4% potassium chloride);

[0109] Weighting material (barite): Weighting to the density of anti-mud ball drilling fluid is 1.15g / cm 3 .

[0110] (4) Preparation of anti-mud ball drilling fluid:

[0111] Take 400g of well site water and place it in a 1000mL high stirring cup, add 1.6g of sodium hydroxide and 0.8g of sodium carbonate while stirring at a speed of 8000r / min, and stir at high speed (the high-speed stirring in this embodiment is 8000r / min) for 5min; then add 3.2g of cross-linked carboxymethyl starch and stir at high speed for 5min; then add 8.0g of humic acid resin and stir at high speed for 5min; then add 1.2g of partially hydrolyzed polyacrylamide and stir at high speed for 10min; then add 12.0g of inhibitor and stir at high speed for 5min; then add 12.0g of anti-mud ball agent and stir at high speed for 5min; then add 8.0g of anti-wear and drag reducer and stir at high speed for 5min; then add 1.2g of xanthan gum and stir at high speed for 30min; then add 16.0g of sodium chloride and 16.0g of potassium chloride and stir at high speed for 5min; then add barite until the density of the anti-mud ball drilling fluid is 1.15g / cm 3 , stir at high speed for 30 minutes to obtain the anti-mud ball drilling fluid.

[0112] (5) Performance evaluation of anti-mud ball drilling fluid:

[0113] The anti-mud ball drilling fluid was packaged into an aging tank and rolled aged at 120°C for 16 hours. The rheological properties of the anti-mud ball drilling fluid were tested at 50°C, and the results are shown in Table 1. The low temperature and low pressure (API) filtration loss of the anti-mud ball drilling fluid was tested at room temperature and 100 psi pressure difference, and the high temperature and high pressure (HTHP) filtration loss of the anti-mud ball drilling fluid was tested at 120°C and 500 psi pressure difference. The pH value, friction coefficient, rolling recovery rate and surface tension were tested at room temperature, and the results are shown in Table 2.

[0114] Example 2

[0115] The steps of the preparation method of the anti-mud ball drilling fluid in this embodiment are as follows:

[0116] (1) Preparation of inhibitors:

[0117] Taking lauric acid as a benchmark, 30 parts by mass of lauric acid and 10 parts by mass of toluene are mixed and heated to 90°C, 60 parts by mass of diethylenediamine are added with stirring, and a condensation reaction occurs at 90°C for 8 hours, during which the generated water, excess reactants and toluene are evaporated; the product after cooling to room temperature is uniformly mixed with dimethyldialkylammonium chloride and distilled water in a mass ratio of 5:3:3 to obtain an inhibitor.

[0118] (2) Preparation of anti-mud ball agent:

[0119] Taking polyoxyalkyl methyl allyl ether as a benchmark, 50 parts by mass of polyoxyalkyl methyl allyl ether is dissolved in 100 parts by mass of distilled water, 5 parts by mass of vinyl triethoxy silane are added with stirring, the temperature is raised to 90°C, 1.5 parts by mass of initiator ammonium persulfate are added with stirring, and a free radical polymerization reaction occurs at 90°C for 5 hours. The product after being cooled to room temperature is uniformly mixed with octadecylamine polyoxyethylene ether, isomeric tridecyl alcohol polyoxyethylene ether and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol in a mass ratio of 6:2:2:3 to obtain an anti-mud ball agent.

[0120] (3) Formula of anti-mud ball drilling fluid:

[0121] Taking the mass of 400g of well site water as the calculation basis, the anti-mud ball drilling fluid of this embodiment includes the following components according to the mass percentage of the well site water:

[0122] pH adjuster (0.5% sodium hydroxide + 0.5% sodium carbonate);

[0123] Fluid loss reducer (cross-linked carboxymethyl starch): 1.2%;

[0124] Plugging agent (humic acid resin): 4.0%;

[0125] Coating agent (partially hydrolyzed polyacrylamide): 0.6%;

[0126] Inhibitors: 5.0%;

[0127] Anti-mud ball agent: 5.0%;

[0128] Anti-wear and drag reducing agent (anti-wear and drag reducing agent CX300-A): 3.0%;

[0129] Thickener (xanthan gum): 0.5%

[0130] Inorganic salt (7.5% sodium chloride + 7.5% potassium chloride);

[0131] Weighting material (barite): Weighting to the density of anti-mud ball drilling fluid is 1.30g / cm 3 .

[0132] (4) Preparation of anti-mud ball drilling fluid:

[0133] Take 400g of well site water and place it in a 1000mL high stirring cup, add 2.0g of sodium hydroxide and 2.0g of sodium carbonate while stirring at a speed of 8000r / min, and stir at high speed (the high-speed stirring in this embodiment is 8000r / min) for 5min; then add 4.8g of cross-linked carboxymethyl starch and stir at high speed for 5min; then add 16.0g of humic acid resin and stir at high speed for 5min; then add 2.4g of partially hydrolyzed polyacrylamide and stir at high speed for 10min; then add 20.0g of inhibitor and stir at high speed for 5min; then add 20.0g of anti-mud ball agent and stir at high speed for 5min; then add 12.0g of anti-wear and drag reducer and stir at high speed for 5min; then add 2.0g of xanthan gum and stir at high speed for 30min; then add 30.0g of sodium chloride and 30.0g of potassium chloride and stir at high speed for 5min; then add barite until the density of the anti-mud ball drilling fluid is 1.30g / cm 3 , stir at high speed for 30 minutes to obtain the anti-mud ball drilling fluid.

[0134] (5) The performance evaluation of the anti-mud ball drilling fluid is the same as that of Example 1.

[0135] Example 3

[0136] The steps of the preparation method of the anti-mud ball drilling fluid in this embodiment are as follows:

[0137] (1) Preparation of inhibitors:

[0138] Taking succinic acid as a benchmark, 20 parts by mass of succinic acid and 7 parts by mass of xylene are mixed and heated to 90°C, 50 parts by mass of hexamethylenediamine are added with stirring, and a condensation reaction occurs at 80°C for 6 hours, during which the generated water, excess reactants and xylene are evaporated; the product after cooling to room temperature is uniformly mixed with polyethylene diamine and deionized water in a mass ratio of 45:25:25 to obtain an inhibitor.

[0139] (2) Preparation of anti-mud ball agent:

[0140] Taking polypropylene glycol allyl ether as a benchmark, 40 parts by mass of polypropylene glycol allyl ether were dissolved in 100 parts by mass of deionized water, 3 parts by mass of 3-(methacryloyloxy)propylmethyldimethoxysilane were added with stirring, the temperature was raised to 90°C, 0.08 parts by mass of initiator azobisisobutylamidine hydrochloride was added with stirring, and a free radical polymerization reaction occurred at 90°C for 4 hours. The product after being cooled to room temperature was uniformly mixed with octadecylamine polyoxyethylene ether, lauryl alcohol polyoxyethylene ether and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol in a mass ratio of 50:15:15:25 to obtain an anti-mud ball agent.

[0141] (3) Formula of anti-mud ball drilling fluid:

[0142] Taking the mass of 400g of well site water as the calculation basis, the anti-mud ball drilling fluid of this embodiment includes the following components according to the mass percentage of the well site water:

[0143] pH adjuster (0.4% sodium hydroxide + 0.4% sodium carbonate);

[0144] Fluid loss reducer (cross-linked carboxymethyl starch): 1.0%;

[0145] Sealing agent (humic acid resin): 3.5%;

[0146] Coating agent (partially hydrolyzed polyacrylamide): 0.4%;

[0147] Inhibitors: 4.0%;

[0148] Anti-mud ball agent: 4.0%;

[0149] Anti-wear and drag reducing agent (anti-wear and drag reducing agent CX300-A): 2.5%;

[0150] Thickener (xanthan gum): 0.4%

[0151] Inorganic salt (4% sodium chloride + 6% potassium chloride);

[0152] Weighting material (barite): Weighting to the density of anti-mud ball drilling fluid is 1.20g / cm 3 .

[0153] (4) Preparation of anti-mud ball drilling fluid:

[0154] Take 400g of well site water and place it in a 1000mL high stirring cup, add 1.6g of sodium hydroxide and 1.6g of sodium carbonate while stirring at a speed of 8000r / min, and stir at high speed (the high-speed stirring in this embodiment is 8000r / min) for 5min; then add 4.0g of cross-linked carboxymethyl starch and stir at high speed for 5min; then add 14.0g of humic acid resin and stir at high speed for 5min; then add 1.6g of partially hydrolyzed polyacrylamide and stir at high speed for 10min; then add 16.0g of inhibitor and stir at high speed for 5min; then add 16.0g of anti-mud ball agent and stir at high speed for 5min; then add 10.0g of anti-wear and drag reducer and stir at high speed for 5min; then add 1.6g of xanthan gum and stir at high speed for 30min; then add 16.0g of sodium chloride and 24.0g of potassium chloride and stir at high speed for 5min; then add barite until the density of the anti-mud ball drilling fluid is 1.20g / cm 3 , stir at high speed for 30 minutes to obtain the anti-mud ball drilling fluid.

[0155] (5) The performance evaluation of the anti-mud ball drilling fluid is the same as that of Example 1.

[0156] Example 4

[0157] (1) The preparation method of the inhibitor is the same as that of Example 1.

[0158] (2) The preparation method of the anti-mud ball agent is the same as that of Example 1.

[0159] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 2.

[0160] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 2.

[0161] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0162] Example 5

[0163] (1) The preparation method of the inhibitor is the same as that of Example 2.

[0164] (2) The preparation method of the anti-mud ball agent is the same as that of Example 2.

[0165] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 1.

[0166] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0167] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0168] Example 6

[0169] (1) The preparation method of the inhibitor is the same as that of Example 3.

[0170] (2) The preparation method of the anti-mud ball agent is the same as that of Example 3.

[0171] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 1.

[0172] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0173] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0174] Example 7

[0175] (1) The preparation method of the inhibitor is the same as that of Example 3.

[0176] (2) The preparation method of the anti-mud ball agent is the same as that of Example 3.

[0177] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 2.

[0178] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 2.

[0179] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0180] Example 8

[0181] (1) The preparation method of the inhibitor is the same as that of Example 1.

[0182] (2) The preparation method of the anti-mud ball agent is the same as that of Example 1.

[0183] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 3.

[0184] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 3.

[0185] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0186] Example 9

[0187] (1) The preparation method of the inhibitor is the same as that of Example 2.

[0188] (2) The preparation method of the anti-mud ball agent is the same as that of Example 2.

[0189] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 3.

[0190] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 3.

[0191] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0192] Example 10

[0193] (1) The preparation method of the inhibitor is the same as that of Example 2.

[0194] (2) The preparation method of the anti-mud ball agent is the same as that of Example 2.

[0195] (3) The formula of the anti-mud ball drilling fluid is the same as that of Example 2.

[0196] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 2.

[0197] (5) The performance evaluation method of the anti-mudball drilling fluid is the same as that of Example 1, except that the rolling aging temperature and the HTHP test temperature are changed to 150°C.

[0198] Embodiment 11

[0199] (1) The preparation method of the inhibitor is the same as that of Example 2.

[0200] (2) The preparation method of the anti-mud ball agent is the same as that of Example 2.

[0201] (3) The formula of the anti-mudball drilling fluid is the same as that of Example 3, except that 10% of sodium bentonite powder is added.

[0202] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 3, except that 40 g of sodium bentonite powder is added before the barite and stirred for 10 min.

[0203] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0204] Example 12

[0205] (1) The preparation method of the inhibitor is the same as that of Example 2.

[0206] (2) The preparation method of the anti-mud ball agent is the same as that of Example 2.

[0207] (3) The formula of the anti-mudball drilling fluid is the same as that of Example 3, except that 20% of sodium bentonite powder is added.

[0208] (4) The preparation method of the anti-mud ball drilling fluid is the same as that of Example 3, except that 80 g of sodium bentonite powder is added before the barite and stirred for 10 minutes.

[0209] (5) The performance evaluation method of the anti-mud ball drilling fluid is the same as that of Example 1.

[0210] Table 1 Rheological performance evaluation data of each anti-mud ball drilling fluid in Examples 1 to 12

[0211]

[0212]

[0213] Note: AV is the apparent viscosity; PV is the plastic viscosity, YP is the dynamic shear force, and the dynamic plastic ratio is the ratio of the dynamic shear force to the plastic viscosity. They are the 6th and 3rd revolution readings of a six-speed rotational viscometer respectively.

[0214] Table 2 Comprehensive performance evaluation data of the anti-mud ball drilling fluids in Examples 1 to 10

[0215]

[0216] Note: FL API FL is the low temperature and low pressure filtration loss; HTHP is the high temperature and high pressure filtration loss; the surface tension is the surface tension of the anti-mud ball drilling fluid filtrate.

[0217] According to the data of Examples 1 to 9 in Table 1 and Table 2, the anti-mudball drilling fluid has good rheological properties, low plastic viscosity, and a dynamic-plastic ratio generally higher than 0.8, and has good suspended sand carrying performance; and the low-temperature and low-pressure filtration loss and the high-temperature and high-pressure filtration loss are both low, meeting the drilling requirements; the rolling recovery rate is generally higher than 90%, and the anti-mudball drilling fluid has good coating inhibition; the friction coefficient is lower than 0.1, and the anti-mudball drilling fluid has good lubrication performance; the filtrate surface tension is low, and the anti-mudball drilling fluid has a certain wetting reversal performance, which can change the surface properties of the drill cuttings to form a hydrophobic diaphragm, and effectively prevent the drill cuttings from agglomerating and pilling.

[0218] According to the data of Examples 2 and 10 in Tables 1 and 2, after the aging temperature is increased from 120°C to 150°C, the performance changes in various aspects are small, indicating that the anti-mud ball drilling fluid has good temperature resistance and meets the requirements of most high mudstone formations for drilling fluid temperature resistance.

[0219] According to the data of Examples 9, 11 and 12 in Table 1 and Table 2, after being contaminated with 10% and 20% sodium bentonite, the performance of the anti-mudball drilling fluid changed little, indicating that the anti-mudball drilling fluid has good inhibition performance.

[0220] It can be seen from the above embodiments that the anti-mudball drilling fluid provided by the present invention has good inhibition and anti-mudball performance, excellent comprehensive performance, can meet the requirements of high-speed drilling in offshore oil fields, effectively inhibit the hydration expansion and dispersion of mudstone cuttings in high-mudstone formations, and shorten the drilling cycle.

[0221] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An anti-mud ball agent, characterized in that: The invention comprises the following components: polyether-siloxane copolymer, fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol; The mass ratio of the polyether-siloxane copolymer to the fatty amine polyoxyethylene ether is 40-60:10-20; The mass ratio of the polyether-siloxane copolymer to the fatty alcohol polyoxyethylene ether is 40-60:10-20; The mass ratio of the polyether-siloxane copolymer to the acetylene glycol is 40-60:20-30.

2. The anti-mud ball agent according to claim 1, characterized in that: The fatty amine polyoxyethylene ether includes one or two of dodecylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether; The fatty alcohol polyoxyethylene ether includes one or more of lauryl alcohol polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether; The acetylene glycol includes one or more of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol.

3. The method for preparing the anti-mud ball agent according to any one of claims 1 to 2, characterized in that: The following steps are involved: The unsaturated polyether, the unsaturated organosiloxane, the initiator and water are mixed to carry out a free radical polymerization reaction to obtain a polyether-siloxane copolymer; The polyether-siloxane copolymer is fourthly mixed with fatty amine polyoxyethylene ether, fatty alcohol polyoxyethylene ether and acetylene glycol to obtain an anti-mud ball agent.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the unsaturated polyether to the unsaturated organosiloxane is 30-50:1-5; The unsaturated polyether includes one or more of polyethylene glycol methyl allyl ether, polyoxyalkyl methyl allyl ether, polypropylene glycol allyl ether and polyethylene glycol diallyl ether; The unsaturated organic siloxane includes one or more of 3-(methacryloyloxy)propyltrimethoxysilane, vinyltriethoxysilane, 3-(methacryloyloxy)propylmethyldimethoxysilane and 3-(acryloyloxy)propyltrimethoxysilane.

5. An anti-mud ball drilling fluid, characterized in that: It includes drilling fluid glue and weighting material; the drilling fluid glue includes water and components accounting for the following mass percentages of the water: pH regulator 0.6%~1.0%, fluid loss reducer 0.8%~1.2%, plugging agent 2.0%~4.0%, coating agent 0.3%~0.6%, inhibitor 3.0%~5.0%, anti-mud ball agent 3.0%~5.0%, anti-wear and drag reducer 2.0%~3.0%, viscosity enhancer 0.3%~0.5%, inorganic salt 8%~15%; The anti-mud ball agent is the anti-mud ball agent according to any one of claims 1 to 2 or the anti-mud ball agent obtained by the preparation method according to any one of claims 3 to 4; The amount of the weighting material is determined according to the density requirement.

6. The anti-mud ball drilling fluid according to claim 5, characterized in that: The preparation method of the inhibitor comprises the following steps: firstly mixing an organic carboxylic acid, a first organic amine and an azeotropic agent for condensation reaction to obtain an amide, and secondly mixing the amide with a second organic amine and water to obtain the inhibitor.

7. The anti-mud ball drilling fluid according to claim 6, characterized in that: The mass ratio of the organic carboxylic acid to the first organic amine is 10-30:40-60; The mass ratio of the organic carboxylic acid to the entrainer is 10-30:5-10; The organic carboxylic acid includes one or more of tartaric acid, succinic acid, malic acid, lauric acid and 4-methyl-4-phenyl-2-pentenoic acid; The first organic amine includes one or more of ethylenediamine, diethylenediamine, 2-propyleneamine, 1,2-dimethylpropylamine, hexamethylenediamine and hexamethylenetetramine.

8. The anti-mud ball drilling fluid according to claim 6 or 7, characterized in that: The second organic amine includes one or more of tetramethylammonium chloride, dimethyldialkylammonium chloride, choline chloride, polyethyleneimine and polyetherdiamine; The mass ratio of the amide to the second organic amine is 40-50:20-30.

9. The method for preparing the anti-mud ball drilling fluid according to any one of claims 5 to 8, characterized in that: The following steps are involved: (1) mixing a pH regulator, a fluid loss reducer, a plugging agent, a coating agent, an inhibitor, an anti-mud ball agent, an anti-wear drag reducer, a tackifier, an inorganic salt and water to obtain a drilling fluid gel; (2) The drilling fluid gel and the weighting material are mixed to a target density to obtain the anti-mud ball drilling fluid.

10. Use of the anti-mudball drilling fluid according to any one of claims 5 to 8 or the anti-mudball drilling fluid obtained by the preparation method according to claim 9 in high-speed drilling of high-mudstone formations in offshore oil fields.

Images