A method for improving drilling speed in shale-containing formations

Abstract

The application provides a method for improving drilling speed of a shale formation, and the method comprises the following steps: (1) during drilling, a batch of composite mud ball inhibitor is pumped into the drill pipe every 2-4 stands; the number of times of pumping the composite mud ball inhibitor is 6-20; (2) after 6-10 stands of drilling, a batch of mud is pumped; steps (1) to (2) are repeated until the required drilling depth is reached. The method provided by the application utilizes the interval of the stand connection to pump the composite mud ball inhibitor into the drill pipe, which is sprayed from the water eye of the drill bit and rapidly covers the surface of the drill bit and the rock formation to form a hydrophobic film, thereby playing a role in inhibiting shale cutting hydration, preventing mud balls and preventing cuttings from wrapping the drill bit; the mud pumped to the bottom of the well plays a role in diluting and adjusting the performance of the well mud; and the method provided by the application can significantly improve the rock breaking efficiency and improve the mechanical drilling speed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of drilling technology, and relates to a drilling method, in particular to a method for improving the drilling speed of a shale formation. BACKGROUND

[0002] With the increasing demand for oil and gas energy, the drilling of offshore oil wells is rapidly increasing. Unlike land drilling, offshore oil and gas drilling is costly, with the cost of using a drilling platform being more than ten times that of land drilling. Therefore, it is necessary to shorten the well construction period as much as possible to save the cost of offshore oil well drilling.

[0003] Shortening the drilling period of offshore oil wells is the key to reducing the cost of offshore oil well drilling. However, in the process of improving the mechanical drilling speed of offshore oil and gas wells, the phenomenon of mud balling caused by the late carrying of drill cuttings often occurs, which can cause annular unsmoothness and pump pressure rise, and further cause various complex problems in the well.

[0004] CN102250595A discloses a drilling fluid for active shale drilling, which is applied to oil field drilling and comprises bentonite, coating inhibitor, flow pattern regulator, high-temperature-resistant polymer filtrate reducer, potassium chloride, polymeric pure, polyamine inhibitor, anti-mud ball fast drilling agent, and water. The anti-mud ball drilling agent disclosed therein is composed of fatty alcohol ether phosphate, which mainly reduces the water absorption of clay through PO4 3- Fe 2+ forms phosphide crystal nuclei, and then grows into phosphide crystal grains, and finally accumulates to form a phosphide film adsorbed on the drilling tool and the metal surface, thereby reducing the hydration of clay and preventing the adhesion of clay on the metal surface, so as to clean the drill bit and improve the rock breaking efficiency.

[0005] CN104130758A discloses a dendritic polyamine-based polymer drilling fluid for mudstone drilling, which is composed of dendritic polyamine-based polymer, drilling fluid bentonite, soda ash, polymeric coating agent, potassium polyacrylate, hydrolyzed polyacrylonitrile ammonium salt, anti-mud ball lubricant, and water. The use of dendritic polyamine-based polymer improves the inhibitory property of the drilling fluid, greatly improves the inhibitory property of the drilling fluid on clay and drill cuttings, reduces the plasticity of claystone, avoids the water absorption and swelling and dispersion of claystone, prevents the mud ball of the drill bit, and is beneficial to improving the mechanical drilling speed.

[0006] CN105969323A discloses a kind of high-density water-based drilling fluid for shale gas horizontal well, and its preparation raw materials include shielding temporary plugging agent, inhibition anti-sloughing agent, solid lubricant, anti-mud ball cleaner, potassium chloride, sodium hydroxide, fluid loss additive, flow pattern regulator and barite.It can occur electrostatic effect on the surface of drill bit, drill cuttings and clay particles in drilling fluid through the use of polyether polyol, and physical and chemical adsorption, thereby improving the adsorption characteristics of drill pipe metal surface, reducing the bit balling, thereby improving the rate of penetration.

[0007] But the technical solutions provided by the prior art to improve the rate of penetration in field application are simply adding drilling fluid into whole well slurry or maintaining glue solution, which cannot timely exert the efficacy of treatment agent, and often cannot improve the long-term rate of penetration effect.Therefore, a method for improving the drilling speed of shale-containing formation is provided, which is beneficial to further reduce the drilling cost of offshore oil well. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for improving the drilling speed of shale-containing formation, which can sufficiently improve the effects of anti-mud balling and anti-mud balling, effectively avoid the problem of poor anti-mud balling and anti-mud balling effect caused by blind whole well slurry addition or maintenance glue solution fine water long addition, and help to improve the rock breaking efficiency and real-time rate of penetration of shale-containing formation.

[0009] To achieve this purpose, the technical solutions adopted by the present application are as follows:

[0010] The present application provides a method for improving the drilling speed of shale-containing formation, which comprises the following steps:

[0011] (1) During drilling, pump 1 batch of composite anti-mud ball inhibitor into the drill pipe every 2-4 stands;

[0012] (2) After continuing to drill for 6-10 stands, pump 1 batch of mud;

[0013] Repeat steps (1) to (2) until the desired drilling depth is reached.

[0014] The number of times of pumping the composite anti-mud ball inhibitor in step (1) refers to repeating the process of pumping 1 batch of composite anti-mud ball inhibitor into the drill pipe every 2-4 stands for 6-20 times, for example, 6 times, 8 times, 10 times, 12 times, 15 times, 16 times, 18 times or 20 times, but not limited to the listed values, other values not listed within the value range are also applicable.

[0015] The "column" of the present application is composed of 3 drill pipes connected together, the length of the drill pipe in the field is about 9.5-9.8 m, therefore, the length of the column of the present application is 28.7-29.4 m, which is not specifically limited in the present application.

[0016] During drilling, the newly generated drilling cuttings are prone to irreversible hydration expansion and hydration dispersion. The method provided by the present application utilizes the gap of the connected column to pump the composite mud ball inhibitor into the drill pipe, and restores circulation after the column is connected. When drilling continues, the composite mud ball inhibitor in the drill pipe remains a high concentration as a material slug; and under the dual adsorption of the amine group and the alcohol group in the composite mud ball inhibitor, the hydration inhibition effect on the mudstone cuttings can be effectively improved; the composite mud ball inhibitor can also prevent the mutual aggregation of drilling cuttings particles, thereby effectively improving the mud ball prevention effect; the composite mud ball inhibitor is sprayed from the water eye of the drill bit at the same time as it rapidly covers the surface of the drill bit and the rock formation to form a hydrophobic film, which plays a role in inhibiting the hydration of mudstone cuttings and preventing the rock cuttings from wrapping the drill bit when the drill bit breaks the rock formation.

[0017] After pumping the composite mud ball inhibitor for a certain number of times, the method provided by the present application pumps mud to the bottom of the well, which can carry a wave of drilling cuttings and play a role in diluting and adjusting the performance of the well mud.

[0018] The method provided by the present application significantly improves the rock breaking efficiency and increases the mechanical drilling speed by controlling the timing of adding the composite mud ball inhibitor and the mud.

[0019] Preferably, the pumping amount of the 1 batch of composite mud ball inhibitor in step (1) is 0.5-1.5 m 3 , for example, it can be 0.5 m 3 , 0.6 m 3 , 0.8 m 3 , 1 m 3 , 1.2 m 3 or 1.5 m 3 , but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0020] Preferably, the composite mud ball inhibitor in step (1) is composed of mud ball inhibitor and inhibitor with a mass ratio of (5-7):(3-5).

[0021] In the composite mud ball inhibitor of the present application, the mass ratio of the mud ball inhibitor to the inhibitor is (5-7):(3-5), for example, it can be 5:5, 5.5:4.5, 6:4, 6.5:3.5 or 7:3, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0022] Preferably, the mud ball inhibitor is composed of fatty amine polyoxyethylene ether, organosilicon modified polyether and acetylenic diol ethoxylate.

[0023] Preferably, the mass ratio of the fatty amine polyoxyethylene ether, the silicone-modified polyether and the acetylenic diol ethoxylate is (4-6):(2-4):(1-2), for example, it can be 4:4:2, 5:4:1, 5:3:2, 6:2:2 or 6:3:1, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0024] Preferably, the inhibitor is composed of a polyether diamine, a polyethylene imine and a polyethylene glycol.

[0025] Preferably, the mass ratio of the polyether diamine, the polyethylene imine and the polyethylene glycol is (15-35):(5-20):(45-65), for example, it can be 15:20:65, 20:15:65, 30:20:50, 35:20:45 or 30:15:55, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0026] Preferably, the funnel viscosity of the slurry in step (2) is 35-55s, for example, it can be 35s, 40s, 45s, 50s or 55s, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0027] The "funnel viscosity" in the present application refers to the Marsh funnel viscosity.

[0028] Preferably, the yield stress of the slurry in step (2) is 8-15Pa, for example, it can be 8Pa, 10Pa, 12Pa, 14Pa or 15Pa, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0029] Preferably, the dynamic plasticity ratio of the slurry in step (2) is 0.8-1.2Pa / mPa·s, for example, it can be 0.8Pa / mPa·s, 0.9Pa / mPa·s, 1Pa / mPa·s, 1.1Pa / mPa·s or 1.2Pa / mPa·s, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0030] Preferably, the 3rpm reading of the slurry in step (2) is 7-12, for example, it can be 7, 8, 9, 10, 11 or 12, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0031] The "3rpm reading" in the present application refers to the 3rpm reading in the continuous testing process of the six-speed rotary viscometer.

[0032] Preferably, the pumping amount of the batch of slurry in step (2) is 10-18m 3 , for example, it can be 10m3 , 11m 3 , 12m 3 , 13m 3 , 14m 3 , 15m 3 , 16m 3 or 18m 3 , but not limited to the listed values, other unlisted values within the range are also applicable.

[0033] As a preferred technical solution of the method, the method comprises the following steps:

[0034] (1) During drilling, 1 batch of composite mud ball inhibitor is pumped into the drill pipe every 2-4 stands; the number of times of pumping the composite mud ball inhibitor is 6-20 times; the pumping amount of the 1 batch of composite mud ball inhibitor is 0.5-1.5 m 3 ;

[0035] The composite mud ball inhibitor is composed of a mud ball inhibitor and an inhibitor in a mass ratio of (5-7):(3-5);

[0036] The mud ball inhibitor is composed of a fatty amine polyoxyethylene ether, a silicone-modified polyether and an acetylenic diol ethoxylate in a mass ratio of (4-6):(2-4):(1-2);

[0037] The inhibitor is composed of a polyether diamine, a polyethyleneimine and a polyethylene glycol in a mass ratio of (15-35):(5-20):(45-65);

[0038] (2) After continuing drilling for 6-10 stands, 1 batch of mud is pumped; the pumping amount of the 1 batch of mud is 10-18 m 3 ; the funnel viscosity of the mud is 35-55 s, the dynamic shear force is 8-15 Pa, the dynamic plastic ratio is 0.8-1.2 Pa / mPa·s, and the 3-rotation reading is 7-12;

[0039] Steps (1) to (2) are repeated until the required drilling depth is reached.

[0040] The numerical range of the present application includes not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges that are not mentioned, and the present application does not exhaustively list the specific point values included in the range for the sake of brevity and simplicity.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] The method provided by the application pumps the composite mud ball inhibitor into the drill pipe by using the gap of the kelly, restores circulation after the kelly is connected, and continues drilling, so that the composite mud ball inhibitor in the drill pipe remains a very high concentration as a material slug; and the dual adsorption of amine groups and alcohol groups in the composite mud ball inhibitor can effectively improve the hydration inhibition effect on the shale debris; the composite mud ball inhibitor can also prevent the mutual aggregation of drill cuttings particles, thereby effectively improving the mud ball prevention effect; the composite mud ball inhibitor is sprayed from the water eye of the drill bit and rapidly covers the surface of the drill bit and the rock stratum to form a hydrophobic film, thereby playing a role in inhibiting the hydration of the shale cuttings and preventing the cuttings from wrapping the drill bit when the drill bit breaks the rock stratum; after the composite mud ball inhibitor is pumped for a certain number of times, mud is pumped to the bottom of the well, which can carry a wave of cuttings and play a role in diluting and adjusting the performance of the well mud; by controlling the timing of adding the composite mud ball inhibitor and the mud, the rock breaking efficiency is significantly improved, and the rate of penetration is improved. DETAILED DESCRIPTION

[0043] The technical solutions of the application are further described below through a specific embodiment.

[0044] In order to clearly illustrate the technical solutions of the application, the fatty amine polyoxyethylene ether in the specific embodiment is selected from KL-1812; the silicone-modified polyether is selected from WET-267; the acetylenic diol ethoxylate is selected from Surfynol 2502; the polyether diamine is selected from Jeffamine EDR-148; the polyethylene imine is selected from Guohua Reagent, and the CAS number is 9002-98-6; and the polyethylene glycol is selected from PEG-1000.

[0045] The above is not considered as a further limitation of the fatty amine polyoxyethylene ether, the silicone-modified polyether, the acetylenic diol ethoxylate, the polyether diamine, the polyethylene imine, and the polyethylene glycol.

[0046] Comparative Example 1

[0047] The drilling object of the present comparative example is a 12.25in well section of the second opening of a certain offshore oil well, the designed well depth is 3577m, the open hole length is 2642m, and the open hole section is a high shale content formation, the clay mineral content is 64wt%, and the hydration is extremely easy.

[0048] The present comparative example uses the method of adding an inhibitor to the whole mud before drilling the second opening to improve the inhibition, the average rate of penetration is 100m / h in the first 300m, and the funnel viscosity is maintained between 45s and 50s, but the rate of penetration gradually decreases to 65m / h during the continuous drilling process, the funnel viscosity gradually rises to 60s-70s, and a large amount of mud balls are returned, the pump pressure is also unstable, and the annulus is not smooth.

[0049] The inhibitor described in the comparative example is composed of polyether diamine, polyethylene imine and polyethylene glycol in a mass ratio of 35:5:60.

[0050] Example 1

[0051] The example provides a method for improving the drilling speed of a shale formation, the treatment of the method is the same as that of Comparative Example 1, which solves the problem of poor effect of adding an inhibitor to the whole mud, and the method comprises the following steps:

[0052] (1) During drilling, a batch of composite mud ball inhibitor is pumped into the drill pipe every 3 stands; the number of times of pumping the composite mud ball inhibitor is 10 times; the pumping amount of the batch of composite mud ball inhibitor is 1 m 3 ; after 10 times of pumping the composite mud ball inhibitor, the mud pump is reconnected to the upper water tank to restore circulation, and drilling continues, the pump pressure returns to stable, the funnel viscosity is maintained at 60-70 s and no longer continues to rise, and the mechanical drilling speed gradually increases to 80 m / h;

[0053] The composite mud ball inhibitor is composed of a mud ball inhibitor and an inhibitor in a mass ratio of 5:5;

[0054] The mud ball inhibitor is composed of fatty amine polyoxyethylene ether, silicone modified polyether and acetylenic diol ethoxylate in a mass ratio of 6:2:2;

[0055] The inhibitor is composed of polyether diamine, polyethylene imine and polyethylene glycol in a mass ratio of 35:5:60;

[0056] (2) After continuing to drill for 8 stands, a batch of mud is pumped, the normal vibration screen returns, and there is no sticky soft rock debris; the pumping amount of the batch of mud is 15 m 3 ; the funnel viscosity of the mud is 42 s, the dynamic shear force is 9 Pa, the dynamic plastic ratio is 0.92 Pa / mPa·s, and the 3-turn reading is 8;

[0057] Repeat steps (1) to (2) until the second opening is completed, during which no mud ball is generated, the funnel viscosity is controlled between 50-56 s, the maximum mechanical drilling speed is as high as 130 m / h, the average mechanical drilling speed reaches 95 m / h, and the speed-up effect is remarkable.

[0058] Example 2

[0059] The example provides a method for improving the drilling speed of a shale formation, the treatment of the method is the same as that of Comparative Example 1, which solves the problem of poor effect of adding an inhibitor to the whole mud, and the method comprises the following steps:

[0060] (1) drilling process, every 2 column, to the drill pipe pumped 1 batch of composite mud ball inhibitor; pump composite mud ball inhibitor 20 times; the pumping amount of 1 batch of composite mud ball inhibitor is 0.5m 3 ; after pumping 20 times of composite mud ball inhibitor, mud pump is reconnected with the upper water tank to restore circulation, continue drilling, pump pressure returns to stable, funnel viscosity is maintained at 60-65s and no longer continues to rise, the mechanical drilling speed gradually increases to 90m / h;

[0061] The composite mud ball inhibitor is composed of mud ball inhibitor and inhibitor with a mass ratio of 6:4;

[0062] The mud ball inhibitor is composed of fatty amine polyoxyethylene ether, silicone modified polyether and acetylenic diol ethoxylate with a mass ratio of 5:4:1;

[0063] The inhibitor is composed of polyether diamine, polyethylene imine and polyethylene glycol with a mass ratio of 35:20:45;

[0064] (2) continue drilling for 6 columns, pump 1 batch of mud, and the vibrating screen returns to normal without sticky soft rock debris; the pumping amount of 1 batch of mud is 10m 3 ; the funnel viscosity of the mud is 55s, the dynamic shear force is 15Pa, the dynamic plastic ratio is 1.2Pa / mPa·s, and the 3 rotation reading is 12;

[0065] Repeat steps (1) to (2) until the end of the second opening, during which no mud ball is generated, the funnel viscosity is controlled between 54-60s, the maximum mechanical drilling speed is as high as 132m / h, and the average mechanical drilling speed reaches 99m / h, the speed-up effect is remarkable.

[0066] Example 3

[0067] The embodiment provides a method for improving drilling speed in mud-containing rock formation, and the treatment of the method is the same as that of comparative example 1, which solves the problem of poor effect of adding inhibitor in whole well mud, and the method comprises the following steps:

[0068] (1) drilling process, every 4 column, to the drill pipe pumped 1 batch of composite mud ball inhibitor; pump composite mud ball inhibitor 6 times; the pumping amount of 1 batch of composite mud ball inhibitor is 1.5m 3 ; after pumping 6 times of composite mud ball inhibitor, mud pump is reconnected with the upper water tank to restore circulation, continue drilling, pump pressure returns to stable, funnel viscosity is maintained at 62-68s and no longer continues to rise, the mechanical drilling speed gradually increases to 92m / h;

[0069] The composite mud ball inhibitor is composed of mud ball inhibitor and inhibitor with a mass ratio of 6:4;

[0070] The anti-mud ball agent is composed of fatty amine polyoxyethylene ether, silicone modified polyether and acetylene glycol ethoxylate with a mass ratio of 4:4:2;

[0071] The inhibitor is composed of polyether diamine, polyethyleneimine and polyethylene glycol with a mass ratio of 15:20:65;

[0072] (2) After drilling 6 columns, pump 1 batch of mud, and the vibrating screen returns to normal without sticky soft rock debris; the pumping amount of the 1 batch of mud is 18m 3 ; The funnel viscosity of the mud is 35s, the dynamic shear force is 8Pa, the dynamic plastic ratio is 0.8Pa / mPa·s, and the 3-turn reading is 7;

[0073] Repeat steps (1) to (2) until the second opening is completed, during which no mud balls are generated, the funnel viscosity is controlled between 48-55s, the highest mechanical drilling speed is as high as 141m / h, and the average mechanical drilling speed reaches 102m / h, and the speed-up effect is remarkable.

[0074] Example 4

[0075] The method for improving the drilling speed of a mudstone-containing formation provided in this embodiment is the same as that in Example 1, except that the anti-mud ball agent is composed of fatty amine polyoxyethylene ether and silicone modified polyether with a mass ratio of 6:2.

[0076] Mud balls occur during the second opening in this embodiment, the funnel viscosity is controlled between 65-72s, the highest mechanical drilling speed is 111m / h, and the average mechanical drilling speed is 67m / h, and the speed-up effect is poor.

[0077] Example 5

[0078] The method for improving the drilling speed of a mudstone-containing formation provided in this embodiment is the same as that in Example 1, except that the anti-mud ball agent is composed of fatty amine polyoxyethylene ether and acetylene glycol ethoxylate with a mass ratio of 6:2.

[0079] Mud balls occur during the second opening in this embodiment, the funnel viscosity is controlled between 63-69s, the highest mechanical drilling speed is 108m / h, and the average mechanical drilling speed is 63m / h, and the speed-up effect is poor.

[0080] Example 6

[0081] The method for improving the drilling speed of a mudstone-containing formation provided in this embodiment is the same as that in Example 1, except that the anti-mud ball agent is composed of silicone modified polyether and acetylene glycol ethoxylate with a mass ratio of 1:1.

[0082] Mud balls appeared during the second opening period, the funnel viscosity was controlled between 60-67s, the highest mechanical drilling speed was 113m / h, the average mechanical drilling speed was 60m / h, and the speed-up effect was poor.

[0083] Example 7

[0084] The example provides a method for improving the drilling speed of a mudstone-containing formation, wherein the rest is the same as in example 1, except that the inhibitor is composed of polyether diamine and polyethylene imine in a mass ratio of 35:5.

[0085] Mud balls appeared during the second opening period, the funnel viscosity was controlled between 65-75s, the highest mechanical drilling speed was 107m / h, the average mechanical drilling speed was 61m / h, and the speed-up effect was poor.

[0086] Example 8

[0087] The example provides a method for improving the drilling speed of a mudstone-containing formation, wherein the rest is the same as in example 1, except that the inhibitor is composed of polyethylene imine and polyethylene glycol in a mass ratio of 5:60.

[0088] Mud balls appeared during the second opening period, the funnel viscosity was controlled between 68-76s, the highest mechanical drilling speed was 99m / h, the average mechanical drilling speed was 56m / h, and the speed-up effect was poor.

[0089] Example 9

[0090] The example provides a method for improving the drilling speed of a mudstone-containing formation, wherein the rest is the same as in example 1, except that the inhibitor is composed of polyether diamine and polyethylene glycol in a mass ratio of 35:60.

[0091] Mud balls appeared during the second opening period, the funnel viscosity was controlled between 62-68s, the highest mechanical drilling speed was 105m / h, the average mechanical drilling speed was 66m / h, and the speed-up effect was poor.

[0092] Comparative Example 2

[0093] The drilling object of the comparative example is a 12.25in well section in the second opening of a certain offshore oil well, with a design well depth of 3750m and a bare hole length of 2569m. The bare hole section is a high-mudstone-containing formation with a clay mineral content of 58wt%, which is prone to hydration.

[0094] In the comparative example, the inhibition was improved by adding a composite mud ball inhibitor to the whole well mud during the second opening drilling. The average mechanical drilling speed was 110m / h in the early stage, and the funnel viscosity was maintained between 40-50s. However, when drilling continued to 1612m, obvious pump choking and torque bumping phenomena appeared, the funnel viscosity rose to 65s, and the pump choking and torque bumping phenomena also appeared during the reverse reaming and short tripping process. A large amount of sticky and soft cuttings were returned after pushing the thick plug to clean the wellbore.

[0095] The composite mud ball inhibitor of the present comparative example is composed of a mud ball inhibitor and an inhibitor at a mass ratio of 5:5; the mud ball inhibitor is composed of a fatty amine polyoxyethylene ether, a silicone-modified polyether and an acetylenic diol ethoxylate at a mass ratio of 6:2:2; the inhibitor is composed of a polyether diamine, a polyethylene imine and a polyethylene glycol at a mass ratio of 35:5:60.

[0096] Example 10

[0097] The present example provides a method for improving the drilling speed of a shale-containing formation, the treatment of the method is the same as that of Comparative Example 2, which solves the problem of poor effect of the whole mud additive inhibitor, and the method comprises the following steps:

[0098] (1) During drilling, 1 batch of composite mud ball inhibitor is pumped into the drill pipe every 2 stands; the number of times of pumping the composite mud ball inhibitor is 12 times; the pumping amount of 1 batch of composite mud ball inhibitor is 0.8 m 3 ; after 12 times of pumping the composite mud ball inhibitor, the mud pump is reconnected to the upper water tank to restore circulation, and drilling continues, and the pump choking and torque phenomenon disappears, and the funnel viscosity is maintained at about 65 s and no longer continues to rise;

[0099] The composite mud ball inhibitor is composed of a mud ball inhibitor and an inhibitor at a mass ratio of 5:5;

[0100] The mud ball inhibitor is composed of a fatty amine polyoxyethylene ether, a silicone-modified polyether and an acetylenic diol ethoxylate at a mass ratio of 55:35:10;

[0101] The inhibitor is composed of a polyether diamine, a polyethylene imine and a polyethylene glycol at a mass ratio of 30:20:50;

[0102] (2) After continuing to drill for 7 stands, 1 batch of mud is pumped, and the vibration screen is normally returned without sticky soft cuttings; the pumping amount of 1 batch of mud is 12 m 3 ; the funnel viscosity of the mud is 45 s, the dynamic shear force is 10 Pa, the dynamic plastic ratio is 0.9 Pa / mPa·s, and the 3-rotation reading is 9;

[0103] Repeat steps (1) to (2) until the end of the second opening, during which no mud ball is generated, and no pump choking and torque phenomenon occurs, the funnel viscosity is controlled between 45-51 s, the maximum mechanical drilling speed is as high as 145 m / h, the average mechanical drilling speed reaches 101 m / h, and the speed-up effect is remarkable.

[0104] Comparative Example 3

[0105] The drilling object of the present comparative example is a 12.25in well section of a second opening of an offshore oil well, with a designed well depth of 3749m and a bare hole length of 2378m. The bare hole section is a high shale content formation, with a clay mineral content of 65wt%, which is prone to hydration.

[0106] In the present comparative example, the drilling of the second opening is performed by adding a composite mud ball inhibitor to the whole mud to improve the inhibition. The composite mud ball inhibitor is also added to the maintenance mud. The maximum ROP is up to 150m / h in the first 400m, and the funnel viscosity is maintained at 45-55s. However, the ROP is significantly reduced after drilling for another 300m, with the maximum ROP being only 80m / h and the average ROP being only 45m / h. The test funnel viscosity is increased to 70s, and a small amount of mud ball is returned during the circulation and cleaning of the wellbore. The drill bit is covered with a large amount of shale, and the teeth are not visible.

[0107] The composite mud ball inhibitor of the present comparative example is composed of a mud ball inhibitor and an inhibitor at a mass ratio of 5:5. The mud ball inhibitor is composed of a fatty amine polyoxyethylene ether, a silicone modified polyether and an acetylenic diol ethoxylate at a mass ratio of 6:2:2. The inhibitor is composed of a polyether diamine, a polyethylene imine and a polyethylene glycol at a mass ratio of 35:5:60.

[0108] Example 11

[0109] The present example provides a method for improving the drilling speed of a shale formation. The treatment of the method is the same as that of Comparative Example 3, which solves the problem of poor effect of adding an inhibitor to the whole mud. The method comprises the following steps:

[0110] (1) During drilling, 1 batch of composite mud ball inhibitor is pumped into the drill pipe every 4 stands. The number of times of pumping the composite mud ball inhibitor is 10. The pumping amount of 1 batch of composite mud ball inhibitor is 1.2m 3 After 10 times of pumping the composite mud ball inhibitor, the mud pump is connected to the upper water tank again to restore circulation, and drilling continues. The funnel viscosity is maintained at about 65-70s and does not continue to rise.

[0111] The composite mud ball inhibitor is composed of a mud ball inhibitor and an inhibitor at a mass ratio of 6:4.

[0112] The mud ball inhibitor is composed of a fatty amine polyoxyethylene ether, a silicone modified polyether and an acetylenic diol ethoxylate at a mass ratio of 55:35:10.

[0113] The inhibitor is composed of a polyether diamine, a polyethylene imine and a polyethylene glycol at a mass ratio of 20:20:60.

[0114] (2) After drilling for another 6 stands, 1 batch of mud is pumped, and the normal vibration screen returns no sticky soft rock debris. The pumping amount of 1 batch of mud is 18m3 ; the funnel viscosity of the mud is 38s, the dynamic shear force is 8Pa, the dynamic plastic ratio is 0.85Pa / mPa·s, and the 3-turn reading is 7;

[0115] Steps (1) to (2) are repeated until the two openings are completed, during which no mud ball is generated, the annulus is unobstructed, the funnel viscosity is controlled between 48-55s, the maximum mechanical drilling speed is as high as 125m / h, the average mechanical drilling speed reaches 90m / h, and the speed-up effect is remarkable.

[0116] To sum up, the method provided by the application utilizes the gap of the kelly to pump the composite mud ball inhibitor into the drill pipe, restores circulation after the kelly is connected, and continues drilling, so that the composite mud ball inhibitor in the drill pipe remains a very high concentration as a material slug; and under the dual adsorption of amine groups and alcohol groups in the composite mud ball inhibitor, the hydration inhibition effect on mudstone cuttings can be effectively improved; the composite mud ball inhibitor can also prevent mutual aggregation of drill cutting particles, thereby effectively improving the mud ball prevention effect; the composite mud ball inhibitor is sprayed from the water eye of the drill bit at the same time as it rapidly covers the surface of the drill bit and the rock formation to form a hydrophobic film, and when the drill bit breaks the rock formation, the effect of inhibiting the hydration of mudstone cuttings and preventing the rock cuttings from wrapping the drill bit is achieved; after the composite mud ball inhibitor is pumped for a certain number of times, mud is pumped to the bottom of the well, which can carry a wave of drill cuttings and has the effect of diluting and adjusting the performance of the well mud; by controlling the timing of adding the composite mud ball inhibitor and the mud, the rock breaking efficiency is significantly improved, and the mechanical drilling speed is increased.

[0117] The above specific embodiments further specifically describe the purpose, technical solutions and advantages of the application, and it should be understood that the above description is only for specific embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method for improving drilling speed in mudstone formations, characterized in that, The method includes the following steps: (1) During the drilling process, every 2-4 vertical columns are connected, one batch of composite anti-mud ball inhibitor is pumped into the drill pipe; the number of times the composite anti-mud ball inhibitor is pumped is 6-20 times. The composite anti-mud ball inhibitor in step (1) is composed of an anti-mud ball agent and an inhibitor in a mass ratio of (5-7):(3-5); the anti-mud ball agent is composed of fatty amine polyoxyethylene ether, organosilicon modified polyether, and acetylenol ethoxy compound; the inhibitor is composed of polyether diamine, polyethyleneimine, and polyethylene glycol. (2) After drilling 6-10 more columns, pump one batch of mud. Repeat steps (1) to (2) until the desired drilling depth is reached.

2. The method according to claim 1, characterized in that, The pumping rate of the composite anti-mud ball inhibitor in step (1) is 0.5-1.5 m³. 3 .

3. The method according to claim 1, characterized in that, The mass ratio of the fatty amine polyoxyethylene ether, the organosilicon modified polyether, and the acetylenol ethoxy compound is (4-6):(2-4):(1-2).

4. The method according to claim 1, characterized in that, The mass ratio of polyether diamine, polyethyleneimine and polyethylene glycol is (15-35):(5-20):(45-65).

5. The method according to claim 1, characterized in that, The funnel viscosity of the mud in step (2) is 35-55s.

6. The method according to claim 1, characterized in that, The dynamic shear force of the mud in step (2) is 8-15 Pa.

7. The method according to claim 1, characterized in that, The dynamic-to-plastic ratio of the mud in step (2) is 0.8-1.2 Pa / mPa·s.

8. The method according to claim 1, characterized in that, The 3-turn reading of the mud in step (2) is 7-12.

9. The method according to claim 1, characterized in that, The pumping rate of one batch of mud in step (2) is 10-18 m³. 3 .

10. The method according to claim 1, characterized in that, The method includes the following steps: (1) During drilling, every 2-4 drill pipes, pump one batch of composite anti-mud ball inhibitor into the drill pipe; the number of pumping operations for the composite anti-mud ball inhibitor is 6-20 times; the pumping volume of one batch of composite anti-mud ball inhibitor is 0.5-1.5m. 3 ; The composite anti-mud ball inhibitor is composed of an anti-mud ball agent and an inhibitor in a mass ratio of (5-7):(3-5); The anti-mud balling agent is composed of fatty amine polyoxyethylene ether, organosilicon modified polyether and acetylenol ethoxy compound in a mass ratio of (4-6):(2-4):(1-2). The inhibitor is composed of polyether diamine, polyethyleneimine and polyethylene glycol in a mass ratio of (15-35):(5-20):(45-65); (2) After drilling 6-10 more columns, pump one batch of drilling mud; the pumping volume of the one batch of drilling mud is 10-18 m³. 3 The slurry has a funnel viscosity of 35-55 s, a dynamic shear force of 8-15 Pa, a dynamic plasticity ratio of 0.8-1.2 Pa / mPa·s, and a 3-turn reading of 7-12. Repeat steps (1) to (2) until the desired drilling depth is reached.