An ultra-high temperature soil-free drilling fluid and its preparation method

Abstract

The present invention discloses an ultra-high temperature clay-free drilling fluid, which comprises a polyamine cross-linked viscosifier. The polyamine cross-linked viscosifier comprises a cross-linked product of 2-acrylamido-2-methylpropanesulfonic acid and polyethylenepolyamine. In the drilling fluid provided by the present invention, the polyamine cross-linked viscosifier is used to replace bentonite, so that the drilling fluid has good rheological properties, filtration loss properties, plugging and anti-collapse properties, sedimentation stability and anti-pollution ability at high temperatures, and can effectively protect the reservoir.

Description

Technical Field

[0001] The present invention relates to the field of oil engineering drilling fluids, and particularly to an ultra-high temperature clay-free drilling fluid and a preparation method thereof. Background Art

[0002] In deep and ultra-deep well drilling, the commonly used polysulfonate water-based drilling fluid at present uses bentonite as the basic material to maintain the structural force of the drilling fluid. Due to the colloidal properties of bentonite, affected by factors such as end-face rearrangement and dispersion, the structural force is relatively strong. However, when the drilling cycle is long, the excessive dispersion of bentonite will form a sub-micron state, seriously affecting the mechanical drilling rate. Affected by the clay minerals in the cuttings, the rheology is not easy to control. And in high-temperature situations, it is extremely easy to have high-temperature thickening or high-temperature thinning, and the performance of the drilling fluid deteriorates sharply, resulting in problems such as barite settlement, too high viscosity, and large high-temperature and high-pressure water loss, affecting the normal progress of drilling and even causing serious accidents.

[0003] If a drilling fluid system formed by an ultra-high temperature polymer that can replace bentonite is used, it can effectively prevent the significant decline in the viscosity increase and filtration loss reduction effects of the drilling fluid. Since the clay colloidal particles are in the micro-nano size range, they are easy to enter the reservoir pore throats and microfractures, and are not easily acidified, which will cause fluid channel blockage, and thus cause reservoir damage, and it is not easy to protect the reservoir, so it is not suitable as a substitute material for bentonite.

[0004] At present, there have been reports on clay-free drilling fluids, but the existing clay-free drilling fluid systems have the disadvantages of poor stability, insufficient high-temperature resistance, and insufficient plugging and anti-collapse properties. In the prior art, Patent CN106433581B discloses a clay-free high-temperature resistant reservoir drilling fluid system, which uses potato cross-linked starch as a filtration loss reducer and xanthan gum as a viscosity increasing and gel strength enhancing agent. The high temperature resistance of this system is only 150 °C, and it is used in the reservoir, but the plugging and anti-collapse performance of this system is not mentioned, and it still cannot meet the requirements under ultra-high temperature conditions. Patent CN104893689A discloses a clay-free drilling fluid system, which uses high-temperature resistant modified starch as a filtration loss reducer and xanthan gum as a viscosity increasing and gel strength enhancing agent, with a high temperature resistance of 140 °C, and does not mention the ultra-high temperature performance and plugging and anti-collapse performance. Patent CN104140793A discloses a cationic alkyl glycoside clay-free drilling fluid, which uses cationic alkyl glycoside as an inhibitor and xanthan gum, high-viscosity sodium carboxymethyl cellulose, and low-viscosity sodium carboxymethyl cellulose as viscosity increasing and gel strength enhancing agents, but the high temperature resistance performance is only 150 °C.

[0005] In summary, the existing drilling fluids have the problems of weak high-temperature resistance and insufficient plugging and anti-collapse performance. There is still no clay-free drilling fluid with a use temperature above 180 °C, which cannot meet the requirements of deep and ultra-deep well drilling. Summary of the Invention

[0006] In view of the above problems existing in the prior art, the present invention provides an ultra-high temperature clay-free drilling fluid, which uses a polyamine cross-linked viscosity increasing agent to replace the bentonite polymer, can reduce the dispersion of the clay phase, and improve the temperature resistance and plugging and anti-collapse performance of the drilling fluid. The present invention also provides a preparation method of the ultra-high temperature clay-free drilling fluid.

[0007] In a first aspect of the present invention, there is provided an ultra-high temperature clay-free drilling fluid, comprising a polyamine cross-linked viscosity increasing agent, and the polyamine cross-linked viscosity increasing agent comprises a cross-linked product of 2-acrylamido-2-methylpropanesulfonic acid and polyalkylene polyamine.

[0008] In the present invention, the ultra-high temperature means that the use temperature is above 180 °C.

[0009] According to some embodiments of the present invention, the polyalkylene polyamine has a weight average molecular weight of 70,000 - 80,000, preferably 75,000.

[0010] According to some embodiments of the present invention, the polyamine cross-linked viscosity increasing agent, by weight, comprises 50 - 200 parts of 2-acrylamido-2-methylpropanesulfonic acid and 3 - 20 parts of polyalkylene polyamine.

[0011] According to some embodiments of the present invention, the polyamine cross-linked viscosity increasing agent, by weight, comprises 60 - 130 parts of 2-acrylamido-2-methylpropanesulfonic acid and 7 - 16 parts of polyalkylene polyamine.

[0012] According to some embodiments of the present invention, the drilling fluid does not include bentonite. According to some embodiments of the present invention, based on 1000 parts by weight of water, the content of the polyamine cross-linked viscosity increasing agent is 5 - 10 parts.

[0013] According to some embodiments of the present invention, based on 1000 parts by weight of water, the content of the polyamine cross-linked viscosity increasing agent is 7 - 8 parts.

[0014] According to some embodiments of the present invention, it comprises a polyamine cross-linked viscosity increasing agent, a temperature-resistant polymer viscosifier, a heat-stable filtrate reducer, a plugging and anti-collapse agent, an organic amine inhibitor, a lubricant, potassium chloride and water.

[0015] According to some embodiments of the present invention, based on 1000 parts by weight of water, it comprises the following components in parts by weight:

[0016] 5 - 10 parts of polyamine cross-linked viscosity increasing agent, 5 - 15 parts of temperature-resistant polymer viscosifier, 80 - 135 parts of heat-stable filtrate reducer, 10 - 15 parts of organic amine inhibitor, 40 - 70 parts of plugging and anti-collapse agent, 5 - 10 parts of lubricant and 50 - 70 parts of potassium chloride.

[0017] The second aspect of the present invention provides a method for preparing the drilling fluid described in the first aspect, including preparing a polyamine crosslinked viscosifier and then mixing the polyamine crosslinked viscosifier with other components of the drilling fluid.

[0018] According to some embodiments of the present invention, the method for preparing the polyamine crosslinked viscosifier includes mixing 2-acrylamido-2-methylpropanesulfonic acid, polyethylenepolyamine, and a catalyst and reacting them.

[0019] According to some embodiments of the present invention, the catalyst is selected from Na2CO3, NaOH, or KOH.

[0020] According to some embodiments of the present invention, based on 50-200 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, the amount of the catalyst used is 8-33 parts by weight.

[0021] According to some embodiments of the present invention, the catalyst is added in two portions, and the catalyst added for the first time accounts for 3 / 8 to 5 / 8 of the total weight of the catalyst.

[0022] According to some embodiments of the present invention, after adding the catalyst for the first time, the mixture is reacted at 60-70 °C for 24-48 h.

[0023] According to some embodiments of the present invention, after adding the remaining catalyst for the second time, the mixture is reacted at 40-70 °C for 10-24 h.

[0024] According to some embodiments of the present invention, the method for preparing the polyamine crosslinked viscosifier includes mixing an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, a solution of polyethylenepolyamine, and a solution of the catalyst.

[0025] According to some embodiments of the present invention, the concentration of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid is 10-20 wt%.

[0026] According to some embodiments of the present invention, the concentration of the solution of polyethylenepolyamine is 3-10 wt%.

[0027] According to some embodiments of the present invention, the concentration of the solution of the catalyst is 4-11 wt%.

[0028] According to some embodiments of the present invention, the amounts of each raw material used are: 5-10 parts by weight of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, 1-2 parts by weight of the solution of polyethylenepolyamine, and 2-3 parts by weight of the solution of the catalyst.

[0029] According to some embodiments of the present invention, it includes the following preparation steps:

[0030] S1. Mix the polyamine crosslinked viscosifier with water and hydrate to obtain a base slurry;

[0031] S2. Mix the temperature-resistant polymer viscosifier, heat-stable filtration reducer, plugging and anti-collapse agent, organic amine inhibitor, lubricant, potassium chloride with the base mud obtained in S1 to obtain an ultra-high temperature soil-free drilling fluid.

[0032] According to some embodiments of the present invention, the hydration time in S1 is 5 - 7 h.

[0033] According to some embodiments of the present invention, the hydration time in S1 is 6 h.

[0034] According to some embodiments of the present invention, the drilling fluid further includes barite.

[0035] According to some embodiments of the present invention, the drilling fluid further includes a pH regulator.

[0036] According to some embodiments of the present invention, the pH regulator is one or both of potassium hydroxide and sodium hydroxide.

[0037] According to some embodiments of the present invention, the high-temperature resistant polymer viscosifier is one or more of terpolymer-based viscosifiers, sulfonate copolymer-based viscosifiers, copolymers of acrylamide - sulfonated methyl propane, vinyl polymers, and acrylamide copolymers.

[0038] According to some embodiments of the present invention, the heat-stable filtration reducer is one or more of petroleum resin-based filtration reducers, humic acid-based filtration reducers, and synthetic resin-based filtration reducers.

[0039] According to some embodiments of the present invention, the petroleum resin-based filtration reducer includes the petroleum product modified product SGW.

[0040] According to some embodiments of the present invention, the humic acid-based filtration reducer includes sulfomethylated lignite AMC.

[0041] According to some embodiments of the present invention, the synthetic resin-based filtration reducer includes one or both of sulfomethylated phenolic resin SMP-3 and modified lignite resin TSH-2.

[0042] According to some embodiments of the present invention, the heat-stable filtration reducer is a mixture of multiple of KFT-II, SGW, SMP-3, TSH-2, and SMC.

[0043] According to some embodiments of the present invention, the plugging and anti-collapse agent is one or more of rigid plugging and anti-collapse agents, deformable plugging and anti-collapse agents, and nano / micro-meter plugging agents.

[0044] According to some embodiments of the present invention, the rigid plugging and anti-collapse agent is one or more of ultra-fine calcium carbonates with different particle sizes.

[0045] According to some embodiments of the present invention, the deformation plugging anti-collapse agent is one or more of sulfonated asphalt, natural asphalt, and modified asphalt.

[0046] According to some embodiments of the present invention, the deformation plugging anti-collapse agent is sulfonated asphalt.

[0047] According to some embodiments of the present invention, the nano-micro-meter plugging agent is a mixture of rigid and elastic plugging agents with a particle size of 10 - 100 microns.

[0048] According to some embodiments of the present invention, the organic amine inhibitor is one or more of organic polyamine inhibitors, polyetheramine inhibitors, and polyamine inhibitors.

[0049] According to some embodiments of the present invention, the lubricant is a liquid lubricant or a solid lubricant.

[0050] According to some embodiments of the present invention, the solid lubricant is one or more of polystyrene plastic balls, graphite, carbon black, and glass microspheres.

[0051] According to some embodiments of the present invention, the liquid lubricant is one or more of mineral oil, hydrocarbon lubricants, and ester lubricants.

[0052] According to some embodiments of the present invention, the liquid lubricant is preferably an ester lubricant.

[0053] According to some embodiments of the present invention, the hydrocarbon lubricant is white oil or poly-α-olefin.

[0054] According to some embodiments of the present invention, the ester lubricant is one or more of butyl stearate, polyethylene glycol ester, pentaerythritol oleate, and synthetic fatty acid ester.

[0055] According to some embodiments of the present invention, the ester lubricant is preferably a synthetic fatty acid ester lubricant.

[0056] According to some embodiments of the present invention, the heat-stable fluid loss reducer includes 20 - 30 parts of heat-stable fluid loss reducer SGW, 20 - 30 parts of sulfomethylated phenolic resin SMP-3, 20 - 30 parts of modified lignite resin TSH-2, and 20 - 30 parts of sulfomethylated lignite SMC.

[0057] According to some embodiments of the present invention, the plugging anti-collapse agent includes 20 - 30 parts of rigid plugging agent, 10 - 20 parts of deformation plugging agent, and 10 - 20 parts of nano-micro-meter plugging agent.

[0058] According to some embodiments of the present invention, the density of the drilling fluid is 1.30 - 2.00 g / cm 3 .

[0059] According to some embodiments of the present invention, the preparation method of the drilling fluid comprises the following preparation steps:

[0060] S1. Add a polyamine crosslinked viscosifier to water, dissolve and hydrate to obtain a base slurry;

[0061] S2. Add a temperature-resistant polymer viscosifier to the base slurry and dissolve to obtain a mixture;

[0062] S3. Add a heat-stable fluid loss reducer, an organic amine inhibitor, a plugging and anti-collapse agent, a lubricant and potassium chloride to the mixture obtained in S2, and dissolve to obtain an ultra-high temperature soil-free drilling fluid.

[0063] (1) The ultra-high temperature soil-free drilling fluid provided by the present invention uses a polyamine crosslinked viscosifier to replace the conventionally used bentonite, avoiding the excessive dispersion of bentonite, having easy-to-control rheology, good high-temperature resistance, stable viscosity at 180 °C, and no high-temperature thickening or high-temperature thinning.

[0064] (2) The drilling fluid provided by the present invention is added with a polyamine crosslinked viscosifier, and has stable rheology, strong resistance to high-valence ions such as calcium ions and poor soil pollution in an environment of high calcium ions and poor soil pollution, and can meet the construction requirements of oilfield sites.

[0065] (3) The drilling fluid provided by the present invention has good inhibition, good reservoir protection performance, and good anti-blocking and anti-collapse effects. Specific embodiments

[0066] To make the present invention easier to understand, the present invention will be described in detail below in conjunction with embodiments. These embodiments are only illustrative and are not limited to the application scope of the present invention.

[0067] The test method of the present invention is as follows:

[0068] (1) The test standard for apparent viscosity is GBT 16783.1-2014;

[0069] (2) The test standard for plastic viscosity is GBT 16783.1-2014;

[0070] (3) The test standard for dynamic shear force is GBT 16783.1-2014;

[0071] (4) The test standard for API fluid loss is GBT 16783.1-2014;

[0072] (5) The test standard for HTHP (180 °C) fluid loss is GBT 16783.1-2014;

[0073] (6) The test standard for the high-temperature settling coefficient (7 days) is GBT 16783.1-2014.

[0074] In the present invention, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was purchased from Sinopharm Chemical Reagent Co., Ltd., with a CAS number of 15214-89-8;

[0075] Polyethylene polyamine was purchased from Xiya Chemical Technology (Shandong) Co., Ltd., with a CAS of 68131-73-7 and a weight-average molecular weight of 30,000 - 75,000;

[0076] The catalyst solution is an aqueous solution of Na2CO3;

[0077] The high-temperature and calcium-resistant polymer viscosifier is a high-temperature and calcium-resistant viscosifier purchased from Chevron Phillips Chemical Company, with a grade of vinyl polymer HE300, abbreviated as HE300;

[0078] The heat-stable filtration reducer SGW was purchased from Beijing Hongqin Petroleum Auxiliary Agent Co., Ltd.;

[0079] Sulfomethylated phenolic resin was purchased from Shandong Deshunyuan Petroleum Technology Co., Ltd., with a grade of SMP-3;

[0080] Modified lignite resin was purchased from Turpan Shengyun Industry and Trade Co., Ltd., with a grade of TSH-2;

[0081] Sulfomethylated lignite was purchased from Xinjiang Jiangrun Oilfield Drilling and Production Aid Co., Ltd., with a grade of SMC;

[0082] The polyamine inhibitor was purchased from Sinopec Research Institute of Petroleum Engineering Technology, with a grade of SMJA-1 and the corresponding patent number CN201110334894.4;

[0083] The rigid plugging agent is two kinds of ultra-fine calcium carbonate with different particle sizes purchased from Xinjiang Jiangrun Oilfield Drilling and Production Aid Co., Ltd., with grades of SQ-1 and SQ-2 respectively;

[0084] The deformable plugging agent is elastic graphite purchased from Halliburton Company, USA, with a grade of STEELSEAL;

[0085] The nano / micro-meter plugging agent was purchased from Sinopec Research Institute of Petroleum Engineering Technology, with a grade of SMNP-1 and the corresponding patent number CN201610937073.2;

[0086] The environmentally friendly lubricant was purchased from Sinopec Research Institute of Petroleum Engineering Technology, with a grade of SMLUB-E and the corresponding patent number CN202010081895.1.

[0087] Barite was purchased from Xinjiang Jiangrun Oilfield Drilling and Production Aid Co., Ltd.

[0088] Preparation Example 1

[0089] Prepare polyamine crosslinked viscosity reducer 1.

[0090] (1) Prepare an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid with a concentration of 15 wt%.

[0091] (2) Add 1.5 g of 7 wt% aqueous solution of polyethylenepolyamine to 7 g of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid.

[0092] (3) Add 2.5 g of 8 wt% catalyst solution to the solution in step (2), and stir and react the mixture at 65 °C for 36 h.

[0093] (4) Add another 2.5 g of 8 wt% catalyst solution and continue to react at 55 °C for 17 h.

[0094] (5) Obtain the polyamine crosslinked viscosity reducer by distillation and drying.

[0095] Preparation Example 2

[0096] Prepare polyamine crosslinked viscosity reducer 2.

[0097] (1) Prepare an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid with a concentration of 10 wt%.

[0098] (2) Add 2 g of 10 wt% aqueous solution of polyethylenepolyamine to 5 g of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid.

[0099] (3) Add 2 g of 4 wt% catalyst solution to the solution in step (2), and stir and react the mixture at 60 °C for 24 h.

[0100] (4) Add another 3 g of 4 wt% catalyst solution and continue to react at 40 °C for 10 h.

[0101] (5) Obtain the polyamine crosslinked viscosity reducer by distillation and drying.

[0102] Preparation Example 3

[0103] Prepare polyamine crosslinked viscosity reducer 3.

[0104] (1) Prepare an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid with a concentration of 20 wt%.

[0105] (2) Add 1 g of 3 wt% aqueous solution of polyethylenepolyamine to 10 g of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid.

[0106] (3) Add 1 g of 11 wt% catalyst solution to the solution in step (2), and stir the mixture at 70 °C for 48 h;

[0107] (4) Add another 0.6 g of 11 wt% catalyst solution and continue the reaction at 70 °C for 24 h;

[0108] (5) Distill and dry to obtain the polyamine cross-linked thickening and fluid loss control agent.

[0109] Preparation Example 4

[0110] Prepare polyamine cross-linked thickening and fluid loss control agent 4.

[0111] The preparation method is the same as that of Preparation Example 1, except that in step (2), 2 g of polyethylenepolyamine aqueous solution is added to 4 g of 2-acrylamido-2-methylpropanesulfonic acid aqueous solution.

[0112] Example 1

[0113] Prepare ultra-high temperature soil-free drilling fluid.

[0114] (1) Set the stirring speed to 8000 rpm, take 400 mL of water and add it to the high-speed stirring cup. While stirring, add 2 g of polyamine cross-linked thickening and fluid loss control agent 1 and disperse and dissolve it evenly;

[0115] (2) Set the stirring speed to 8000 rpm, and slowly add 6 g of temperature-resistant polymer viscosifier while stirring. After adding, continue stirring for 5 minutes to dissolve it completely;

[0116] (3) Then set the stirring speed to 6000 rpm, and slowly add 12 g of heat-stable fluid loss control agent SGW, 8 g of sulfomethylated phenolic resin SMP-3, 10 g of modified lignite resin TSH-2, 10 g of sulfomethylated lignite SMC, 4 g of polyamine inhibitor, 12 g of rigid plugging agent, 8 g of deformable plugging agent, 8 g of nano / micro-meter plugging agent, 4 g of environmentally friendly lubricant SMJH-1, and 20 g of KCl at intervals of 5 minutes. After all are added, continue stirring for 20 minutes to dissolve them completely;

[0117] (4) Set the stirring speed to 8000 rpm, add barite until the density reaches 1.30 g / cm 3 , and continue stirring for 20 minutes to disperse and dissolve it, thus obtaining the ultra-high temperature soil-free drilling fluid.

[0118] Example 2

[0119] Prepare ultra-high temperature soil-free drilling fluid.

[0120] (1) Set the stirring speed to 8000 rpm, take 400 mL of water and add it to the high-speed stirring cup. While stirring, add 4 g of polyamine cross-linked thickening and fluid loss control agent 1 and disperse and dissolve it evenly;

[0121] (2) Set the stirring speed to 8000 rpm, and slowly add 2 grams of temperature-resistant polymer viscosifier while stirring. After adding, continue stirring for 5 minutes to fully dissolve it;

[0122] (3) Then set the stirring speed to 6000 rpm, and slowly add 12 grams of heat-stable filtration reducer SGW, 12 grams of sulfomethylated phenolic resin SMP-3, 12 grams of modified lignite resin TSH-2, 12 grams of sulfomethylated lignite SMC, 6 grams of polyamine inhibitor, 12 grams of rigid plugging agent, 4 grams of deformable plugging agent, 8 grams of nano-micro plugging agent, 2 grams of environmental protection lubricant SMJH-1, and 28 grams of KCl at intervals of 5 minutes. After all are added, continue stirring for 20 minutes to fully dissolve them;

[0123] (4) Set the stirring speed to 8000 rpm, add barite until the density reaches 1.50 g / cm 3 , and continue stirring for 20 minutes to disperse and dissolve it, thus obtaining the ultra-high temperature soil-free drilling fluid.

[0124] Example 3

[0125] Prepare the ultra-high temperature soil-free drilling fluid.

[0126] (1) Set the stirring speed to 8000 rpm, take 400 mL of water and add it to the high-speed stirring cup, and add 2.5 grams of polyamine crosslinked viscosifier 1 while stirring to disperse and dissolve it evenly;

[0127] (2) Set the stirring speed to 8000 rpm, and slowly add 5 grams of temperature-resistant polymer viscosifier while stirring. After adding, continue stirring for 5 minutes to fully dissolve it;

[0128] (3) Then set the stirring speed to 6000 rpm, and slowly add 8 grams of heat-stable filtration reducer SGW, 8 grams of sulfomethylated phenolic resin SMP-3, 8 grams of modified lignite resin TSH-2, 8 grams of sulfomethylated lignite SMC, 5 grams of polyamine inhibitor, 12 grams of rigid plugging agent, 8 grams of deformable plugging agent, 8 grams of nano-micro plugging agent, 4 grams of environmental protection lubricant SMJH-1, and 24 grams of KCl at intervals of 5 minutes. After all are added, continue stirring for 20 minutes to fully dissolve them;

[0129] (4) Set the stirring speed to 8000 rpm, add barite until the density reaches 1.80 g / cm 3 , and continue stirring for 20 minutes to disperse and dissolve it, thus obtaining the ultra-high temperature soil-free drilling fluid.

[0130] Example 4

[0131] Prepare the ultra-high temperature soil-free drilling fluid.

[0132] (1) Set the stirring speed to 8000 rpm. Take 400 mL of water and add it to the high-speed stirring cup. While stirring, add 3.5 grams of polyamine cross-linked viscosifier 1 and disperse and dissolve it evenly.

[0133] (2) Set the stirring speed to 8000 rpm. While stirring, slowly add 3 grams of temperature-resistant polymer viscosifier. After adding, continue stirring for 5 minutes to fully dissolve it.

[0134] (3) Then set the stirring speed to 6000 rpm. Slowly add 8 grams of heat-stable filtration reducer SGW, 8 grams of sulfomethylated phenolic resin SMP-3, 8 grams of modified lignite resin TSH-2, 8 grams of sulfomethylated lignite SMC, 4 grams of polyamine inhibitor, 8 grams of rigid plugging agent, 4 grams of deformable plugging agent, 4 grams of nano / micro-meter plugging agent, 4 grams of environmentally friendly lubricant SMJH-1, and 20 grams of KCl at intervals of 5 minutes. After all are added, continue stirring for 20 minutes to fully dissolve them.

[0135] (4) Set the stirring speed to 8000 rpm. Add barite until the density reaches 2.00 g / cm 3 , and continue stirring for 20 minutes to disperse and dissolve it, then the ultra-high temperature soil-free drilling fluid is obtained.

[0136] Example 5

[0137] Prepare ultra-high temperature soil-free drilling fluid.

[0138] The preparation method is the same as that of Example 1, except that the polyamine cross-linked viscosifier is polyamine cross-linked viscosifier 2.

[0139] Example 6

[0140] Prepare ultra-high temperature soil-free drilling fluid.

[0141] The preparation method is the same as that of Example 1, except that the polyamine cross-linked viscosifier is polyamine cross-linked viscosifier 3.

[0142] Example 7

[0143] Prepare ultra-high temperature soil-free drilling fluid.

[0144] The preparation method is the same as that of Example 1, except that the polyamine cross-linked viscosifier is polyamine cross-linked viscosifier 4.

[0145] Example 8

[0146] Prepare ultra-high temperature soil-free drilling fluid.

[0147] The preparation method is the same as that of Example 1, except that the addition amount of the polyamine cross-linked viscosifier is 1 gram.

[0148] Example 9

[0149] Prepare an ultra-high temperature clay-free drilling fluid.

[0150] The preparation method is the same as that of Example 1, except that the addition amount of the polyamine cross-linked viscosity-increasing agent is 5 grams.

[0151] Test Example 1

[0152] The drilling fluid samples prepared in Examples 1-7 were respectively filled into an aging tank and aged in a high-temperature roller furnace at 180 °C for 16 hours. Take out the samples and stir for 5 minutes, set the rotation speed to 8000 rpm, and then measure the apparent viscosity, plastic viscosity, dynamic shear force, API filtration loss, HTHP (180 °C) filtration loss, and high-temperature settlement coefficient (7 days) of each sample respectively. The test results are shown in Table 1.

[0153] The results are shown in Table 1.

[0154] Table 1 Test results of the conventional properties of the drilling fluid samples

[0155]

[0156]

[0157] According to the test results in Table 1, the apparent viscosity range of the ultra-high temperature clay-free drilling fluid samples prepared in the above Examples 1-9 is 36-49 mPa·s, the plastic viscosity range is 28-39 mPa·s, the dynamic shear force range is 9-12 Pa, the API filtration loss range is 1.0-3.6 mL, the HTHP filtration loss range is 9.6-13.8 mL, and the high-temperature settlement coefficient range is 0.510-0.521. It can be seen that this system has good rheology, high-temperature resistance, and high-temperature settlement stability.

[0158] The dosage of the polyamine cross-linked viscosity-increasing agent in Example 1 and Examples 8-9 is different. The drilling fluid prepared in Example 1 has a lower filtration loss and a lower high-temperature settlement coefficient than the drilling fluids prepared in Examples 5-7, indicating that the polyamine cross-linked viscosity-increasing agent obtained by Preparation Example 1 of the present application has better filtration loss reduction and high-temperature stability effects on the drilling fluid. Adding the polyamine cross-linked viscosity-increasing agent to the drilling fluid system of the present invention can improve the high-temperature resistance of the drilling fluid, effectively prevent the drilling fluid from increasing or decreasing in viscosity, and avoid a significant decrease in the filtration loss reduction effect of the drilling fluid.

[0159] Test Example 2

[0160] 10.6 g of anhydrous calcium chloride was added to the drilling fluids prepared in Examples 1-7 respectively, with the calcium ion concentration being 10000 mg / L. After stirring evenly, they were filled into an aging tank and aged in a high-temperature roller furnace at 180 °C for 16 hours. The samples were taken out, stirred for 5 min, the rotation speed was set at 8000 rpm, and then the apparent viscosity, plastic viscosity, yield point, API filtration loss, HTHP (180 °C) filtration loss and high-temperature settlement coefficient (7 days) of each sample were measured respectively. The test results are shown in Table 2.

[0161] Table 2 Test Results of Calcium Resistance of Drilling Fluid Samples

[0162]

[0163]

[0164] According to the test results shown in Table 2, the apparent viscosity range of the ultra-high temperature soil-free drilling fluid samples prepared in the above Examples 1-9 was 22-52 mPa·s, the plastic viscosity range was 16-42 mPa·s, the yield point range was 4-10 Pa, the API filtration loss range was 1.2-6.4 mL, the HTHP filtration loss range was 10.8-18.8 mL, and the high-temperature settlement coefficient range was 0.512-0.542. The drilling fluid of Example 1 had stable rheology, a small increase in high-temperature and high-pressure filtration loss, and good high-temperature settlement stability compared with Examples 5-7 in an environment of high calcium ion contamination and aging at 180 °C, indicating that the polyamine cross-linked viscosity increasing agent synthesized according to Preparation Example 1 had excellent calcium contamination resistance.

[0165] Test Example 3

[0166] 30 g of bentonite for drilling fluid from Xinjiang Zhongfei Xiazijie Bentonite Co., Ltd. was added to the drilling fluids prepared in Examples 1, 5, 6, and 7 respectively. After stirring evenly, they were filled into an aging tank and aged in a high-temperature roller furnace at 180 °C for 16 hours. The samples were taken out, stirred for 5 min, the rotation speed was set at 8000 rpm, and then the apparent viscosity, plastic viscosity, yield point, API filtration loss, HTHP (180 °C) filtration loss and high-temperature settlement coefficient (7 days) of each sample were measured respectively. The test results are shown in Table 3.

[0167] Table 3 Test Results of Soil Contamination Resistance of Drilling Fluid Samples

[0168]

[0169] According to the test results shown in Table 3, the apparent viscosity range of the ultra-high temperature clay-free drilling fluid samples prepared in the above Examples 1-7 is 38-45 mPa·s, the plastic viscosity range is 30-40 mPa·s, the yield point range is 6-9 Pa, the API filtration loss range is 2.2-3.0 mL, the HTHP filtration loss range is 10.4-14.8 mL, and the high-temperature settlement coefficient range is 0.502-0.520. It can be seen that compared with Examples 5-7, the drilling fluid in Example 1 has stable rheology under bentonite pollution, the increase in the high-temperature high-pressure filtration loss is not significant, and the high-temperature settlement stability is good, indicating that the polyamine cross-linked viscosity increasing agent synthesized according to Preparation Example 1 has excellent anti-bentonite pollution ability.

[0170] Test Example 4

[0171] Referring to the petroleum and natural gas industry standard SY / T 5613-2016, the shale rolling recovery rate test was carried out on the ultra-high temperature clay-free drilling fluid prepared in Example 1. The fresh water shale rolling recovery rate is 30%. The test results are shown in Table 4.

[0172] Table 4 Shale rolling recovery rate test results

[0173] Drilling fluid Experimental conditions Shale rolling recovery rate (%) Example 1 Hot rolling at 180°C for 16 h 92.3％ Cationic polysulfonate drilling fluid Hot rolling at 180°C for 16 h 78.2％ Oil-based drilling fluid Hot rolling at 180°C for 16 h 95.4％ Silicate drilling fluid Hot rolling at 180°C for 16 h 87.8％

[0174] Among them, the polysulfonate drilling fluid is the drilling fluid used on-site in the Shunbei Oilfield of Sinopec; the oil-based drilling fluid is the self-developed LVHS OBM drilling fluid of the Sinopec Research Institute of Petroleum Engineering Technology; the silicate drilling fluid is the BorSTAB drilling fluid developed by Yangtze University.

[0175] According to the test results shown in Table 4, the ultra-high temperature clay-free drilling fluid prepared in Example 1 has excellent inhibition compared with other drilling fluids, and the rolling recovery rate at 180 °C reaches 92.3%, which is equivalent to that of the oil-based drilling fluid.

[0176] Test Example 5

[0177] Referring to the petroleum and natural gas industry standard SY / T 6540-2002, the core permeability recovery value test of the Tahe Carboniferous reservoir was carried out on the drilling fluid prepared in Example 1. The test results are shown in Table 5.

[0178] Table 5 Static pollution permeability recovery value test results

[0179]

[0180] According to the test results shown in Table 5, the static pollution reservoir core permeability recovery values of the ultra-high temperature clay-free drilling fluid prepared in Example 1 are all greater than 90%, indicating that the ultra-high temperature clay-free drilling fluid of the present application has good reservoir protection performance.

[0181] In summary, the ultra-high temperature soil-free drilling fluid provided by the present invention can withstand temperatures above 180°C, has a calcium ion resistance of 10,000 mg / L, a soil pollution resistance of 10%, a reservoir permeability recovery value greater than 90%, has good rheology, high temperature resistance and high temperature settlement stability, and has excellent resistance to high-valence ion pollution, and can effectively protect the reservoir.

[0182] The above are only the preferred examples of the present invention. It should be pointed out that for those of ordinary skill in the art, under the technical inspiration provided by the present invention, as common general knowledge in the art, other equivalent variations and improvements can also be made, which should also be regarded as the protection scope of the present invention.

Claims

1. A super-high temperature soil-free drilling fluid, characterized in that, It includes a polyamine cross-linked viscosifier, and the polyamine cross-linked viscosifier includes a cross-linked product of 2-acrylamido-2-methylpropanesulfonic acid and polyalkylene polyamine; Calculated by weight parts, the polyamine cross-linked viscosifier includes 50-200 parts of 2-acrylamido-2-methylpropanesulfonic acid; 3-20 parts of polyalkylene polyamine.

2. The drilling fluid according to claim 1, characterized in that, Calculated by weight parts, the polyamine cross-linked viscosifier includes 60-130 parts of 2-acrylamido-2-methylpropanesulfonic acid; 7-16 parts of polyalkylene polyamine.

3. The drilling fluid according to claim 1, characterized in that, The drilling fluid does not include bentonite.

4. The drilling fluid according to any one of claims 1 to 3, characterized in that, Calculated based on 1000 weight parts of water, the content of the polyamine cross-linked viscosifier is 5-10 parts.

5. The drilling fluid according to claim 4, wherein Calculated based on 1000 weight parts of water, the content of the polyamine cross-linked viscosifier is 7-8 parts.

6. The drilling fluid according to any one of claims 1 to 3, characterized in that, It includes a polyamine cross-linked viscosifier, a temperature-resistant polymer viscosifier, a heat-stable filtration reducer, a plugging and anti-collapse agent, an organic amine inhibitor, a lubricant, potassium chloride and water.

7. The drilling fluid according to claim 6, wherein, Calculated based on 1000 weight parts of water, it includes the following components by weight: 5-10 parts of polyamine cross-linked viscosifier, 5-15 parts of temperature-resistant polymer viscosifier, 80-135 parts of heat-stable filtration reducer, 10-15 parts of organic amine inhibitor, 40-70 parts of plugging and anti-collapse agent, 5-10 parts of lubricant and 50-70 parts of potassium chloride.

8. The preparation method of the drilling fluid according to any one of claims 1-7, characterized in that, It includes preparing a polyamine cross-linked viscosifier, and then mixing the polyamine cross-linked viscosifier with other components of the drilling fluid.

9. The preparation method according to claim 8, characterized in that, The preparation method of the polyamine cross-linked viscosifier includes mixing 2-acrylamido-2-methylpropanesulfonic acid, polyalkylene polyamine and a catalyst and carrying out a reaction.

10. The preparation method according to claim 9, characterized in that, The catalyst is selected from Na2CO3, NaOH or KOH.

11. The preparation method according to claim 9, characterized in that, Calculated based on 2-acrylamido-2-methylpropanesulfonic acid being 50-200 weight parts, the dosage of the catalyst is 8-33 weight parts.

12. The preparation method according to claim 9, characterized in that, The catalyst is added in two times, and the catalyst added for the first time accounts for 3 / 8 to 5 / 8 of the total weight of the catalyst.

13. The preparation method according to claim 12, characterized in that, After adding the catalyst for the first time, the mixture is reacted at 60-70°C, and the reaction time is 24-48h.

14. The preparation method according to claim 12, wherein After adding the remaining catalyst for the second time, the mixture is reacted at 40-70°C, and the reaction time is 10-24h.

15. The preparation method according to any one of claims 8-14, characterized in that, It includes the following preparation steps: S1. Mix the polyamine cross-linked viscosifier with water and hydrate to obtain a base slurry; S2. Mix the temperature-resistant polymer viscosifier, the heat-stable filtration reducer, the plugging and anti-collapse agent, the organic amine inhibitor, the lubricant, potassium chloride with the base slurry obtained in S1 to obtain an ultra-high temperature clay-free drilling fluid.

16. The preparation method according to claim 15, wherein, The hydration time in S1 is 5-7h.

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