阅读说明：本技术 一种地质钻探环保型冲洗液体系及其制备方法 (Environment-friendly type flushing fluid system for geological drilling and preparation method thereof ) 是由 鲍海山 牛索安东主 苏延鹤 王伟超 张文龙 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种地质钻探环保型冲洗液体系及其制备方法,该环保型冲洗液体系包括质量百分比为1-4％的基质、0.1-0.5％的增粘剂、0.1％-0.2％的包被剂、0.8-1％的降失水剂、0.1-0.2％的抑制剂,其余组成为清水；所述基质选自膨润土；所述降失水剂为复合型降失水剂；该环保型冲洗液体系组成原料具有良好护壁性能,组成原料来源广泛、性能稳定、并且环保无毒。其制备方法简单、成本低廉,方便大规模化生产,具有较好的市场推广应用价值。(The invention discloses an environment-friendly flushing fluid system for geological drilling and a preparation method thereof, wherein the environment-friendly flushing fluid system comprises 1-4% of matrix, 0.1-0.5% of tackifier, 0.1-0.2% of coating agent, 0.8-1% of fluid loss agent, 0.1-0.2% of inhibitor and the balance of clear water by mass percentage; the matrix is selected from bentonite; the fluid loss agent is a compound fluid loss agent; the environment-friendly flushing fluid system has the advantages that the raw materials have good wall protection performance, are wide in source and stable in performance, and are environment-friendly and non-toxic. The preparation method is simple, low in cost, convenient for large-scale production and good in market popularization and application value.)

1. An environment-friendly type flushing fluid system for geological drilling is characterized in that: comprises 1 to 4 mass percent of matrix, 0.1 to 0.5 mass percent of tackifier, 0.1 to 0.2 mass percent of coating agent, 0.8 to 1 mass percent of fluid loss agent, 0.1 to 0.2 mass percent of inhibitor and the balance of clear water; the matrix is selected from bentonite.

2. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the environment-friendly flushing fluid system comprises 4 mass percent of matrix, 0.3 mass percent of tackifier, 0.2 mass percent of coating agent, 1 mass percent of fluid loss agent, 0.2 mass percent of inhibitor and the balance of clear water.

3. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder.

4. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the bentonite is sodium bentonite.

5. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the tackifier is one or two of carboxymethyl cellulose or sodium carboxymethyl cellulose.

6. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the coating agent is one or two of a zwitter-ion FA367 type coating agent or a synthetic FA141 type coating agent.

7. An environmentally friendly fluid system for geological drilling according to claim 1, characterized in that: the inhibitor is one or two of potassium polyacrylate or potassium silicate.

8. The method for preparing an environment-friendly flushing fluid system for geological drilling according to any one of claims 1-7, characterized in that: selecting the raw materials according to the mass percentage, and preparing according to the following steps,

s1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

9. The method of preparing an environmentally friendly irrigation fluid system for geological drilling according to claim 8, wherein: the stirring time in the step S2 is 10-15 min; the stirring time in the step S4 is 10-12 min; the stirring time in the step S5 is 20-25 min; the stirring time in the step S6 is 20-25 min.

Technical Field

The invention relates to the technical field of environment-friendly flushing fluids, in particular to an environment-friendly flushing fluid system for geological drilling and a preparation method thereof.

Background

Geological exploration is used as basic, antecedent and strategic work of national economic construction, occupies a great position for a long time, and makes contribution of non-extinguishment for ensuring the sustainable, rapid and coordinated development of national economy. However, with the rapid economic development of our country, the phenomena of soil pollution, water pollution, air pollution, biodiversity destruction, secondary geological disasters and the like caused by large-scale and extensive mineral exploration and development activities are frequently rare, and the contradiction between environmental protection and resource guarantee is increasingly prominent.

In the prior art, the environment-friendly flushing fluid mainly based on synthetic base, water base, methyl glucose and the like cannot meet the requirement of maintaining the stability of the hole wall in drilling of coal complex strata in a plateau area, the accurate formula of the environment-friendly flushing fluid is difficult to obtain, and the cost of additive materials is very high, so that the environment-friendly flushing fluid is not suitable for geological drilling work with relatively small scale degree.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an environment-friendly flushing fluid system for geological drilling and a preparation method thereof, wherein the flushing fluid system has stronger inhibition capability, can inhibit the phenomena of dispersion, slurry making, diameter reduction and the like of a water-sensitive stratum, has lower flushing fluid water loss, prevents free water from entering the stratum, influences the stability of a hole wall, has proper specific gravity, maintains the pressure balance in the hole, and has the characteristics of no toxicity, easy biodegradation, small environmental influence and the like. In order to realize the purpose of the invention, the invention adopts the following technical scheme:

an environment-friendly flushing fluid system for geological drilling comprises 1-4% of matrix, 0.1-0.5% of tackifier, 0.1-0.2% of coating agent, 0.8-1% of fluid loss agent, 0.1-0.2% of inhibitor and the balance of clear water by mass percentage; the matrix is selected from bentonite.

Furthermore, the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder.

Further, the environment-friendly flushing fluid system for geological drilling comprises, by mass, 4% of a matrix, 0.3% of a tackifier, 0.2% of a coating agent, 1% of a fluid loss agent, 0.2% of an inhibitor and the balance of clear water.

Further, the bentonite is sodium bentonite;

further, the tackifier is one or two of carboxymethyl cellulose or sodium carboxymethyl cellulose;

further, the coating agent is one or two of a zwitterionic FA367 type coating agent or a synthetic FA141 type coating agent;

further, the inhibitor is one or two of potassium polyacrylate or potassium silicate.

A preparation method of an environment-friendly washing fluid system for geological drilling, which selects raw materials according to the mass percentage and prepares the washing fluid system according to the following steps,

s1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

Further, the stirring time in the step S2 is 10-15 min. The stirring time in the step S4 is 10-12 min. The stirring time in the step S5 is 20-25 min. The stirring time in the step S6 is 20-25 min.

Compared with the prior art, the invention has the following beneficial effects:

1. the potassium polyacrylate or potassium silicate is selected as the inhibitor, and potassium ions in the potassium polyacrylate or potassium silicate have the effects of preventing hydration dispersion and inhibiting reduction, so that the hydration expansion and the spalling of the water-sensitive mudstone of the coal-based stratum can be effectively inhibited, and the hydration dispersion and the slurrying of rock powder and stratum clay particles are inhibited.

2. The composite environment-friendly water reducing agent is selected as the water reducing agent, and a large amount of fibrous plugging materials in the composite environment-friendly water reducing agent can plug nano-scale micro pores and cracks in the coal-based stratum, so that free water in flushing fluid is effectively prevented from entering the stratum, and the strength of rocks at the wall of a mudstone hole of the coal-based stratum is stabilized.

3. The environment-friendly flushing fluid system for geological drilling provided by the invention has no solid-liquid layering phenomenon in the system, and the selected raw materials have good compatibility and fluidity, the flushing fluid system has low water loss and good filtration performance, and the quality of mud cakes can be better improved.

4. The environment-friendly flushing fluid system for geological drilling provided by the invention has the advantages that the raw materials of the system have good wall protection performance, the sources of the raw materials are wide, the performance is stable, and the system is environment-friendly and nontoxic.

5. The environment-friendly type flushing fluid system for geological drilling provided by the invention is simple in preparation method, low in cost, convenient for large-scale production and good in market popularization and application value.

6. The biodegradability degradation rate of the environment-friendly flushing fluid system is more than or equal to 70 percent; the biotoxicity EC50 value was > 10X 10 mg/L.

Detailed Description

The technical solution in the embodiment of the present invention will be clearly and completely described below:

the first embodiment is as follows:

an environment-friendly flushing fluid system for geological drilling comprises 1% of matrix, 0.1% of tackifier, 0.1% of coating agent, 0.8% of fluid loss agent, 0.1% of inhibitor and the balance of clear water by mass percentage; the matrix is selected from bentonite; the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder. The bentonite is sodium bentonite; the tackifier is carboxymethyl cellulose; the coating agent is a zwitterion FA367 type coating agent; the inhibitor is potassium polyacrylate;

the preparation method of the environment-friendly type flushing fluid system for geological drilling comprises the following steps of selecting raw materials according to the mass percentage.

S1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

Further, the stirring time in step S2 is 10 min. The stirring time in step S4 is 10 min. The stirring time in step S5 is 20 min. The stirring time in step S6 is 20 min.

Example two:

an environment-friendly flushing fluid system for geological drilling comprises 2 mass percent of matrix, 0.3 mass percent of tackifier, 0.15 mass percent of coating agent, 0.9 mass percent of fluid loss agent, 0.15 mass percent of inhibitor and the balance of clear water; the matrix is selected from bentonite; the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder. The bentonite is sodium bentonite; the tackifier is sodium carboxymethyl cellulose; the coating agent is an artificially synthesized FA141 type coating agent; the inhibitor is potassium silicate.

The preparation method of the environment-friendly type flushing fluid system for geological drilling comprises the following steps of selecting raw materials according to the mass percentage.

S1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

Further, the stirring time in step S2 is 12 min. The stirring time in step S4 is 11 min. The stirring time in step S5 is 22 min. The stirring time in step S6 is 22 min.

Example three:

a preparation method of an environment-friendly flushing fluid system for geological drilling comprises 4% of matrix, 0.5% of tackifier, 0.2% of coating agent, 1% of fluid loss agent, 0.2% of inhibitor and the balance of clear water by mass percentage; the matrix is selected from bentonite; the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder. The bentonite is sodium bentonite; the tackifier is carboxymethyl cellulose and sodium carboxymethyl cellulose; the coating agent is a zwitterion FA367 type coating agent and a synthetic FA141 type coating agent; the inhibitor is potassium polyacrylate and potassium silicate;

the preparation method of the environment-friendly type flushing fluid system for geological drilling comprises the following steps of selecting raw materials according to the mass percentage.

S1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

Further, the stirring time in step S2 is 15 min. The stirring time in step S4 is 12 min. The stirring time in step S5 is 25 min. The stirring time in step S6 is 25 min.

Example four:

an environment-friendly flushing fluid system for geological drilling comprises, by mass, 4% of matrix, 0.3% of tackifier, 0.2% of coating agent, 1% of fluid loss agent, 0.2% of inhibitor and the balance of clear water; the matrix is sodium bentonite; the fluid loss agent is a compound fluid loss agent consisting of modified starch, hydrolyzed ammonium salt, silicate, a plugging agent and graphite powder; the tackifier is carboxymethyl cellulose; the coating agent is a zwitterion FA367 type coating agent; the inhibitor is potassium polyacrylate.

The preparation method of the environment-friendly type flushing fluid system for geological drilling comprises the following steps of selecting raw materials according to the mass percentage.

S1, filling clear water into a field slurry mixing tank;

s2, adding a matrix into clear water, and fully stirring and uniformly mixing;

s3, adding a tackifier into the uniformly stirred mixture;

s4, adding a fluid loss agent into the mixture obtained in the step 3, and stirring to dissolve the fluid loss agent;

s5, adding a coating agent into the mixture obtained in the step 4, and fully stirring;

and S6, adding an inhibitor into the mixture obtained in the step 5, and mixing and stirring to finish the preparation.

Further, the stirring time in step S2 is 15 min. The stirring time in step S4 is 12 min. The stirring time in step S5 is 25 min. The stirring time in step S6 is 25 min.

The environmental-friendly washing liquid formula of the fourth embodiment is subjected to comprehensive performance evaluation

1 evaluation of inhibition Properties

The coal-series stratum belongs to a sedimentary stratum and is also called a water-sensitive stratum in drilling engineering, and the stratum has the characteristics of hydration dispersion and hydration expansion, so that the evaluation of the inhibition performance of the flushing fluid is an important index for judging whether the flushing fluid can meet the drilling construction of the coal-series sedimentary stratum, and the evaluation of the inhibition performance of the environment-friendly flushing fluid is respectively evaluated by three main methods, namely a rock debris recovery rate experiment, a relative expansion rate experiment and a sample soaking experiment.

1.1 debris recovery test

An environment-friendly flushing fluid optimization basic formula rock debris recovery rate evaluation experiment is carried out, an XGRL-4 type high-temperature roller furnace and an LHG-2 type aging axe are mainly adopted to carry out an indoor rolling dispersion experiment, a rock sample is selected from Jurassic siltstone on a typical coal-series stratum in a mining area in trees in Qinghai province, the rock sample is pretreated after being taken from the site, adsorbed impurities are firstly removed, then the rock sample is crushed by a grinding body, and then particles smaller than 10 meshes and larger than 6 meshes are collected by 10-mesh and 6-mesh standard inspection sieves and are stored in a wide-mouth bottle for later use.

Weighing 50g of 10-6-mesh rock sample particles, putting the particles into an aging axe, adding 350ml of different experimental solutions and solutions of environment-friendly flushing fluid systems into the aging axe respectively, putting the aging axe into a roller furnace, rolling for 16 hours, taking out the aging axe, cooling to room temperature, pouring the flushing fluid and rock debris into a 40-mesh standard sieve for screening and washing, drying screen residues at 105-DEG temperature in a constant-temperature drying box for 4 hours, standing in the air for 24 hours, and weighing, wherein the experimental results are shown in Table 1.

TABLE 1 Experimental data sheet for rock debris recovery

Formulation of	Test solution	Mass g of rock debris recovered	The recovery rate of rock debris is high
				1#	Water (W)	13.25	26.50
2#	7% potassium chloride solution	42.60	85.20
				3#	10% sodium chloride solution	24.65	49.30
4#	3% sodium silicate solution	31.35	62.70
				5#	3% potassium silicate solution	40.70	81.50
6#	30% sodium chloride solution	30.65	61.30
				7#	Environment-friendly flushing liquid solution	43.65	87.30

The experimental results are as follows: as can be seen from Table 1, the rock debris recovery quality after the solution in the formula of the environment-friendly flushing liquid system is rolled and dispersed for 16 hours is 43.65 g, and the rock debris recovery rate is 87.30%, which shows that the rock debris recovery rate can be effectively improved, and the rock debris recovery rate of the solution in the environment-friendly flushing liquid is higher than that of a 7% potassium chloride solution in a 2# formula and that of a 3% potassium silicate solution in a 4# formula, thus showing that the indoor preferable environment-friendly flushing liquid system has strong inhibition performance and good function of inhibiting the dispersion of the coal-based stratum mud shale.

1.2 relative expansion Rate test

The method mainly adopts an NP-01 type shale expansion tester, a rock core sample is pressed by adopting Ningxia Zhongwei nano bentonite, the rock core sample is dried for 4 hours at the temperature of 105 ℃ in a constant temperature drying box, 10g of the nano bentonite is weighed, and the rock core sample is pressurized to 4Mpa on a special press and maintained for 10 minutes to obtain the artificial rock core sample.

And (3) mounting the sample on a shale expansion instrument, soaking the core sample by using different solutions, flushing fluids and test solutions respectively, measuring the linear expansion amount per hour within 6 hours, and calculating the relative expansion rate and the relative expansion reduction rate, wherein the experimental result is shown in table 2.

TABLE 2 measurement of linear expansion

Formulation of

Test solution

1h

2h

3h

4h

5h

6h

1#

Distilled water

6.57mm

8.51mm

9.15mm

9.52mm

9.63mm

9.69mm

2#

5% potassium chloride solution

4.46mm

5.78mm

6.20mm

6.47mm

6.54mm

6.58mm

3#

4% vegetable gum solution

4.00mm

5.19mm

5.58mm

5.80mm

5.87mm

5.91mm

4#

Environment-friendly flushing fluid

2.95mm

3.82mm

4.11mm

4.28mm

4.33mm

4.36mm

5#

Potassium-based flushing fluid

2.49mm

3.23mm

3.47mm

3.61mm

3.65mm

3.68mm

6#

Polymer rinse

3.35mm

4.34mm

4.66mm

4.85mm

4.91mm

4.94mm

TABLE 3 Experimental data sheet of relative expansion ratio

Formulation of	Test solution	Relative expansion ratio	Relative expansionRate of reduction of swelling
				1#	Distilled water	100％	0％
2#	5% potassium chloride solution	68％	32％
				3#	4% vegetable gum solution	61％	39％
4#	Environment-friendly flushing fluid	45％	55％
				5#	Potassium-based flushing fluid	38％	62％
6#	Polymer rinse	51％	49％

The experimental results are as follows: as can be seen from tables 2 and 3, the relative expansion rate of the solution in the formula of the environment-friendly flushing liquid system is 45%, and although the linear expansion amount and the relative expansion rate are higher than those of potassium-based flushing liquid solutions, the linear expansion amount and the relative expansion rate are lower than those of polymer flushing liquid and other 2 solutions. The higher the relative expansion rate and the lower the relative expansion reduction rate are analyzed according to the theoretical definition of the expansion rate, the worse the performance of the flushing fluid for inhibiting the hydration expansion of the shale is, on the contrary, the better the inhibition performance is, and the experimental data and results show that: the environment-friendly flushing fluid and the optimized basic formula system have better inhibition performance and can basically meet the drilling construction requirements of coal-based sedimentary formations.

1.3 core sample soaking experiment

Taking 40g of nano bentonite, putting the nano bentonite into a pressure barrel, putting the pressure barrel on a press machine, pressing the pressure barrel for 60min at 8MPa to prepare a core sample, respectively immersing the core sample into different test solutions, and observing the change condition of the core sample along with time, wherein the experimental result is shown in table 4.

Table 4 core soaking experiment data table

Formulation of	Test solution	Phenomenon(s)
			1#	Tap water	Peeling off slightly in 1min, and completely disintegrating at 2h15
2#	5% Potassium chloride	Peeling off in 5min, and completely disintegrating in 3h
			3#	4% vegetable gum	Peeling off a little after 3min, and completely disintegrating after 6h
4#	1% Polymer	Peeling off a little at 3min, and completely disintegrating at 2h30
			5#	Environment-friendly flushing fluid	A small amount of peeling is generated within 3min, cracks are generated within 36h, and the peeling is not generated within 48h
6#	Potassium-based flushing fluid	A small amount of spalling after 3min, cracks after 24h and partial spalling after 48h

The experimental results are as follows: as can be seen from Table 4, the core sample soaked by the environmental-friendly flushing fluid formula solution is obviously more stable than the core sample soaked by other test solutions, the core sample is still not peeled after 48 hours, and the surface of the core soaked by the environmental-friendly flushing fluid solution is very hard, which indicates that the environmental-friendly flushing fluid can form a hydration protective film on the surface of the core sample, thereby reducing the entry of free water in the solution, ensuring the stability of the internal mechanical structure of the sample, and preventing the instability and collapse of the core sample.

2 evaluation of Sand layer Permeability

The permeability of the sand layer of the environment-friendly flushing fluid with the optimized formula is evaluated, an FA-BX permeability filtration tester is mainly adopted, in order to simulate the infiltration process of the flushing fluid in the stratum, 20-40-mesh quartz sand is adopted in the experiment as a simulated sand bed of the coal-series sedimentary stratum and the recent and near-solid loose high-permeability stratum in Qinghai province, the permeation condition of the flushing fluid is observed through a cup body in the experiment, the permeation amount, the invasion depth and the formed mud cake quality of different test liquids are further evaluated through experimental data, and the experimental result is shown in a table 5.

TABLE 5 Sand bed Permeability test data sheet

The experimental results are as follows: as can be seen from Table 5, the 3# and 4# formula solutions have a certain effect of reducing permeation plugging, but the 4# formula solution has a strong capability of plugging a permeable sand layer after being added, the surface of a simulated sand layer can be plugged to form a compact mud cake, but the 3# and 4# formula solutions have better capability of plugging the sand layer than the 1# and 2# formula solutions in terms of the quality of the mud cake, and the 4# formula solution of the environment-friendly flushing fluid system can form an effective sealing layer in a shorter time.

From this experiment, it is found that there are two main ways of forming mud cake with the washing liquid: one is that at the surface of the formation, the washing liquid particles cannot enter the pores at all, filtration and penetration occur, and a mud skin is formed at the surface of the formation, in which case the effluent is very clean and almost free of washing liquid or soil particles. In another mode, when the pore space of the stratum is larger than the particle in part of the flushing liquid, the particle in the part of the flushing liquid can possibly enter the stratum, the particle in the entering flushing liquid can be blocked at the narrow part of some pores due to the fact that the pore space of the stratum is a reducing channel, the subsequent flushing liquid particles cannot pass through and are gathered on the surface layer, and finally the subsequent flushing liquid particles are gathered on the surface layer from the surface layer and are transferred to the surface layer to form a mud cake and permeable zone.

Therefore, the key for optimizing and selecting the performance of the flushing fluid in a loose and high-permeability stratum is the formation of a watertight or slightly pervious mud cake, the formation of the mud cake is indicated by small permeation amount in the formation process, the formation of the mud cake is easy, the formation of the mud cake is indicated by small permeation amount, the compaction of the mud cake is indicated, and the quality of the mud skin is indicated by small permeation amount and small permeation amount.

3. Evaluation of resistance to formation water contamination

The evaluation of the stratum water pollution resistance of the environment-friendly flushing liquid basic formula is mainly characterized in that the change of the flushing liquid performance is tested and analyzed by adopting a stratum water pollution simulation method, 0-20% of simulated stratum water is added into the environment-friendly flushing liquid basic formula respectively, the simulated stratum water is taken from surface river water near Dachaidan Shangdui, the strength of the stratum water pollution resistance of the environment-friendly flushing liquid basic formula is further illustrated by measuring various performances after the environment-friendly flushing liquid basic formula is polluted by the simulated stratum water, and the experimental result is shown in a table 6.

1# formulation: environment-friendly flushing fluid formula solution

And 2# formula: environment-friendly flushing fluid formula solution and 5% simulated formation water

And 3# formula: environment-friendly flushing fluid formula solution and 10% simulated formation water

And 4, formulation: environment-friendly flushing fluid formula solution and 15% simulated formation water

And 5# formula: environment-friendly flushing fluid formula solution and 20% simulated formation water

Table 6 simulated formation water pollution experiment data table

The experimental results are as follows: as can be seen from Table 6, with continuous pollution of simulated formation water, the density, the funnel viscosity, the apparent viscosity and other properties of the flushing fluid system are gradually diluted and reduced, the change ranges of the plastic viscosity and the dynamic-shear ratio are smaller within 5% -15% of the pollution amount, the change of the dynamic-shear force is smaller within 5% -10% of the pollution amount, and the water loss amount is gradually increased along with the pollution amount. The Qinghai coal-saving series stratum geological drilling generally adopts a diamond drill bit to drill, the size of rock powder particles generated by grinding the drill bit is relatively small, the annular gap between the hole walls is also small, and the requirement of the common plastic viscosity of 4-15mpa.s and the requirement of the common plastic viscosity of 0.1-0.4pa/mpa.s on carrying the rock powder in the circulation process of flushing fluid and the requirement of the suspended rock powder when the flushing fluid stops circulating can be met.

The experimental result of the simulated formation water pollution shows that 0-20% of the simulated formation water is respectively added into the basic formula of the environment-friendly flushing liquid, although the changes of important rheological parameters such as plastic viscosity, dynamic shear force, dynamic-plastic ratio and the like of the flushing liquid in the formulas 1# to 5# are within the normal requirement range, when the pollution of the formation water in the formula 5# reaches 20%, the filtration loss of the flushing liquid is increased to 11ml, and the density of the flushing liquid is reduced to 1.02g/cm³In summary, the basic formula of the environment-friendly flushing liquid has the formation water pollution resistance and the pollution bearing capacity within 0-15 percent, and can meet the requirement of coal-series formationDrilling construction needs.

4. Evaluation of resistance to invasion of rock powder

The evaluation of the environmental-friendly flushing fluid basic formula for resisting rock powder invasion is characterized in that wood coal field Jurassic formation shale is selected and ground indoors into rock powder, 5% -20% of rock powder is added into a system respectively, various performances after being polluted by the rock powder are measured, then experimental result evaluation analysis is carried out, the influence of the increase of the rock powder on the viscosity of flushing fluid and the stability of the flushing fluid are mainly analyzed, the rock powder invasion resistance of the environmental-friendly flushing fluid basic formula is further explained, and the experimental results are shown in table 7.

1# formulation: environment-friendly flushing fluid formula solution

And 2# formula: environment-friendly flushing fluid formula solution and 5% rock powder

And 3# formula: environment-friendly flushing fluid formula solution and 10% rock powder

And 4, formulation: environment-friendly flushing fluid formula solution and 15% rock powder

And 5# formula: environment-friendly flushing fluid formula solution and 20% rock powder

TABLE 7 tables of invasion experiment data of rock-resistant powder

The experimental results are as follows: as can be seen from Table 7, the density of the flushing fluid system gradually increased with the continuous invasion of the rock powder particles, wherein the density of the formulation No. 5 increased to 1.22g/cm after 200 g of rock powder was added³The change ranges of the apparent viscosity, the plastic viscosity, the dynamic shear force and the dynamic-plastic ratio of the washing liquid are small, and the water loss change range of the 1# to 5# formula washing liquid is 8-9 ml/min30, so that the environment-friendly washing liquid formula solution has good inhibition performance and rock powder invasion resistance, can effectively control clay particles in a shale stratum to absorb water and expand and rock powder to disperse and slurry, and has good flocculation effect.

The results of the rock powder invasion resistance experiment show that: 0-20% of rock powder is respectively added into the basic formula of the environment-friendly flushing liquid, performance indexes such as apparent viscosity, plastic viscosity, dynamic shear force, dynamic-plastic ratio, filtration loss and the like of the flushing liquid are changed in a small range, but the influence on the rheological property and stability of a flushing liquid system is small, so that the inhibition of the high-molecular polymer optimized by the basic formula of the environment-friendly flushing liquid on the dispersion of the rock powder in a coal-based stratum is good, and the influence of the invasion of the rock powder on the rheological property of the flushing liquid in the drilling process can be effectively inhibited.

5. Evaluation of environmental Properties

The environmental protection performance evaluation of the basic formula of the flushing fluid is mainly carried out from three aspects of biotoxicity, biodegradability and heavy metal, wherein the biotoxicity adopts a luminous bacteria method to measure EC₅₀The value is evaluated, the biodegradability is evaluated by adopting a BOD/COD ratio evaluation method, the effective contents of lead, zinc, cadmium, nickel, copper, total chromium and barium in a flushing fluid system are measured and evaluated by heavy metals, the environmental protection performance detection of the item is entrusted to be analyzed and measured by Shandong Shengsheng Gonggong monitoring technology Limited company in China petrochemical Shengli oil field, and an environmental protection performance detection report is provided.

5.1 evaluation of biotoxicity

The research adopts a luminous bacteria method to carry out biotoxicity test on the environment-friendly flushing fluid formula solution, and the evaluation index is EC_50,Concentration EC of the substance to be evaluated when the luminous power of the luminescent bacteria is reduced by half₅₀The larger the value, the less toxic the substance to be evaluated.

TABLE 8 oil field chemical and drilling fluid biotoxicity grading Q/SY 111-

According to the national oil field chemical agent and drilling fluid biotoxicity classification Q/SY 111-2004 standard (Table 8), the biotoxicity of the indoor preferred flushing fluid basic formula is tested by adopting a biotoxicity testing method, the test result is shown in Table 9, and the test result shows that: EC of environment-friendly flushing fluid formula solution₅₀A value greater than > 3X 10⁴mg/L, reaching the direct discharge standard.

TABLE 9 biotoxicity assay data sheet

And (3) testing results: as can be seen from the detection results in Table 9, the solution of the washing liquid formula shows no toxicity in biotoxicity, and meets the requirements of national relevant environmental standards.

5.2 evaluation of biodegradability

The biodegradability of the environmental-friendly flushing liquid formula solution is evaluated by a BOD/COD ratio evaluation method commonly used in sewage treatment, the evaluation standard of the biodegradability is shown in a table 10, and the detection data of the biodegradability is shown in a table 11.

TABLE 10 evaluation criteria for biodegradability of wastewater treatment

TABLE 11 tables of biodegradability test data

Note: BOD₅Representing 5d biochemical oxygen consumption.

And (3) testing results: BOD of preferred eco-friendly rinse solution formulations₅The biochemical oxygen demand is less than or equal to 100mg/L, and the optimal environment-friendly flushing liquid formula solution can be degraded by microorganisms within the specified value of the sewage comprehensive discharge standard, thereby meeting the environment-friendly requirement.

5.3 evaluation of heavy metals

The evaluation of the influence of the heavy metal in the solution of the heavy metal washing liquid formula mainly refers to pollutants of the first class of national Integrated wastewater discharge Standard of GB8978-1996, the total 7 selected heavy metal evaluation items are lead, zinc, cadmium, chromium, nickel, copper and barium respectively, the effective content in the solution of the heavy metal washing liquid formula is detected, and the detection result is shown in Table 12.

Table 12 heavy metal detection data table

And (3) testing results: the heavy metal content of the solution of the preferable environment-friendly washing liquid formula is within the standard value of GB8978-1996 national Integrated wastewater discharge Standard, which indicates that the basic formula of the preferable environment-friendly washing liquid has no potential heavy metal pollution exceeding standard and toxic hazard and meets the requirement of environmental protection.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention by equivalent replacement or change according to the technical solution and the modified concept of the present invention within the technical scope of the present invention.