Method and apparatus for recovering weighting agents from high density spent water-based drilling fluids

Abstract

This invention provides a method and apparatus for recovering weighting agents from high-density waste water-based drilling fluid, belonging to the field of waste drilling fluid recovery technology. The method includes sequential electrolysis and solid-liquid separation of the drilling fluid to be treated, obtaining a solid phase containing weighting agents. The electrolysis conditions include: voltage 4V-36V; current 4-20A. The green degelatinizing and weighting agent recovery device and process of this invention mainly utilizes an organic combination of electric field sedimentation and cyclone classification to achieve rapid degelatinization of waste drilling fluid, solid-liquid separation of waste drilling fluid, and recovery of barite.

Description

Technical Field

[0001] This invention relates to the field of waste drilling fluid recycling technology, specifically to a method and apparatus for recycling weighting agents in high-density waste water-based drilling fluid. Background Technology

[0002] As drilling depth increases, formation pressure gradually increases from the surface to the deeper layers of the formation, requiring a corresponding increase in the density of the drilling fluid. For water-based drilling fluid systems, achieving higher density necessitates the addition of more and denser weighting materials (weighting agents).

[0003] Due to the large volume of drilling fluid used and the large number of oil and gas wells, the consumption of weighting agents is enormous. High-density drilling fluids have a high solids content, with a density of 2.0 g / cm³. 3 Taking the above drilling fluid as an example, the solid waste in each cubic meter of drilling fluid can reach over 1 ton. In the southwestern working area of ​​my country, the density of drilling fluid is 2.0 g / cm³. 3 The above-mentioned high-density wells are numerous, with each well using approximately 2000 tons of barite. The cost of barite accounts for an average of over 35% of drilling fluid costs. Therefore, realizing barite recycling will effectively reduce the amount of waste solids to be disposed of and achieve resource utilization.

[0004] Meanwhile, drilling fluid is a highly stable colloidal suspension system. Traditional physical methods for solid-liquid separation and weighting agent recovery suffer from problems such as difficult unloading, high energy consumption, and significant vibration. Chemical methods require the addition of breaker agents, but the dosage is enormous, the overall processing is complex, and the polymers or metal ions in the breaker agents can cause secondary pollution. Furthermore, the flocculation effect needs improvement. Drilling fluid has a high content of fine particles and high viscosity, making sorting and recovery difficult. Currently, there is a lack of high-capacity, high-efficiency, and cost-effective recovery technologies and processes. Current drilling fluid separation methods mainly include five approaches: mechanical separation (online), mechanical separation + chemical breaker (for waste drilling fluid), chemical breaker (online), electrocoagulation (for waste drilling fluid), and chemical breaker + electrocoagulation (for waste drilling fluid). However, all five methods have certain drawbacks. Summary of the Invention

[0005] The device and process of this invention are mainly aimed at disrupting the colloidal stability of high-density drilling fluids and recovering the useful solid phase therein. They combine electrocoagulation and mechanical separation in an organic way to quickly achieve the graded sedimentation and separation of particles of different sizes, reducing further pollution problems caused by chemical decolloiding.

[0006] This invention utilizes a DC power supply and metal plates to electro-treat waste high-density drilling fluid, thereby disrupting its colloidal stability. The drilling fluid, after its colloidal stability has been disrupted, is then fed into a hydrocyclone separator with or without water for solid-liquid separation. The solid phase material is then cleaned, separated, dried, stored, and ready for use.

[0007] The technical solution of this invention is to provide a method for recovering weighting agents from drilling fluid.

[0008] A method for recovering weighting agents from drilling fluid (or waste drilling fluid) to be treated includes sequential electrolysis and solid-liquid separation of the drilling fluid to be treated to obtain a solid phase containing weighting agents;

[0009] The electrolysis conditions include: voltage 4V-36V; current 4-20A.

[0010] Optionally, the electrolysis uses the drilling fluid to be treated as the electrolyte and a metal plate as the electrode.

[0011] Optionally, the electrodes used in the electrolysis include an anode and a cathode, with the distance between the anode and the cathode being 3 to 5 cm.

[0012] Optionally, the metal plate is made of iron, aluminum, copper or zinc.

[0013] Optionally, the electrolysis time is 3 to 10 minutes.

[0014] Optionally, the density of the drilling fluid to be treated is 1.5 g / cm³. 3 ~2g / cm 3 .

[0015] Optionally, the solid-liquid separation is performed using a cyclone separation method.

[0016] Optionally, the conditions for the cyclone separation method include: controlling the inlet discharge rate to (1.0~1.5) m³ / s. 3 / h, preferably using SH / L30 core tube for cyclone separation.

[0017] Optionally, the cyclone separation method includes a first cyclone separation and a second cyclone separation; the first cyclone separation yields a solid phase I, which is then mixed with water and subjected to a second cyclone separation.

[0018] Optionally, the solid phase containing the weighting agent is further post-processed.

[0019] Optionally, the post-processing includes drying and ball milling granulation.

[0020] Optionally, the drying conditions include: the solid phase moisture content after drying is <10%.

[0021] Optionally, the conditions for ball milling granulation include: particle size d90 <75μm.

[0022] Optionally, the recovery efficiency of the weighting agent in the drilling fluid to be treated is 71% to 88%.

[0023] Optionally, the recovery purity of the weighting agent in the drilling fluid to be treated is ≥90%.

[0024] The present invention also provides a device for recovering weighting agents in drilling fluid, comprising an electrolytic cell and a solid-liquid separator connected in sequence; the electrolytic cell is provided with electrodes connected to a power source; the electrodes include an anode and a cathode, and the distance between the anode and the cathode is 3-5 cm.

[0025] Optionally, the electrode is a metal plate, and the metal plate is made of iron, aluminum, copper or zinc.

[0026] Optionally, the solid-liquid separator has two sets connected in sequence.

[0027] Optionally, the solid-liquid separator is a hydrocyclone.

[0028] Optionally, the power source is an AC power source or a DC power source.

[0029] Optionally, the solid-liquid separator is two sets of hydrocyclones connected in sequence.

[0030] The electrolytic gel breaking system includes an adjustable DC power supply, metal electrode plates, an electrolytic gel breaking tank, and related accessories; the separation system for high-density solid materials and low-density base liquid and their dissolved substances includes a stirring system, a water addition system, a solid-liquid separation system, a drying system, a collection and storage system, and related auxiliary equipment.

[0031] The DC power supply is adjustable in both output voltage and output current, and its input power source can be industrial AC or DC. The output voltage of the DC power supply should be controllable between 4V and 36V.

[0032] Setting the gel-breaking current to 4-10A maximizes the electrode's gel-breaking ability on the drilling fluid.

[0033] The electrodes in the electrolytic cell are movable electrodes with adjustable spacing, meaning the electrode spacing can be adjusted by moving the electrodes.

[0034] The electrode plates are made of metals with good electrical conductivity, such as aluminum, iron, zinc, copper and their alloys. Their shape and material can be changed according to the shape of the electrolytic cell and the price of the metal, the conditions of use, etc.

[0035] The electrolytic rupture tank can be square, rectangular, or round, and the material can be metal or plexiglass, etc., which can be adjusted according to the site, environment, and cost; its auxiliary equipment includes, but is not limited to, wires, valves, connectors, water pumps, etc.

[0036] Solid-liquid separation systems can be achieved through centrifugation or cyclone separation.

[0037] In the aforementioned green degelatinizing and weighting agent recovery process for waste high-density water-based drilling fluid, the mud pump displacement is set to (1.0~1.5) m³ / s. 3 / h.

[0038] Different electrode spacings correspond to the optimal gel breaking conditions for drilling fluids of different densities. The adjustable electrode spacing allows the equipment to perform targeted gel breaking treatment on waste drilling fluids of different densities.

[0039] This invention eliminates the potential environmental hazards of traditional solidification and landfill methods. No chemical agents or even water are needed during the electrolytic breaking process of waste drilling fluid, thus avoiding secondary pollution from chemical reagents. The breaking process is green, environmentally friendly, and pollution-free, reducing the amount and cost of subsequent drilling waste disposal.

[0040] The solid-liquid separation system can separate the solid phase and the liquid phase (including the base liquid and its dissolved substances) by centrifugation or cyclone. The speed and feed pressure of the centrifugation or cyclone system are adjustable. Its auxiliary equipment includes, but is not limited to, motors, switches, valves, wires, water pumps and other related equipment and items.

[0041] During the solid-liquid separation process, only some water is added or no water is added, and no other chemical agents are required, thus avoiding secondary environmental pollution. At the same time, barite, the solid weighting material in water-based waste drilling fluid, is reused, reducing the overall cost of drilling fluid use and improving the resource utilization rate of drilling waste.

[0042] The green degelatinizing and weighting agent recovery device and process for waste high-density water-based drilling fluid of the present invention mainly uses an organic combination of electric field sedimentation and cyclone classification to achieve rapid degelatinization of waste drilling fluid, solid-liquid separation of waste drilling fluid, and recovery of barite. The specific effects are reflected in the following aspects:

[0043] (1) The high-density drilling fluid is rapidly destabilized, and then the system after gel breaking is subjected to solid-liquid separation. Finally, the high-value and high-volume useful components in the high-density waste drilling fluid are effectively recovered. The three parts are interconnected, completing the entire process of waste drilling fluid from electrolytic gel breaking and destabilization to solid phase recovery, effectively reducing the cost of drilling fluid use and having high industrial application value.

[0044] (2) Applying an external electric field to break up drilling fluid has high practical value. The electric field method breaks up waste drilling fluid without adding chemical additives or introducing new pollutants. It effectively avoids the interaction between new uncertain factors and drilling fluid and eliminates the possibility of secondary pollution caused by these factors. It is a green and environmentally friendly technology.

[0045] (3) By introducing a cyclone device, solid particles of different sizes and densities can be quickly separated, thereby achieving efficient recovery of the effective component barite and reduction of drilling fluid waste, thus achieving the dual purpose of environmental protection and recycling.

[0046] (4) The treatment cost of well fluid effectively reduces the related costs generated by solidification and landfill methods. Attached Figure Description

[0047] Figure 1 The principle and flowchart of the method for recovering weighting agents from waste drilling fluid of the present invention.

[0048] Figure 1 In the middle, 1-mud tank; 2-mud pump; 3-WYJ-60150 DC power supply; 4-electric colloid breaking tank; 5-mud pump; 6-first agitator; 7-mud pump; 8-first hydrocyclone; 9-mud pump; 10-mud pump; 11-second agitator; 12-wastewater storage tank; 13-hydrocyclone; 14-rotary flash dryer; 15-ball mill; 16-storage device. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and examples.

[0050] As a preferred embodiment, the present invention provides a green degumming and weighting agent recovery device for waste high-density water-based drilling fluid. The device includes a mud tank 1, a mud pump 2, a DC power supply 3, an electro-degumming tank 4, a mud pump 5, a first agitator 6, a mud pump 7, a first hydrocyclone 8 (XC II F 150), a mud pump 9, a mud pump 10, a second agitator 11, a wastewater storage tank 12, a second hydrocyclone 13 (XC II F 150), a rotary flash dryer 14 (ZPG-5000), a ball mill 15, and a storage device 16.

[0051] The mud tank 1 is circulatedly connected to the mud pump 2; the mud pump 2 is connected to the electrolytic breaking tank 4; the power supply is connected to the electrolytic breaking tank 4; the breaking tank is equipped with electrodes, including an anode and a cathode; the electrolytic breaking tank 4 is connected to the first agitator 6 via the mud pump 5; the first agitator 6 is connected to the first hydrocyclone 8 via the mud pump 7; the overflow of the first hydrocyclone 8 is connected to the wastewater storage tank 12 via the mud pump 9, and the underflow of the first hydrocyclone 8 is connected to the second agitator 11; both the first agitator 6 and the second agitator 11 can be connected to a water source; the second agitator 11 is connected to the second hydrocyclone 13 via the mud pump 10; the overflow of the second hydrocyclone 13 is connected to the wastewater storage tank 12, and the underflow of the second hydrocyclone 8 is connected to the flash dryer 14; the flash dryer 14 is connected to the ball mill 15; the ball mill is connected to the storage device 16.

[0052] As a preferred embodiment, the present invention provides a green degumming and weighting agent recovery process for waste high-density water-based drilling fluid, which is carried out using the aforementioned green degumming and weighting agent recovery device for waste high-density water-based drilling fluid, and includes the following steps:

[0053] Adjust the flow rate and use a mud pump to pump the waste drilling fluid from the mud tank into the electrolytic cell. Adjust parameters such as electrode distance, current intensity and energizing time to fully destroy the colloidal stability of the drilling fluid.

[0054] Add water to the waste high-density drilling fluid after degelation or directly pass it to a hydrocyclone separator. Adjust the pressure parameters of the hydrocyclone separator to separate the high-density solid phase from the low-density base fluid and its dissolved substances.

[0055] The high-density solid phase is purified by adding water in a certain proportion and then performing a secondary vortex.

[0056] The high-density solid phase (weighting agent) after secondary swirl is transferred to a rotary flash dryer for drying to obtain the weighting agent solid phase, which is then ground in a ball mill and finally collected and stored for later use.

[0057] Parameter measurement method in the example:

[0058] Apparent viscosity (Pa·s) was measured using a six-speed rotational viscometer according to GB16783.1 method.

[0059] Plastic viscosity (Pa·s) was tested using a six-speed rotational viscometer according to GB16783.1 method.

[0060] Zeta potential (mV) was measured using a potentiometer, following the operating procedures and requirements of the potentiometer.

[0061] Particle size distribution D50 (μm) was measured using a laser particle size analyzer, according to the operating procedures and requirements of a dry laser particle size analyzer.

[0062] Calculation of barite recovery rate (wt%):

[0063] Weigh the mass of barite added to the drilling fluid (W1) and the mass of barite recovered (W2) separately, and calculate according to the following formula:

[0064]

[0065] Calculation of the purity (%) of recovered barite. The density (g / cm³) of pure barite was determined according to the method in GB / T 5005-2010. 3 )ρ1, and the density of the recovered barite (g / cm³) 3 The determination of ρ2. The purity of recovered barite is calculated according to the following formula:

[0066]

[0067] The percentage of residue on the 75μm sieve (%) was tested according to GB / T 5005-2010 method using a 75μm sieve conforming to ASTM E161.

[0068] Example 1 has a density of 1.5 g / cm³. 3 Methods for recovering weighting agents from waste drilling fluids

[0069] (1) Take the well mud from well 4 of the Gubei Ancient Slope 2 at a depth of 2450m and increase its density to 1.5g / cm³ using barite. 3 As the waste drilling fluid used in the experiment, aluminum electrode plates were inserted into the waste drilling fluid for electrolysis. With an electrode plate distance of 5 cm and a current intensity of 4 A, a gelled waste liquid was obtained after 3 minutes of electrolysis. The performance parameters of the waste drilling fluid and the gelled waste liquid were tested separately, as shown in Table 1. The comparison shows that the electrolytic gelling treatment effectively destroyed the colloidal stability of the waste drilling fluid.

[0070] Table 1 shows a density of 1.5 g / cm³. 3 Changes in physical properties of drilling fluid systems before and after electrolytic rupture.

[0071]

[0072] (2) Mix the debonded waste liquid with water at a volume ratio of 1:1 until homogeneous, and then pass the mixture through a hydrocyclone separator, controlling the inlet discharge rate to 1.0 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation to achieve separation of solid and liquid phases (including base liquid and its dissolved substances).

[0073] (3) After the solid phase and water are mixed evenly at a volume ratio of 1:1, the mixture is passed through a hydrocyclone separator with the inlet discharge rate controlled at 1.0 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation, secondary cyclone separation to purify the solid phase, and obtaining the purified solid phase.

[0074] (4) The purified solid phase was transferred to a rotary flash dryer and dried at 105℃ for 4 hours. It was then milled by a ball mill to obtain particles with a diameter of <74μm. Finally, the particles were collected and stored for future use. The recovered purified solid phase was divided into three equal parts, and the recovery effect of barite in the three parts was tested. The results are shown in Table 2.

[0075] Table 2 Comparison of barite density and pure barite density

[0076]

[0077] As shown in Table 2, the density is 1.5 g / cm³. 3The average recovery efficiency of barite from waste drilling fluid can reach over 71%, with a recovery purity of over 90%. Based on the market price of barite (1000-1200 yuan / t), its density is 1.5 g / cm³. 3 The waste drilling fluid can recover 0.46 tons of barite per cubic meter, saving 460 yuan per cubic meter of drilling fluid.

[0078] Example 2 has a density of 1.8 g / cm³. 3 Methods for recovering weighting agents from waste drilling fluids

[0079] (1) Take the well mud from well 4 of the Gubei Ancient Slope 2 at a depth of 2450m and increase its density to 1.8g / cm³ using barite. 3 As the waste drilling fluid used in the experiment, iron electrode plates were inserted into the waste drilling fluid for electrolysis. With an electrode plate distance of 3 cm and a current intensity of 10 A, after 10 minutes of electrolysis, a gelled waste liquid was obtained. The performance parameters of the waste drilling fluid and the gelled waste liquid were tested separately, as shown in Table 3. The comparison shows that the electrolytic gelling treatment effectively destroyed the colloidal stability of the waste drilling fluid.

[0080] Table 3 shows a density of 1.8 g / cm³. 3 Changes in physical properties of drilling fluid systems before and after electrolytic rupture.

[0081]

[0082] (2) Mix the debonded waste liquid and water at a volume ratio of 1:1 until homogeneous, and then pass the mixture through a hydrocyclone separator, controlling the inlet discharge rate to 1.2 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation to achieve separation of solid phase and liquid phase (including base liquid and its dissolved substances).

[0083] (3) After the solid phase and water are mixed evenly at a volume ratio of 1:1, the mixture is passed through a hydrocyclone separator with the inlet discharge rate controlled at 1.2 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation, secondary cyclone to purify the solid phase, and obtain the purified solid phase.

[0084] (4) The purified solid phase was transferred to a rotary flash dryer and dried at 105℃ for 4 hours. It was then milled by a ball mill to obtain particles with a diameter of <74μm. Finally, the particles were collected and stored for future use. The recovered purified solid phase was divided into three equal parts, and the recovery effect of barite in the three parts was tested. The results are shown in Table 4.

[0085] Table 4 Comparison of barite density and pure barite density

[0086]

[0087] As shown in Table 4, the density is 1.8 g / cm³.3 The average recovery efficiency of barite from waste drilling fluid can reach over 77%, with a recovery purity of over 90%. Based on the market price of barite (1000-1200 yuan / t), its density is 1.8 g / cm³. 3 The waste drilling fluid can recover 0.74 tons of barite per cubic meter, saving 741 yuan per cubic meter of drilling fluid.

[0088] Example 3 High density (2.0 g / cm³) 3 Methods for recovering weighting agents from waste drilling fluids

[0089] (1) Take well mud from well 4 of the Gubei Ancient Slope 2 at a depth of 2450m and increase its density to 2.0 g / cm³ using barite. 3 As experimental waste drilling fluid, aluminum electrode plates were inserted into the waste drilling fluid (2.0 g / cm³). 3 Electrolysis was performed on the waste drilling fluid. With an electrode distance of 5 cm and a current intensity of 8 A, after 5 minutes of energization, a degelatinated waste liquid was obtained. The performance parameters of the waste drilling fluid and the degelatinated waste liquid were tested separately, as shown in Table 5. The comparison shows that the electrolytic degelatination treatment effectively destroyed the colloidal stability of the waste drilling fluid.

[0090] Table 5 shows a density of 2.0 g / cm³. 3 Changes in physical properties of drilling fluid systems before and after electrolytic rupture.

[0091]

[0092] (2) Mix the debonded waste liquid and water at a volume ratio of 1:1 until homogeneous, and then pass the mixture through a hydrocyclone separator, controlling the inlet discharge rate to 1.5 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation to achieve separation of solid and liquid phases (including base liquid and its dissolved substances).

[0093] (3) After the high-density solid phase and water are mixed evenly at a volume ratio of 1:1, the mixture is passed through a hydrocyclone separator with the inlet discharge rate controlled at 1.5 m³ / s. 3 / h, using SH / L30 core tubes for cyclone separation, secondary cyclone separation to purify the solid phase, and obtaining the purified solid phase.

[0094] (4) The purified solid phase was transferred to a rotary flash dryer and dried at 105℃ for 4 hours. It was then milled by a ball mill to obtain particles with a diameter of <74μm. Finally, the particles were collected and stored for future use. The recovered purified solid phase was divided into three equal parts, and the recovery effect of barite in the three parts was tested. The results are shown in Table 6.

[0095] Table 6 Comparison of barite density and pure barite density

[0096]

[0097] As shown in Table 6, the density is 2.0 g / cm³. 3 The average recovery efficiency of barite from waste drilling fluid can reach over 88%, with a recovery purity of over 90%. Based on the market price of barite (1000-1200 yuan / t), its density is 2.0 g / cm³. 3 The waste drilling fluid can recover 1.82 tons of barite per cubic meter of drilling fluid, saving 1,820 yuan per cubic meter of drilling fluid.

Claims

1. A method for recovering weighting agents from drilling fluid to be treated, characterized in that, A device for recovering weighting agents in drilling fluid is used to sequentially electrolyze and separate solids and liquids in the drilling fluid to be treated, thereby obtaining a solid phase containing weighting agents. The device for recovering weighting agents in drilling fluid includes an electrolytic cell and a solid-liquid separator connected in sequence. The electrolytic cell is equipped with electrodes, which are connected to a power source. The electrode includes an anode and a cathode, with the distance between the anode and the cathode being 3 to 5 cm; The electrode is a metal plate, and the metal plate is made of iron, aluminum, copper or zinc; The electrolysis uses the drilling fluid to be treated as the electrolyte. The electrolysis conditions include: voltage 4V-36V; current 4-20A; The density of the drilling fluid to be treated is 1.5 g / cm³. 3 ~2g / cm 3 ; The electrolysis time is 3 to 10 minutes.

2. The recycling method according to claim 1, characterized in that, The solid-liquid separation method is used.

3. The recycling method according to claim 2, characterized in that, The conditions for the cyclone separation method include: Control the inlet discharge rate to (1.0~1.5) m³. 3 / h, preferably using SH / L30 core tube for cyclone separation.

4. The recycling method according to claim 2, characterized in that, The cyclone separation method includes a first cyclone separation and a second cyclone separation; the first cyclone separation yields a solid phase I, which is then mixed with water and subjected to a second cyclone separation.

5. The recycling method according to claim 1, characterized in that, The solid phase containing the weighting agent is also post-processed; The post-processing includes drying and ball milling granulation; The drying conditions include: the moisture content of the solid phase after drying is <10%. The conditions for ball milling granulation include: particle size d 90 <75μm.

6. The recycling method according to claim 1, characterized in that, The recovery efficiency of the weighting agent in the drilling fluid to be treated is 71% to 88%. The recovery purity of the weighting agent in the drilling fluid to be treated is ≥90%.

7. The recycling method according to claim 1, characterized in that, The solid-liquid separator is provided with two sets connected in sequence. And / or, the power source is an AC power source or a DC power source.

8. The recycling method according to claim 1, characterized in that, The solid-liquid separator is a hydrocyclone.

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