CN107165595B - Method for hermetically removing harmful gas in drilling fluid - Google Patents
Method for hermetically removing harmful gas in drilling fluid Download PDFInfo
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- 239000012530 fluid Substances 0.000 title claims abstract description 190
- 238000005553 drilling Methods 0.000 title claims abstract description 186
- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000000926 separation method Methods 0.000 claims abstract description 165
- 239000007789 gas Substances 0.000 claims description 150
- 239000007788 liquid Substances 0.000 claims description 51
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 36
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims description 36
- 239000003795 chemical substances by application Substances 0.000 claims description 35
- 230000003009 desulfurizing effect Effects 0.000 claims description 20
- 238000005086 pumping Methods 0.000 claims description 15
- 239000007787 solid Substances 0.000 claims description 15
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 13
- 229910052717 sulfur Inorganic materials 0.000 claims description 13
- 239000011593 sulfur Substances 0.000 claims description 13
- 230000009467 reduction Effects 0.000 claims description 12
- 238000012544 monitoring process Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000004064 recycling Methods 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 18
- 230000015572 biosynthetic process Effects 0.000 description 8
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- 231100000331 toxic Toxicity 0.000 description 7
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000001802 infusion Methods 0.000 description 2
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- 229940079593 drug Drugs 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
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- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
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- 238000010992 reflux Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
- E21B21/063—Arrangements for treating drilling fluids outside the borehole by separating components
- E21B21/067—Separating gases from drilling fluids
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
- E21B21/068—Arrangements for treating drilling fluids outside the borehole using chemical treatment
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/08—Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure
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- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
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Abstract
The invention discloses a method for hermetically removing harmful gas in drilling fluid, and relates to the technical field of oil drilling hermetic drilling processes. The drilling fluid containing harmful gas returns to the ground from the well, and the harmful gas in the drilling fluid is separated out through three-stage separation treatment.
Description
Technical Field
The invention relates to the technical field of oil drilling closed drilling processes, in particular to a method for removing harmful gas in drilling fluid in an atmosphere isolated closed drilling circulation system, and more particularly relates to a method for removing harmful gas in drilling fluid in a closed manner.
Background
The underbalanced drilling refers to a drilling process when the pressure of a drilling fluid column of a shaft is smaller than the pressure of a stratum in the drilling process, has the advantages of improving the drilling efficiency, discovering and protecting a reservoir, improving the yield of oil gas and the like, and has wide market prospect at home and abroad. During underbalanced drilling, formation fluid enters the wellbore and returns to the surface with the drilling fluid, since the formation pressure is greater than the bottom hole fluid column pressure. The returned fluid contains volatile hydrocarbon gas or hydrogen sulfide and other toxic and harmful gases. At present, the domestic main ground treatment equipment generally adopts a gas-liquid two-phase separator, and due to certain pressure in the device, the gas-liquid two-phase separator can only separate most slug flow or large bubble gas in the drilling fluid, and the higher the pressure is, the more adverse to the separation of the gas is. Harmful gas such as hydrogen sulfide in the form of small bubbles which is difficult to separate is also left in the drilling fluid. If the drilling fluid which is not completely separated and cleaned is discharged into an open device such as an oil skimming tank or a vibrating screen, poisonous and harmful gases such as hydrogen sulfide and the like are volatilized to cause serious threats to well site personnel and the surrounding environment. Thus, when drilling operations are currently performed in sulfur-bearing formations, underbalanced drilling techniques cannot be used when the hydrogen sulfide concentration is greater than 50 ppm. Even during conventional overbalanced drilling (i.e., the pressure of the drilling fluid column in the wellbore is greater than the pressure of the formation), when a formation containing unpredictable toxic and harmful gases such as hydrogen sulfide is drilled, the formation gases volatilized into the atmosphere will cause harm to personnel and the environment if no relevant surface gas treatment equipment is provided.
With the promulgation of the new "safety production law of the people's republic of China" and the "environmental protection law of the people's republic of China", the environment protection and the safety production are increasingly emphasized and strict by the nation and the society. The process method for completely and hermetically removing toxic and harmful gases in the drilling fluid in the drilling process becomes a necessary trend.
The invention discloses an invention patent with a publication number of CN101525993A, namely a method for monitoring and controlling hydrogen sulfide in sulfur-bearing stratum underbalanced drilling well in 2009 and 9 days in 2009, wherein the invention patent is characterized in that the content of hydrogen sulfide in drilling fluid is monitored when the drilling fluid passes through a closed sampler, a monitored hydrogen sulfide content signal is input into a control system, the control system converts the monitored hydrogen sulfide content signal into the amount of a required desulfurizing agent and sends an instruction, and the desulfurizing agent is injected into a four-phase separator to react the hydrogen sulfide in the drilling fluid with the desulfurizing agent so as to remove residual hydrogen sulfide.
In the method for treating hydrogen sulfide in the prior art, the excessive addition of the sulfur removal agent into the drilling fluid can affect the performance of the drilling fluid material to a certain extent, so that the addition amount of the sulfur removal agent is limited to a certain extent, and after the addition amount of the sulfur removal agent is limited, the removal effect and efficiency of the hydrogen sulfide can be affected, and the hydrogen sulfide in the drilling fluid can not be removed well.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention provides a method for hermetically removing harmful gas in drilling fluid, which can be used for treating harmful gases such as hydrogen sulfide and the like in different forms in the drilling fluid in a grading manner in a drilling fluid ground treatment system completely isolated from the atmosphere, completely avoids the harm to personnel, equipment and the environment after the toxic and harmful gas invades the drilling fluid and volatilizes in the atmosphere environment, prevents accidents, and meets the urgent requirements of drilling safety and environmental protection.
In order to solve the problems in the prior art, the invention is realized by the following technical scheme:
the method for removing harmful gas in drilling fluid in a sealed way, the drilling fluid containing harmful gas returns to the ground from a well and enters a ground drilling fluid sealing treatment system, and is characterized in that: the drilling fluid containing harmful gas returns out of the well, enters a primary separator after pressure reduction, the drilling fluid separated by the primary separator is directly guided into a secondary separator for secondary separation, and the working pressure of the secondary separator is less than that of the primary separator; the drilling fluid separated by the secondary separator is pumped into a third-stage separation system by a centrifugal pump, and in the third-stage separation system, the participating gas is separated by adopting a structural mode of combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; introducing the gas separated from each stage of separation system into a gas treatment device for treatment; and the drilling fluid separated by the third-stage separation system is discharged into a solid control system for treatment, and the drilling fluid treated by the solid control system is discharged into a well for circulation.
A gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, and when the existence of unseparated gas is monitored, a desulfurizing agent is injected into a liquid inlet pipeline of the third-stage separation system through a dosing device, so that hydrogen sulfide in the drilling fluid in the third-stage separation system reacts with the desulfurizing agent; if the gas is still completely treated, injecting a sulfur removal agent into a liquid inlet pipeline of the secondary separator through a dosing device, and reacting hydrogen sulfide in the drilling fluid in the secondary separator with the sulfur removal agent; and by analogy, a desulfurizing agent is injected into a liquid inlet pipeline of the primary separator through a dosing device, so that hydrogen sulfide in the drilling fluid in the primary separator reacts with the desulfurizing agent.
A gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, when the existence of unseparated gas is monitored, a branch pipeline is arranged on a liquid discharge pipeline of the third-stage separation system, and unseparated and clean drilling fluid discharged from the third-stage separation system is reinjected into the third-stage separation system for recirculation treatment; if the drilling fluid can not be completely separated, a branch pipeline is arranged on a liquid discharge pipeline of the secondary separator, and the drilling fluid separated by the secondary separator is injected back into the secondary separator for recycling treatment.
And (4) bypassing the solid control system to directly inject the drilling fluid treated in the third-stage separation system into the well for circulating treatment.
In the third-stage separation system, the separation of the participating gases is carried out by adopting a structural mode combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; the method specifically comprises the following steps: the drilling fluid treated by the secondary separator enters a separation tank in a third-stage separation system, centrifugal separation is carried out, gas after centrifugal separation is separated from the upper part of the separation tank, and the separated drilling fluid falls into the separation tank; heating and adjusting the drilling fluid through a drilling fluid heating system; stirring and disturbing fluid at the bottom of the drilling fluid in the separation tank; pumping the drilling fluid at the drilling fluid outlet in the separation tank to the liquid level of the drilling fluid for spraying; arranging a vacuum system in the separating tank, and pumping the separating tank to a negative pressure state through the vacuum system; the vacuum system pumps the gas in the separation tank to the gas treatment device.
Entering a primary separator after pressure reduction, specifically comprising: and the returned drilling fluid is subjected to pressure reduction through a throttling manifold, and the throttling manifold comprises a first-stage throttling manifold or a multi-stage throttling manifold which are connected in series.
In the third stage separation system, the gas treated by the gas treatment device is conveyed to an ignition device for ignition and combustion.
And in the third-stage separation system, collecting the gas treated by the gas treatment device, and injecting the collected treated gas into the well for repeated circulation.
Compared with the prior art, the beneficial technical effects brought by the invention are as follows:
1. the method is characterized in that a three-stage separation system is adopted to carry out step-by-step depressurization separation on high-pressure fluid containing toxic and harmful gases such as hydrogen sulfide and the like returned from a wellhead, and harmful gases of bubbles in different forms in the drilling fluid are subjected to stage treatment. In the third-stage separation system, a structural mode combining negative pressure extraction separation, under-liquid turbulence, fluid temperature control and the like is adopted to separate residual micro-bubble gas which is difficult to separate, so that the separation efficiency of the equipment is improved to the maximum extent. The invention is provided with gas treatment equipment for desulfurization and the like to carry out environment-friendly treatment on the separated gas. The separated gas can be ignited and combusted, and can be injected into the well for circulation after being re-pressurized in the gas-filled well drilling, so that the consumption of equipment resources is saved, and the use cost is reduced.
2. The invention has the unique advantages that the invention also adopts three-level safety measures of medicament injection, bypass reflux and circulating reinjection to control the drilling fluid treatment control process when the ground separation system can not completely separate the toxic and harmful gases, and avoids the harm to personnel and environment caused by the volatilization of the toxic and harmful gases such as hydrogen sulfide and the like to the atmosphere in the solid control system to the maximum extent. Meanwhile, the pressure of the vertical pipe before the single connection is released to a separation system, so that the safety of drilling operation is improved, and the requirements of safety and environmental protection are met.
3. The drilling fluid containing harmful gases such as hydrogen sulfide returns to the ground from a wellhead through a pipeline a and enters a ground drilling fluid closed treatment system. The pressure of the returned fluid is high, and the throttling pipe with high pressure level is arranged to reduce the pressure of the system, so that the well control risk caused by that the returned drilling fluid is directly led into the separator and possibly exceeds the working pressure of equipment is avoided. If the pressure of the fluid returned from the wellhead is too high when drilling in the reservoir section of the high-pressure high-sulfur-content gas well, the ground circulating pressure can be reduced step by adopting a mode of serially connecting the double throttling system devices, so that the overweight working load of a single throttling manifold is avoided, the foaming phenomenon of the drilling fluid caused by the overhigh pressure drop is also avoided, and the separation efficiency is improved.
4. The high-pressure fluid enters the primary separator through a pipeline b after being depressurized through a throttle manifold, and the primary separator has certain working pressure (more than or equal to 2.5 MPa). Because the higher the pressure is, the lower the separation efficiency of the separator is, the primary separator can only separate the gas which returns the plug flow bubbles or large bubbles in the middle section of the drilling fluid. The operating pressure of the pipeline should be greater than the operating pressure of the primary separator. In the present invention, the primary separator 3 may be a conventional liquid-gas separator or other known type of separator.
5. And directly introducing the drilling fluid separated by the primary separator into a secondary separator for secondary separation through a pipeline c. The working pressure of the second-stage separator is smaller than that of the primary separator and is about 1.0-2.5 MPa. In the second-stage separation, most of gas in the drilling fluid is separated completely, but the micro bubbles with the diameter less than 3mm are still not easy to be completely separated under certain pressure. The operating pressure of line c should be greater than the operating pressure of the second stage separator. In the present invention, the second stage separator may be a conventional liquid-gas separator, a multi-phase separator, or other known type of separator.
6. And pumping the drilling fluid separated by the second-stage separator into a third-stage separation system by a high-speed centrifugal sand pump through a pipeline. And if the pressure of the second-stage separation system is higher, the drilling fluid is directly discharged into the third-stage separation system by pressure through a bypass pipeline. The working pressure of the third-stage separation system can be adjusted through a negative pressure system, and the pressure range is about-0.05-0.5 MPa. In the third-stage separation system, the residual micro gas is separated by adopting a structure mode combining negative pressure extraction separation, under-liquid turbulence, fluid temperature control and the like. The third stage separation system in the present invention may be a known negative pressure separation apparatus or a specially designed gas-liquid separation system.
7. In the third-stage separation system, the drilling fluid is subjected to temperature rise regulation in the separation tank through the drilling fluid heating system, the solubility of hydrogen sulfide is reduced under the influence of the temperature rise of the drilling fluid, and part of hydrogen sulfide gas is separated from the drilling fluid. The stirring mechanism is arranged in the tank, so that fluid at the bottom of the drilling fluid can be stirred and disturbed, and the separation of hydrogen sulfide gas in the high-viscosity drilling fluid is facilitated. Meanwhile, the underwater turbulent flow spraying mechanism is arranged in the middle of the tank, drilling fluid near a drilling fluid outlet in the tank is pumped to the bottom layer drilling fluid in the middle of the tank to be sprayed, and hydrogen sulfide of micro bubbles which are not easy to separate and are at the bottom of the drilling fluid can be circulated to the liquid level to be degassed and separated. The upper space in the tank is pumped to a negative pressure state by a vacuum system, so that the diameter of hydrogen sulfide bubbles in the drilling fluid is increased along with the reduction of pressure in the process of rising to the liquid level, the buoyancy is increased, and the rapid rising and separation of the bubbles are facilitated.
Drawings
FIG. 1 is a schematic process flow diagram of the process of the present invention;
FIG. 2 is a schematic process flow diagram of the process of the present invention for different process requirements;
FIG. 3 is a schematic flow diagram of a third stage separation system of the present invention.
Detailed Description
Example 1
Referring to the attached fig. 1, this embodiment discloses:
a method for removing harmful gas in drilling fluid in a closed manner comprises the steps that drilling fluid containing harmful gas returns out of the ground from a well and enters a ground drilling fluid closed treatment system, drilling fluid containing harmful gas returns out of the well, the drilling fluid enters a primary separator after being subjected to pressure reduction, the drilling fluid separated by the primary separator is directly guided into a secondary separator for secondary separation, and the working pressure of the secondary separator is smaller than that of the primary separator; the drilling fluid separated by the secondary separator is pumped into a third-stage separation system by a centrifugal pump, and in the third-stage separation system, the participating gas is separated by adopting a structural mode of combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; introducing the gas separated from each stage of separation system into a gas treatment device for treatment; and the drilling fluid separated by the third-stage separation system is discharged into a solid control system for treatment, and the drilling fluid treated by the solid control system is discharged into a well for circulation.
Example 2
Referring to the attached fig. 1, this embodiment discloses:
a method for removing harmful gas in drilling fluid in a closed manner comprises the steps that drilling fluid containing harmful gas returns out of the ground from a well and enters a ground drilling fluid closed treatment system, drilling fluid containing harmful gas returns out of the well, the drilling fluid enters a primary separator after being subjected to pressure reduction, the drilling fluid separated by the primary separator is directly guided into a secondary separator for secondary separation, and the working pressure of the secondary separator is smaller than that of the primary separator; the drilling fluid separated by the secondary separator is pumped into a third-stage separation system by a centrifugal pump, and in the third-stage separation system, the participating gas is separated by adopting a structural mode of combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; introducing the gas separated from each stage of separation system into a gas treatment device for treatment; and the drilling fluid separated by the third-stage separation system is discharged into a solid control system for treatment, and the drilling fluid treated by the solid control system is discharged into a well for circulation. A gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, and when the gas which is not separated is detected to exist, the gas can be treated by adopting one or more of the following three methods:
A. a gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, and when the existence of unseparated gas is monitored, a desulfurizing agent is injected into a liquid inlet pipeline of the third-stage separation system through a dosing device, so that hydrogen sulfide in the drilling fluid in the third-stage separation system reacts with the desulfurizing agent; if the gas is still completely treated, injecting a sulfur removal agent into a liquid inlet pipeline of the secondary separator through a dosing device, and reacting hydrogen sulfide in the drilling fluid in the secondary separator with the sulfur removal agent; by analogy, a desulfurizing agent is injected into a liquid inlet pipeline of the primary separator through a dosing device, so that hydrogen sulfide in the drilling fluid in the primary separator reacts with the desulfurizing agent;
B. a gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, when the existence of unseparated gas is monitored, a branch pipeline is arranged on a liquid discharge pipeline of the third-stage separation system, and unseparated and clean drilling fluid discharged from the third-stage separation system is reinjected into the third-stage separation system for recirculation treatment; if the drilling fluid can not be completely separated, a branch pipeline is arranged on a liquid discharge pipeline of the secondary separator, and the drilling fluid separated by the secondary separator is injected back into the secondary separator for recycling treatment;
C. and (4) bypassing the solid control system to directly inject the drilling fluid treated in the third-stage separation system into the well for circulating treatment.
The three treatment methods can be used by one treatment method, or can be combined in pairs or used simultaneously.
Example 3
As another preferred embodiment of the present invention, the present embodiment discloses:
a method for removing harmful gas in drilling fluid in a closed manner comprises the steps that drilling fluid containing harmful gas returns out of the ground from a well and enters a ground drilling fluid closed treatment system, drilling fluid containing harmful gas returns out of the well, the drilling fluid enters a primary separator after being subjected to pressure reduction, the drilling fluid separated by the primary separator is directly guided into a secondary separator for secondary separation, and the working pressure of the secondary separator is smaller than that of the primary separator; the drilling fluid separated by the secondary separator is pumped into a third-stage separation system by a centrifugal pump, and in the third-stage separation system, the participating gas is separated by adopting a structural mode of combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; introducing the gas separated from each stage of separation system into a gas treatment device for treatment; and the drilling fluid separated by the third-stage separation system is discharged into a solid control system for treatment, and the drilling fluid treated by the solid control system is discharged into a well for circulation. Entering a primary separator after pressure reduction, specifically comprising: and the returned drilling fluid is subjected to pressure reduction through a throttling manifold, and the throttling manifold comprises a first-stage throttling manifold or a multi-stage throttling manifold which are connected in series. In the third stage separation system, the gas treated by the gas treatment device is conveyed to an ignition device for ignition and combustion.
A gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, when the existence of unseparated gas is monitored, the gas monitoring instrument is arranged at the liquid discharge port of the third-stage separation system, and when the existence of unseparated gas is monitored, a desulfurizing agent is injected into a liquid inlet pipeline of the third-stage separation system through a dosing device, so that hydrogen sulfide in the drilling fluid in the third-stage separation system reacts with the desulfurizing agent; if the gas is still completely treated, injecting a sulfur removal agent into a liquid inlet pipeline of the secondary separator through a dosing device, and reacting hydrogen sulfide in the drilling fluid in the secondary separator with the sulfur removal agent; by analogy, a desulfurizing agent is injected into a liquid inlet pipeline of the primary separator through a dosing device, so that hydrogen sulfide in the drilling fluid in the primary separator reacts with the desulfurizing agent;
when the existence of unseparated gas is monitored, a branch pipeline is arranged on a liquid discharge pipeline of the third-stage separation system, and unseparated and clean drilling fluid discharged from the third-stage separation system is reinjected into the third-stage separation system again for recycling treatment; if the drilling fluid can not be completely separated, a branch pipeline is arranged on a liquid discharge pipeline of the secondary separator, and the drilling fluid separated by the secondary separator is injected back into the secondary separator for recycling treatment;
in this embodiment, in the third stage separation system, the gas treated by the gas treatment device is collected, and the collected treated gas is injected into the well for repeated circulation.
Example 4
Referring to the attached drawings 1 and 2 of the specification, the embodiment discloses as a further preferred embodiment of the invention:
a method for removing harmful gas in drilling fluid in a sealed mode includes that the drilling fluid containing harmful gas such as hydrogen sulfide returns to the ground from a wellhead 1 through a pipeline a and enters a ground drilling fluid sealed processing system. The pressure of the returned fluid is high, a high-pressure-level throttle manifold 2 is arranged to reduce the system pressure, the high-pressure fluid is reduced in pressure through the throttle manifold 2 and then enters the primary separator 3 through a pipeline b, and the primary separator 3 has a certain working pressure (greater than or equal to 2.5 MPa). Since the higher the pressure, the lower the separation efficiency of the separator, the primary separator 3 can only separate the gas returning to the section of the drilling fluid, which is a slug flow bubble or a large bubble. The operating pressure of line b should be greater than the operating pressure of the primary separator 3. In the present invention, the primary separator 3 may be a conventional liquid-gas separator or other known type of separator.
The drilling fluid separated by the primary separator 3 is directly led into the secondary separation system 4 through a pipeline c for secondary separation. The working pressure of the second-stage separation system 4 is smaller than that of the primary separator and is about 1.0-2.5 MPa. In the second-stage separation, most of gas in the drilling fluid is separated completely, but the micro bubbles with the diameter less than 3mm are still not easy to be completely separated under certain pressure. The operating pressure of line c should be greater than the operating pressure of the second stage separation system 4. In the present invention, the second stage separation system 4 may be a conventional liquid-gas separator, a multi-phase separator, or other known type of separator.
And pumping the drilling fluid separated by the second-stage separation system 4 into the third-stage separation system 5 by a high-speed centrifugal sand pump 30 through a pipeline d. If the pressure in the second stage separation system 4 is high, the drilling fluid can be directly discharged into the third stage separation system 5 by pressure through a bypass line by closing the valve 39 and opening the valve 38. The working pressure of the third-stage separation system 5 can be adjusted by a negative pressure system, and the pressure range is about-0.05-0.5 MPa. In the third-stage separation system 5, the residual micro gas is separated by adopting a structure mode combining negative pressure extraction, under-liquid turbulence, fluid temperature control and the like. The third stage separation system 5 in the present invention may be a known negative pressure separation apparatus or a specially designed gas-liquid separation system.
The gases separated in the separation systems of the respective stages are introduced into the gas treatment apparatus 6 through the lines h, i, j, respectively, and check valves 13, 14, 15 are provided in the lines to prevent gas from flowing backward. The gas separated by the third stage separation system needs to be pumped into the treatment device 6 by suction equipment such as a vacuum pump 16, and the device can be gas treatment equipment such as desulfurization drying equipment. The treated gas is connected to the ignition device 7 through pipelines k and l for ignition and combustion, and a fire damper 18 is arranged on the pipeline l close to the ignition device to prevent flame from returning when the gas flow is small. If the separated gas also contains nitrogen, carbon dioxide or hydrocarbon gas in the gas-filled well, the separated gas can be collected, the valve 17 on the pipeline l is closed, the valves 20 and 22 on the pipeline m are opened, the multiphase pressure pump 19 is opened to pressurize the gas, and the gas is injected into the well again through the pipelines m and g to participate in the repeated circulation. The valve 23 can also be opened to supplement the amount of gas injected through line n by means of the gas injection device 8. The pipelines m and n are both provided with check valves 24 and 21.
The drilling fluid separated by the three-stage separation system can be directly discharged into the solid control system 10 through the centrifugal sand pump 36 through the pipelines u and e for further treatment, and then is pumped into the well again through the water feeding tank 11 and the mud pump 12 through the pipeline f for circulation. The exhaust port of each stage of separation system is equipped with a harmful gas monitoring instrument, and the liquid outlet of the third stage of separation system is also equipped with a gas monitoring instrument, when the existence of unseparated gas is monitored, the gas can be treated by adopting three-stage treatment measures or by combining mode.
The first-level measure is to open the dosing device 9 and the injection pump 37 thereof, open the valve 33 and inject the relevant treatment agents such as the desulfurizing agent and the like into the liquid inlet pipeline d of the third-level separation system 5 through the pipeline 9c, and the direct injection of the agents into the pipeline has the advantage that the agents can be better mixed with the drilling fluid and react. If the gas is not completely treated, valve 27 is opened again to inject the chemical into liquid inlet line c of second stage separation system 4 via line 9 b. By analogy, when dosing is required, valve 26 is opened to inject the agent via line 9a into inlet manifold b of primary separator 3. It should be noted that the infusion pressure of the medication infusion pump 37 should be higher than the fluid pressure in line b. Each injection line is provided with a one- way valve 25, 28, 32.
The addition of excessive amount of the medicament has certain influence on the performance of the drilling fluid material. A second-stage measure can be taken, namely, firstly, the valve 35 is opened to communicate with a branch pipeline channel o on a liquid discharge pipeline u of the third-stage separation system 5, and the drilling fluid which is not separated completely is reinjected into the third-stage separation system 5 again to be subjected to circulating separation again; if the drilling fluid is not separated completely, the valve 31 is opened to communicate with the branch channel p of the drainage pipeline d of the second-stage separation system 4, and the drilling fluid separated by the second-stage separation system 4 is injected back into the system for circulating separation again. Check valves 29 and 34 are provided in the bypass return lines o and p, respectively, to prevent backflow.
If the amount of gas returned from the formation is too great and all separation equipment cannot fully handle it and the circulation of drilling fluid cannot be stopped, a third level of action may be taken, namely opening valves 40, 44 and closing valves 35, 41, 42, 43. And directly injecting the drilling fluid still containing gas after the treatment of the ground three-stage separation system into the well through pipelines v, q and f by a mud pump 12 for circulating treatment, thereby completing three-stage prevention and control measures for gas treatment.
In the process of tripping, the operations such as connecting a single pipe and the like can be carried out only by relieving the pressure of the stand pipe, and in the drilling fluid closed circulation treatment system, the valves 38 and 47 can be opened, and the pressure of the stand pipe can be discharged into the third-stage separation system 5 through pipelines r and t. Valve 45 can also be opened to vent directly into second stage separation system 4 via lines r, s if the pressure differential between the riser and the separation system is excessive. The pipelines s, t are provided with check valves 46, 48.
Example 5
Referring to fig. 3 of the specification as another preferred embodiment of the present invention, the present embodiment discloses:
in the embodiment, in the third-stage treatment system, the drilling fluid treated by the second-stage separator enters the separation tank 100 in the third-stage separation system, and is subjected to centrifugal separation, the gas after the centrifugal separation is separated from the upper part of the separation tank, and the separated drilling fluid falls into the separation tank; the drilling fluid is subjected to temperature rise regulation through a drilling fluid heating system 200; stirring and disturbing fluid at the bottom of the drilling fluid in the separation tank; pumping the drilling fluid at the drilling fluid outlet in the separation tank to the liquid level of the drilling fluid for spraying; arranging a vacuum system 300 in the separation tank, and pumping the separation tank to a negative pressure state through the vacuum system; the vacuum system pumps the gas in the separation tank to the gas treatment device.
In the present invention, all valves, instruments, pumps, devices, etc. can be controlled by centralized control or other known means. The invention omits the treatment process of other phase substances such as rock debris, oil and the like in the returned drilling fluid, but the gas phase treatment process is included in the protection scope of the invention. If drilling is to be carried out in a lower pressure formation, the present invention can be simplified to a two-stage separation process, the flow diagram of which is shown in FIG. 2. Combinations of the various processes mentioned in this invention may also be used for the treatment, and all of the above processes are included in the scope of the present invention.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed as broadly as the appended claims.
Claims (5)
1. The method for removing harmful gas in drilling fluid in a sealed way, the drilling fluid containing harmful gas returns to the ground from a well and enters a ground drilling fluid sealing treatment system, and is characterized in that: the drilling fluid containing harmful gas returns out of the well, enters a primary separator after pressure reduction, the drilling fluid separated by the primary separator is directly guided into a secondary separator for secondary separation, and the working pressure of the secondary separator is less than that of the primary separator; the drilling fluid separated by the secondary separator is pumped into a third-stage separation system by a centrifugal pump, and in the third-stage separation system, the participating gas is separated by adopting a structural mode of combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; introducing the gas separated from each stage of separation system into a gas treatment device for treatment; the drilling fluid separated by the third-stage separation system is discharged into a solid control system for treatment, and the drilling fluid treated by the solid control system is discharged into a well for circulation;
a gas monitoring instrument is arranged at a liquid discharge port of the third-stage separation system, and when the existence of unseparated gas is monitored, a desulfurizing agent is injected into a liquid inlet pipeline of the third-stage separation system through a dosing device, so that hydrogen sulfide in the drilling fluid in the third-stage separation system reacts with the desulfurizing agent; if the gas is not completely treated, injecting a sulfur removal agent into a liquid inlet pipeline of the secondary separator through a dosing device, and reacting hydrogen sulfide in the drilling fluid in the secondary separator with the sulfur removal agent; by analogy, a desulfurizing agent is injected into a liquid inlet pipeline of the primary separator through a dosing device, so that hydrogen sulfide in the drilling fluid in the primary separator reacts with the desulfurizing agent;
when the existence of unseparated gas is monitored, a branch pipeline is arranged on a liquid discharge pipeline of the third-stage separation system, and unseparated and clean drilling fluid discharged from the third-stage separation system is reinjected into the third-stage separation system again for recycling treatment; if the drilling fluid can not be completely separated, a branch pipeline is arranged on a liquid discharge pipeline of the secondary separator, and the drilling fluid separated by the secondary separator is injected back into the secondary separator for recycling treatment;
and if the gas amount returned from the stratum is too large, all the separation equipment cannot be completely treated, and the circulation of the drilling fluid cannot be stopped, bypassing the solid control system to directly inject the drilling fluid treated in the third-stage separation system into the well for circulation treatment.
2. The method for hermetically removing the harmful gases in the drilling fluid according to claim 1, wherein the method comprises the following steps: in the third-stage separation system, the separation of the participating gases is carried out by adopting a structural mode combining negative pressure pumping separation, under-liquid turbulence and fluid temperature control; the method specifically comprises the following steps: the drilling fluid treated by the secondary separator enters a separation tank in a third-stage separation system, centrifugal separation is carried out, gas after centrifugal separation is separated from the upper part of the separation tank, and the separated drilling fluid falls into the separation tank; heating and adjusting the drilling fluid through a drilling fluid heating system; stirring and disturbing fluid at the bottom of the drilling fluid in the separation tank; pumping the drilling fluid at the drilling fluid outlet in the separation tank to the liquid level of the drilling fluid for spraying; arranging a vacuum system in the separating tank, and pumping the separating tank to a negative pressure state through the vacuum system; the vacuum system pumps the gas in the separation tank to the gas treatment device.
3. A method for hermetically removing harmful gases in drilling fluid according to claim 1 or 2, wherein the method comprises the following steps: entering a primary separator after pressure reduction, specifically comprising: and the returned drilling fluid is subjected to pressure reduction through a throttling manifold, and the throttling manifold comprises a first-stage throttling manifold or a multi-stage throttling manifold which are connected in series.
4. A method for hermetically removing harmful gases in drilling fluid according to claim 1 or 2, wherein the method comprises the following steps: in the third stage separation system, the gas treated by the gas treatment device is conveyed to an ignition device for ignition and combustion.
5. A method for hermetically removing harmful gases in drilling fluid according to claim 1 or 2, wherein the method comprises the following steps: and in the third-stage separation system, collecting the gas treated by the gas treatment device, and injecting the collected treated gas into the well for repeated circulation.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108005600A (en) * | 2017-12-25 | 2018-05-08 | 中国石油集团川庆钻探工程有限公司 | Vacuum type closed vibrating screen |
| CN108222869A (en) * | 2017-12-25 | 2018-06-29 | 中国石油集团川庆钻探工程有限公司 | Safe and environment-friendly closed under-balanced drilling ground operation method |
| CN108104745A (en) * | 2017-12-25 | 2018-06-01 | 中国石油集团川庆钻探工程有限公司 | Safe and environment-friendly closed circulation drilling ground operation method |
| CN108194041A (en) * | 2017-12-25 | 2018-06-22 | 中国石油集团川庆钻探工程有限公司 | Method for removing hydrogen sulfide gas in well drilling |
| CN109184599B (en) * | 2018-08-22 | 2020-11-03 | 中国石油天然气股份有限公司 | Well-flushing return product treatment device and treatment method thereof |
| CN111140227A (en) * | 2019-11-06 | 2020-05-12 | 中国石油集团川庆钻探工程有限公司 | Rapid logging rock debris collecting method for closed drilling circulation system of sulfur-containing stratum |
| CN111206891A (en) * | 2019-11-06 | 2020-05-29 | 中国石油集团川庆钻探工程有限公司 | Closed automatic rock debris collecting device for sulfur-containing stratum |
| CN111140189A (en) * | 2019-11-06 | 2020-05-12 | 中国石油集团川庆钻探工程有限公司 | Quick logging rock debris collecting system of closed drilling circulation system of sulfur-containing stratum |
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