JP2018043221A - Water treatment method for oil and gas fields - Google Patents

Abstract

A technique for providing an accompanying water purification step in an oil / gas mixture treatment method. A digging step of extracting an oil / gas mixture containing gas, oil, accompanying water, and sludge in a plurality of oil fields and gas fields; a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank; Separating sludge and associated water in a separation tank and separating and storing the separated sludge and adjacent water in an adjacent tank or reservoir; transporting the associated water in the tank or reservoir to a waste well; and disposing the associated water in a waste well The method for treating an oil / gas mixture according to claim 1, further comprising a step of purifying an associated water at least immediately before the start of the transporting step. [Selection diagram] Fig. 1

Description

  The present invention relates to a technique for treating accompanying water that is simultaneously produced in a process of extracting oil / gas from an oil field / gas field.

When oil and gas are mined in conventional oil and gas fields, a large amount of associated water is produced, most of which is discarded in the disposal wells. In addition, (i) a large amount of water is consumed in “fracturing water” used in mining using technologies such as horizontal wells and hydraulic fracturing in unconventional oil and gas fields such as shale gas and tight oil. (Ii) Risk of leakage of chemicals to the neighborhood due to truck accidents that transport used fracturing water, etc. (iii) Groundwater sources such as chemical substances contained in fracturing water Leakage, (iv) Methane gas leakage from recovered fracturing water, (v) Landslide due to hydraulic fracturing using fracturing water, occurrence of earthquake, (vi) Increase in mining costs due to the above risk reduction measures (economic benefits) Problem).
Of these, the most concerned is (i) above, and it is said that 3,000 to 10,000 tons of water is used per well (oil well). Water use for hydraulic fracturing was stopped when drought caused serious water shortages. In addition, since used fracturing water contains many chemical substances, it poses potential risks to neighboring communities such as leakage due to accidents, and transports concrete walls and transportation near the groundwater source layer in the surface layer of vertical wells. There are concerns about leakage from previous reservoirs, leakage of methane gas, which is the main component of shale gas and has a global warming potential 20 times that of carbon dioxide, into the atmosphere, and landslides.

In addition, even in unconventional oil fields and gas fields that use a large amount of fracturing water, naturally, when extracting oil and gas, a large amount of accompanying water is produced together with the oil and gas. At present, most of the accompanying water is separated from oil / gas and, in some cases, sludge components, by gravity separation, and then discarded in a waste well.
However, the accompanying water separated by gravity separation is usually in a state where the oil component particles are still dispersed and the scale-generating substance (Total Dissolved Solid, TDS) is high. It cannot be disposed directly in the pond. Moreover, there is a limit to the amount of processing even when it is discarded in a disposal well.
Therefore, there is a need to provide an associated water treatment method for oil and gas fields that is more efficient and has a low environmental impact.

  Under the current state of the prior art described above, the problem to be solved by the present invention is to provide an associated water treatment method that is more efficient and has a lower environmental impact than the associated water produced from the oil and gas fields together with the oil and gas. Furthermore, it is to provide a method for reusing the treated accompanying water as fracturing water for unconventional oil and gas field mining.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have, for example, an accompanying water purification step that can be a desalination treatment step using a forward osmosis membrane system, at least in the transportation step described below. It can be carried out just before the start, concentrating the accompanying water to greatly reduce the transportation cost of the tank lorry to the waste well, and the purified accompanying water is also desalted and removes large oil particles at the same time Therefore, it can be discharged directly into rivers and ponds instead of being discarded in the disposal wells, and this is one of the fracturing water used for unconventional oil and gas field drilling. It has been found that it becomes possible to extract oil and gas more efficiently by reusing as a part, and the present invention has been completed.

That is, the present invention is as follows.
[1] The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank arranged at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the transportation step (IV).
[2] The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank arranged at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the disposal step (V).
[3] The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank arranged at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the transfer step (II).
[4] The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank arranged at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil fields and gas fields, wherein an associated water purification step is provided immediately before the start of the transfer step (II), the transport step (IV), and the disposal step (V).
[5] The oil field / gas according to any one of [1] to [4], wherein the associated water purified in the associated water purification step is reused as part of the fracturing water in the excavation step (I). Paddy water treatment method.
[6] The associated water purification step is a desalination treatment step using one or more systems selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, a distillation system, and a reverse osmosis membrane system. 1], [2], and an associated water treatment method for oil and gas fields according to any one of [4].
[7] The above [3] 3, wherein the accompanying water purification step is a desalination treatment step using one or more systems selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, and a distillation system. Associated water treatment method for oil and gas fields.
[8] In the accompanying water purification step immediately before the transfer step (II), one or more systems selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, and a distillation system are used, and the transport step ( IV) and the accompanying water purification step immediately before the disposal step (V), each independently, one or more selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, a distillation system, and a reverse osmosis membrane system The associated water treatment method for oil and gas fields according to [4] above, which uses a desalination treatment step using a system.
[9] The desalting treatment step includes the following steps:
The accompanying water is caused to counter-flow or co-current with the first osmotic material flow containing the thermal phase separation material having osmotic pressure through the forward osmosis membrane, and the water in the accompanying water is transferred to the first osmotic material flow. The water-rich first osmotic material stream is heated to a first separation temperature (T1) that is not less than the temperature (T0) at which the thermal phase separation material can be thermally separated and is not more than T0 + 30 ° C. A first separation step of separating A1) and a thermal phase separation substance-rich phase (B1); and heating the B1 phase to the first separation temperature (T1) + second separation temperature (T2) of T20 + T1 + 115 ° C A second separation step of separating the water-rich phase (A2) and the thermal phase separation substance-rich phase (B2);
The associated water treatment method for oil and gas fields according to any one of [1] to [8], wherein the process is a desalination treatment step using a forward osmosis membrane system.
[10] The desalting treatment step includes the following steps:
The accompanying water is counter-flowed or co-flowed with the salt-containing second osmotic substance flow through the forward osmosis membrane, and the water in the accompanying water is moved to the second osmotic substance flow to thereby form a second water-rich second. The osmotic material stream is mixed in a state that is incompatible with the first osmotic material stream containing the thermal phase separation material, and water is transferred to the first osmotic material stream so as to move the water-rich first osmotic material stream. Is heated to a first separation temperature (T1) not lower than the temperature (T0) of the thermal phase separation substance and not higher than T0 + 30 ° C., so that the water-rich phase (A1) and the thermal phase separation substance-rich phase ( A first separation step of separating into B1); and heating the B1 phase to the first separation temperature (T1) + second separation temperature (T2) of 20 ° C. or more and T1 + 115 ° C. or less to form a water-rich phase (A2) A second separation step for separating into a thermal phase separation substance-rich phase (B2);
The associated water treatment method for oil and gas fields according to any one of [1] to [8], wherein the process is a desalination treatment step using a forward osmosis membrane system.

  The associated water purified by the associated water treatment method for oil and gas fields according to the present invention is desalted and large oil particles have been removed, so instead of discarding in the disposal well, Since it can be discharged into rivers and ponds, it contributes to reducing environmental impacts such as drinking water pollution and earthquakes. Furthermore, if the accompanying water purification process is performed immediately before the start of the transportation process, the accompanying water is reduced in volume, so that the transportation cost of the tank lorry to the waste well can be greatly reduced. Furthermore, this purified associated water can be reused as a part of the fracturing water required in large quantities in the unconventional oil and gas field mining process.

FIG. 1 is an explanatory diagram for explaining each step in the accompanying water treatment in an oil field and a gas field, and locations where the accompanying water purification step is performed. FIG. 2 is a flow diagram of the first embodiment when the accompanying water purification step is a desalination treatment step using a forward osmosis membrane system. FIG. 3 is a flow diagram of the second embodiment when the accompanying water purification step is a desalination treatment step using a forward osmosis membrane system.

Hereinafter, embodiments of the present invention will be described in detail.
[Oil and gas fields]
In this specification, the term “oil field / gas field” is not only a conventional type oil field / gas field, but also an unconventional type which is an energy resource mined from other than oil fields and natural gas fields that have been developed in the past. Oil fields and gas fields, for example, crude oil field, shale oil field, oil sand field, sand oil field, natural gas field, shale gas field, coalbed methane field, and coal seam gas field.

[Drilling process]
In conventional oil and gas fields, it is common to mine several hundred meters in a vertical well. In the latter oil field, water and gas are reinjected using the EOR method to reduce oil and gas output. There is also a way to recover. Also, in general shale oil and gas mining, first, a vertical well is bent halfway, a horizontal well is drilled along a shale layer that is several thousand meters underground, and the fracture described below is performed there. Ring water is fed and a special sand grain called proppant is slid into the fracture made by applying pressure. This supports the fact that the fracture does not close naturally and enables continuous recovery of shale gas, tight oil, etc., and this process is called hydraulic fracturing (commonly called fracking).
In such a drilling process, an oil / gas mixture containing oil, gas, associated water, and sludge is taken out from the well.

[Fracturing water]
In this specification, the term “fracturing water” or fracturing fluid uses techniques such as horizontal wells and hydraulic fracturing in unconventional oil and gas fields such as shale gas and tight oil. It means the liquid used in mining and is also called flacking water.
Generally, 90% or more of the fracturing fluid is water, and the remaining few% is proppant, and it contains chemicals such as acids, preservatives, gelling agents, friction reducing agents and the like in a proportion of less than 1%. .

[Built water]
In the present specification, the term “associated water” means water associated with oil, gas, and sludge taken out in the drilling of the oil field / gas field. Usually contains TDS component.
The TDS concentration in the associated water produced from oil and gas fields is generally 500 ppm to 300,000 ppm. When the TDS concentration is 500 ppm or less, the accompanying water can be discharged into rivers and ponds without purification. In addition, the content of oil droplets in associated water produced from oil and gas fields is generally 50 ppm or more and 500,000 ppm. When this oil droplet content is less than the discharge regulation value, it can be discharged into a river or pond as it is.

[Transfer process]
The oil / gas mixture collected from each oil well is continuously transferred to the following gravity separation tanks through piping (generally, a length within a radius of about 1 mile from the gravity separation tank).

[Gravity separation tank, reservoir]
In this specification, the term “gravity separation tank” refers to the separation of associated water and sludge from oil and gas by the action of gravity from the mixture of oil, gas, associated water and sludge produced from oil and gas fields. It means a single-stage or multi-stage tank or / and a pit. The “weight separation tank” is also called a separation tank, a baffle tank, a vortex tank, a heater treater, and the like.
Accompanying water and sludge are temporarily stored in a reservoir (generally about 5000 ton) located adjacent to the gravity separation tank.
Gravity separation tanks and reservoirs are generally installed for every 10 wells. Currently, the distance from oil and gas wells to gravity separation tanks tends to be within a mile radius.

[Transportation process, disposal process]
The accompanying water temporarily stored in the reservoir is transported by tank lorry to a common waste well located at a predetermined distance (generally about 5 to 50 miles) from the reservoir, and finally in the common waste well. Returned deep underground and discarded.
Common waste wells are generally installed for every 20 gravity separation tanks and 20 reservoirs according to the size of the oil and gas fields. In this case, n = 20 in FIG. The distance from the gravity separation tank to the reservoir tends to be within 100 meters, and the distance from the reservoir to the waste well tends to be 5 miles or more and 50 miles or less.

[Accompanying water purification process]
The associated water purification process used in the present invention uses a system including a desalination treatment facility, and may include an oil removal facility and a particulate removal facility.
As shown in FIG. 1, in one embodiment, an accompanying water purification step is provided immediately before the start of the transportation step, and the accompanying water concentrated and reduced in the accompanying water purification step is discarded in a waste well, The purified accompanying water is discharged into rivers and ponds or reused as part of the fracturing water. In another embodiment, an accompanying water purification process is provided immediately before the start of the separation / storage process, and the accompanying water concentrated and reduced in the accompanying water purification process is discarded in a waste well and purified. The accompanying water is discharged into rivers and ponds or reused as part of the fracturing water. In another embodiment, an accompanying water purification step is provided immediately before the start of the disposal step, and the accompanying water concentrated and reduced in the accompanying water purification step is discarded in the disposal well and purified Are discharged into rivers and ponds or reused as part of the fracturing water. Furthermore, in another embodiment, the said embodiment can be combined arbitrarily.

The associated water purification process can be a desalting process using one or more systems selected from the group consisting of forward osmosis membrane systems, membrane distillation systems, distillation systems, and reverse osmosis membrane systems. The equipment can be a nanofiltration system, a crystallizer system, or a water softening system.
For treatment of associated water produced from oil and gas fields, a forward osmosis membrane system and a membrane distillation system that can treat water with high salt concentration and high TDS concentration in a compact and inexpensive manner are particularly preferred.
The accompanying water purification step may be accompanied by an oil removal facility. The oil removal equipment is often selected from pressurized flotation filtration equipment represented by IGF / DGF / DAF, oxidation equipment, biological treatment equipment, hydrocyclone equipment, etc., but is not limited thereto.
The accompanying water purification step may be accompanied by a particulate removal facility. Fine particle removal equipment includes multimedia filter equipment, walnut shell filter equipment, sand filtration equipment, microfiltration membrane equipment, microfiltration equipment, ultrafiltration membrane equipment, ultrafiltration equipment, IGF / DGF / DAF Although it is often selected from representative pressurized flotation filtration equipment, coagulation sedimentation equipment, hydrocyclone equipment, etc., it is not limited to this.

[Two-stage desalting (heated multi-stage separation)]
Here, a desalination treatment facility using a forward osmosis membrane system will be described as an example and described in detail with reference to the drawings.
FIG. 2 is a flow diagram of the first embodiment when the accompanying water purification step is a desalination treatment step using a forward osmosis membrane system. The accompanying water 102 containing water 101 is caused to flow countercurrently or in parallel with the first osmotic material stream 103 containing the thermal phase separation material through the semipermeable membrane 104, and the water 101 is made into the first osmotic material stream 103. The stream 105 is moved to obtain a stream 105, and the stream 105 is heated by the heat exchanger 106 to a temperature at which the thermal phase separation material is thermally separated, and the first water rich stream 108 and the first thermal phase separation material rich stream 109 are separated in the separation device 107. To separate. The first thermal phase separation rich stream 109 is heated to a temperature higher than that of the first stage thermal phase separation process in the heat exchanger 113, and the second water rich stream 115 and the second thermal phase separation substance rich stream 116 are separated in the separation device 114. The second water-rich stream 115 is filtered through the filtration membrane 110 to obtain purified water 111 and a membrane recovery stream 112. The second thermal phase separated material rich stream 116 is reused as the first osmotic material stream 103. At this time, the first water-rich stream 108 is mixed with the membrane recovery stream 112, for example, but may be mixed with the direct stream 105 or with the feed stream 102. In some cases, the first water rich stream 108 may be provided with another post-treatment device. The membrane recovery stream 112 is also mixed with, for example, the stream 105, but may be mixed with the second hot phase separated material rich stream 116 or may be mixed with the feed stream 102. Then, the concentrated stream 117 is injected into the waste well and discarded as in the conventional case, and the purified water 111 is reused as fracturing water. Further, this two-stage desalting method may be only the first stage thermal phase separation process or the second stage thermal phase separation process.

  FIG. 3 is a flow diagram of the second embodiment when the accompanying water purification step is a desalination treatment step using a forward osmosis membrane system. The accompanying water 202 containing water 201 is caused to flow countercurrently or in parallel with the second osmotic material stream 203 containing salt through the semipermeable membrane 204, and the water 201 is moved to the second osmotic material stream 203. , A flow 205 is brought into contact with the first osmotic material stream 206 containing the thermal phase separation material from the second osmotic material stream 203, the first osmotic material stream 206 and the water 201 in the separation device 207. And is heated to a temperature at which the heat phase is separated by the heat exchanger 209, and the first water rich stream 211 and the first osmotic material stream (first heat phase separated material rich stream) 212 are separated by the separation device 210. To separate. The first thermal phase separated material rich stream 212 is heated again to a temperature higher than that in the first stage thermal phase separation process by the heat exchanger 216, and the second water rich stream 218 and the second thermal phase separated material are separated by the separation device 217. Separating into the rich stream 219, the second thermal phase separated substance rich stream 219 is reused as the first osmotic substance stream 206, and the second water rich stream 218 is filtered through the filtration membrane 213 to be purified water 214 and membrane recovery stream 215. Get. At this time, the first water-rich stream 211 is mixed with, for example, the membrane recovery stream 215, but may be mixed directly with the stream 205 or with the feed stream 202. In some cases, the first water-rich stream 211 may be provided with another post-treatment device. The membrane recovery stream 215 is also mixed with, for example, the stream 205, but may be mixed with the stream 208, may be mixed with the accompanying water 202, or may be provided with another post-treatment device depending on circumstances. Then, the concentrated stream 220 is injected into the waste well and discarded in the same manner as before, and the purified water 214 is reused as fracturing water. Further, this two-stage desalting method may be performed only in the first-stage thermal phase separation process or only in the second-stage thermal phase separation process.

  The semipermeable membrane has pores sized to allow the accompanying water to pass but not to pass the solute. A reverse osmosis membrane can also be used, but a forward osmosis membrane is preferred. The material of the film is not particularly limited, and examples thereof include cellulose acetate, polyamide, polybenzimidazole, and polyvinyl alcohol. The form of the semipermeable membrane and the form of the membrane module are not particularly limited, and in the form of the semipermeable membrane, any of a flat membrane, a hollow fiber membrane, etc. may be used. A hollow fiber membrane is preferred from the viewpoint of effective use of the membrane. In the form of the membrane module, any of a plate and frame type, a hollow fiber type, a spiral type and the like may be used. A forward osmosis process is adopted as a method of permeating the solvent. The membrane surface through which the osmotic material flow flows may be on the active layer side or on the opposite side of the active layer.

  For osmotic streams containing salt as the main component of the solute, for example, sodium hydroxide, sodium carbonate, sodium silicate, sodium sulfate, sodium phosphate, sodium formate, sodium succinate, sodium tartrate, lithium sulfate, ammonium sulfate, carbonate Ammonium, ammonium carbamate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, sodium chloride, magnesium chloride, disodium monohydrogen phosphate, monosodium dihydrogen phosphate, potassium phosphate, potassium carbonate, manganese sulfate Sodium citrate, sodium thiosulfate, sodium sulfite and the like can be used. These penetrants can be used alone or in combination.

  The thermal phase separation substance refers to a substance that is phase-separated from the solvent by heating the solution in a state dissolved in the solvent. Water-rich refers to a solution having a lower concentration of the thermal phase separation substance in the two-phase solution subjected to the thermal phase separation, and a solution having a higher concentration of the thermal phase separation substance is rich in the thermal phase separation substance. It is called a solution.

  As the thermal phase separation substance, polyalkylene polymer, polyvinyl alcohol polymer, polyvinyl acetate polymer, acrylic acid polymer, polyacrylamide polymer, ionic liquid polymer, polyether-modified silicone and the like can be used. The polyalkylene polymer is a polymer containing at least a part of an ethylene oxide unit. Examples thereof include polyethylene oxide, polyethylene oxide / polypropylene oxide copolymer, polyethylene oxide / polybutylene oxide copolymer, and modified hydrophobic groups thereof. It is done. Hydrophobic groups include hydrocarbon groups. These thermal phase separation materials can be used alone or in combination.

Hereinafter, the forward osmosis process using a semipermeable membrane will be described.
In the forward osmosis process, an osmotic flow having a higher osmotic pressure than the feed flow needs to flow through the semipermeable membrane. At this time, if the osmotic pressure is high, the feed stream can be concentrated to a high concentration. By concentrating the feed stream to a high concentration, the amount of the concentrated feed stream that is discharged can be reduced. Therefore, it is preferable that the concentration rate of the feed stream is high, and that the feed stream is concentrated at least twice. In addition, if the difference in osmotic pressure between the supply flow and the osmotic substance flow is large, the permeation rate of the solvent that permeates the membrane increases, so that the membrane area can be reduced and the equipment cost can be reduced. For this reason, it is better that the osmotic pressure of the osmotic substance flow is high.

  In the second mode of FIG. 2, when recovering water from the accompanying water, if the concentration rate of the accompanying water is doubled, the osmotic pressure of the concentrated flow is about 60 atm, but the water is moved through the semipermeable membrane. The osmotic pressure of the first osmotic material flow is preferably 80 atm or more in order to ensure the driving force for causing the osmotic flow and the driving force for moving water from the second osmotic material flow to the first osmotic material flow. Drive to move the water by double the concentration rate of the accompanying water when processing the accompanying water with high salt concentration such as the accompanying water of oil field or gas field, for example, the accompanying water with the salt concentration of 8 wt% When ensuring the force, the osmotic pressure of the first osmotic material flow is preferably 145 atm or more. Thus, it is preferable that the osmotic pressure of the first osmotic material flow is high, but on the other hand, in order to regenerate the first osmotic material flow having a high osmotic pressure, high energy is required. The pressure is preferably 250 atm or less, more preferably 200 atm or less, and still more preferably 175 atm or less.

From the viewpoint of separability when performing solution separation, the viscosity of the thermal phase separation substance is preferably 250 mPa · s or less, and more preferably 100 mPa · s or less. This viscosity means a value obtained by measuring a 90 wt% aqueous solution of a thermal phase separation substance at 30 ° C. using a cone of R24 at an angle of 1 ° 34 ′ in a viscometer TVL-33L (Toki Sangyo Co., Ltd.). .
The osmotic material can be used as it is as the osmotic material flow, but a solution dissolved in an appropriate solvent can also be used as the osmotic material flow. The solvent used here is preferably compatible with the solvent to be separated and recovered, and more preferably the same substance. The osmotic pressure of the osmotic material flow is set to be higher than the accompanying water.

  Mixing may be performed when the second osmotic material stream containing the salt and the first osmotic material stream containing the thermal phase separation material are in direct contact to move the water. For example, line mixing may be performed or a mixer may be used. Separation is performed after the contact, and may be, for example, gravity sedimentation or centrifugation. Contact and separation may be performed simultaneously by countercurrent extraction, and the contact or mixing and separation process may be performed multiple times.

In membrane filtration of a water-rich flow after thermal phase separation, for example, ultrafiltration may be performed, or microfiltration, nanofiltration, or reverse osmosis filtration may be used. However, from the viewpoint of the quality of the purified water, it is desirable that 90% or more, more preferably 95% or more, and even more preferably 99% or more of the remaining substance in the water-rich stream is blocked by the filtration membrane. Further, from the viewpoint of water recovery efficiency, the purified water recovered by membrane filtration is preferably 50%, more preferably 70%, and even more preferably 90% or more of the solution supplied to the filtration membrane. desirable.
The thermal phase separation of the thermal phase separation substance-rich stream may be one stage, two stages, three stages or more.

The heat-separable temperature (T0) means that the water-rich first osmotic material stream is heated while stirring in a small glass reactor TEM-V (Pressure-resistant Glass Industry Co., Ltd.), and stirring is stopped for 10 minutes. When placed, it refers to the temperature at which droplets that have joined the upper phase of water can be visually confirmed.
By performing the thermal phase separation in multiple stages, the amount of residual material contained in the water-rich phase can be reduced. Most of the remaining material contained in the water-rich phase is material (eg, inorganic salts) that was dissolved in the water-rich first osmotic material stream. It is considered that when the first osmotic material stream is separated into a water-rich phase and a heat-phase separated material-rich phase, the first osmotic material stream is distributed according to the amount of water in each phase and is in an equilibrium state. That is, the substance dissolved in the first osmotic substance flow is easily distributed to the water-rich phase among the two phases subjected to the thermal phase separation. Therefore, in the first-stage thermal phase separation, the remaining material is distributed to the water-rich phase (A1), and in the second-stage thermal phase separation, the thermal phase-separated substance-rich phase (B1) obtained in the first stage is phased. It is possible to obtain a water-rich phase (A2) in which the concentration of residual substances is reduced by separation.

The water-rich phase (A1) taken out in the first-stage thermal phase separation is sufficient if there is a sufficient amount of water that dissolves the remaining substances. Therefore, the first separation temperature (T1) is the temperature at which heat separation is possible. (T0) or more is sufficient. On the other hand, if the first separation temperature (T1) is set to a temperature considerably higher than the temperature (T0) at which heat separation is possible, the water-rich phase (A1) increases, and the water recovery rate decreases. Therefore, the first separation temperature (T1) is preferably T0 or more and T0 + 30 ° C or less, and more preferably T0 or more and T0 + 20 ° C or less.
The water rich phase (A2) taken out in the second stage thermal phase separation is obtained by treating the thermal phase separated substance rich phase (B1) obtained in the first stage at a temperature sufficiently higher than the first separation temperature (T1). Thus, the water recovery rate can be increased. However, when the thermal phase separation temperature is too high, there are problems such as an increase in equipment cost to secure pressure resistance performance and an increase in energy loss due to heat dissipation. Therefore, the second separation temperature (T2) is preferably T1 + 20 ° C. or higher and T1 + 115 ° C. or lower, and more preferably T1 + 30 ° C. or higher and T1 + 90 ° C. or lower.

  The concentration of the thermal phase separation substance in water containing the thermal phase separation substance that is a water-rich flow is preferably 200 ppm or more and 20,000 ppm or less. As a result of the study by the present inventors, it has been confirmed that the presence of the salt in the contained water, which will be described later, has the effect of preventing the freezing as well as the effect of rust generation on the piping. It has been found that the thermal phase separation substance contained in the contained water has an effect of suppressing the rust generation of the pipe by the salt against the influence of the salt. In order to exhibit the effect of suppressing the rust generation of the pipe due to the salt, the concentration of the polymer (thermal phase separation substance) is preferably 200 ppm or more at the lower limit, more preferably 500 ppm or more, and even more preferably 1,000 ppm or more. 2,500 ppm or more is particularly preferable. On the other hand, the concentration of the polymer (thermal phase separation substance) is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, further preferably 5,000 ppm, and 4,000 ppm or less. It is particularly preferred. The thermal phase separation substance has a freezing prevention effect due to sufficient freezing point depression even in the above concentration range, and when the upper limit is 20,000 ppm or less, the viscosity of the water containing the thermal phase separation substance does not become excessively high. Even if it performs a refinement | purification process (for example, filtration process by a nano filter), it can carry out easily and is preferable.

  Examples of the thermal phase separation substance in the water containing the thermal phase separation substance include polyalkylene polymer, polyvinyl alcohol polymer, polyvinyl acetate polymer, acrylic acid polymer, polyacrylamide polymer, ionic liquid polymer, and polyether-modified silicone. The polyalkylene polymer is a polymer containing at least a part of an ethylene oxide unit, and examples thereof include polyethylene oxide, polyethylene oxide / polypropylene oxide copolymer, polyethylene oxide / polybutylene oxide copolymer, and modified hydrophobic groups thereof. . Hydrophobic groups include hydrocarbon groups. The thermal phase separation material can be alone or in a mixture.

The salt concentration in the heat phase separation substance-containing water is preferably 0.1 wt% or more and 6.0 wt% or less. When the salt is contained in the contained water within the above range, the freezing point of the contained water is lowered and an antifreezing effect is also obtained. Therefore, the lower limit of the salt concentration is 0.1 wt% or more, preferably 0.6 wt% or more, more preferably 1.0 wt% or more.
On the other hand, since the presence of salt in the contained water may cause rusting of the piping, the upper limit of the salt concentration is preferably 6.0 wt% or less, more preferably 3.5 wt% or less. Moreover, when 3.5 wt% or less is further purified in the subsequent membrane separation step, the filtration pressure can be set to an appropriate value.

  The salt in the water containing the thermal phase separation substance is a salt containing at least an inorganic salt or an organic salt selected from metal salts and / or ammonium salts, such as sodium chloride, sodium hydroxide, sodium carbonate, sodium silicate, sulfuric acid. Sodium, sodium phosphate, sodium formate, sodium succinate, sodium tartrate, lithium sulfate, ammonium sulfate, ammonium carbonate, ammonium carbamate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, magnesium chloride, disodium phosphate It is a salt containing at least an inorganic salt or an organic salt selected from the group consisting of monohydrogen, monosodium dihydrogen phosphate, potassium phosphate, potassium carbonate, manganese sulfate, sodium citrate, sodium thiosulfate, and sodium sulfite. It can be.

[Monitoring of associated water treatment costs]
Currently, in the associated water treatment method in oil fields and gas fields, when the total amount of associated water in the usable waste wells does not exceed the limit amount, a new waste well is excavated when the limit amount is approached. The present situation is that the accompanying water exceeding the above limit amount is discarded in the new waste well. When the oil / gas mixture is transported from the oil well to the gravity separation tank by piping, and transported from the reservoir adjacent to the gravity separation tank to the common waste well by a tank lorry loaded with accompanying water for a long distance (generally about 20 miles) However, since it is transported using piping in other cases, the transportation cost accounts for a high proportion of the total cost of the accompanying water treatment, and cost reduction is required.
At present, the distance from the oil and gas wells to the gravity separation tank tends to be within a mile radius. If it is more than 1 mile away, there will be a problem of transportation costs in the case of trucks and the like, and when transporting using piping, it will cause piping clogging due to sludge contained in the accompanying water.
Similarly, the distance from the gravity separation tank to the reservoir tends to be within 100 m, and the distance from the reservoir to the waste well tends to be not less than 5 miles and not more than 50 miles.

Accompanying water purification process cost, accompanying water transportation cost, and accompanying water disposal cost are the following relational expressions:
(Corporate water purification process costs) <(Volume reduction associated water transport fee) + (Volume reduction associated water disposal well usage fee)
If this is not satisfied, there is no cost merit, so it is necessary to consider the efficiency of the accompanying water treatment so as to satisfy this relationship. In general, oil fields and gas fields may have multiple similar water purification treatment facilities in the vicinity, in which case the operation status of each of the equipment for gravity separation tanks, the equipment for water purification treatment for the accompanying water, and the waste wells Introduced a system that instructs and controls the most efficient implementation of the accompanying water treatment by comprehensively analyzing the location of the transport tank lorry, the location where the accompanying water is loaded, the operation status of the transportation destination, etc. You can also
At least the first step of the computer program of the command / control system is (accompanying water purification process cost) <(reduced volume concentration associated water transport fee) + (reduced volume concentrated associated water disposal well usage fee) Step of selecting the oil field to be established; As a second step, the step of minimizing the total treatment cost of the concomitant associated water, specifically, (concentration associated water transport distance (transportation time) + waiting time for using the waste well ) To minimize the total treatment cost by monitoring the associated water disposal process status (waiting state of the truck) of the nearby disposal wells at the time of occurrence of the concentrated associated water .

Hereinafter, although the Example at the time of using the desalination process using a forward osmosis membrane system as an accompanying water purification process is described concretely, this invention is not limited only to these.
In the following examples, water was used as a solvent, AH-0673A (Toho Chemical Co., Ltd.) was used as a thermal phase separation substance, and ammonium sulfate (Wako Pure Chemical Industries, Ltd.) was used as an inorganic salt. The concentration of the thermal phase separation substance in the solution was measured by the refractive index using PAL-RI manufactured by Atago Co., Ltd. The concentration of ammonium sulfate in the solution was measured by titration using a barium chloride solution (Sigma Aldrich Co.) and Alizarin Red S (Sigma Aldrich Co.) solution, and the titration end point was determined by visual observation of a change in color tone.
A solution containing 63.5 wt% AH-0673A and 0.60 wt% ammonium sulfate is obtained as a water-rich first osmotic material stream, and is 20 with respect to AH-0673A heat separable temperature (T0, 60 ° C.). A hot phase separation was performed at 80 ° C., which is a high temperature, and a first hot phase separation material-rich stream was subjected to a thermal phase separation at 150 ° C. As a comparative example, a solution containing 63.5 wt% AH-0673A and 0.60 wt% ammonium sulfate was subjected to thermal phase separation at 80 ° C. and 150 ° C., respectively.

The water recovery rate is obtained, for example, by the thermal phase separation process in the water contained in 1 kg of the solvent-rich first osmotic material stream (flow 208) entering the first stage thermal phase separation process in FIG. It refers to the ratio of the solvent weight of the water-rich phase.

Water recovery (%) = 100 × (water weight of water-rich phase obtained from 1 kg of first osmotic material stream) / (water weight contained in 1 kg of water-rich first osmotic material stream)

That is, in the separation methods A and B, since the thermal phase separation is one stage, out of the water contained in 1 kg of the first osmotic material stream, the water rich phase (A1, That is, the ratio of the solvent weight of 211). In the separation methods C, D, and E, the thermal phase separation process is a two-stage process, so among the water contained in 1 kg of the first osmotic material stream, the water rich phase (A2) obtained from 1 kg of the first osmotic material stream. I.e. the proportion of water weight of 218).
The salt removal rate is calculated from the weight of inorganic salt (ammonium sulfate) contained in 1 kg (208) of the water-rich first osmotic material stream entering the first stage thermal phase separation process to the water-rich phase obtained by the thermal phase separation process. The value obtained by subtracting the weight of the inorganic salt contained therein and dividing the value after the reduction by the weight of the inorganic salt contained in 1 kg (208) of the water-rich first osmotic material stream entering the first stage thermal phase separation is 100. It is multiplied.
Salt removal rate (%) = 100 × {(inorganic salt weight contained in 1 kg water-rich first osmotic substance stream) − (inorganic salt weight contained in water-rich phase obtained from 1 kg first osmotic substance stream) )} / (Mineral salt weight in 1 kg water-rich first osmotic flow)
In the separation methods A and B, the water-rich phase means a water-rich phase (A1, ie 211), and in the separation methods C, D and E, the water-rich phase is a water-rich phase (A2, ie 218). Means.
As for the water recovery rate and salt removal rate in FIG. 2, 1 kg of the solvent-rich first osmotic material flow entering the first stage thermal phase separation process is flow 105, A1 is flow 108, and A2 is The flow of reference numeral 115 was obtained in the same manner as in FIG.

When the thermal phase separation was performed at 150 ° C. in one stage, the recovery rate of water was as high as 63.6%, but the salt in the feed stream to the thermal phase separation process could not be removed (less than 5%). When the thermal phase separation was performed at 80 ° C. in one stage, the water recovery rate was moderate at 24.5%, but the salt removal rate was still low at 14.9%. In contrast, as shown in the examples, when two-stage thermal phase separation was performed at 80 ° C. and 150 ° C., the water recovery rate was 36.7%, and the salt removal rate was 86. High production water of 0% could be obtained.
When two-stage thermal phase separation was performed at 80 ° C. and two-stage thermal phase separation was performed at 150 ° C., the water recovery rate was very low.

Table 2 shows the results of the first-stage thermal phase separation (thermal phase separation at 80 ° C. in the example and 150 ° C. in the comparative example).
The concentration of AH-0673A in the first hot phase separated substance-rich stream in the comparative example was 81.2 wt%, and the concentration in the example was 68.7 wt%. Moreover, the AH-0673A density | concentration of the 1st water rich flow in a comparative example was 3.7 wt%, and the density | concentration in an Example was 9.8 wt%. The thermal phase separation temperature of the comparative example and the example in the first stage thermal phase separation process is different, and the thermal phase separation temperature is higher in the comparative example, so the concentration of the thermal phase separation material in the hot phase separation rich flow is higher. Thus, the concentration of the thermal phase separation material in the water-rich stream is lowered. This is a phenomenon generally understood for a thermal phase separation material exhibiting a lower critical solution temperature (LCST).

  For the examples, the first hot phase separated material rich stream was heated to 150 ° C. to obtain a second water rich material stream and a second hot phase separated material rich stream. The respective concentrations are shown in Table 3. The concentration of ammonium sulfate contained in the second water-rich stream is 0.64 wt%, which is a value equal to or less than 1/4 compared with 2.73 wt% of the comparative example in which the thermal phase separation is performed at 150 ° C. in one stage. . In addition, the concentration of AH-0673A contained in the second water-rich stream in the examples was 1.6 wt%. This is a value of ½ or less compared to 3.7 wt% of the comparative example in which the thermal phase separation is performed at 150 ° C. in one stage, and greatly reduces the thermal phase separation substance in the water-rich stream. I found out.

  As described above, in the water recovery process using the thermal phase separation material, the amount of the residual material contained in the water-rich stream can be reduced, and thereby water can be recovered efficiently.

Rust generation cannot be confirmed even when water containing a heat phase separation material containing 1.6 wt% of AH-0673A as a heat phase separation material and 0.64 wt% of ammonium sulfate as an inorganic salt is exposed to a pipe made of SUS316 for 10 days. It was.
Even if the water containing the heat phase separation substance containing 1.6 wt% of AH-0673A as the heat phase separation substance and 0.64 wt% of ammonium sulfate as the inorganic salt is allowed to stand in an environment of −0.1 ° C. for 12 hours or more, it solidifies. I did not.

  The associated water purified by the associated water treatment method for oil and gas fields according to the present invention is desalted and large oil particles have been removed, so instead of discarding in the disposal well, Since it can be discharged into rivers and ponds, it contributes to reducing environmental impacts such as drinking water pollution and earthquakes. Furthermore, if the accompanying water purification process is performed immediately before the start of the transportation process, the accompanying water is reduced in volume, so that the transportation cost of the tank lorry to the waste well can be greatly reduced. Furthermore, this purified associated water can be reused as a part of the fracturing water required in large quantities in the unconventional oil and gas field mining process.

DESCRIPTION OF SYMBOLS 101 Water 102 Accompanying water 103 First osmotic material stream containing thermal phase separation substance 104 Semipermeable membrane 105 Flow composed of water 101 and first osmotic substance stream 103 106 Heat exchanger 107 Separator 108 First water rich stream 109 First Thermal phase separation substance rich stream 110 Filtration membrane 111 Purified water 112 Membrane recovery stream 113 Heat exchanger 114 Separation device 115 Second water rich stream 116 Second thermal phase separation substance rich stream 117 Concentrated stream (discarded in waste well)
DESCRIPTION OF SYMBOLS 201 Water 202 Accompanying water 203 The 2nd osmotic material stream 204 containing salt 204 The semipermeable membrane 205 The flow which consists of the water 201 and the 2nd osmotic material stream 206 The 1st osmotic material stream containing a thermal phase separation material 207 Separation apparatus 208 2nd osmosis | permeation 209 Heat exchanger 210 Separator 211 First water rich stream 212 First thermal phase separated substance rich stream 213 Filtration membrane 214 Purified water 215 Membrane recovery stream 216 Heat exchanger 217 Separator 218 Two-water rich stream 219 Second thermal phase separation material rich stream 220 Concentrated stream (discarded in the waste well)

Claims (10)

The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank disposed at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the transportation step (IV). The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank arranged at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the disposal step (V). The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank disposed at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil and gas fields, characterized in that an associated water purification step is provided immediately before the start of the transfer step (II). The following steps:
(I) a drilling process for extracting an oil / gas mixture containing gas, oil, associated water, and sludge in a plurality of oil fields / gas fields;
(II) a transfer step of continuously transferring the oil / gas mixture to a gravity separation tank disposed at a predetermined distance from the oil / gas field;
(III) separating the gas, the oil, the sludge and the associated water in the gravity separation tank, and separating and storing the sludge and the associated water in an adjacent tank or reservoir;
(IV) a transporting process for transporting the accompanying water in the tank or the reservoir to a disposal well disposed at a predetermined distance from the reservoir; and (V) a discarding process for discarding the accompanying water to the disposal well;
In the oil / gas mixture processing method, including
An associated water treatment method for oil fields and gas fields, wherein an associated water purification step is provided immediately before the start of the transfer step (II), the transport step (IV), and the disposal step (V).   The associated water of the oil field / gas field according to any one of claims 1 to 4, wherein the associated water purified in the associated water purification step is reused as part of fracturing water in the excavation step (I). Processing method.   The said accompanying water purification process is a desalination process using one or more systems selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, a distillation system, and a reverse osmosis membrane system. And the associated water treatment method for oil fields and gas fields according to any one of items 4 and 4 above.   The oil field / gas field according to claim 3, wherein the accompanying water purification step is a desalination treatment step using one or more systems selected from the group consisting of a forward osmosis membrane system, a membrane distillation system, and a distillation system. The accompanying water treatment method.   In the accompanying water purification step immediately before the transfer step (II), one or more systems selected from the group consisting of forward osmosis membrane systems, membrane distillation systems, and distillation systems are used, and the transfer step (IV), And the accompanying water purification step immediately before the disposal step (V), each independently uses one or more systems selected from the group consisting of forward osmosis membrane systems, membrane distillation systems, distillation systems, and reverse osmosis membrane systems. The associated water treatment method for oil and gas fields according to claim 4, wherein the desalination treatment step is performed. The desalting process includes the following steps:
The accompanying water is caused to counter-flow or co-current with the first osmotic material flow containing the thermal phase separation material having osmotic pressure through the forward osmosis membrane, and the water in the accompanying water is transferred to the first osmotic material flow. The water-rich first osmotic material stream is heated to a first separation temperature (T1) that is not less than the temperature (T0) at which the thermal phase separation material can be thermally separated and is not more than T0 + 30 ° C. A first separation step of separating A1) and a thermal phase separation substance-rich phase (B1); and heating the B1 phase to the first separation temperature (T1) + second separation temperature (T2) of T20 + T1 + 115 ° C A second separation step of separating the water-rich phase (A2) and the thermal phase separation substance-rich phase (B2);
The accompanying water treatment method of an oil field / gas field according to any one of claims 1 to 8, which is a desalination treatment step using a forward osmosis membrane system. The desalting process includes the following steps:
The accompanying water is counter-flowed or co-flowed with the salt-containing second osmotic substance flow through the forward osmosis membrane, and the water in the accompanying water is moved to the second osmotic substance flow to thereby form a second water-rich second. The osmotic material stream is mixed in a state that is incompatible with the first osmotic material stream containing the thermal phase separation material, and water is transferred to the first osmotic material stream so as to move the water-rich first osmotic material stream. Is heated to a first separation temperature (T1) not lower than the temperature (T0) of the thermal phase separation substance and not higher than T0 + 30 ° C., so that the water-rich phase (A1) and the thermal phase separation substance-rich phase ( A first separation step of separating into B1); and heating the B1 phase to the first separation temperature (T1) + second separation temperature (T2) of 20 ° C. or more and T1 + 115 ° C. or less to form a water-rich phase (A2) A second separation step for separating into a thermal phase separation substance-rich phase (B2);
The accompanying water treatment method of an oil field / gas field according to any one of claims 1 to 8, which is a desalination treatment step using a forward osmosis membrane system.

Images