CN-121990697-A - Treatment device and method for produced water of liquid hydrocarbon-containing gas field

Abstract

The invention belongs to the technical field of oilfield water treatment, and particularly relates to a system and a method for treating produced water of a liquid hydrocarbon-containing gas field. The treatment system comprises a separation device, a settling tank and a scaling device which are communicated in sequence. The treatment method comprises the following steps of 1) separating produced water of a liquid hydrocarbon-containing gas field in a separation device to obtain a water-hydrocarbon mixed solution, 2) mixing the water-hydrocarbon mixture and crude oil according to a volume ratio of 3-1:1, conveying the mixture to a settling tank, separating the crude oil liquid hydrocarbon mixture and settled water through gravity settling, and conveying the crude oil liquid hydrocarbon mixture to a scaling device through pipelines, and 3) conveying the settled water to the scaling device, wherein an iron removing agent, a calcium magnesium removing agent and a demulsifier are sequentially added, and then, after a precipitation reaction is carried out, the upper layer is subjected to water injection. The method can realize the recovery of liquid hydrocarbon, reduce the hydrocarbon content in water, and treat the sedimentation water by the treating agent so as to meet the requirement of oilfield reinjection water.

Inventors

• LI JUNCHENG
• ZHANG TING
• LI BENGANG
• LUO LINGYAN
• LV YONGSHENG
• ZHU ZHIYONG
• LI CHANGZHONG
• ZHOU BINGXIN
• LIN XIANG
• YONG SHUO
• WANG TAO
• GUAN KEMING

Assignees

• 中国石油天然气股份有限公司

Dates

Publication Date

20260508

Application Date

20241101

Claims (10)

1. 1. A treatment system for produced water of a liquid hydrocarbon-containing gas field is characterized by comprising a separation device, a settling tank and a scaling device which are sequentially communicated.
2. 2. The system for treating produced water of a hydrocarbon gas field containing liquid as set forth in claim 1, wherein said separation device is a three-phase separation device.
3. 3. A method for treating produced water from a liquid hydrocarbon-containing gas field, using the system for treating produced water from a liquid hydrocarbon-containing gas field according to claim 1, comprising: the method comprises the following steps: Step 1), the produced water of the liquid hydrocarbon-containing gas field enters a separation device for separation to obtain a water-hydrocarbon mixed solution; step 2) mixing the water-hydrocarbon mixture and crude oil according to a volume ratio of 3-1:1, then conveying the mixture to a settling tank, separating a crude oil liquid hydrocarbon mixture and settled water through gravity settling, and realizing the output of the crude oil liquid hydrocarbon mixture through a pipeline; and 3) conveying the settled water to a scaling device, sequentially adding an iron removing agent, a calcium and magnesium removing agent and a demulsifier, and performing precipitation reaction to obtain reinjection water on the upper layer.
4. 4. A method for treating produced water of a liquid hydrocarbon containing gas field as set forth in claim 3, wherein the mass of water in the water-hydrocarbon mixture obtained in step 1) is less than 0.4%.
5. 5. A method for treating produced water of a liquid hydrocarbon containing field as set forth in claim 3 wherein the water hydrocarbon mixture and crude oil are mixed in step 2) for a period of 35 to 45 minutes.
6. 6. A process for the treatment of produced water from a liquid hydrocarbon containing field as claimed in claim 3, wherein in step 2) the hydrocarbon mixture is mixed with crude oil and fed to a settling tank at a flow rate of 1.5-2L/h for separation.
7. 7. A method for treating produced water of a liquid hydrocarbon containing field as set forth in claim 3, wherein said iron remover in step 3) is delivered at a flow rate of 0.4 to 0.5g/h.
8. 8. A process for treating produced water of a liquid hydrocarbon containing field as claimed in claim 3, wherein the transporting flow rate of said decalcification agent in step 3) is 0.3-0.4g/h.
9. 9. A method for treating produced water of a liquid hydrocarbon containing gas field as claimed in claim 3, wherein in step 3) the demulsifier is hyperbranched polyethyleneimine and the conveying flow rate is 0.3-0.4g/h.
10. 10. A method for treating produced water of a liquid hydrocarbon containing field as claimed in claim 3, wherein the demulsifier is obtained by reacting a hyperbranched polymer with an amphiphilic surfactant.

Description

Treatment device and method for produced water of liquid hydrocarbon-containing gas field Technical Field The invention belongs to the technical field of oilfield water treatment, and particularly relates to a device and a method for treating produced water of a liquid hydrocarbon-containing gas field. Background After oil-water separation, the extracted crude oil is dissolved with liquid hydrocarbon in the separated water, and the liquid hydrocarbon is directly discharged into the environment to cause environmental pollution and waste of water resources, so that the extracted water can be used for oilfield reinjection after being treated and modified. The water quality modification is developed in China for many years, has a good application effect in oilfield reinjection water, and is a relatively mature technology. However, due to the large difference of oilfield sewage, it is difficult to find a good agent or process suitable for all sewage treatment systems. Therefore, new medicaments and process improvements are purposefully developed according to the actual condition of the oilfield site, and the oilfield development requirements are better met. How to reduce the oil content of produced water is a problem to be solved in the prior art. Jinhua and the like test the water quality modification technology on site in a secondary sewage treatment station of a hong Kong oilfield, and add a water quality modifier and a water purifying agent in the original treatment system flow to adjust the pH value of sewage and realize the aim of clear water. Sludge discharged in the process enters a sludge tank and is subjected to filter pressing to form sludge cakes containing oil sludge for treatment. The oil content in the sewage after the adjustment of the field test reaches the reinjection index of less than or equal to 5mg/L, and the median value of the particle size of the suspended matters basically reaches the standard. The method for reinjection of the 4-field Tarim Hade of the Tarim oil field adopts the mode of separate treatment of clear water and sewage and reinjection of the clear water and the sewage respectively, so that the ground cost and the operation workload are increased, and the possibility of corrosion and scaling of the injected water is increased. Liu Shijing, mixing sewage and clear water according to the ratio of 6:4, regulating pH value of sewage system to induce scaling, adding flocculant to remove precipitate, adding bactericide, corrosion inhibitor and scale inhibitor, and making external transmission. Indoor researches show that the oil content and suspended matter content of the mixed water after treatment meet the standards. The technological scheme of oil flotation water treatment includes adding water insoluble organic matter 300-2000PPM into water to be treated, dispersing in water mechanically, adding coagulant 30-300PPM and flocculant 2-20PPM, mixing to react to form alum to adsorb water dirt, separating water from the alum, and recovering water insoluble organic matter for reuse. Although the method can meet the reinjection requirement after the treatment of the produced water, the liquid hydrocarbon cannot be separated and then is conveyed along with the crude oil, so that the resource waste is caused. Disclosure of Invention The invention aims to provide a treatment device for produced water of a liquid hydrocarbon-containing gas field, which overcomes the technical problems in the prior art. The invention aims to provide a method for treating produced water of a liquid hydrocarbon-containing gas field, which is used for recovering liquid hydrocarbon and reinjecting the produced water after treatment. Therefore, the technical scheme provided by the invention is as follows: a system for treating produced water of a gas field containing liquid hydrocarbon comprises a separating device, a settling tank and a scaling device which are sequentially communicated. The separation device is a three-phase separation device. A method for treating produced water of a liquid hydrocarbon-containing gas field adopts a treatment system of the produced water of the liquid hydrocarbon-containing gas field, and comprises the following steps: Step 1), the produced water of the liquid hydrocarbon-containing gas field enters a separation device for separation to obtain a water-hydrocarbon mixed solution; step 2) mixing the water-hydrocarbon mixture and crude oil according to a volume ratio of 3-1:1, then conveying the mixture to a settling tank, separating a crude oil liquid hydrocarbon mixture and settled water through gravity settling, and realizing the output of the crude oil liquid hydrocarbon mixture through a pipeline; and 3) conveying the settled water to a scaling device, sequentially adding an iron removing agent, a calcium and magnesium removing agent and a demulsifier, and performing precipitation reaction to obtain reinjection water on the upper layer. The mass of water in the water-hydroc