《石油与天然气化工》2013第1期英文摘要
发布时间:2013年03月07日        点击数量:4066
Feb.2013,Vol.42,No.1
CHEMICAL ENGINEERING OF OIL & GAS
ABSTRACTS
 
Erosion-corrosion in oil and gas production(Part 1)
Baotong Lu(Materials Engineering Department,Southwest Research Institute,San Antonio,TX,USA).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp1~10,2013(ISSN 1007-3426, IN CHINESE)
AbstractChallenges due to erosion-corrosion in oil and gas production are briefly reviewed. The achievements of the author’s group on the modeling of synergistic effects erosion are summarized. The erosion-corrosion mechanisms, the methods to evaluate the erosion-corrosion resistance of materials and the approaches to mitigate the damage caused by erosion-corrosion are discussed in this article. This article is presented in two parts. Part 1 focuses on the background, the concepts relating to synergism of erosion/corrosion and corrosion in erosive fluids.
Key words: erosion-corrosion, petroleum, evaluation, mitigation
 
Energy saving technology on FCC gasoline etherification unit
Sun Fangxian1, Wen Shichang1, Li Xin2, Chen Ting2(1. CPECC East-China Design Branch, Qingdao 266071, Shandong, China;2. Xinjiang Xinfeng Company Limited, Urumqi 830000, Xinjiang, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp11~14,2013(ISSN 1007-3426, IN CHINESE)
Abstract: According to the analysis of the process characteristics and the energy consuming structure for FCC gasoline etherification unit, the determination of energy consumption reduction for the unit should take the process technology and the heat source of reboilers into consideration. The mixed phase bed & catalytic distillation combination process is an energy saving etherification process to some extent. The application of hot oil as the heat source of reboilers could reduce the energy consumption of about 30 percent compared to the use of steam as the heat source.
Key words: FCC gasoline, etherification, energy saving, hot oil system, mixed phase bed, catalytic distillation
 
Problems and solutions of LPG desulfurization process by amine in the light hydrocarbon fractionation unit
Wang Guoqiang(Light hydrocarbon fractionation Branch of Daqing Oilfield Chemical Company Limited, Daqing 163411, Heilongjiang, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp15~17,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Reasons causing the instability for longterm operation of liquefied gas amine desulfurization in the light hydrocarbon fractionation unit were investigated. It was determined that the amine foaming and LPG copper corrosion below the standard cause the instability. The effects of the two critical factors were studied in details in this paper. The analysis showed that the amine foaming resulted from the dirtiness of desulfurization system, LPG containing methanol, the accumulation of the salt with high heat-stability and operation fluctuation. The copper corrosion of LPG below the standard resulted from amine entering LPG and a certain amount of organic sulfur and elemental sulfur not being removed from LPG. According to the analysis of the causes, the corresponding solutions were proposed.
Key words: mine foaming, LPG copper corrosion, heat stable salt, organic sulfur
 
Performance analysis and improvement measurement for electro-desalting of crude oil with high-salt and high-water content
Gao Hongli1, Zeng Maohui2(1.Guangdong University of Petrochemical Technology, Maoming 525000, Guangdong, China;2.SINOPEC Maoming Company, Maoming 525000, Guangdong, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp18~21,2013(ISSN 1007-3426, IN CHINESE)
Abstract: The performance analysis of electro-desalting of several types of crude oil with high-salt and high-water content in atmospheric-vacuum distillation unit in Sinopec Maoming Company were conducted. The effects of critical factors on desalting, such as properties of crude oil, water injection, demulsifiers models, mixing intensity, temperature of desalting,and electric field strength, were analyzed. The results showed that pre-dewatering operation can be optimized by increasing the residence time of the crude oil in the oil tank, increasing the dehydration temperature and injecting demulsifier in the crude oil tank. Meanwhile, the problem of the dehydration outlet stream containing oil can be solved using the bidirectional demulsification and the optimization of the injection process. In addition, regularly clearing the oil spill in tank bottom, and optimizing the operational parameters can also improve the desalination effect.
Key words: high-salt and high-water crude oil, atmospheric-vacuum distillation, electro-desalting,  improvement
 
Deep hydrodesulfurization of FHUDS-2 catalyst in Zhenhai mixed oil
Wang Kun1, Fang Xiangchen2, Liu Jihua2, Song Yongyi2, Liu Wei2, Liu Honghai1(1.College of Petrochemical Technology, Liaoning University of Petroleum & ChemicalTechnology,Fushun 113001,Liaoning, China; 2. Fushun Research Institute of Petroleum and Petrochemical, SINOPEC, Fushun 113001, Liaoning, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp22~25,2013(ISSN 1007-3426, IN CHINESE)
Abstract: In the smallscale test apparatus, the deep hydrodesulfurization property of FHUDS-2 catalyst was evaluated by using Zhenhai mixed fuel. Additionally, the transformation mechanism of sulfides on the FHUDS-2 catalyst was studied . The results showed that 4,6-DMDBTs were the most difficult removal sulfide, and it has low sensitivity to temperature. The ratio of 4,6-DMDBTs increased gradually in product. FHUDS-2 catalyst has excellent performance of deep or ultra deep hydrodesulfurization. Under the conditions of partial pressure of hydrogen 6.4 MPa, volume space velocity 1.5 h-1, volume ratio of hydrogen to oil 500, and reaction temperature 360~370 ℃ or reaction temperature 360 ℃, partial pressure of hydrogen 6.4 MPa, volume ratio of hydrogen to oil 500, and volume space velocity 1.0~1.5 h-1, FHUDS-2 catalyst could produce the deep and ultra-deep diesel fuel satisfying the European Ⅳ and European Ⅴ emission standards.
Key words: Zhenhai mixed oil,catalyst FHUDS-2, deep hydrodesulfurization
 
Process check and performance evaluation of the new kettle reboiler in solvent regeneration unit
Zou Chao(Cangzhou Company,SINOPEC,Cangzhou 061000, Hebei, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp26~29,2013(ISSN 1007-3426, IN CHINESE)
Abstract: The process check for kettle type rebolier based on Aspen B-JAC was discussed in this paper by using a new kettle type reboiler in Cangzhou refinery tail gas desulfurization solvent regeneration unit as an example introduced. The discussed simulation can be used as a reference for the design and checking of new kettle type reboiler. This paper also evaluated the advantages of the heat exchanger in anticorrosion, energy saving, environmental protection and improvement of products quality.
Key words: Aspen B-JAC, kettle reboiler, process check, performance  evaluation
 
Applicability of AGA and Weaver indices for natural gas interchangeability in China
Zhang Yangjun, Qin Chaokui,Xiao Litao(College of Mechanical Engineering, Tongji University, Shanghai 201804,China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp30~36,2013(ISSN 1007-3426, IN CHINESE)
Abstract: LNG has been steadily increasing its share of the global gas trade. The United States and European countries have studied the interchangeability of natural gas according to specific situations and provided results of the relevant studies. In China, the import of LNG is steadily increasing, but the problems regarding quality and interchangeability were not fully understood and resolved. In this paper, a study on applicability of Weaver indices has been completed. The experiments were conducted for 17 typical gas appliances and 11 natural gas sources with 187 test conditions. Comparing the experimental results with the results predicted by Weaver indices, it suggested that the limits of Lifting JL need to change to ≥0.95, Incomplete Combustion JI need to change to ≤0.04 and the limit of AGA index Lifting IL change to ≤1.05.
Key words: natural gas, LNG, interchangeability, Weaver index, AGA index
 
Comparative analysis of growth characteristics of hydrate formation on the surface of suspended water droplet and bubble
Zhang Jian, Liu Daoping, Su Xing, Yang Xiaoshu, Kang Ying(Refrigeration Technology Institute, University of Shanghai for Science and Technology, Shanghai 200093, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp37~41,2013(ISSN 1007-3426, IN CHINESE)
Abstract: The present research of gas hydrate formation under rich gas environment and rich liquid environment was introduced. The comparative analysis of growth characteristics of hydrate formed on the suspended water droplet and on the surface of the bubble was conducted based on the experimental phenomena and results. The growth characteristics and mechanism of the both was summarized. The prospects for future development of hydrate growth kinetics was also discussed.
Key words: hydrate,growth characteristics, comparative analysis, bubbles, suspended water droplet
 
Optimal selection of pyrolysis feedstock from light hydrocarbons and refinery resources for high yield of butadiene
Xu Jiang, Song Bangyong, Jing Yuanyuan, Mu Zhenzhen,Yang Libin, Chang Guizu(Lanzhou Petrochemical Research Center of PetroChina, Lanzhou 730060, Gansu, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp42~44,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Comparative analysis of butadiene yield in the pyrolysis products of four kinds of light hydrocarbons and refinery resources, proposed that the raw feedstock with high cycloalkanes (especially C6~C8 cycloalkanes) content, low pyrolysis temperature, and high wateroil ratio are favorable for high butadiene yield. To maximize the economic benefits, the effects of the yield of butadiene, olefin market price and the coking problem must be taken into consideration in the selection of pyrolysis feedstock.
Key words: butadiene,refinery resources,pyrolysis feedstock,pyrolysis conditions,optimization
 
Overall performance study on P110SS sulfur-resistant casing in the high sulfide gas well annulus protection fluid
Huang Xuesong1,2, Lu Guiwu1, Zhang Qingsheng2, Wang Shutao2, Guan Jianqing2, Hui Xiaomin2, Chen Yong2(1.China University of Petroleum, Beijing 102249, China;2.Production Engineering Research Institute, Zhongyuan Oilfield, Puyang 457001, Henan, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp45~48,2013(ISSN 1007-3426, IN CHINESE)
AbstractThe behaviors of corrosion and galvanic nickel based alloy couple of sulfurresistant casing P110SS in the high sulfide gas well annulus protection fluid were studied. This study was conducted in a high temperature/pressure reactor which simulated the operating environment of oil ring annulus in Puguang Gas Field well. In addition, P110SS sulfur-resistant casing overall performance such as collapse strength, pipe body yield strength and internal pressure strength was also analyzed. Without the presence of hyperbaric H2S/CO2, the annulus protection fluid protected the casing excellently and the galvanic accelerated couple corrosion on P110SS casing was not significant. Thus, the collapse strength, pipe body yield strength and internal pressure strength of P110SS casing were reduced slightly. However, in the hyperbaric environment of H2S 5.0 MPa , CO2 3.0 MPa, the annulus protection fluid did not protect the casing properly and the corrosion rate was increased by around 100 times. Additionally, the galvanic accelerated couple corrosion on P110SS casing was significant. As a consequence, the performance of P110SS casing including the collapse strength, pipe body yield strength and internal pressure strength was decreased considerably.
Key wordsP110SS sulfur-resistant casing, annulus protection fluid, hyperbaric H2S/CO2 environment, collapse strength, pipe body yield strength, internal pressure strength
 
Research development on formation damage induced by shale drilling
Lu Zhanguo,  Li Qiang,  Li Jianbing, Song Fei, Liu Heng(SINOPEC Shengli Oil Production Research Institute, Dongying 257000, Shandong, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp49~52,2013(ISSN 1007-3426, IN CHINESE)
AbstractAlong with the world energy demand rising, unconventional energy such as shale gas, tight gas, and CBM, etc. have emerged as the supplement of conventional energy. However, due to specialties of unconventional reservoir, i.e., low porosity, low permeability, easy expansion and fragility, this kind of reservoir can be readily damaged irreversibly during the reservoir development. In order to understand the mechanism of formation damage induced by drilling in unconventional reservoirs, research on the formation damage by shale drilling domestically and internationally was systematically reviewed. In addition, existing problems in the study of formation damage were analyzed and suggestions for next formation protection were given. Based on the analysis, it was found that the study of formation damage by shale drilling is mainly reflected in two aspects, i.e. formation damage induced by drilling technology and drilling fluid. However, there are fewer studies of borehole stability in unconventional reservoirs and lack of deep understanding of the formation damage mechanism induced by drilling fluids. Based on the development of formation damage by shale drilling, the studies of borehole stability in unconventional reservoirs, mechanism of formation damage induced by drilling fluids and the optimization of drilling fluids will be conducted systematically.
Key words: shale gas, formation damage, drilling fluid, borehole stability, mineral composition, permeability, porosity
Evaluation on rheological properties of GTL based drilling fluids
Shen Li, Wang Baotian, Gong Xinjun, Chen Erding, Zhang Haiqing, Wang Haifeng(Drilling Engineering Technology Company, Shengli Petroleum Administration, Dongying 257064, Shandong, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp53~57,2013(ISSN 1007-3426, IN CHINESE)
Abstract: In view of rheology control problem for gas-to-liquid (GTL) based drilling fluid system, the influence of various factors on the rheological properties was studied. The results showed that the amount of emulsifier employed should be moderate, i.e., insufficient or excessive quantity will have a certain impact on the rheological properties. Further, organic clay, viscosifier, oil/water ratio and temperature are the main factors affecting the synthetic drilling fluid rheology. The organic clay content of 3%~4% is appropriate to a non-weighting drilling fluid, while 1.5%~3% content is desirable to a weighting drilling fluid. Usually the greater the density is, the smaller the amount of the organic clay is. The plastic viscosity and yield stress of a drilling fluid can be significantly increased with an increase of water content. Viscosifier and temperature have great influences on the viscosity and gels. Viscosifier dosage should be less than 1%, and a proper temperature resistant agent should be added at high temperatures.
Key words: GTL based drilling fluid, rheological property, plastic viscosity, yield stress
 
Scaling type in alkaline-surfactant-polymer (ASP) flooding in the fourth plant of Daqing Oilfield
Xu Guomin, Jiang Yumei, Dang Qinggong, Xu Zhiyan(Fourth Plant of Daqing Oilfield, Daqing 163318, Heilongjiang, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp58~60,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Scaling often has serious influences on the normal production and development in the process of oilfield production. The problem of scaling became severe in the fourth plant of Daqing Oilfield after ASP flooding was applied. The scale does not dissolve in acid or alkali. In order to solve this problem, a high pressure physical model device was applied to simulate the scaling in the field. Based on analysis of the permeability and chemical elements of the core in the scaling reservoir, the reason for scaling was analyzed and expounded comprehensively, thereby providing theoretical basis for descaling and antiscaling measures.
Key words: ASP flooding, scaling in oilfield, scaling reason, scaling type
 
Corrosion research of 3Cr steel in CO2 environment
Zhang Renyong1,2, Qi Yaquan3, Shi Daiyan1,2, Chen Yongbin1,2, Zhang Jinzhong1,2, Ju Lan1,2(1.China Petroleum Engineering Co., Ltd. Southwest Company, Chengdu 610041, Sichuan, China;2.Department for Tubular Goods Corrosion and Protection in Sour Oil and Gas Fields of KeyLaboratory of Petroleum Tubular Goods Engineeing, CNPC, Chengdu 610041, Sichuan,China;3.Tazhong Project Management Department of PetroChina Tarim Oilfield Company,Korla 841000, Xinjiang, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp61~63,2013(ISSN 1007-3426, IN CHINESE)
Abstract: The corrosion behaviors of 3Cr steel in simulative CNOOC CO2 environment have been studied with a high-temperature and high-pressure reactor. Under the conditions that temperature was 60℃, CO2 partial pressure was 1.5 MPa and the flow velocity of corrosive medium was 1 m/s, two kinds of 3Cr steel samples present severe uniform corrosion, the average corrosion rate of 3Cr steel are 3.85 mm/a and 3.24 mm/a respectively. The corrosion products of 3Cr steel in CO2 environment have been analyzed by SEM and EDS. The result indicates that the products of 3Cr steel have two layers, the outer main structure is FeCO3 with stacking loose and low adhesion, the inner layer is product film with enrichment Cr.
Key words: 3Cr steel, CO2 corrosion, corrosion product, micro morphology
 
A high temperature resistant crosslinking acidsystem for carbonate reservoir
Chen Fu1, Xiao Chengchuan1, Huang Leiguang2, Zeng Ke2, Yao Jun2(1. Chemistry and Chemical Engineering School of Southwest Petroleum University,Chengdu 610500, Sichuan, China;2.Fracturing Company of Greatwall Drilling Company, 124107) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp64~67,2013(ISSN 1007-3426, IN CHINESE)
Abstract: In this paper, a high temperature resistant crosslinking acid for high temperature acid fracturing operation in the carbonate reservoir is developed through screening the crosslinking acid thickener and crosslinker and remixing with acid additives. Acid thickener and crosslinker are crucial to the comprehensive performances of the crosslinking acid under high temperature. DM3802 and JL-10 were screened as the best thickener and the best crosslinker respectively through analyzing of acid solubility, thermostability, crosslinking time, crosslinked viscosity and time of temperature resistance. The dosages were also determined. The compatibility experiment with acid additives also showed the excellent compatibility of this crosslinking acid system. It shows that the crosslinking acid system possesses the characteristics of good high temperature resistance, superb rheological profiles, good prop-carrying capacity, controlled leak-off and good gel breaking property under 120 ℃.
Key words: carbonate reservoir, acid fracturing, high temperature resistance, crosslinking acid
 
Development status and outlook of natural gas analysis and measurement technology in China
Zeng Wenping1,2, Huang Liming1, Luo Qin1,2, Tang Meng1,2,Chi Yongjie1,2(1.Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gasfield Company,Chengdu 610213, Sichuan, China;2.Natural Gas Quality Supervision and Inspection Center for Petroleum Industry,Chengdu 610213, Sichuan, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp68~73,2013(ISSN 1007-3426, IN CHINESE)
Abstract: In the field of analysis and measurement of natural gas, China has established a series of technologies acting on international convention. The article summarizes the detection technologies including sampling of natural gas, composition analysis, detection of sulfide content, determination of water/hydrocarbon dew point, solid particulate matter, other hazardous and noxious substances, property parameter calculation,and preparation of reference material. Quality assurance to analysis result was also put forward from the aspects of proficiency test in laboratory as well as analysis comparison. With rapid development of natural gas industry and increasing international trade of natural gas, new demand was raised in analyzing and measuring natural gas. The paper also outlooks the development direction of natural gas analysis and measurement technology.
Key words: natural gas, measurement technology, traceability, reference material, proficiency test
 
Paraxylene trace impurities and purity determination method comparison and optimization
Wang Yue,Guo Yuanyuan(PetroChina Urumqi Petrochemical Company,Urumqi 830019,Xinjiang, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp74~77,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Internal standard method for the determination of trace impurity by internal standard substance addition to eliminate the effects of operating conditions fluctuation on the results, improves the accuracy of the analytic result. By comparing the internal standard method and area normalization method for the determination of trace impurities in paraxylene, internal standard method has the advantages of high sensitivity, small interfering effect, and low detection limit. The optimized internal standard method is more suitable for the determination of trace impurities.
Key words: paraxylene, trace, internal standard method, internal standard substance, area normalization method, optimization
 
Microorganism corrosion contribution rate in oilfield reinjection water
Chen Haoyu1, Miao Wei1, Wang Weidong2, Zhang Xiuxia1(1. China University of Petroleum (East China),Tianjin 300384, China;2. Research Institute of Oil Production Technology,Shengli Oilfield Branch Company,Sinopec, Dongying 257000, Shandong, China).CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp78~82,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Three methods of high temperature steam sterilization, centrifugal degerming and filtration sterilization are used to investigate different changes of corrosion extent in Shengli Oilfield Ninghai area reinjection water caused by removing bacteria and contribution rate in reinjection water corrosion by microorganism. The results show that high temperature steam sterilization can remove all the germs, as well as change water chemical property. Through centrifugal degerming, water chemical property remains the same, but germs cannot be completely removed. By filtration sterilization, water chemical property undergoes no change while germs are completely removed. Besides, it can better reflect the role of microorganisms in corrosion. The research results indicate that microorganism is the leading factor of reinjection water corrosion in Ninghai area where the contribution rate is 57% to 72%.
Key words: microbiological corrosion, high temperature steam sterilization, centrifugation degerming, filtration degerming, reinjection water
 
Application of pomegranate husk extract in the treatment of oilfield produced water
Chen Gang, Pang Min, Mo Yunjuan, Zhang Min, Hou Xiaoqing, Su Huijun, Zhang Jie(School of Chemistry and Chemical Engineering, Xi'an Shiyou University,Xi'an 710065, Shaanxi, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp83~85,2013(ISSN 1007-3426, IN CHINESE)
Abstract: Application of pomegranate husk extract in the treatment of oilfield produced water was carried out based on the abundant fruits resource of Shaanxi province. Pomegranate husk was extracted with ethanol, and the extract was screened as corrosion and bacteria inhibitors. The results show that the extract is effective for corrosion inhibiting. The polarization curve showed that extract was a mixing type inhibitor. The extract is active against sulfate reducing bacteria (SRB), but inefficient against iron bacteria (FB) and total general bacteria (TGB).
Key words: pomegranate husk, treatment of oilfield produced water, corrosion inhibiting, bacteria inhibiting
New progress of Shengli Oilfield reinjection sewage treatment technology
Zhong Rubing(Research Institute of Oil Production Technology,Shengli Oilfield Branch Company,Sinopec, Dongying 257000, Shandong, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp86~90,2013(ISSN 1007-3426, IN CHINESE)
Abstract: According to the reinjection sewage treatment situation in Shengli Oilfield, the oilfield sewage treatment technology progress was introduced. Aiming at the characteristics of sewage treatment in Shengli Oilfield, the tests and application of three kinds of technology were introduced: ①the secondary level nitrogen flotation technology improved the oil removal effect and reduced the corrosion of the pipe network and equipment; ②aiming at the reinjection sewage of strong corrosion, the electrochemical preoxidation technology was implemented, and its implementation was introduced in detail; ③aiming at the water reinjection produced from chemical flooding, the high gradient coalescence flotation technology was studied and tested. The high gradient coalescence flotation field test was introduced in detail. The future development of oilfield sewage treatment technology was prospected finally.
Key words: Shengli Oilfield,reinjection sewage treatment technology, secondary level nitrogen flotation, electrochemical preoxidation, high gradient coalescence flotation
 
Formation water treatment method and application in XC gas field of Sichuan
Han Feng(Sinopec Sousthwest Petroleum Branch, Chengdu 610081, Sichuan, China) .CHEMICAL ENGINEERING OF OIL & GAS, VOL.42, NO.1,pp91~94,2013(ISSN 1007-3426, IN CHINESE)
Abstract: For XC gas field producing large quantities of formation water that is high salinity and difficult to treat, three dirty water treatment methods were used including the reaching standard discharge, reinjection of formation water and low temperature multi-effect distillation. Field tests have shown that the reaching standard discharge is limited for further development in the gas fields due to the high investment and processing costs; the reinjection of formation water and low temperature distillation method gradually become the focus in XC gas field water treatment mode because of its low investment, high treatment efficiency, and resource recycling.
Key words: gas field, formation water, treatment, application