Acquisition and Analysis of Transient Data through Unsteady-State Core Flooding Experiments

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Benjamin Shepherd
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1 Journal of Petroleum Dec Vol.52 No.4 PP.73~88 Acquisition and Analysis of Transient Data through Unsteady-State Core Flooding Experiments Hong-Seng Liang * Chi-Lun Huang Chung-Hao Lee Chi-Wei Wang Shun-Lung Lin Te-Kun Huang Exploration & Development Research Institute, CPC Corporation, Taiwan 1 Ta Yuan, Wen Fa Rd., Wen Sheng, Miaoli, Taiwan, R.O.C. Dynamic displacement experiments and two-phase flow numerical estimation program are presented in this study. Unsteady-state core-flooding system was designed and utilized for an oil-water dynamic displacement experiment. Two in-situ sandstone core plug samples with restored wettability were used to investigate relative permeability via tetradecane and synthetic brine as non-wetting and wetting phase fluids. The transient data (pressure drop and produced fluid volume) were collected automatically for oil-water relative permeability computation. For the relative permeability analysis, an inverse method program was constructed with four components: (1) a finite-difference Eclipse black oil model of the flow through the core; (2) functional Cory-type power law model of relative permeability in terms of a set of adjustable parameters found by minimizing an objective function; (3) the objective function formed by the sum of the square of the differences between the observations and calculated data; (4) the Gauss-Newton with Levenberg-Marquardt modification procedure for the Least-Squares problem to minimize the objective function definition. All the above processes are embodied in MatLab program which is constructed in this study to estimate the relative permeability curve. Keywords: Unsteady-State Core-Flooding Test, Relative Permeability, Inverse Problem, Objective Function

2 Journal of Petroleum Dec Vol.52 No.4 PP.89~99 Case Studies of Improving Caustic Injection in Crude Distillation Unit Chao-Tai Chen* Chong-Chien Lai Refining and Manufacturing Research Institute, CPC Corporation, Taiwan 217, Min-Sheng S. Rd., Chia-Yi, Taiwan 600, R.O.C. Yuan-Der Chen Huang-Ming Ko Ta Lin Refinery, CPC Corporation, Taiwan 50, Fourth Section Yen-Hai Rd. Hsiao-Kang, Kaohsiung, Taiwan 812, R.O.C. Wei-Cheng Wang, Pen Liu Retiree, CPC Corporation, Taiwan Desalting, caustic addition, neutralizing amine, filming inhibitor and water washing are the common measures for reducing the crude tower overhead corrosion caused by hydrogen chloride (HCl). The use of caustic addition to reduce the amount of HCl produced by hydrolysis of residual unstable chloride salts is a more than 60 years old technology. This method is cheap and effective, but also has certain caustic-related problems if it is used improperly. Many refineries stopped using caustic addition due to a number of problems eventually revealed. To minimize these side effects, caustic addition in crude distillation unit (CDU) must be used efficiently and at a suitable rate. This article describes both cases of modified caustic injection after the desalters, then the results before and after the modification were compared. Case 1:

3 Journal of Petroleum Dec Vol.52 No.4 Although the desalting of CDU A could reach to 1ptb or less salt in desalted crude after optimizing desalter operation, but two problems were still remained: high overhead HCl content and severe air fan tubes corrosion during the operation cycle from October, 2007 to November, The ph of desalter effluent water was also low sometimes. Therefore, the restore of caustic injection was considered again. The original caustic injection point after the desalter of CDU A was designed at the bottom outlet of flash drum, and a leakage occurred in the inlet pipe of hot crude charge pump due to the caustic injection in the past. A new injection point at the outlet of 2nd stage desalter was set up to replace the original in the turnaround at the end of The caustic solution was also diluted to 3 ~ 4 fold with water to get a better and more uniform dispersion in desalted crude oil. The Cl - amounts of overhead condensate water before and after the caustic injection modification were compared based on the same salt contents of desalted crude. The averaged salt amounts in desalted crude were 0.85ptb and 0.83ptb for the periods of Mar to Mar (before modification) and Jan to Nov (after modification) respectively, almost the same, and the corresponding chlorides contents in the overhead condensate water were ppm and 82.78ppm respectively. The decrease ratio of overhead Cl- amount is more than one-third. According to our trackings, so far the overhead chloride content has not significantly increased, nor the caustic stress corrosion at the inlet pipe of hot crude charge pump has occurred. Case 2: The downstream caustic injection point of CDU B was located in front of the furnace, where the temperature is higher and coupled with concentrated caustic, it led pipe cracked 3 times during an operation cycle. Because the scheduled turnaround was about 3 months later at that time, so the inter-stage injection between the desalters was suggested and closed the other injection points. In the meantime the concentration of caustic was diluted by half. The main results after the adjustment were summarized as follows: 1. The amount of caustic addition was reduced significantly to 2.61ptb, about the quarter of the previous one. 2. The average chloride ion contents of the crude tower overhead increased from 15 ppm to 37.2ppm, but still in the acceptable range. 3. In order to maintain the overhead ph as before, the monthly average amount of overhead amine neutralizer increased to 30%. The averaged T-Fe contents in the overhead condensing water were 0.184ppm and 0.192ppm before and after the adjustment, respectively, which were almost the same. 4. The ph of the crude desalter effluent increased from 6.3 to

4 Journal of Petroleum Dec Vol.52 No.4 Appropriate caustic injection into desalted crude is effective in lowering HCl formed from hydrolysis of residual chloride salts and subsequent crude tower overhead corrosion rate. Accordingly, it is responsible for a fairly low additional contamination of the resid (ATB) with sodium and producing a catalytically processable resid. It is still an available means for controlling crude tower overhead corrosion. While it does not eliminate the need for proprietary chemicals, it can significantly improve crude tower overhead ph control and reduce the amount of organic neutralizers and corrosion inhibitors, lowering down the operating and maintenance costs of CDU. Keywords: Overhead Corrosion Control, Caustic Injection, Caustic Embrittlement, Crude Distillation

5 Journal of Petroleum Dec Vol.52 No.4 PP.101~108 Investigation of Environment- Assisted Cracking in Amine Unit Kuei-Sen Chang* Wen-Hung Weng Chun-Chi Su Meng-Hung Chen Gao-Shee Leu Refining and Manufacturing Research Institute CPC Corporation, Taiwan No.217, Min-Sheng S. Rd., Chia-Yi 60051, Taiwan, R.O.C This study discusses environment-assisted cracking problems of equipment and pipelines in amine units of refineries through failure analysis processes and case studies. The first case is the outlet pipeline of a lean amine surge tank, and the failure mechanism is amine stress corrosion cracking from the analysis results. The second case is the broken gate valve between a reflux drum and a sulfur recovery unit, and the failure mechanism of the broken gate valve is sulfide stress corrosion cracking (SSCC). We conclude the correlation between the two kinds of stress corrosion cracking and the location of equipment/pipelines in amine units through the investigation of corrosion cracking mechanism and root cause of the failure objects. In the meantime, we hope to prevent similar stress corrosion cracking in amine units from happening again by this study. In the end, this article proposes a post-weld heat treatment (PWHT) which is an effective method for improving the cracking resistance of weldments in amine service in order to avoid the possible occurrence of occupational accidents and economic losses. Keywords: Amine Unit, Amine Stress Corrosion Cracking, Sulfide Stress Corrosion Cracking, Postweld Heat Treatment

6 Journal of Petroleum Dec Vol.52 No.4 PP.109~121 The Study of Inherently Safer Design Strategy on Hazard Prevention for Dust Explosions Yu-Te Sung Quality Health Safety Environment Division, CTCI Corporation. 89, Sec. 6, Zhongshan N. Rd., Taipei 11155, Taiwan, R.O.C Dust is a hidden high-risk in industrial environments. Inherently Safer Designs Strategy is one of means to control the risk. Its main purpose is to remove the defects in essence, including getting rid of the danger caused in the processing and afterwards, in order to improve the safety. This study analyses the factors influencing the dust explosions, design indicators in the possibility of happening and intensity characteristics: Cubic Law, the air vent ratio, Pressure Piling endanger. Inherently Safer Designs Strategy is applied to utilize intensification/minimization, substitution, attenuation, limitation of effects, etc. to dispel and control the potential danger factors of dust explosions and precautionary measures. Inherently Safer Designs Strategy makes it possible to keep people and properties away from harms induced by dust. Also this strategy can be applied in other processes to prevent the essential dangers for the better protection. Keywords: Inherently Safer Design Strategy, Dust Explosions, Cubic Law, Pressure Piling

7 Journal of Petroleum Dec Vol.52 No.4 PP. 123~130 Efficacy Trials of No.1 EGCG GreenTea Po-Long Wu * Hsiao-Ping Lee Chih-Wen Li Mao-Yuan Tu Refining and Manufacturing Research Institute CPC Corporation, Taiwan No.217, Min-Sheng S. Rd., Chia-Yi 60051, Taiwan, R.O.C. In order to understand whether green tea can prevent body fat accumulation, we monitored body weight change, food consumption and food utilization of animals, as well as size and number changes of fat cells. Obese Sprague-Dawley rats induced by high energy diet were divided into four groups: normal diet group (ND), high energy diet group (HE), low-dose group (HE-L, ml / kg / day, equivalent to 1 times of the recommended human dose) and high-dose group (HE-H, ml / kg / day, equivalent to 5 times of the recommended human dose). Rats were continuously administered with green tea for 8 weeks, then the animals were sacrificed and analyzed. The results showed both HE-L or HE-H groups had lower body weight, abdominal fat amount and food utilization as compared to HE group. In addition, the sizes of fat cells in HE-L and HE-H groups were significantly smaller than that in HE group. This study reveals CPC s green tea products could prevent body fat accumulation and could improve dyslipidemia induced by high-fat diet, which has the potential to be the anti-obesity functional food. Keywords: Green Tea, Body Fat Accumulation, High Energy Diet

A Study of the Purification of Lean Solvent in Aromatics Extraction Unit.

Journal of Petroleum Mar. 2017 Vol.53 No.1 PP.71~80 A Study of the Purification of Lean Solvent in Aromatics Extraction Unit. Jing-Wei Ko* Wan-Rong Chen Zong-Cheng Lai Ming-Chang Tsai Hong-Hong Xue CPC