Impact of inert gas injection rate on reducing hydrogen risk during AP1000 post-inerting

2017 ◽  
Vol 110 ◽  
pp. 230-233 ◽  
Author(s):  
Xuefeng Lyu ◽  
Xiaobo Lee ◽  
Ke Ji ◽  
Yu Yu ◽  
Shengfei Wang
2021 ◽  
Author(s):  
Sagun Devshali ◽  
Ravi Raman ◽  
Sanjay Kumar Malhotra ◽  
Mahendra Prasad Yadav ◽  
Rishabh Uniyal

Abstract The paper aims to discuss various issues pertaining to gas lift system and instabilities in low producer wells along with the necessary measures for addressing those issues. The effect of various parameters such as tubing size, gas injection rate, multi-porting and gas lift valve port diameter on the performance analysis of integrated gas lift system along with the flow stability have been discussed in the paper. Field X is one of the matured offshore fields in India which has been producing for over 40 years. It is a multi-pay, heterogeneous and complex reservoir. The field is producing through six Process Complexes and more than 90% of the wells are operating on gas lift. As most of the producing wells in the field are operating on gas lift, continuous performance analysis of gas lift to optimize production is imperative to enhance or sustain production. 121 Oil wells and 7 Gas wells are producing through 18 Wellhead platforms to complex X1 of the field X. Out of these 121 oil wells, 5 are producing on self and remaining 116 with gas lift. In this paper, performance analysis of these 116 flowing gas lift wells, carried out to identify various problems which leads to sub-optimal production such as inadequate gas injection, multi-porting, CV choking, faulty GLVs etc. has been discussed. On the basis of simulation studies and analysis of findings, requisite optimization/ intervention measures proposed to improve performance of the wells have been brought out in the paper. The recommended measures predicted the liquid gain of about 1570 barrels per day (518 barrels of oil per day) and an injection gas savings in the region of about 28 million SCFD. Further, the nodal analysis carried out indicates that the aforementioned gas injection saving of 28 million SCFD would facilitate in minimizing the back pressure in the flow line network and is likely to result in an additional production gain of 350 barrels of liquid per day (65 barrels of oil per day) which adds up to a total gain of 1920 barrels of liquid per day (583 barrels of oil per day). Additionally, system/ nodal analysis has also been carried out for optimal gas allocation in the field through Integrated Production Modelling. The analysis brings out a reduction in gas injection by 46 million SCFD with likely incremental oil gain of ~100 barrels of oil per day.


2021 ◽  
Author(s):  
Kok Liang Tan ◽  
Sulaiman Sidek ◽  
Syakirin M. Nazri ◽  
Haziqah Hamzah

Abstract Immiscible Water Alternating Gas (iWAG) scheme was adopted in Echo field, offshore Sarawak Malaysia, to increase recovery factor of the matured oil reservoir after more than two (2) decades of peripheral water injection. It was implemented through four (4) horizontal wells located at reservoir’s eastern and western flanks. Since the commencement of iWAG injection, multiple challenges occured interrupting the stable injection that halting the success of this integrated mega scale project. It started with prolonged iWAG performance test run due to surface constraint, measurement and well issues on executing switching test, followed with low injectivity during switching operation. Subsequently, injectivity issues occured in the gas phase after several injection cycles. In addition to that, injector wells facing high downtime due to surface facilities and well integrity issues, causing low injection rates and unavailability to meet cycle volume within the stipulated duration. Reactivation of iWAG benefiter wells also prove to be challenging due to wells have been idle for a long time and multiple interventions required to revive the well. Injection data for both gas and water phase were analysed to improve iWAG operating procedure and understand the wells performance. INJ-J2 was installed with temporary pressure gauge during the water to gas switching, while the other two (2) wells are equipped with Permanent Downhole Gauge (PDG) to monitor the well injectivity. Application of non-intrusive flowmeter was also proven useful in calibrating the Flow Transmitter (FT) for both water and gas injectors, ensuring the accuracy and precision in the water and gas injection measurement. Besides that, fluid temperature trending was referred to validate on the meter measurement. Low injection rate compared to original plan were reviewed with the Reservoir Management Plan (RMP). Several approaches are implemented in order to achieve the iWAG RMP target and idle well reactivation. Analysis of injection data showed that gas injectivity issue occurred after the water to gas switching cycle. Injectivity improves slightly after long duration of continuous gas injection and applying higher Tubing Head Pressure (THP), unfortunately some wells remain with low injectivity because of insufficient discharge pressure to push the water from the near-wellbore deep into the reservoir to improve injection. Low injection rate issue is mitigated by extending injection cycle duration in order to meet the RMP cycle volume. Besides that, wells are normally injected with higher injection rate to cater for the high downtime. Both gas and water injection are balanced to ensure that the wells reached their cycle volume at similar duration. With limited new field discovery by the Operator, tertiary recovery on the mature field is inevitable. However, there is less implementation of iWAG in offshore field. Through this paper, authors wish to provide insights and lesson learnt for others when planning for iWAG tertiary recovery, taking account of various challenges faced.


Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2571 ◽  
Author(s):  
Jingrui Li ◽  
Jietuo Wang ◽  
Teng Liu ◽  
Jingjin Dong ◽  
Bo Liu ◽  
...  

High-pressure direct-injection (HPDI) natural gas marine engines are widely used because of their higher thermal efficiency and lower emissions. The effects of different injection rate shapes on the combustion and emission characteristics were studied to explore the appropriate gas injection rate shapes for a low-speed HPDI natural gas marine engine. A single-cylinder model was established and the CFD model was validated against experimental data from the literature; then, the combustion and emission characteristics of five different injection rate shapes were analyzed. The results showed that the peak values of in-cylinder pressure and heat release rate profiles of the triangle shape were highest due to the highest maximum injection rate, which occurred in a phase close to the top dead center. The shorter combustion duration of the triangle shape led to higher indicated mean effective pressure (IMEP) and NOx emissions compared with other shapes. The higher initial injection rates of the rectangle and slope shapes had a negative effect on the ignition delay periods of pilot fuel, which resulted in lower in-cylinder temperature and NOx emissions. However, due to the lower in-cylinder temperature, the engine power output was also lower. Otherwise, soot, unburned hydrocarbon (UHC), and CO emissions and indicated specific fuel consumption (ISFC) increased for both rectangle and slope shapes. The trapezoid and wedge shapes achieved a good balance between fuel consumption and emissions.


2019 ◽  
Vol 129 ◽  
pp. 249-252 ◽  
Author(s):  
Xuefeng Lyu ◽  
Xiangyuan Meng ◽  
Boxue Wang ◽  
Fenglei Niu ◽  
Shuai Liu ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document