Simulation of immiscible water-alternating-CO2 flooding in the Liuhua Oilfield Offshore Guangdong, China

In this paper, the immiscible water-alternating-CO2 flooding process at the LH11-1 oilfield, offshore Guangdong Province, was firstly evaluated using full-field reservoir simulation models. Based on a 3D geological model and oil production history, 16 scenarios of water-alternating-CO2 injection operations with different water alternating gas (WAG) ratios and slug sizes, as well as continuous CO2 injection (Con-CO2) and primary depletion production (No-CO2) scenarios, have been simulated spanning 20 years. The results represent a significant improvement in oil recovery by CO2 WAG over both Con-CO2 and No-CO2 scenarios. The WAG ratio and slug size of water affect the efficiency of oil recovery and CO2 injection. The optimum operations are those with WAG ratios lower than 1:2, which have the higher ultimate oil recovery factor of 24%. Although WAG reduced the CO2 injection volume, the CO2 storage efficiency is still high, more than 84% of the injected CO2 was sequestered in the reservoir. Results indicate that the immiscible water-alternating-CO2 processes can be optimized to improve significantly the performance of pressure maintenance and oil recovery in offshore reef heavy-oil reservoirs significantly. The simulation results suggest that the LH11-1 field is a good candidate site for immiscible CO2 enhanced oil recovery and storage for the Guangdong carbon capture, utilization and storage (GDCCUS) project

Screening and simulation of offshore CO2-EOR and storage:A case study for the HZ21-1 oilfield in the Pearl River Mouth Basin, Northern South China Sea

CO2-enhanced oil recovery (CO2-EOR) and storage is currently the most effective and economic technology for reducing CO2 emissions from burning fossil fuels in large scale. This paper is the first effort of proposing a modelling assessment of CO2-EOR and storage in the HZ2-1 oilfield in the Pearl River Mouth Basin in northern South China Sea offshore Guangdong Province. We attempt to couple the multi-parameter dimensionless quick screening model and reservoir compositional simulation for optimization of site screen and injection simulation. Through the quick screening, the reservoirs are ranked by FOR dimensionless recovery R-D, and by CO2 storage in pore volume SCO2. Our results indicate that SCO2 is highly pressure dependent and not directly related to R-D. Of these reservoirs, CO2-EOR and storage potential of the M10 was estimated through a compositional simulation as a case study based on a 3D geological model. Nine scenarios of CO2 injection operations have been simulated for 20 years with different well patterns and injection pressures. The simulation results represent an obvious improvement in oil production by CO2 flooding over No - CO2 production. The best operation for M10 is miscible CO2 flooding, which led to the higher recovery factors of 52%(similar to)58% and CO 2 stored masses of 8.1 x 10(6 similar to)10.8 x 10(6)t The optimum operation for CO2 injection should be set well pattern in region of injector I1 and high injection pressure for miscible flooding. In a whole, the HZ21-1 field can be used as a candidate geological site for GDCCUS project. We are fully aware of the limitation in the primary modelling including reservoir and fluid properties and production history matching, and regard this study as a general and hypothetic proposal

The Spatial Distribution and Potential for Energy Recovery of Urban-Rural Wastes in Guangdong Province, Southern China

Abstract Wastes-to-energy (WTE) has been widely recognized as an effective way to save resources while minimizing environmental pollution, which has become the key issue for a sustainable society. Urban-rural wastes include all kinds of waste generated during human activities, which have a wide range from municipal solid waste (MSW) to agricultural residues and animal excrement, etc. In order to evaluate their potential for energy recovery and greenhouse gas (GHG) mitigation in Guangdong province, the generation, spatial distribution and energy potential of three typical waste streams (i.e. MSW, agricultural residues and animal excrement) were investigated using statistical and estimation methods. Results showed that: (1) MSW was mainly concentrated in the Pearl River Delta, but agricultural residues and animal excrement mainly distributed in the East Wing, West Wing and Mountainous Areas; (2) energy potential of studied wastes at least can reach 15.661 million tons of coal-equivalent and corresponding GHG mitigation is 41.720 million tons CO2 equivalent. The pattern of distributed utilization may be appropriate for rural wastes, such as agricultural residues and animal excrement, because recycling is difficult due to they are dispersed distribution. Results of this study may help decision-makers to evaluate the proper management of urban-rural wastes and can be a reference for other developing countries

Case analysis on textile wastewater subjected to combined physicochemical-biological treatment and ozonation

The large amount of wastewater produced by the textile industry necessitates a cost-effective technology for enhanced wastewater treatment. In this study, a combined processing method was established to enhance discharge water quality. This process incorporated a pretreatment system, a biological contact oxidation unit, an ozone oxidation unit, and an intensive treatment system. Through this treatment approach, the ozonation of textile wastewater was examined to determine the effects of ozone dosage, ozonation time, and color/chemical oxygen demand (COD) of feed wastewater. Results revealed that the color and COD removal rates increased with increased ozone dosage. Color and COD decreased whereas NH3-N slightly increased with the progress of ozonation. Color removal rate decreased whereas ozone dosage increased with increased feed color and COD. Feed color greatly influenced ozone dosage but not COD. Color removal rate during ozonation can be controlled to 50%-55% at a response time of approximately 2 h. The average ozone dosage was 51 g m(-3). After treatment by the combined process, the final discharge water was able to meet the national first-grade emission standard (GB4287-2012). The total removal rates of COD and color reached 95.2% and 95.4%, respectively. The cost of wastewater treatment amounted to only approximately 1.70 Yuan RMB m(-3) wastewater

Quick assessment to ascertain technical rational well spacing density in artificial water flooding oilfield

Optimization of technical rational well spacing density (TRWSD) is a crucial part of the study of oilfield development. However, the methods widely used previously have some disadvantages as followings: (1) Some quoted theories and formulas for algorithms are intractable. (2) Some are incompatible with the reality as they assumed too many conditions which are more ideal. (3) The influence factors considered by other algorithms are not comprehensive and irrational. (4) In applications, the applicable conditions are ignored by some algorithms. Aiming at the problems above, this paper has built a quick estimation model of TRWSD and proposed a new optimizing method of TRWSD, based on the comprehensive investigation of pressure distribution and the theoretical model of rational ratio of oil to water wells (RROWW) in artificial water flooding oilfield. Verification by reservoir numerical simulation model and actual data of the field implementation shows that the TRWSD model is reliable, and practical. It is revealed from the studies that the injection-production pressure system factors are the main ones to control TRWSD except water cut, such as the oil-bearing area of producing geological reserves, liquid productivity index, injection-production ratio and number of injection-production wells, and so on. And compared with the previous ones, the TRWSD method comprehensively takes into account such the factors as injection-production unbalance, density difference between oil and water, volume factor, start-up pressure gradient of injection wells, start-up pressure gradient of production wells and so on. Hereinafter, the new model can be applied for the calculation of the TRWSD and related parameters at any injection-production development stages, reservoir types and reservoir pressure distributions in artificial water flooding oilfield, all of which means that the new method has a strong promising adaptabilities and prospects in the water flooding oilfield with close well spacings or during high water cut stage

Ventilation and air conditioning system of deep-buried subway station in sub-tropical climates: Energy-saving strategies

Subway systems are rapidly developing, and their energy consumption is considerably growing. The ventilation and air conditioning system in the subway station is the key energy-consuming system. It consumes a large amount of energy every day to provide a comfortable environment for passengers, and it has therefore received increasingly more attention from researchers worldwide. In this work, the variation law of the ventilation and air conditioning system of a subway station is analyzed from three aspects (energy consumption, load, and temperature) based on field test data, and the problems existing in the operation and management of the system are analyzed. For example, the results show that the total load of fresh air in the station was as high as 34-37%, and about 30 min was required to adjust the indoor temperature to a stable state. In addition, three general models and seven energy-saving strategies are put forward, and their energy saving potentials are estimated. After optimization, the ventilation and air conditioning system is found to reduce energy consumption by more than 30%. Not only are common problems that exist in the actual operation of the subway station ventilation and air conditioning system found in this research, but valuable measured data is also provided for the theoretical research of the thermal environment of the subway and the design of environmental control systems

Source Apportionment and Health Risk Assessment of Heavy Metals in Eastern Guangdong Municipal Solid Waste

This research focused on the contents of the five most bio-toxic heavy metals, As, Cd, Hg, Cr, and Pb of 26 municipal solid waste (MSW) samples from the Eastern Guangdong Area. To investigate the apportion of the heavy metal source, Pearson correlation and principal component analysis (PCA) were introduced as major approaches. The health risks posed to MSW workers exposed to heavy metals in MSW were assessed using a Monte Carlo simulation combined with the US Environmental Protection Agency Health Risk Assessment Model. The As, Cd, Hg, Cr, and Pb contents of the east Guangdong MSW were (0.76 +/- 0.75), (2.14 +/- 4.44), (0.11 +/- 0.14), (55.42 +/- 31.88), and (30.67 +/- 20.58) mg/kg, respectively. Hg, Cr, and Pb were potentially derived from glass, textile, food waste, and white plastic, while As and Cd were mainly derived from soil and food waste in the MSW. The non-carcinogenic risks of heavy metal in MSW exposure to MSW workers could be ignored. However, the heavy metals in MSW might pose carcinogenic risks, with the probabilities for male and female workers being 35% and 45%, respectively. The non-carcinogenic and carcinogenic risk indices were slightly higher for female workers under the same exposure situations

Comparative environmental and economic life cycle assessment of dry and wet anaerobic digestion for treating food waste and biogas digestate

Anaerobic digestion (AD) has proven to be a promising option for food waste (FW) management, due to the significant potential of recovering energy from waste. In this study, the environmental and economic impacts of six scenarios for FW and biogas digestate management in Shenzhen, China, were evaluated using life cycle assessment (LCA) and life cycle cost (LCC) analysis. GaBi model was employed to perform LCA on the basis of CML 2001 methodology, while LCC analysis was conducted using net present value to evaluate the economic efficiency. Results showed that dry AD coupled with biogas digestate incineration not only exhibited the best net environmental benefits with the reduction of 195 kg CO2 per ton of FW, but also appeared to be the most economically feasible option with the lowest LCC (446.223 thousand CNY). With respect to the FW treatment technology, dry AD scenarios exhibited better environmental benefits associated with global warming, human toxicity, marine aquatic ecotoxicity and photochemical ozone creation potential, compared to those in wet AD. Regarding post treatment for biogas digestate, incineration appeared to be the best option compared to the landfill and compost. Moreover, sensitivity analysis indicated that dry AD coupled with biogas digestate incineration exhibited least vulnerable to the change in biogas production environmentally. The outcomes of this study will contribute to developing the optimal FW management strategy for mitigating the environmental and economic impacts in terms of both environmental and economic sustainability

Five Design Challenges

PLEASE NOTE: Where applicable, the audio has been removed from this file due to copyrighted material. The garments shown here represent the Classes of \u2713, \u2712 and \u2711 . The garments were created in response to the following five design challenges: Sophomores, Class of \u2713: Re-Innovative Design: explore the properties of recycled materials other than fabric while creating a wearable piece. Print Design Project create a garment that makes optimal use of printed fabric designed by a RISD Textiles student. Juniors, Class of \u2712: Knitwear Design: explore the properties of knits and design cut-and-sew and machine-knit garments. Tailoring Project: interpret traditional tailoring techniques to create a look with a jacket. Seniors, Class of \u2711: Cocktail Collection: design a collection of contemporary cocktail apparel in collaboration with the current RISD Museum exhibition Cocktail Culture: Ritual and Invention in American Fashion, 1920-1980