Methods for simultaneously evaluating reserve and permeability of undersaturated coalbed methane reservoirs using production data during the dewatering stage

In this work,a flowing material balance equation(FMBE) is established for under saturated coalbed methane(CBM) reservoirs,which considers immobile free gas expansion effect at the dewatering stage.Based on the established FMBE,five straight-line methods are proposed to determine the control area,initial water reserve,initial free gas reserve,initial adsorbed gas reserve,original gas in place,as well as permeability at the same time.Subsequently,the proposed FMBE methods for undersaturated CBM reservoirs are validated against a reservoir simulation software with and without considering free gas expansion.Finally,the proposed methods are applied in a field case when considering free gas expansion effect.Validation cases show that the straight-line relationships for the proposed five FMBE methods are excellent,and good agreements are obtained among the actual reserves and permeabilities and those evaluated by the proposed five FMBE methods,indicating the proposed five FMBE methods are effective and rational for CBM reservoirs.Results show that a small amount of free gas will result in a great deviation in reserve evaluation;hence,the immobile free gas expansion effect should be considered when establishing the material balance equation of undersaturated CBM reservoirs at the dewatering stage.

Flow and mass balance analysis of eco-bio infiltration system

A structued stormwater infiltration system was developed and constructed at a university campus and monitoring of storm events was performed during a one- year operation period. The flow and pollutant mass balances were analyzed and the overall efficiency of the system was assessed. While significant positive correla- tions were observed among rainfall, runoff and discharge volume （R2= 0.93-0.99; p 〈 0.05）, there was no sig- nificant correlations existed between rainfall, runoff, discharge volume and pollutant load. The system was more effective in reducing the runoff volume by more than 50% for small storm events but the difference between the runoff and discharge volume was significant even with rainfall greater than 10ram. Results showed that the pollutant reduction rates were higher compared to the runoff volume reduction. Average pollutant reduction rates were in the range of 72% to 90% with coefficient of variation between 0.10 and 0.46. Comparable with runoff reduction, the system was more effective in reducing the pollutant load for small storm events, in the range of 80% to 100% for rainfall between 0 and 10mm; while 65% to 80% for rainfall between l0 and 20mm. Among the pollutant parameters, particulate matters was highly reduced by the system achieving only a maximum of 25% discharge load even after the entire runoff was completely discharged. The findings have proven the capability of the system as a tool in stormwater manage- ment achieving both flow reduction and water quality improvement.

Simulation of mass balance behavior in a large-scale circulating fluidized bed reactor

We determine using a compound model the influence of the mass of granular matter on the behavior of a supercritical circulating fluidized bed （CFB） reactor. Population balance enables a stationary-regime modeling of the mass flow of granular matter inside a CFB unit in a large-scale. The simulation includes some important dynamic processes of gas-particle flows in fluidized bed such as attrition, fragmenta- tion, elutriation, and fuel combustion. Numerical calculations with full boiler loading were performed of operational parameters such as furnace temperature, furnace pressure, feeding materials mass flows, and excess air ratio. Furthermore, three bed inventory masses were adopted as experimental variables in the simulation model of mass balance. This approach enables a sensitivity study of mass flows of granular matter inside a CFB facility. Some computational results from this population balance model obtained for a supercritical CFB reactor are presented that show consistency with the operational data for large-scale CFB units.

The controller placement problem or the controller selection problem?

In SDN,the control logic of packet processing devices is moved onto the SDN centralized controller.This decoupled networking architecture creates some critical concerns when compared to traditional distributed architectures.One primary concern in this architecture is the placement of the controller,which is commonly known as the CPP.From our extensive literature review,we identify that there is no strict placement rule that best fits every network in SDN.Dynamic addition and deletion of controllers is inevitable.Motivated from this,in this paper,we attempt to transform the CPP into a CSP.We show that,in the dynamic SDN environment,researchers need to pay attention to CSP issues.The clear advantage of CSP over CPP is that,in the dynamic SDN ecosystem,we can answer fundamental questions about the control plane performance,i.e.,minimum number of controllers,their workload distribution,and placement/locations.Furthermore,we can meet strict,application-specific,QoS constraints.

Phosphorus status, use and recycling in a Chinese peri-urban region with intensive animal husbandry and cropping systems Results from case study in a Sino-German applied research collaboration project

The Sino-German research collaboration project,"Recycling of organic residues from agricultural and municipal origin in China"(2008–2012),comprising different interdisciplinary research groups,and also German small and medium-sized enterprises,aimed at developing integrated strategies and solutions for the recycling of organic residues in China.In an intensive crop-livestock agricultural region in the Shunyi District of Beijing,five typical cropping systems were investigated.The research was conducted in the form of analyses of phosphorus(P)in soil,plants,animal feed,animal products,manures,mineral and organic fertilizers and the derivation of the corresponding nutrient balances and P flows.The mean annual P balance surplus was492 kg·ha–1·yr–1 P for the vegetable production system,significantly higher(P<0.05)than that for orchards(130 kg·ha–1·yr–1 P)and cereal crops(83 kg·ha–1·yr–1 P).Plant-available P(Olsen-P)concentrations of topsoils(0–20 cm)had good correlations with the amounts of P applied(from mineral and organic sources).Compared to results from the Second Chinese National Soil Survey of 1981,mean concentrations of available P in soils of 19 plots investigated in Shunyi District increased 10-fold(from 7.3 to 60 mg·kg–1)from 1981 to 2009.On average,the critical limit for Olsen-P concentrations(>30 mg·kg–1)that can lead to increased risk of P loss was exceeded in all five cropping systems.With feed additives,the"natural background value"(Chinese Environmental Quality Standard for Soils)of copper and zinc in topsoils was exceeded at several sites.Screening for several substances in the veterinary antibiotic classes of sulfonamides,tetracyclines,and fluoroquinolones revealed widespread topsoil contamination.Calculated livestock densities were 10.6 livestock units per ha arable land in 2007.Animal husbandry is increasingly conducted in large operations,making traditional ways of reuse difficult to apply.Comparing three management systems for treatment of organic residues from a pig farm via aerobic(composting)or anaerobic(biogas)treatment in a life cycle assessment,the resulting cropland demand for a sustainable land application of biogas effluent varied between 139 and 288 ha·yr–1,well above the cropland area owned by the farm(10 ha).The mismatch problems in the above context between business-as-usual and improving performance are framed and discussed as(1)the mismatch between centralized animal husbandry and smallholder farming,(2)the mismatch between livestock density and cropland,(3)nutrient(including P)recycling and increasing organic matter content versus energy production,(4)subsidies for compost production and biogas,as well as(5)advances in the regulatory framework in China.