Correlation between per-well average dynamic reserves and initial absolute open flow potential(AOFP) for large gas fields in China and its application

Based on performance data of over 600 wells in 32 large gas fields of different types in China, the correlation is established between per-well average dynamic reserves( G) and average initial absolute open flow potential(IAOFq) of each field, and its connotation and applicability are further discussed through theoretical deduction. In log-log plot, G vs. IAOFq exhibit highly dependent linear trend, which implicates the compatibility between G and IAOFq attained through development optimization to reach the balance among annual flow capacity, maximum profits and certain production plateau, that is to match productivity with rate maintenance capacity. The correlation can be used as analogue in new gas field development planning to evaluate the minimum dynamic reserves which meet the requirement of stable and profitable production, and facilitate well pattern arrangement. It can also serve as criteria to appraise the effectiveness and infill drilling potential of well patterns for developed gas fields.

A New Method for the Dynamic Reserves of Gas Condensate Reservoir Using Cyclic Gas Injection Based on the Effects of Reinjection Ratio and Water Influx

As we all know, cyclic gas injection is one of the most effective development methods to improve condensate oil recovery. When dealing with the calculation of the reserves, the injection-production differences and water influx create great influence on the accuracy. Based on the existing research, we proposed a new material balance equation which considered the differences of composition between produced and injected fluids and the effect of water influx, and a solution was provided in this paper. The results of the method are closer to the actual situation because they are built on the law of conservation of mass, and the using of curve fitting method can not only avoid the use of water influx coefficient but also obtain the water influx rate and reserves at the same time. The YH-23 gas condensate reservoir is taking as a typical subject to do the research, which has been exploited by cycle gas injection for 14 years. Three different methods are used to calculate the reserves, and the results show that the method proposed in this paper has minimum error of 2.96%.

Drivers of Land Cover Dynamics for Pugu and Kazimuzumbwi Forest Reserves in Kisarawe, Tanzania

Forests that are close to growing urban centres have been subject to constant deforestation and degradation from various factors. This study assesses the drivers of land cover dynamics in Pugu and Kazimzumbwi forest reserves in the context of urban and peri-urban expansion of Dar es Salaam for the past three decades. The study adopted review of relevant literature and household survey from three settlements surrounding the forest reserves. One hundred and fifty (150) households were collected from Buyuni, Chanika and Masaki in Ilala and Kisarawe and administered with semi-structured questionnaire to collect information on migration, use of forest products by communities and perception on climate change and variability. SPSS computer program was used to analyse the questionnaire data while tables and graphs were adopted for presentation of the results. Rural-urban and internal urban migration in Dar es Salaam was identified as one of the primary drivers of land cover dynamics in peri-urban areas and adjoining environments. The migration was intensified by push drivers which include urban growth, market of land and reliance on forest product among community members as source of their livelihoods. The increased rainfall variability accompanied with high temperature has contributed to frequent droughts which compromises rainfed agriculture. Thus, the successful conservation of the forest will require strengthened enforcement of protection measures supported with introduction of alternative livelihood strategies for majority of poor community members.

The “fracture-controlled reserves” based stimulation technology for unconventional oil and gas reservoirs

To solve the problems facing the economic development of unconventional oil and gas, a new concept and corresponding technology system of reservoir stimulation based on "fracture-controlled reserves" are put forward. The "fracture-controlled reserves" stimulation technology is to realize the three-dimensional producing and economic and efficient development of unconventional hydrocarbon resources by forming a fracture system that well matches "sweet spots" and "non-sweet spots". The technical route of the stimulation technology is "three optimizations and controls", that is, control the scope of sand body through optimizing well spacing, control the recoverable reserves through optimizing fracture system, and control the single well production reduction through optimizing energy complement method. The "fracture-controlled reserves" stimulation emphasizes the maximization of the initial stimulation coefficient, the integration of energy replenishment, stimulation and production, and prolonging the re-fracturing cycle or avoiding re-fracturing. It aims at realizing the three-dimensional full producing and efficient development of reservoir in vertical and horizontal directions and achieving the large-scale, sustainable and high profitable development of unconventional oil and gas resources. The stimulation technology was used to perform 20 pilot projects in five typical tight-oil, shale gas blocks in China. The fracturing and producing effects of tight oil improved and the commercial development for shale gas was realized.

Dynamic channel reservation scheme based on priorities in LEO satellite systems

According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels is the key of this strategy. In order to obtain the optimal thresholds, the traffic is predicted based on the high-speed deterministic movement property of LEO satellites firstly. Then, a channel allocation model based on Markov is established. Finally, the solution of the model is obtained based on the genetic algorithm. Without user location, this strategy effectively reduces handover failures and improves channel utilization by adjusting dynamically the thresholds according to traffic conditions. The simulation results show that the system＇s overall quality of service can be improved by this strategy.

Two-stage stochastic approach for spinning reserve allocation in dynamic economic dispatch

A novel approach was proposed to allocate spinning reserve for dynamic economic dispatch.The proposed approach set up a two-stage stochastic programming model to allocate reserve.The model was solved using a decomposed algorithm based on Benders' decomposition.The model and the algorithm were applied to a simple 3-node system and an actual 445-node system for verification,respectively.Test results show that the model can save 84.5 US $ cost for the testing three-node system,and the algorithm can solve the model for 445-node system within 5 min.The test results also illustrate that the proposed approach is efficient and suitable for large system calculation.

Dynamic Economic Dispatch for Wind Power System Considering System Security and Spinning Reserve

In this paper, dynamic economic dispatch model is proposed for power systems with bulk wind power integration. The wind turbine generators are assumed to partially undertake the spinning reserve for the thermal generator. A double-layer optimization model is proposed. The outer layer use the differential evolution to search for the power output of thermal generators, and the inner layer use the primal-dual interior point method to solve the OPF of the established output state. Finally, the impact of spinning reserve with wind power on power system operating is validated.

Dynamic random channel reservation protocol

Demand assignment MAC protocols have been used widely in wireless networks. It can effectively utilize wireless bandwidth. Some strategies can he used by demand assignment MAC protocols to further improve their efficiency. The concept of transmit probability is introduced. This concept allows a request slot to be assigned to many different traffic classes at the same time. Based on it, the dynamic random channel reservation （DRCR） protocol is proposed. The DRCR protocol operates dynamically by observing the traffic conditions. It uses information about the recent traffic conditions to assign transmit probability with which an mobile station can select request slots with lower traffic. The performance of DRCR is evaluated and compared with RSCA. The results show that DRCR is more stable than RSCA, it offers shorter delays of requests than RSCA and can relieve heavily stressed traffic classes faster than RSCA.

Evaluation of ovarian reserve dynamics by assessment of serum antimullerian hormone secretion level

【Objective】To evaluate ovarian reserve dynamics in relation to age in women of reproductive age.【Methods】Serum level of AMH of 176 women of reproductive age was retrospective analyzed.【Results】The average age of all patients was(34.7±0.6)years.A gradual serum AMH level decrease in relation to age was detected.This decrease was especially notable after age of 30.Serum level of AMH dispersion also decreased with age.【Conclusions】Due to general negative trend of serum AMH level in relation to age,value of this marker is unequal at different ages.This marker has the most value for women aged 30~39 years.Due to high variability of serum AMH in young women assessment should be done several times to reveal marker dynamics.

Spatiotemporal dynamics of ecological variation of waterbird habitats in Dongtan area of Chongming Island

Based on Landsat TM images, we explored the pattern of variation of suitable waterbird habitats from 1990 to 2008 in the Dongtan area of Chongming Island at the Changjiang (Yangtze) River mouth. By applying our highly accurate indicator model (R=0.999, P<0.01), we quantified the variations of fluctuation intensity for local waterbird habitats during 1990-2008, and for the main waterbird groups (Anatidae, Charadriidae, Ardeidae and Laridae) from 2006 to 2008, to evaluate the impact of habitat quantity change on the waterbird habitat status and the population dynamics of the different waterbird groups. The results show that the aquaculture ponds (AP) and the Scirpus mariqueter zone (SMZ) underwent drastic habitat changes during certain periods (AP: 1997-2000, 2000-2003, 2005-2008; SMZ: 1997-2000), and the fluctuation intensity differed among habitat types in the order AP>SMZ>TSH (total suitable habitat)>BSA (bare mud flat and shallow water area). The abandonment of tracts of aquaculture ponds in Dongtan in mid-2006 brought about an intensive population fluctuation, caused by rapidly changing habitat with the population expanding to adjacent areas. At present, Anatidae and Ardeidae are threatened in the Dongtan area with declining populations because of their very "picky" habitat requirements (i.e., high reliance on AP). The Charadriidae experienced enormous population declines in the late 1990s, however, they have since recovered to normal levels as habitat change has stabilized. Our findings suggest that the current challenges for habitat management are the protection and stabilization of AP and SMZ habitats.

Computational fluid dynamics modeling in intracranial atherosclerotic disease

Intracranial atherosclerotic disease(ICAD)is an important cause for ischemic stroke and transient ischemic stroke(TIA)throughout the world,especially in Asians,which is not fully appreciated,partly due to its inaccessibility and limitations of current neuroimaging methods.The computational fluid dynamics(CFD)modeling technique provides a novel approach to reveal the hemodynamic characteristics in ICAD,e.g.,the distributions of pressure,wall shear stress and flow velocity.In this review article,we aim to provide an overview of the general methodology of CFD modeling in arterial stenotic diseases,the established application of this technique in coronary artery disease,and more importantly,perspectives and challenges of this technique in the investigation of ICAD.Promising findings of preliminary studies using a CFD model for hemodynamic analysis in ICAD warrant verifications.Further studies in this area will help rectify loopholes in the current secondary prevention strategy,and inform individualized treatment for ICAD patients in the near future.

苍山洱海国家级自然保护区森林资源动态

目的:了解云南苍山洱海国家级自然保护区(以下简称“保护区”)森林资源近20年的动态变化特征,为保护区编制经营管理方案提供指导。方法:以2005、2015年森林资源调查矢量数据、2021年森林、草原、湿地监测数据、第三次全国土地调查数据为基础数据,基于GIS技术,分析保护区森林资源动态。结果:保护区土地利用类型中,有林地面积最大,并逐年增加;林地中,3个调查年度均以有林地和灌木林地为主,面积占保护区总面积的60.82%以上;保护区森林覆盖率2005—2015年间逐年增加,2015—2021年间增加值逐步趋于稳定;蓄积量以有林地蓄积为主,并逐年增加;乔木林地面积和蓄积量以栎类、云南松、华山松和苍山冷杉为主,且逐年增加;乔木林地中幼龄林、中龄林、近熟林和成熟林比重相对均衡,过熟林面积较少;各年度郁闭度等级均以中为主,且郁闭度等级为中和密的乔木林地面积和蓄积量均逐年增加。结论:保护区森林质量和生态防护功能逐年提高,后期森林资源管理以增加栎类等阔叶林为主。

松辽盆地北部深层火山岩气藏勘探开发关键技术

松辽盆地北部徐家围子断陷火山岩气藏是徐深气田的主力气藏,具有岩性多样、储层非均质性强的特点,面临气藏富集规律不清、优质储层预测难、气井产能和井控储量变化规律复杂、剩余气挖潜难度大等一系列技术难点和挑战。通过开展火山岩气藏成藏演化过程分析、火山岩喷发期次描述、有效储层预测、井控储量评价、剩余潜力描述等工作,攻关形成了火山岩气藏成藏评价、三级火山体精细刻画、动态储量评价、剩余潜力评价及挖潜等技术。建立了“低渗增长型+高渗稳定型”2类动态储量模式及动静结合“六参数”挖潜技术政策界限,落实了烃源岩生气期及气藏成藏期,明确了气藏富集受源岩、断裂、储层、盖层四因素的联合控制,实现了对火山岩储层内部结构的精细表征,搞清了2类气井动态储量增长规律,形成了不同类型剩余气的挖潜技术对策。基于火山岩气藏一系列勘探开发关键技术的创新,徐深气田的天然气产量逐年攀升,形成的系列技术在大庆油田已得到全面推广应用,并取得了明显效果,有效支撑了大庆油田天然气产量的持续稳定增长。研究成果可为同类型气藏的勘探开发提供有效的技术指导。

独立监管、激励协同:粮食社会责任储备管理研究

粮食企业社会责任储备是企业储备的重要组成部分,做好粮食企业社会责任储备管理,让承储企业具备责任担当是发挥储备效能的关键。基于政府是否对参与社会治理的公众进行激励,构建政府—承储企业—公众的三方演化博弈,根据社会责任储备“龙头试点—规模推行”发展特点,创新性引入企业规模动态变量,通过系统动力学对博弈系统进行仿真,研究在不同监管模式下企业行为的演化过程和策略选择,得到粮食企业社会责任储备分级管理方式,对极端应急情况进行仿真,对应急物资管理也有一定适用性。研究结果表明:对于大型承储企业,政府可以实施独立监管,激励公众参与社会责任储备管理可提升管理绩效;对于中小型承储企业,政府需要激励公众共同参与社会责任储备管理,才能达到理想管理效果;在极端应急情况下,政府对小微主体规制力量不足,需要对小微主体投机行为施加高额罚款并调动公众参与协同治理,才能达到理想管理效果。最后,从加快建立社会责任储备承储企业分级管理长效机制、鼓励公众多渠道参与社会责任储备管理实践、适当扩大大型承储企业社会责任储备承储比例、加强大型承储企业与中小型承储企业的应急保障连接、加强承储企业社会责任品牌建设和信息发布机制等五个方面提出相关政策建议。

考虑新能源发电出力特征的电煤储备决策模型

随着新能源占比不断升高,电力保供安全受到新能源发电出力不确定性的影响,强化电煤储备能力成为确保新型电力系统安全稳定运行的关键任务。基于k-均值聚类原理对多时间尺度的新能源发电出力数据进行特征提取,以解决新能源发电出力的计量与电煤储备决策时间尺度不匹配的难题。在此基础上,兼顾经济性和安全性要求,设计综合响应日常电力生产需求和应对极端天气影响的电煤二元储备结构,将所提取的新能源发电出力特征纳入考虑,构建电煤储备动态规划模型并给出相应的求解思路。最后,以我国N省实际数据为例开展算例分析,结果显示电煤储备中心这种二元储备结构能够以较低的代价实现大多数应急情景下的供电安全,为应对极端天气等异常事件所额外支付的储备成本仅占未发生中断的总成本的3%。研究结果能够为煤炭储备中心的运营提供管理启示与决策参考。

顺北油气田断溶体油藏产量预测模型研究及应用

Arps递减曲线方程是油气田开发初期产量预测中应用较为普遍的方法,基本是参考类似油藏拟合参数以定压差生产为开发政策指导进行产量预测,对于顺北断溶体油藏地层压力下降明显,且储集层在地饱压差内的非线性流动特征明显,存在唯一的非线性惯性阻力,无法通过描述线性流动特征的采油指数来表征,存在误差较大、产量预测结果单一的缺点。通过分析顺北油气田产量递减特征,基于物质平衡原理,构建动态储量模型,结合顺北油气田通用产能方程和产能评价指标成果,形成了新的断溶体油藏弹性驱产量预测方法,用于指导断溶体油藏弹性驱开发阶段的生产管理,有更高的适应性和准确率,也为断溶体油藏开展产能建设方案经济评价优化、指导油井开发政策奠定了基础、提供多开发政策方案决策支撑。

无人机三维建模技术在露采矿山动态储量监测中的应用

针对无人机矿山测绘现有技术无法满足储量动态监测的精细化要求等问题,通过研究矿山多源异构数据融合、地形三维建模、矿体三维地质建模、精细储量自动计算方法,完成露采矿山储量无人机精细化动态监测系统的研发,实现了各矿种界内与越层越界精细动态储量的自动计算。应用结果表明,系统应用于矿体与矿界不规则露采矿山储量动态监测相对误差可达3%以内;能适应矿体与矿界不规则、地形变化大等复杂情况;成果可直观、准确展现矿山的开采状况;可显著提高露天矿储量动态监测的精度和效率。

计及动态频率响应约束的高比例风电电力系统日前-日内联合调度策略

高比例风电电力系统具有转动惯量低、调频能力弱等特征,容易引发频率安全问题。现有计及频率安全约束的调度策略研究中,调频手段主要为惯性响应与一次调频,鲜见在单机故障等大功率扰动下考虑系统旋转备用与紧急功率支撑的动态响应作用。对此,在日前-日内联合调度模型中引入预想小功率扰动及大功率扰动下的系统动态频率响应约束。首先,分别构建两种预想功率扰动下的系统动态频率响应模型,采用阶梯备用等方法进行模型降阶,并进一步推导两种模型下的频率指标解析式。其次,提出计及动态频率响应约束的日前-日内联合调度架构,并分别构建日前及日内调度模型。进而,针对调度模型中最大频差约束导致的非线性问题,采用两阶段迭代方法求解。最后,开展算例分析,结果表明,所提联合调度策略能够兼顾系统运行经济性要求与频率安全性要求。

四川栗子坪自然保护区不同海拔土壤氮组分垂直特征及季节动态

[目的]为揭示四川栗子坪国家级自然保护区土壤氮组分(全氮、水解氮、铵态氮、硝态氮)沿海拔梯度的垂直分布差异及其与理化因子响应关系。[方法]于2022年3,6,9,12月测定并分析四川栗子坪海拔1800,2100,2400,2700 m土壤氮组分及理化因子的垂直变化特征,并采用多变量方差分析及冗余分析法,分析环境因子与氮组分的关系及季节动态。[结果](1)海拔、季节及交互作用对土壤氮组分有显著影响,3,6,9,12月铵态氮含量表现为海拔2100 m>2400 m>1800 m>2700 m,硝态氮含量表现为海拔2400 m>2100 m>2700 m>1800 m,沿月份梯度增加,全氮含量呈增加趋势,水解氮、铵态氮、硝态氮含量呈先减后增趋势,12月全氮和硝态氮含量有最大值分别为1.25 g/kg和8.26 mg/kg,3月水解氮和铵态氮含量有最大值185.14,5.80 mg/kg。全氮、水解氮、铵态氮、硝态氮沿土层变化规律有一致性,呈“V”形;(2)不同季节和海拔理化因子垂直变化特征与氮组分差异较大,土壤全磷、有效磷、速效钾含量沿土层深度增加先增后减;(3)影响土壤氮组分的关键因子存在季节差异,3,12月为有机质、非毛管孔隙度、速效钾、全磷、有效磷和毛管孔隙度,6,9月为有机质、全钾、毛管孔隙度、全磷和速效钾。[结论]研究结果为自然保护土壤养分对海拔和季节响应机制及生态保护综合治理提供具体生产实践依据。

堵河源自然保护区庙台槭种群动态及空间分布

目的:探究湖北堵河源自然保护区庙台槭(Acer miaotaiense)生存现状、数量动态和分布格局,为保护庙台槭种群提供科学依据。方法:通过编制静态生命表,绘制存活曲线、死亡率和消失率曲线、生存函数曲线,分析种群龄级数量与动态特征;采用时间序列预测种群未来发展趋势;采用单变量成对相关函数分析种群的空间分布格局。结果:庙台槭种群呈不规则金字塔型,种群为增长型,但对外界干扰的敏感性较高。庙台槭种群的存活曲线为Deevey-Ⅱ型,死亡率和消失率随着龄级的增加,均呈现先陡增后陡降再缓增,峰值均出现在Ⅲ龄级。庙台槭种群的生存率随龄级增大而逐渐降低,累计死亡率随龄级增大而逐渐升高;第Ⅲ龄级后种群逐渐衰退。种群未来个体数量会随着龄级增大而增大,但会随经历的龄级时间跨度增大而逐渐减少。种群在0.5 m尺度为聚集分布,但在不同尺度整体呈随机分布。结论:庙台槭天然更新能力弱,种子萌发率低可能是幼苗缺乏的关键。种群保护实践中,应优先保护庙台槭天然生境,确保种群数量逐步恢复,同时加强人工繁育以促进种群自身的繁殖能力。