超深超高压裂缝性致密砂岩气藏高效开发技术——以塔里木盆地克拉苏气田为例

塔里木盆地库车坳陷克拉苏气田属于国内罕见的超深超高压裂缝性致密砂岩气藏,气田开发在超深圈闭及断层的落实、储层气水分布的预测、气藏精细描述、裂缝活动性变化的评价及预测、动态监测资料录取、渗流机理研究及对水侵的预测和治理等方面面临诸多难题。为此,通过开展超深复杂构造地震处理解释、裂缝性致密储层定量描述与地质建模、断层活动性评价、超高压气井动态监测以及超高压条件下的渗流机理实验,结合考虑水侵影响的优化开发技术政策,攻关形成了适用于该气藏的系列配套开发技术,并应用于气田开发实践。结果表明:(1)对于山前超深复杂构造,宽方位、高覆盖、高密度的地震采集技术和基于高精度速度模型的叠前深度偏移处理技术可以有效改善地震资料的品质,提高圈闭和断层的落实程度;(2)沿轴线高部位集中布井的井网可以较好地规避构造偏移的风险,实现储量的有效动用、延缓边部水侵;(3)防水、控水、排水是裂缝性致密砂岩气藏开发全生命周期都需要考虑的关键问题,温和开采、见水排水是主要的开发技术对策;(4)系列配套开发技术在该气田取得了良好的应用效果,钻井成功率、产能到位率均达到100%,高效井比例达到78%,该气田年产气量从3×10~8 m~3快速上升到74×10~8 m~3。     

Nature inspired 21 branches sneezewort/Achillea ptarmica plant growth pattern–shaped antenna for Ku‐band applications

This reported paper presents the design and analysis of wideband nature inspired planar antenna of 46 × 18 × 1.6 mm³ size, designed using FR4 (Flame Retardant) substrate. The antenna patch is delineated from the growth pattern of sneezewort plant with supplementary notion of golden ratio in branching and branch width. The total number of branches in each stage follows the Fibonacci series and the branch width is calculated from the golden ratio concept. Starting from one feed line and two branches, the maximum numbers of branches are increased to 20. There has been significant enhancement in the radiation performance of proposed geometry by increasing the number of branches to 21 and by modifying ground with T‐shaped slot. The antenna covers wide impedance bandwidth of 8.2 to 16.5 GHz by possessing stable radiation characteristics.     

砂砾岩含水层下综放开采导水裂隙演化及防治水措施

以伊犁矿区第三系砂砾岩含水层下综放开采为工程背景，利用相似模拟实验研究了采动引起覆岩的破断特征。结果表明，工作面推进到135 m左右，裂隙带即与砂砾岩含水层贯通，这对于6-7煤层安全高效开采造成较大威胁。为了保障工作面回采安全，设计了超前探放水钻孔，累计泄水量344 800 m³，大幅度减少了对粗砂岩流砂层的补给作用；对首采综放工作面现场观测表明，垮落到采空区的粗砂岩流砂层成为湿润的固体砂，固体砂覆盖于采空区又起到防灭火的作用，对矿井安全生产十分有利。     

A low power and low phase-noise 91~96 GHz VCO in 90 nm CMOS

This paper reports a 94 GHz CMOS voltage-controlled oscillator (VCO) using both the negative capacitance (NC) technique and series-peaking output power and phase noise (PN) enhancement technique. NC is achieved by adding two variable LC networks to the source nodes of the active circuit of the VCO. NMOSFET varicaps are adopted as the required capacitors of the LC networks. In comparison with the conventional one, the proposed active circuit substantially decreases the input capacitance (C_in) to zero or even a negative value. This leads to operation (or oscillation) frequency (OF) increase and tuning range (TR) enhancement of the VCO. The VCO dissipates 8.3 mW at 1 V supply. The measured TR of the VCO is 91~96 GHz, close to the simulated (92.1~96.7 GHz) and the calculated one (92.2~98.2 GHz). In addition, at 1 MHz offset from 95.16 GHz, the VCO attains an excellent PN of – 98.3 dBc/Hz. This leads to a figure-of-merit (FOM) of ?188.5 dBc/Hz, a remarkable result for a V- or W-band CMOS VCO. The chip size of the VCO is 0.75 × 0.42 mm², i.e. 0.315 mm².     

风速时间序列混沌判定方法比较研究

混沌识别是对非线性时间序列进行混沌预测的前提。针对时间序列风速确定性与随机性相结合的复杂非线性特征,研究了不同的混沌识别方法,并对风速时间序列进行混沌特征识别。应用随机噪声、周期运动及经典混沌系统的时间序列对所选方法进行可靠性验证。对美国国家风能研究中心M2测风塔实测时间序列风速数据进行非线性混沌特征识别。结果表明:风速时间序列具有明显的混沌特征;各风速时间序列表现出不同程度的混沌特征;各混沌识别方法对风速时间序列混沌特征的表达形式不同,互为补充,相互验证。     

Investigation of seasonal variations of Beijing pavement condition data using unevenly spaced dynamic panel data model

Beijing municipal highway administration started to collect pavement condition data on its major expressways since 2006. It is advised in the Chinese practice standard that data collection shall be conducted on annual basis. However, pavement data are usually collected at different seasons of the year, which may cause significant seasonal variations in the observed condition. Moreover, for some reasons, data are missing for some of the pavement sections at certain years, which could bring up difficulties in performance model estimation and inference. These concerns have been simply neglected in past practice. This study proposed an unevenly spaced dynamic panel data model to investigate the seasonal patterns of a performance indicator called Ride Quality Index (RQI). A quasi-differencing approach was adopted for the estimation. Data collected from the 5th Ring Road of Beijing were used in the case study. It was found that RQI data collected during the fall season are expected to be lower than that collected during the spring or summer seasons. Findings from this research would be helpful to pavement engineers in using unevenly spaced pavement condition data for future condition estimation.     

Dual-PISA: An index for aggregation operations on time series data

Aggregation operations play an essential role in time series database management. As the number of data increases, it is difficult for current solutions, such as summary table and MapReduce-based methods to respond to such queries with low latency. Other approaches, such as segment tree-based methods, have a poor insertion performance when the data size exceeds the available memory. This paper proposes a Persistent Index for Segmented Aggregations (PISA), which has fast insertion performance and low latency for aggregation queries. PISA uses a forest to overcome the performance disadvantage of insertion in traditional segment trees. By defining two kinds of tags, namely code number and serial number, we propose an algorithm to accelerate queries by avoiding unnecessary reading data on disk. Additionally, we extend it to Dual-PISA to tolerate a range of unordered data, which is very important in the real world. Dual-PISA is stored on disk and is hugely memory-efficient — only takes a few hundred bytes of memory for billions of data points. Dual-PISA can be easily implemented on both traditional databases and NoSQL systems. It handles aggregation queries within milliseconds on a commodity server, for a time range that contains tens of billions of data points.     

A finite line source simulation model for geothermal systems with series- and parallel-connected boreholes and independent fluid loops

A model for the simulation of geothermal systems with parallel- and series-connected boreholes is presented. Mass and heat balance problems are formulated for each component in the system and are assembled into system-level problems. A third problem is formulated to account for heat transfer in the bore field, using the finite line source solution. This third problem is coupled to the system-level heat balance problem by an analytical solution of the heat transfer inside boreholes with multiple U-tubes. The simulation model allows for any number of independent fluid loops within the bore field or within individual boreholes and allows for combinations of specified inlet fluid temperatures and heat extraction rates in independent fluid loops. The model accounts for the axial variation of the fluid and borehole wall temperatures and heat extraction rates. The capabilities of the model are demonstrated through three example simulations.     

滇西龙陵平达花岗岩体成岩时代及其地球化学特征

滇西龙陵平达地区的花岗岩体要是加里东运动早期以及燕山—喜山期岩浆活动形成的岩浆响应。通过应用实验仪器ME-XRF26dX射线荧光光谱仪、ME-MS81电感耦合等离子体质谱完成对花岗岩样品的主量元素、稀土元素以及微量元素的测定。在该研究区内,岩性以花岗岩、花岗闪长岩为主,SiO_2含量平均70.9%,Al_2O_3含量13.8%～18.2%,K_2O含量3.39%～5.83%,Na_2O平均含量2.48%,显现出"富硅、高铝—钠、高镁—钾",高钾钙碱性系列的特点,属于过铝质花岗岩;稀土元素总量偏高,平均137×10~(-6),轻重稀土元素比值在1.52～8.2,分馏较为强烈,轻稀土含量介于32×10~(-6)～197×10~(-6),相对富集,重稀土范围为14.4×10~(-6)～65.8×10~(-6),相对亏损,Eu显现出明显的负异常特征,曲线向右倾;同时Sr=0.1×10~(-6)～136×10~(-6),Yb平均1.9×10~(-6),符合低Sr低Yb的特征,即花岗岩在低或者中等压力下形成,可能为碰撞作用有关的钙碱性花岗岩。结合前人的研究成果,对该区晚中生代花岗岩开展系统的岩相学、矿物学、锆石U-Pb测年等研究,为未来整个龙陵地区花岗岩体的研究工作提供参考。     

电压源逆变器混合多矢量预测共模电压抑制方法

近年来,为了减小共模电压对电压源逆变器的影响,模型预测共模电压抑制方法得到广泛研究。然而,常规的电压源逆变器模型预测共模电压抑制方法每个控制周期仅采用一个非零电压矢量作用,导致其电流谐波较大。为此,提出了一种混合多矢量模型预测共模电压抑制方法。首先给出了所提多矢量模型预测共模电压抑制方法的实现原理。其次详细分析了死区和电流纹波对共模电压的影响,并进一步对所提多矢量法进行改进。改进的方法在电流扇区7内使用单个非零电压矢量作用,而在其他扇区内使用多个非零电压矢量作用,从而不仅可以完全将共模电压限制在±Vdc/6之内,而且可以减小电流的总谐波畸变率。仿真和实验结果验证了该方法的有效性。