Treatment on oil/water gel deposition behavior in non-heating gathering and transporting process with polymer flooding wells

Against a background of crude oil shortage and low-carbon economy, optimization and simplification of oil–gas gathering and transporting play an indispensable role in efficient development of oilfield. Profit from the high efficient utilization of the produced liquid self-energy, single-pipe non-heating gathering and transporting process has been recognized in polymer flooding wells of Daqing oilfield (China). However, it is also facing the challenges of deposition, partial blockage, high wellhead pressure, production fluctuation and environment management. A field investigation of the application for the non-heating process and the variation of polymer flooding wellhead pressure were recently carried out. The flow patterns of the oil, water and gas mixture in single-pipe process were identified, and the locations where the gel deposition was most likely to occur were estimated. Deposition inhibitions and removal processes were practiced, and the operation parameters under different working conditions were optimized. The results indicated that single-pipe non-heating process could reduce 20% of the investment and 30% of the running cost and could also make the wellhead pressure of some wells exceed the maximum allowable operating pressure of oil gathering pipelines. There appears to be a proportional relationship among water content, flow rate, residual polymer concentration and gel deposition behavior in a certain range of gathering radius. The gel deposition rate of the produced liquid with polymer concentration of higher than 600 mg/L and the water content of 90.5% reached 0.1154 mm/h in the coldest climate under the normal flow rate of 85 t/d, and the theoretical pigging period was <10 days. Gelation nucleation which was related to emulsification was induced by the transition and coexistence of separated flow and dispersed flow in non-heating gathering pipelines. The main deposition located on the beginning of pipelines, manifold, valve and elbow, and wellhead pressure of 350 psi was created in the test period of 20 days. Although using chemical inhibition method could still obtain a drag reduction rate of more than 25% under crude oil gelation temperature, the fact of the centralization disability of wellhead dosing facilities and the potential threat of chemical inhibitors to the environment could not be ignored. The noticeable energy consumption and potential risks of pipeline restarting may be encountered using facilities improvement and sphere pigging operation in gel deposition behavior treatment. A relation schema which could be used to predict deposition rate and extract thermal flush period according to the actual working condition was established. The successful application of the non-heating gathering and transporting process combated the traditional view that heat tracing is essential for maintaining the surface process in extremely cold area. Furthermore, the results contributed to the existing literature in establishing subsurface and surface parts integration idea for a green field development and accelerate further application of non-heating gathering and transporting process.     

扬子板块西北缘早中泥盆世构造演化：来自略阳地区踏坡组岩石学、锆石年代学和微量元素组成的约束

碧口地块北缘下中泥盆统踏坡组的物源长期被认为来自碧口地块新元古界基底——碧口岩群,但一直缺少碎屑锆石物源数据的支持。本文对略阳地区泥盆系踏坡组不同层位的3个碎屑岩样品开展了系统的岩石学、锆石岩相学及其U-Pb定年和微量元素组成研究。锆石晶体特征对比分析显示,研究样品存在两种类型的锆石:普遍发育变质增生边的碎屑锆石(剖面北段样品)和不发育变质增生边的典型岩浆成因的碎屑锆石(剖面南、中段样品)。前者显示2个年龄峰值(～2.5 Ga主峰、～2.0 Ga次峰),还形成了2473±24 Ma的上交点年龄和359±84 Ma的下交点年龄,而后者两个样品有着一致的年龄峰值(～2.0 Ga主峰、～2.5 Ga次峰和～1.39 Ga微小峰值)。3个样品的谐和年龄均大于1.3 Ga,并不能限定踏坡组的沉积时代,且均不支持其物源主要来自碧口岩群的传统认识。碎屑锆石地球化学判别图解指示它们的源岩主要为形成于造山带环境中的花岗岩类(花岗闪长岩和英云闪长岩)、基性岩和钾镁煌斑岩。基于样品中的岩屑类型,结合区域地质、古流向、锆石年龄对比和源岩判别,认为踏坡组的原始物源来自位于扬子板块北缘的太古宙—古元古代基底(鱼洞子杂岩和崆岭杂岩),并且鱼洞子杂岩在踏坡组沉积后期曾大面积出露/抬升。同时表明碧口地块可能至少在早中泥盆世就与扬子板块拼合在一起了。     

大直径灌注桩的桩身完整性检测

桩身完整性检测的目的是查明桩的完整性,查清缺陷及其位置,以保证工程质量,不遗留事故隐患。常用的高、低应变,声波透射法三种动力测试方法在大直径灌注桩中所具有的特性及三种测试方法互为验证、多角度的分析研究可综合评价桩身完整性。     

黔南上司地区石炭系有孔虫:兼论华南维宪阶有孔虫生物地层序列

石炭纪时期有孔虫具有演化快、分布广、数量丰富、分异度高的特点,对于地层的划分对比具有极为重要的意义。与全球其他重要的石炭纪沉积区相比,华南有孔虫生物地层划分精度相对较低。本文首次较为系统地报道了华南石炭系代表性岩石地层单位旧司组和上司组下部丰富的有孔虫化石及其在剖面上的分布情况,并综合现有关于华南的有孔虫化石资料,将华南维宪阶划分为7个有孔虫化石带,自下而上分别为Eoparastaffella simplex带、Viseidiscus/Planoarchaediscus带、Paraarchaediscus带、Pojarkovella nibelis带、Koskinotextularia带、Bradyina带和Janischewskina带。这些有孔虫带可与全球其他典型的石炭纪沉积区进行很好的对比,从而为相关的研究提供一个较为精细的地层格架。通过对黔南上司地区有孔虫的研究,提议中国石炭系区域性年代地层单位上司阶底界可用有孔虫Bradyina的首现定义,并将上司阶与西欧的Warnantian亚阶中上部和俄罗斯的Aleksinian亚阶—Venevian亚阶对比,对应国际维宪阶上部,为全球石炭系年代地层对比提供了可靠的化石依据。     

Correcting the TRMM rainfall product for hydrological modelling in sparsely-gauged mountainous basins

This study developed a correction approach to improve the rainfall field estimation using the TRMM rainfall product in a sparsely-gauged mountainous basin. First, Thiessen polygons were generated to define the measurement domain of each raingauge. Second, the rainfall of TRMM pixels in each Thiessen polygon was corrected using a benchmark method based on the difference between the monthly rainfall estimated by a raingauge and the TRMM pixel that possessed a gauge station (referred to as a gauged pixel). Third, the rainfall values in the gauged pixels were adjusted to the weighted average value of the gauge rainfall and corrected pixel rainfall. Finally, the rainfall in the non-gauged TRMM pixels was corrected as the sum of two terms. The first term is the adjusted rainfall in the corresponding gauged pixel in the same Thiessen polygon, and the second term is the rainfall (after benchmark correction) difference between the current pixel and the gauged pixel. Our results indicate that the corrected rainfall data outperforms the original TRMM product in the simulations of moderate and low flows and outperforms the sparse raingauges in the simulations of both peak and low flows.

EDITOR A. Castellarin; ASSOCIATE EDITOR S. Huang     

Response of evapotranspiration and water availability to the changing climate in Northern Eurasia

We introduce a probabilistic framework for vulnerability analysis and use it to quantify current and future vulnerability of the US water supply system. We also determine the contributions of hydro-climatic and socio-economic drivers to the changes in projected vulnerability. For all scenarios and global climate models examined, the US Southwest including California and the southern Great Plains was consistently found to be the most vulnerable. For most of the US, the largest contributions to changes in vulnerability come from changes in supply. However, for some areas of the West changes in vulnerability are caused mainly by changes in demand. These changes in supply and demand result mainly from changes in evapotranspiration rather than from changes in precipitation. Importantly, changes in vulnerability from projected changes in the standard deviations of precipitation and evapotranspiration are of about the same magnitude or larger than those from changes in the corresponding means over most of the US, except in large areas of the Great Plains, in central California and southern and central Texas.     

IGS超快星历对GPS近实时反演水汽精度的影响研究

将IGS发布的超快星历与最终星历中卫星的坐标及钟差进行对比,初步验证IGS超快星历的精度。在此基础上,以美国国家海洋和大气局ARM实验中GPS连续运行参考站一周的观测数据作为实验对象,利用Bernese软件分别使用IGS最终星历以及超快星历进行GPS反演大气水汽含量的数据解算,将得到的基线精度以及对流层延迟值进行对比,结果表明采用最终星历和超快星历得到的基线精度基本相同,但对流层延迟值相差较大,并且差值较大的时刻一般出现在超快星历的外推时刻,并随着外推时间的增加逐渐增大。为此,本文设计了滑动式动态星历选择方案,通过实验验证,该优化方案能有效的提高近实时对流层延迟解算精度,满足GPS近实时反演大气水汽的精度要求。     

数值试验中时间步长的选取

建立一个二维的海陆风静力模式来讨论时间步长的选取，发现定时间步长不宜取得太大或者太小，必须是某个适当的值。变时间步长的模拟效果要比定步长理想。时间步长越大，海风中心强度模拟值变小。     

“珍珠”（0601）异常急翘路径和内核结构变化的诊断分析及数值研究

使用FY2卫星TBB资料、NCEP最终分析资料(1°×1°)和中尺度模式WRF,对0601号强台风"珍珠"的"急翘"异常转向路径和内核结构变化进行诊断分析和数值模拟。结果表明:"珍珠"移向变化与环境引导气流和位涡倾向1波分量正异常有关,"急翘"前12小时,环境引导气流向北偏转,位涡倾向1波分量正异常对应着"珍珠"移动方向变化;内核非对称结构发展与环境风垂直切变演变有关,垂直切变使得涡旋倾斜,涡旋倾斜方向出现较强的上升运动,导致"珍珠"内核偏南象限对流活动较强。     

波兰郁金香在中国的气候适生地研究

通过对波兰郁金香的水、热条件与中国大陆所有站点进行气候滑移相似分析表明,波兰郁金香在中国最适宜引种的范围很大,气候相似的大部分地方集中在３ 个地区：一是３４ ～３９°Ｎ、１０２～１１４°Ｅ的倒梯形区域;二是３５ ～４２°Ｎ、１１５ ～１２５°Ｅ的倒三角形区;三是西藏的部分地区。