A site selection method of DNS using the particle swarm optimization algorithm

The Domain Name System (DNS) is an essential component of the functionality of the Internet. With the growing number of domain names and Internet users, the growing rate and number of visit quantity and analytic capacity of DNS are also proportional to the Internet users' size. This study (based on the analysis of access popularity and the distribution of massive DNS log data) aims to optimize the configuration of the DNS sites, which has become an important problem. The ArcGIS software is used to show the temporal and spatial distributions of visit source of DNS logs. This study also analyzes the influence of different sites and the dependence on DNS service in different regions of the world. This information is important to further decision‐making on new DNS site selection. This article proposes new DNS site selection solutions, using particle swarm and multi‐objective particle swarm optimization algorithms for one new site and multiple sites, respectively. The results from particle swarm optimization, genetic, and simulated annealing algorithms were compared and experimental results confirmed the correctness and effectiveness of the proposed methods. The proposed methods could also be extended to solve other layout related issues, such as onsite facility layout and road network optimization.     

Methods of identifying gas-bearing reservoirs by logs and applications of volcanic formations

The authors generalized the methods how to identify and evaluate gas zones using logs,and put forward the methods of crossplots and overlays of porosity logs on the identification of volcanic gas-bearing reservoirs in the northern Songliao Basin with good results.This study provides technical clues in deep formations and offers references for other areas to identify oil and gas layers.     

Investigation on influence factors of dual laterologs curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form of dual laterologs, forward modeling technique were applied to calculate the dual laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than lm, the two-peak on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m, the form of logs does not vary significantly. If the formation thickness is greater than 4 m, a platform appears on the logs at the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tend to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between invaded zone, uninvaded formation and adjacentlayers.     

A randomization test for the comparison of ordered sequences

Several algorithms, based on dynamic programming techniques, for comparing, matching, or cross-correlating two ordered sequences of observations now exist. All such algorithms produce one or more optimal matchings, no matter what data are used. This paper presents an empirical method, based on a randomization test, for assessing how well the given sequences are matched or slotted together. The randomization test is designed to test the assumption, implicit in most cross-correlation algorithms, that both sequences comprise observations, at unknown but ordered times, from the same underlying yet unknown function of time. The test is intuitively appealing, easy to implement, works well on both artificial and real data, and requires no complicated parametric modelling.     

裸眼井声波全波测井中纵波和斯通利波的数值研究

本文利用射线展开理论、割线积分技术及留数定理,研究了裸眼井声波全波测井中纵波和斯通利波的性质。下面简要说明数值计算方法。 计算方法 考虑在无限大均匀地层中,有一充满流体的深井。在井轴上放一点状声源,则在井轴上离声源距离为z处的声压为     

电磁波测井资料反演中Jacobi矩阵的快速算法及其特性分析

针对采用单发双收探头同时测量相位差和幅度比,测井响应与地层介电常数和电阻率两者都有关的电磁波测井资料反演问题,构造了其反演目标函数Jacobi矩阵J的快速算法.J直接给出了测井响应随地层参数变化的关系,利用J和它转置矩阵JT的有意义乘积J.JT和JT.J可以方便地对在非均质地层中测井响应特征和仪器的探测特性进行考察分析,为测井资料处理方法研究与仪器改进提供依据.     

Paleomagnetic Logs: A Tool for Dating Lake Erie's Past

An examination of the lithology, paleomagnetic and Mossbauer Effect Spectroscopy (MES) log data and ¹⁴C determinations of cores taken from three small basins located in western Lake Erie, in conjunction with data obtained from earlier studies, has been used to re-evaluate the postglacial history of the area. After the re-advance of the Laurentide Ice Sheet into the Huron basin and the eastern part of the Erie basin during the Port Huron stadial about 13,000 yrs B.P., lacustrine clay was deposited across much of the western Erie basin in a lake ponded against the glacial ice front to the east. However, by 12,000 yrs B.P. as the ice front retreated, the waters from the Huron basin bypassed Lake Erie, first by the Kirkfield outlet to Lake Ontario, and later by the Fossmill and North Bay outlets to the Ottawa River. This resulted in the draining of water from most of the western Erie basin. Extensive swamps choked with plants formed in the small basin areas, and the surrounding low-lying former lake bottom was subjected to subaerial weathering. It would appear that by about 9,500 yrs B.P. there was an increase in surface run off into these basins and the swamps evolved into shallow, relatively warm-water lakes in which calcareous-rich clay was deposited. Isostatic rebound of the northeastern outlets of the Huron basin led to a gradual tilting of the basin and a progressive migration of the southern shoreline of Lake Huron (Lake Stanley phase) to the southwest. By about 5000 yrs B.P. the water level in the southern Huron basin had been raised sufficiently to re-open the Port Huron outlet into the Erie basin. This resulted in a substantial rise in the lake level in the Erie basin, terminated the deposition of calcareous-rich clay in the small basins, and led to the deposition of normal lacustrine sediments in the modern phase of Lake Erie.     

Estimation of Geological Attributes from a Well Log: An Application of Hidden Markov Chains

Geophysical well logs used in petroleum exploration consist of measurements of physical properties (such as radioactivity, density, and acoustic velocity) that are digitally recorded at a fixed interval (typically half a foot) along the length of the exploratory well. The measurements are informative of the unobserved rock type alternations along the well, which is critical for the assessment of petroleum reservoirs. The well log data that are analyzed here are from a North Sea petroleum reservoir where two distinct strata have been identified from large scale seismic data. We apply a hidden Markov chain model to infer properties of the rock type alternations, separately for each stratum. The hidden Markov chain uses Dirichlet prior distributions for the Markov transition probabilities between rock types. The well log measurements, conditional on the unobserved rock types, are modeled using Gaussian distributions. Our analysis provides likelihood estimates of the parameters of the Dirichlet prior and the parameters of the measurement model. For fixed values of the parameter estimates we calculate the posterior distributions for the rock type transition probabilities, given the well log measurement data. We then propagate the model parameter uncertainty into the posterior distributions using resampling from the maximum likelihood model. The resulting distributions can be used to characterize the two reservoir strata and possible differences between them. We believe that our approach to modeling and analysis is novel and well suited to the problem. Our approach has elements in common with empirical Bayes methods in that unspecified parameters are estimated using marginal likelihoods. Additionally, we propagate the parameter uncertainty into the final posterior distributions.     

Fluid Property Discrimination in Dolostone Reservoirs Using Well Logs

The Ordovician Majiagou Formation is one of the main gas-producing strata in the Ordos Basin,China.The identification of hydrocarbon-bearing intervals via conventional well logs is a challenging task.This study describes the litholog of Ma 5(Member 5 of Majiagou Formation)dolostones,and then analyzes the responses of various conventional well logs to the presences of natural gas.The lithology of the gas bearing layers is dominantly of the dolomicrite to fine to medium crystalline dolomite.Natural gas can be produced from the low resistivity layers,and the dry layers are characterized by high resistivities.Neutron-density crossovers are not sensitive to the presences of natural gas.In addition,there are no significant increases in sonic transit times in natural gas bearing layers.NMR(nuclear magnetic resonance)logs,DSI(Dipole Sonic Imager)logs and borehole image logs(XRMI)are introduced to discriminate the fluid property in Majiagou dolostone reservoirs.The gas bearing intervals have broad NMR T_2(transverse relaxation time)spectrum with tail distributions as well as large T_(2gm)(T_2 logarithmic mean values)values,and the T_2 spectrum commonly display polymodal behaviors.In contrast,the dry layers and water layers have low T_(2gm) values and very narrow T_2 spectrum without tails.The gas bearing layers are characterized by low V_p/V_s ratios,low Poisson’s ratios and low P-wave impedances,therefore the fluid property can be discriminated using DSI logs,and the interpretation results show good matches with the gas test data.The apparent formation water resistivity(AFWR)spectrum can be derived from XRMI image logs by using the Archie’s formula in the flushed zone.The gas bearing layers have broad apparent formation water resistivity spectrum and tail distributions compared with the dry and water layers,and also the interpretation results from the image logs exhibit good agreement with the gas test data.The fluid property in Majiagou dolostone reservoirs can be discriminated through NMR logs,DSI logs and borehole image logs.This study helps establish a predictable model for fluid property in dolostones,and have implications in dolostone reservoirs with similar geological backgrounds worldwide.