A review and research on comprehensive characterization of microscopic shale gas reservoir space

In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quantitative research,the combination of qualitative and quantitative research successively as well as the characteristics of each research stage were summarized.In addition,the current problems existing in the characterization methods of shale reservoir space were also analyzed.Furthermore,based on massive actual detection of typical core samples obtained from more than 50 global shale gas wells and relevant practical experience,a comprehensive characterization method of combining qualitative with the semiquantitative characterization was put forward.In detail,the indicators of the qualitative characterization include pore combination type and organic-matter microscopic morphology type,while the core elements of the semi-quantitative characterization include the percentage of the organic-matter area and the plane porosity of the pores of different types.Based on the reference of the naming and classification of rocks,the three-end-member diagram method was used to characterize microscopic shale reservoir space.This is achieved by plotting the three end-member diagram of 3 kinds of first-order critical reservoir spaces,i.e.,organic-matter pores,matrix pores,and micro-fractures,in order to intuitively present the features of the microscopic pore combination.Meanwhile,statistic histograms of organic-matter microscopic morphology type and the plane porosity of different types of pores were adopted to characterize the development degree of second-order pores quantitatively.By this comprehensive characterization method,the importance of both pore combination and the microscopic morphology of organic matter were emphasized,revealing the control of organic-matter microscopic morphology over the organic-matter pores.What is more,high-resolution FE-SEM was adopted to obtain semi-quantitative statistics results.In this way,the features of pore development and pore combination were quantified,not only reflecting the types and storage capacity of the microscopic shale reservoir space,but also presenting the hydrocarbongenerating potential of organic matter in shale.Therefore,the results of this research are capable of providing in-depth microscopic information for the assessment and exploration and development of shale gas resources.

A new parallel meshing technique integrated into the conformal FDTD method for solving complex electromagnetic problems

A new efficient parallel finite-difference time-domain(FDTD) meshing algorithm, based on the ray tracing technique, is proposed in this paper. This algorithm can be applied to construct various FDTD meshes, such as regular and conformal ones. The Microsoft F# language is used for the algorithm coding, where all variables are unchangeable with its parallelization advantage being fully exploited. An improved conformal FDTD algorithm, also integrated with an improved surface current algorithm, is presented to simulate some complex 3D models, such as a sphere ball made of eight different materials, a tank, a J-10 aircraft, and an aircraft carrier with 20 aircrafts. Both efficiency and capability of the developed parallel FDTD algorithm are validated. The algorithm is applied to characterize the induced surface current distribution on an aircraft or a warship.

The Australasian species of Lactarius subgenus Gerardii(Russulales)

This paper provides an overview and identification key of the Australasian species of Lactarius subg.Gerardii.A molecular phylogeny based on the nuc DNA markers ITS,LSU and rpb2,combined with detailed morphological observations resulted in the delimitation of 12 strongly supported and morphologically recognizable species.Five new agaricoid species are described here:Lactarius hora,L.coniculus,L.limbatus,L.leae and L.leonardii.Other agaricoid species belonging to subg.Gerardii are L.atrovelutinus,L.bicolor,L.ochrogalactus and L.reticulatovenosus.Lactarius venosus is also considered as a member but could not be included in the molecular analysis.Two new pleurotoid species are discovered:L.genevievae and L.conchatulus,both close relatives of L.uyedae,but each with distinct characters.Their position within subg.Gerardii is supported in the phylogeny and by their microscopic characters.This study also confirms the existence of multiple cryptic species and species complexes for which species recognition or species delimitation remains problematic as is the case for the Australian species L.wirrabara.In general,detailed macroscopic and microscopic observations are needed to identify species of L.subg.Gerardii.