Based on detailed measurement in the field and a comprehensive analysis of carbonate microfacies， the Pennsylvanian reefal microfacies characteristic and sedimentary environment from Longjiangdong，Guangxi， China are analyzed． The twelve carbonate microfacies have been recognized including micritic/microsparitic limestone， peloidal/aggregate- grain grainstone， bioclastic wackestone/packstone，laminated mudstone，bounds- tone，bioclastic wackestone/packstone with single shell，coral framestone/bafflestone，bioclastic packstones/ grainstones with abundant benthic foraminifera or crinoids，wackestone/mudstone with calcispheres，bioclastic packstone/grainstone，unname reef- building organism framestone and brachiopod grainstone． In addition，four facies have been identified including open platform facies，restricted platform facies，coral reefal facies and shoal facies． According to analysis of microfacies combination and facies evolution，three stages and three reef units during the reef formation process have been noted． The evolution of each stage indicates a repeating fluctu- ation of the sea- level，but the water energy is still relatively low overall，which represents frequent changes of paleoclimate in the early Late Carboniferous．

The authors present the effects of the total organic carbon (TOC inert ) during pyrolysis and how it overall affects the estimates of the hydrocarbon index (HI) using the cross plot S 2 vs． TOC graph． A total of 21 drillcore samples consisting of the non- carbonaceous mudstones，carbonaceous mudstones，coaly mudstones and coals with S 2 ＞ 0． 35 are selected and used． The average TOC for the sampled population is 10． 36 wt%． TOC inert measured from the S 2 vs． TOC graph is 2． 97 wt% and the average pyrolysable TOC live is 7． 39 wt%． The HI is 102 mg HC/g TOC and the pyrolysable HI is 175 mg HC/g TOC，indicating that the TOC inert or mi- neral matrix adsorbs some of the hydrocarbons liberated during pyrolysis resulting into the low HI values which affects the correct determination of the source rock potential． Other applications of the S 2 vs． TOC cross plot have been used to determine the depositional system tracts． The high stand system tract is also determined through this method．

According to the lithological assemblages and elemental geochemistry of the measured profile，the authors studied the sedimentary and tectonic environment of the Late Carboniferous Tangjiatun Formation in Acheng． The results show that the trace elements of mudstone samples from Tangjiatun Formation have the char- acteristics of high Th，V and Cu，but low Ba，Nb and Sr． The rare earth elements are characterized by signifi- cantly light and heavy rare earth elements differentiation，relative enrichment of light rare earth elements，and a negative anomaly of δEu． The Tangjiatun Formation belongs to a marine and delta sedimentary environment， and its tectonic setting is considered as a continental island arc environment．

In order to understand the diagenesis and its influence on porosity and permeability of sandstones from Yingcheng Formation in Jinshan field，applying thin sections，casting and scanning electron microscope， the authors studied petrography，diagenesis，porosity and permeability of Yingcheng Formation sandstone reser- voir． The results show that the reservoir of Yingcheng Formation is mainly composed of lithic arkoses． Sand- stones experienced compaction，pressolution，cementation，metasomatism and dissolution． The primary pores of the sandstones are undeveloped; most of pores are the secondary pores，which are mainly intragranular dissolu- tion pores in feldspar and debris． The compaction and cementation reduced the primary pores in sandstones， the porosity and permeability decreased; while the dissolution formed the secondary pores，resulting in the porosity and permeability increase． Due to compaction and cementation，the porosity and permeability are reduced with increasing of depth． There exists an abnormal enlargement of porosity and permeability within a depth range 2 310- - 2 450 m． In combination with analysis of petrology，the dissolution of feldspar and debris is most deve- loped in the depth range． Therefore，compaction，cementation and dissolution are the important factors which affect the porosity and permeability of sandstones．

In order to solve dynamic problems caused by the internal structure of fluvial reservoir，it is necessa- ry to study the fine anatomy of point bar． Taking Minghuazhen Formation in the northern block of Q oilfield， Bohai Sea as an example，the authors studied identification marks，distribution pattern and scale of point bar based on coring， logging and dynamic data． The results show that the length of point bar and the width of lateral accretion body are 713- 911 m and 71- 111m，respectively; the dip angle and the thickness of lateral accretion bedding are 3.5°- 5.9° and 0.1- 0.5 m． The lateral accretion beddings are the key factor affecting the seepage velocity of the tracer．

Borehole gravity has been used in mineral exploration recently with the advent of slim- hole gravime- ters． It is logical to perform inversion to utilize the information in the newly acquired data． The inversions were carried out by using cokriging，which is a geostatistical method of estimation that minimizes the error variance by applying cross- correlation between several variables． In this study the estimated densities are derived by using boreholes gravity and known densities along the borehole． This method does not need iterative process and computes efficiently． The selection of examples demonstrates that this method has the ability to include physical property from borehole measurements in the inversion． The synthetic examples demonstrate the density variation along a borehole can be well determined without depth constraints in the inversion． The resolution of the reco- vered model can be further improved by including the densities along the borehole for inversion． However，this capability decreases dramatically with the increasing of distance between the anomalous body and the borehole．

In process of seismic exploration，the noise of seismic signals produces serious interference． Conven- tional methods of wavelet threshold denoising cannot fully use the characteristics of seismic signals due to its limitations． There is always a certain degree of deviation between estimated value and actual value． In this stu- dy，a method of seismic data denoising is proposed，the authors use the current coefficients，the parent coeffi- cients and the neighborhood coefficients based on dual- tree complex wavelet transform (DTCWT) and related sub-band denoising model (TrivaShrink) to achieve the optimal estimation of shrinking factor and get the noise reduction of seismic records． It is found that the method is better than conventional methods of wavelet threshold denoising in removing random noise．

Full waveform inversion (FWI) is a high resolution inversion method，which can reveal detailed in- formation of the structure and lithology under complex geological background． It is limited by many kinds of noi- ses when the method applied to the real seismic data． Based on Huber function criterion，the objective function combinates the anti- noise of L 1 norm and the stability of L 2 norm in theory，the authors derive the gradient for- mula of the Huber function by using L- BFGS algorithm for FWI． The new method is proved by synthetic seismic data with the Gaussian noise and the impulse noise． Numerical test results show that L- BFGS algorithm is ap- plied to the frequency domain FWI with the convergence speed and high calculation accuracy，and can effec- tively reduce computer memory usage; and the Huber function is more robust and stable than L 2 norm even with the noises．

Shallow gas is composed of all kinds of shallow buried natural gas resources ( ＜1500 m) with rela- tively small reserve for each gas resource． It has some advantages such as shallow burial depth，good physical properties and the huge accumulations． Based on the Wigner- Vill distribution，a general spectral decomposition method is applied in the shallow gas detection． Cone- shaped kernel function filtering method is used to suppress cross- terms of the Wigner- Ville distribution，which is tested on field seismic data． Because of shallow gas reser- voir has a characteristic that low frequency energy is stronger and high frequency energy is weaker，it indicates the presence of shallow gas successfully．