Intelligent geochemical interpretation of mass chromatograms:Based on convolution neural network

Gas chromatography-mass spectrometry(GC-MS)is an extremely important analytical technique that is widely used in organic geochemistry.It is the only approach to capture biomarker features of organic matter and provides the key evidence for oil-source correlation and thermal maturity determination.However,the conventional way of processing and interpreting the mass chromatogram is both timeconsuming and labor-intensive,which increases the research cost and restrains extensive applications of this method.To overcome this limitation,a correlation model is developed based on the convolution neural network(CNN)to link the mass chromatogram and biomarker features of samples from the Triassic Yanchang Formation,Ordos Basin,China.In this way,the mass chromatogram can be automatically interpreted.This research first performs dimensionality reduction for 15 biomarker parameters via the factor analysis and then quantifies the biomarker features using two indexes(i.e.MI and PMI)that represent the organic matter thermal maturity and parent material type,respectively.Subsequently,training,interpretation,and validation are performed multiple times using different CNN models to optimize the model structure and hyper-parameter setting,with the mass chromatogram used as the input and the obtained MI and PMI values for supervision(label).The optimized model presents high accuracy in automatically interpreting the mass chromatogram,with R2values typically above 0.85 and0.80 for the thermal maturity and parent material interpretation results,respectively.The significance of this research is twofold:(i)developing an efficient technique for geochemical research;(ii)more importantly,demonstrating the potential of artificial intelligence in organic geochemistry and providing vital references for future related studies.

Impact of rock type on the pore structures and physical properties within a tight sandstone reservoir in the Ordos Basin, NW China

The pore-throat systems and physical properties of tight sandstone reservoirs are complex,and deposition is thought to be a fundamental control for them.In this study,the impacts of the full ranges of rock types(from pebbly coarse sandstone to fine sandstone) on the pore structures and physical properties of the Permian tight sandstone reservoir in the eastern Ordos Basin were investigated comprehensively through a series of experiments including conventional physical testing,thin-section analysis,scanning electron microscopy,nuclear magnetic resonance analysis and high-pressure mercury injection tests.The results showed that the coarser-grained sandstones tend to have higher feldspar content and lower percentage of cements,leading to strong dissolution,weak cementation and improved porosity and permeability.The medium sandstone has the highest level of quartz and the lowest average content of feldspar,resulting in strong heterogeneity of physical properties.Only those medium sandstone reservoirs with relatively high content of feldspars have better physical properties.Additionally,the coarser-grained sandstones contain relatively large dissolution pores(nearly 200 μm),whereas the finer-grained sandstones have more intercrystalline pores with a relatively more homogeneous pore structure.The pebbly coarse sandstone and coarse sandstone reservoirs are favorable targets with best physical properties.

Simulations on the multi-shell target ignition driven by radiation pulse in Z-pinch dynamic hohlraum

We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where the hohlraum is composed of a single metal liner,a low-Z plastic foam,and a high-Z metallic foam.The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE.When the peak drive current is 50 MA,simulations suggest that an x-ray pulse with nearly constant radiation temperature(-310 eV)and a duration about 9 ns can be obtained.A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain(G)about 6.19,where G is the ratio of the yield to the absorbed radiation.Through this research,we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.

Factors influencing the aggregation behavior of residual associative polymer in produced oily fluids

The influence of emulsified oil, suspended solids, Fe3＋, Fe2＋, cationic water clarifier and sulfate-reducing （SR） bacteria on the aggregation behavior of residual hydrophobic modified polyacrylamide in treated oily wastewater from polymer flooding was studied by fluorescence spectroscopy and dynamic light scattering. The result of I1/I3 showed that the polarity of hydrophobic microdomains increased, whereas the size of the hydrophobic microdomains may be decreased, where the value of I1/I3 represents the ratio of the intensity of peak 11 （374.0 nm） to that of peak/3 （385.0 nm） of the vibration fine structure of pyrene monomer emission in residual polymer solution. The results of the ratio of I1 at 48 h to I1 at 0 h （I1,48h/I1,0h） indicated that oil and cationic water clarifier could inhibit the aggregation to some extent, while Fe2＋ and suspended solids were helpful for aggregation, and Fe3＋ and SR bacteria had no significant influence on the aggregation of polymer.

Sedimentary environment and model for lacustrine organic matter enrichment:lacustrine shale of the Early Jurassic Da’anzhai Formation,central Sichuan Basin,China

Based on the analysis of element geochemistry and total organic carbon(TOC),this study investigates the main factors controlling organic matter(OM)enrichment,reconstructs the evolution process of the sedimentary environment,and proposes a dynamic OM enrichment model of the Jurassic Da’anzhai(D)Formation,Sichuan Basin.The results indicate that the Sichuan Basin was generally dominated by a warm and oxidizing sedimentary environment,but with some peculiarities,such as a hotter climate in the D1 member and more anoxic lake water in the D2a member.The sedimentary evolution of the Da’anzhai Formation can be divided into a fluctuating sedimentary stage,a stable sedimentary stage and a reef-building stage.The D2a member showed the strongest hypoxia,the weakest weathering,the largest amount of terrestrial inputs,and the highest TOC content.The TOC is positively correlated with reducing conditions and terrestrial inputs,negatively correlated with weathering.Based on these findings,it is suggested that the global climate in the Early Jurassic period had a complex regional effect and the global oceanic anoxic events of the Toarcian did not spread to the Sichuan Basin.Thus,the anoxic deep water,high terrestrial inputs,and weak weathering were conducive to rapid deposition and preservation of lacustrine OM.