Petroleum Generation Kinetics and Geological Implications for Jurassic Hydrocarbon Source Rocks,Hongqi Depression,Hailar Basin,Northeast China

A sample from the Jurassic Tamulangou Fm.and two comparison samples from the Cretaceous Fm.were used to document the hydrocarbon generation kinetics and phase behaviors at two heating rates using the confined gold tube system.The results show that the different heating rates affect the reaction rates,paths and levels of organic matter evolution.The average activation energy and dominant frequency activation energy of liquid hydrocarbon are significantly lower than those of gaseous.Moreover,igneous intrusion had a positive effect on the blooming,enrichment and preservation of organic matter,promoting a Ro increase of 0.09%–1.07%in the Jurassic Tamulangou Fm.Two models were used to simulate the normal and abnormal evolution caused by thermal events combined hydrocarbon generation kinetic parameters.Thermal simulation analysis shows that oil generation was initially slow and then increased rapidly until a burial depth of 1500 m was reached at~128 Ma.The largest hydrocarbon expulsion began at~120 Ma,corresponding to a burial depth of 2450 m.The maximum cumulative yield is 510 mg/g TOC,and it is still in the peak period of hydrocarbon generation,which demonstrates a favorable potential for hydrocarbon exploration.

Sporopollen Assemblages from the Cretaceous Yimin Formation of the Hailar Basin,Inner Mongolia,China

Three sporopollen assemblages are recognized for the first time from the Cretaceous Yimin Formation in the Hailar Basin of eastern Inner Mongolia. They are （in ascending order）： the lmpardecispora-Aequitriradites- Clawttipollenites assemblage; the Triporoletes-Pilosisporites-Asteropollis assemblage; and the Appendicisporites- Asteropollis-Tricolpites assemblage, distributed in Members 1, 2 and 3 of the Yimin Formation respectively. Recognition of this biostratigraphic sequence is very important for the division and correlation of the Yimin Formation in the basin. Meanwhile, the age of the Yimin Formation is considered to be Barremian to Early Albian based on the palynological data.

Rhenium-osmium(Re-Os)geochronology of crude oil from lacustrine source rocks of the Hailar Basin,NE China

Re-Os radiometric dating of crude oil can be used to constrain the timing of hydrocarbon generation,migration or charge.This approach has been successfully applied to marine petroleum systems;however,this study reports on its application to lacustrine-sourced natural crude oils.Oil s amples from multiple wells producing from the Cretaceous Nantun Formation in the Wuerxun-Beier depression of the Hailar Basin in NE China were analysed.Subsets of the Re-Os data are compatible with a Cretaceous hydrocarbon generation event(131.1±8.4 Ma)occurring within 10 Myr of deposition of the Nantun Formation source rocks.In addition,two younger age trends of 54±12 Ma and 1.28±0.69 Ma can be regressed from the Re-Os data,which may reflect the timing of subsequent hydrocarbon generation events.The Re-Os geochronometer,when combined with complementary age dating techniques,can provide direct temporal constraints on the evolution of petroleum system in a terrestrial basin.

Selective dissolution of eodiagenesis cements and its impact on the quality evolution of reservoirs in the Xing＇anling Group,Suderte Oil Field, Hailar Basin, China

Reservoirs in the Xing＇anling Group in the Suderte Oil Field,Hailar Basin exhibit ultra-low to low permeability and high tuffaceous material content.This study comprehensively analyzed diagenesis and quality evolution of these low-permeability reservoirs using thin sections,SEM samples,rock physical properties,pore water data,as well as geochemical numerical simulations.Calcite and analcite are the two main types of cements precipitated in the eodiagenetic stage at shallow burial depths in the reservoirs.These two cements occupied significant primary intergranular pores and effectively retarded deep burial compaction.Petrography textures suggest selective dissolution of massive analcite and little dissolution of calcite in the mesodiagenetic stage.Chemical calculations utilizing the Geochemist＇s Workbench 9.0indicated that the equilibrium constant of the calcite leaching reaction is significantly smaller than that of the analcite leaching reaction,resulting in extensive dissolution of analcite rather than calcite in the geochemical system with both minerals present.Numerical simulations with constraints of kinetics and pore water chemistry demonstrated that the pore water in the Xing＇anling group is saturated with respect to calcite,but undersaturated with analcite,leading to dissolution of large amounts of analcite and no dissolution of calcite.Significant secondary intergranular pores have formed in analcite-cemented reservoirs from selective dissolution of analcite in the mesodiagenetic stage;the analcite dissolution formed preferential flow paths in the reservoirs,which promoted feldspar dissolution;and dissolution of such minerals led to the present reservoirs with medium porosity and low permeability.Calcite-cemented tight reservoirs have not experienced extensive dissolution of cements,so they exhibit ultra-low porosity and permeability.

Climate characteristics of the eastern Mongolian Plateau,China during the early Early Cretaceous(145-132 Ma):Palynological evidence from the Tongbomiao Formation in Well Hong-6,Hailar Basin

This study identified two palynological assemblages,namely Bayanhuasporites-Cycadopites-Protoconiferus and Cicatricosisporites-Cedripites-Perinopollenites,in the Tongbomiao Formation in the Hongqi Sag in the Hailar Basin,Inner Mongolia,China for the first time.The former is distributed in the lower part of the Tongbomiao Formation and is characterized by abundant gymnosperm pollen and diverse fern spores.Among them,the gymnosperm pollen is dominated by Paleoconifer(4.98%-31.62%)and Cycadopite(8.55%-25.23%)pollen grains and also includes other pollen grains such as Classopollis,Parcisporites,Erlianpollis,Callialasporites,and Jiaohepollis.The fern spores in the former palynological assemblage contain Bayanhuasporite(0-8.96%),Granulatisporites(0.93%-6.97%),and some important Cretaceous genera,such as Cicatricosisporites,Concavissimisporites,Densoisporites,Hsuisporites,Foraminisporis,and Leptolepidites.The Cicatricosisporites-Cedripites-Perinopollenites palynological assemblage is distributed in the upper part of the Tongbomiao Formation.Gymnosperm(77.30%),Pinaceae(31.9%),and Paleoconiferus(19.02%)pollen predominate this palynological assemblage,and Quadraeculina,Erlianpollis,and Jiaohepollis pollen are also common in this assemblage.The fern spores in this palynological assemblage include abundant Cicatricosisporites(4.29%).Besides,Concavissimisporites,Aequitriradites,and Leptolepidites are also common in this palynological assemblage.No angiosperm pollen has been found in both palynological assemblages.The identification of both palynological assemblages provides important evidence for the biostratigraphic correlation between the Hailar Basin and its adjacent areas.It also enables the reconstructions of the Berriasian-Valanginian(Early Cretaceous)vegetation and the paleoclimate on the eastern Mongolian Plateau during 141-132 Ma.The vegetation reconstructed on the palynological data of the represented by Hailar Basin in eastern Mongolian Plateau(141.6-141.4 Ma),form conifer forest or conifer broad-leaved mixed forest to conifer forest with shrubs and grassland,the climate belongs to warm temperate and warm-subtropicalt,the highest temperature is estimated to reach 35-38℃.Form 132.3 Ma,the vegetation type is conifer forest,and its paleoclimate is sub-humid warm temperate,the highest temperature is estimated to reach 24-29℃.