Basement faults and overburden faults mainly stretched to north-east and north-west directions in the central Junggar Basin.The Jurassic mainly developed two delta systems of sedimentary facies stretched to north-east and north-west directions.Early dominant activity of basement faults controlled the boundaries of main secondary structural zones,the up-growth of ancient lobes,distribution of main faults and stretching direction of four pressing-twisting structural zones.The minor activity of basement faults in the north-east direction led to crushing of the overburden,so that the Permian lobe zones turned into the surface faulting-crushing zones which were easily eroded and run down by fluvial channel or drainage systems.The main sandstone bodies of Sangonghe Formation and Xishanyao Formation were distributed along the main faults,lobe zones and tectonic line in the north-east direction,which showed the sedimentary was in response to activity of the north-east basement faults.The activity of basement faults controlled the early formation of protogenic petroleum pools,later adjustment and formation of deuterogenic petroleum reservoirs.The overburden faults controlled the formation of petroleum pools by coupling basement faults and forming the combination system of flower structure and orthogyral-reversal structure.The coupling manners included anti-tree bifurcation type,ladder type and chiasm type.The controlling activity of faults on petroleum reservoirs was different in the active stage and in the repose period.There was a reservoir-forming model for triune deuterogenic oil pools with fault-controlled sandstone bodies in lobe zones and upper slope.There was a forming model for protogenic (to mixed) oil pools with facies-controlled sandstone bodies in sag and lower slope.The structural essence of petroleum accumulation along the Permian ridge was the upward-stretching effect of basement faults with dominant and minor activities.The favorable exploration areas and relevant exploration suggestion were brought forward based on these two models.

The intercratonic coal-bearing basins are characterized by slow sedimentary ratio,broadly distributed coal beds,gradual evolution mode of temperature and pressure,as well as weak structural deformation.Taking the Upper Paleozoic of Ordos Basin as an example,the forming process of coal-formed gas reservoir was simulated by PetroMod software.The results show that the lithologic gas reservoirs are dominant in the intercratonic coal-bearing basins.The source kitchen of the coal-formed gas is distributed broadly.The migration pathway of natural gas is short,and there is mainly the vertical migration,while the horizon migration is minority.Superimposed sand bodies and fracture-developed zones are the dominant carriers of gas migration.

The relationship between palaeogeomorphology and development of sand bodies shows that there developed fault through,faults-transfer zone and incised valley in the depression wedges of the Paleogene of Bohai Bay Basin.Three basic valleys all controlled the positions of sandstone and conglomerate fan.The syndepositional tectonic slope-break zone controlled the distributions of sandstone and conglomerate.The thickness of sandstone and conglomerate is bigger at lower part of tectonic slope-break zone,and the distribution directions of sandstone and conglomerate are same as that of the syndepositional tectonic slope-break zone.The characteristics of syndepositional tectonic slope-break zone and its control to the distribution of sand bodies are different in different rifting episode.The main steep-slope faults and gentle-slope faults with dip-reverse strata were developed in the rift initiation episode.The main steep-slope faults and gentle-slope faults with dip-same strata were developed in the rift climax episode.Many syndepositional faulted slope-break zone resulted from above faults controlled the distribution of sand bodies.In post-rift episode,part syndepositional faulted slope-break zone changed into bent slope-break zone.The two kinds of slope-break zones together controlled the distribution of sand bodies.

The comparison of the lithologic reservoir with the structural reservoir shows that the lithologic reservoir has more predominant conditions in formation and distribution.The formation of lithologic traps is earlier,and there are more forming periods.The lithologic reservoirs can be formed only by primary oil-gas migration and secondary oil-gas migration in short distance.The lithologic reservoirs can be charged in the early era and experienced little destroy in the late structural activities.The lithologic reservoirs can be distributed not only in the low-potential areas,but also in the high-potential areas.The lithologic reservoirs can be enriched not only in lowstand system tract,but also in highstand system tract.So the lithologic reservoir has some predominant formation conditions and a great exploration potential.

Numerical simulation of pool-forming history was used to explore oil-gas accumulation and discuss the major controlling factors of pool-forming by modeling the development history of source-reservoir-seal rocks and traps as well as the conditions for migration and preservation of oil and gas,and paleotemperature in the Upper Paleozoic of Kongxi Buried Hill in Huanghua Depression.The study of buried history,geothermal history,source-reservoir-seal assemblage and hydrocarbon-expulsion history of the depression showed that the pools generated by the coal-related source rocks in the Upper Paleozoic were formed in two stages of the Late Mesozoic and the Palaeogene periods to present.In the Late Mesozoic,the hydrocarbon generation quantity was poor and the size of hydrocarbon reservoir was small.The Palaeogene to present was the major stage of pool formation.The formation of pools in the studied area mainly depended on the match of hydrocarbon-generation history,hydrocarbon-expulsion history and structural history and also depended on the preservation conditions of pools after pool formation.The reservoir and cap rocks are the secondary controlling factors for Kongxi Buried Hill in Huanghua Depression.

The Silurian bitumen sandstone in Tarim Basin is spread in the bulk-like,layer-like and heterogeneous spot-like styles in macroscopic scale,while different types of bitumen are filled in the pores and cementations with the filling-type and surrounding-type in microscopic scale.The experimental results show that the traditional analysis on physical properties of sandstone cannot describe the reservoir characteristics and porous structures of different sandstones filled with different types of bitumen.The quantitative measurements were made,and a new method for describing the reservoir characteristics by the use of residual porosity and resdidual permeability was proposed.The further experiment shows that the low-viscosity oil can fill the bitumen sandstone with the residual porosity higher than 4% and dissolve the organic matters,which greatly increase the residual porosity and residual permeability of bitumen sandstone.This kind of sandstone becomes the effective reservoir.

Taibei Depression in the shelf basin of East China Sea has the geological conditions for generating chimney structures,such as very thick source rock,overpressure and abnormal temperature.Based on the source of thermal fluid and geometrical characteristics of chimney structures in Taibei Depression of the shelf basin of East China Sea,the chimney structures were divided into three types and six subtypes.The generation and distribution of the chimney structures and their relations with oil-gas migration and accumulation show that the chimney structures can result in the episodic hydrocarbon expulsion,improve the reservoir characteristics and benefit hydrocarbon migration and accumulation.The layers in the normal pressure zone or the transitional zone from overpressure to normal pressure always are the best plays of gas and oil accumulation.

An integrated study on petroleum accumulation of BZ34 fault zone in Huanghekou Sag was carried out,including the hydrocarbon generation history,conduit system,petroleum sources and petroleum charging processes by means of single well,2-D basin modeling,oil-source correlation and data of fluid inclusion.It is concluded that petroleum migration and accumulation could be completed only in several million years during neotectonic stage.The main controlling factors for the late-stage rapid petroleum charging in neotectonic active zone include active source rock,fast hydrocarbon generation,pass-through conduit system,and high efficiency for hydrocarbon convergence and cross-layer migration.

The mixosedimentite reservoirs in Nanyishan of Qaidam Basin were divided into three types of deforming bedding mixosedimentite layer,horizontal bedding mixosedimentite layer and massive bedding mixosedimentite layer according to bedding structures of rock layers in the reservoirs.The analyses on the origin,composition,rock type,pore structure and physical properties of the rock layers show that the three kinds of mixosedimentite layers correspond to three types of sedimentary environments.The rock composition of mixosedimentite layers controlled the micro-texture of rocks,and the micro-texture of rocks decided the pore structure of rocks and the development degree of the micro-fracture.The pore structure and fractures of rocks finally decided the porosity and permeability of mixosedimentite layers.The reservoir characteristic of the deforming bedding mixosedimentite layer is the best,while that of the massive bedding mixosedimentite layer is the worst if it has not developed a lot of structural fractures.The physical properties of Nanyishan reservoirs are seriously related with the rock features and the distribution of structural fractures.

The observation of diagenetic evolution and pore types of sedimentary rock in Taibei Sag of Tuha Basin shows that the pores of reservoir in Taibei Sag can be defined vertically into six types of the primary pore zones,the primary-induced pore zones,the induced pore zones,the reduced induced pore zones,the secondary induced pore zones and the secondary reduced induced pore zones.The sequence-stratigraphic and comparative analysis show that the distributions of different pore zones are obvious in vertical and horizontal directions.The plane distribution of the induced pore zones,as a whole,showed deep in the west and south parts and shallow in the east and north parts.The effectiveness of reservoir pores correlated to the induced pore zones was determined.The main pores are distributed mostly under the induced pore zones.According to the controlling factors of the reservoir properties,buried history of sedimentary,oil and gas migration,and structure characteristics,the new favorable areas for oil and gas prospecting were predicted,and the controlling factors for lower limit of effective pores in reservoir was analyzed.The results can provide basis for exploration of lithologic oil pool and depression of risk for the deep exploration.

The conventional seismic exploration by adopting source of compression wave and receiver of single component geophone is unsuitable for high-velocity rock outcropped areas such as mountain land,mountain front and tundra areas.The effects of near-surface low-velocity layer and near-surface high-velocity layer on the propagation of reflection wave were analyzed.The results show that seismic data recorded by vertical geophone may approximate to the data of reflected compression wave when the near-surface velocity of rock in outcropped areas is low,which makes the conventional seismic exploration succeed in these areas.In land areas with high-velocity rock outcrops,the seismic data recorded by vertical geophone deviate from the data of reflected compression wave with the increment of dip angle of strata and incident angle of reflection wave,which results in the difficulties of conventional seismic exploration in the near-surface high-velocity rock outcropped areas.The three-component geophone can be taken as a receiver to record the vector field of seismic wave instead of the vertical geophone.The processing technologies of the three-component seismic data in the near-surface high-velocity layer are presented.

The catalytic hydropyrolysis technology was used to release the covalently bound biomarkers from the high-evolution sedimentary organic matter.The reaction mechanism of catalytic hydropyrolysis of kerogen was analyzed.The product distribution and the effects of key variables on the reaction were investigated.The conditions of temperature-programmed reduction from kerogen with catalytic hydropyrolysis technology in fixed-bed were obtained.The upper limit of temperature is 520℃,the heating rate is 5℃/min,the flow rate of hydrogen is 5L/min,the hydrogen pressure is over 10MPa,and the mass fraction of dispersed sulphided molybdenum is 1%.The experiment results show that the catalytic hydropyrolysis technology can be successively applied to study the high-evolution sedimentary organic matter.

The characteristics of sweep efficiency and oil-displacement efficiency during the polymer flooding in the heterogeneous sandstone oilfield were studied by oil-displacement experiments on three-dimensional physical models.The effects of reservoir type with polymer flooding technology on enhanced oil recovery were analyzed.When the barrier exists,the contribution of medium-permeability reservoir to enhance oil recovery is 48.35%.The low-permeability reservoir has a contribution of 30.86%,and the high-permeability reservoir has 20.79%.The analysis shows that the polymer flooding is dominant to improve the sweep efficiency of reservoirs with low and middle permeability.Comparing with water flooding,the viscoelasticity of polymer flooding is favorable for improving the sweep efficiency of reservoirs,but it is limited to enhance oil recovery.

In order to determine the feasibility of a gel system under certain conditions of reservoir,the syneresis behavior that is an important factor affecting the long-term stability of gel in reservoir were studied.It is indicated that the syneresis of xanthan-chromium(III) gel system can be described by means of first-order reaction.The reaction rate constant increases while increasing temperature and the concentration of initial cross-linking agent.The calculation with Arrhenius equation shows that the activation energy is about 144.2 kJ/mol.The salinity has no effect on the syneresis of xanthan-chromium(III) gel system.An evaluation method for sysneresis rate of gel is presented.The syneresis of gel at any temperature can be predicted by means of the activation energy of syneresis reaction.Syneresis of gel under certain conditions is the inherent behavior of gel.Slight syneresis has no effect on the application of gel in the porous media.The prediction results of syneresis are given when the volumes of gel reach 50%,20% and 10% of its original volume.

The depletion experiments on the condensate gas systems with different condensate oil content were carried out in PVT cells and long cores.The condensate oil saturation was tested.The conventional relative permeability curves at the ordinary temperature and low-pressure,and the equilibrium oil-gas relative permeability curve at high pressure and high temperature were determined.The results showed that the recovery of condensate oil from the long cores is two times larger than that in PVT cells.The condensate oil recovery prediction of the depletion experiment in PVT cells and long cores by the two kinds of curves and CMG simulation software showed that the different relative permeability curves with different interfacial tension lead to the variation of condensate oil recovery.It is suggested that the real relative permeability curves should be used in the numerical simulation.For the condensate gas reservoir with low condensate oil,the condensate oil saturation in long cores is higher than that in PVT cells,and there is not evaporation phenomenon.The condensate oil saturation still remains the maximum value in despite of the pressure declining.It shows that the formation in the tight condensate gas reservoir would be damaged by the condensate oil.

The La-Sa-Xing Oil Field in Daqing Oilfield has already entered very high water-cut developing stage.In order to determine the productivity condition of the oilfield,all the log techniques for injection profiles and production profiles in Daqing Oilfield were optimized.The injection profiles and production profiles of test section gained by reservoir numerical simulation were compared with those obtained by logging.For making comparability of the simulation and log results,the injection(production) quantity in the layer was split or combined.The sample deviations between simulation and logging results can be obtained and used to make the dynamic monitor project of oilfield.The dynamic monitor system can be optimized.

Self-resonating cavitation jet is a new type jet with the characteristics of strong pressure oscillation and high-cavitation inception.The effects of working parameters on the improvement of permeability of polluted rock by self-resonating cavitation jets impingement in a high-pressure vessel were investigated.The result shows that the effective depth of cavitation jet on the polluted rocks with different permeability is more than 250 mm.The increasing rate of permeability could be improved with the jet pressure increasing and reduced with the nozzle stand-off distance increasing.Meanwhile,the increasing rate of permeability can reach the maximum at the ambient pressure of 2 MPa.Under the same conditions,the increasing rate resulted from the self-resonating cavitation jet nozzle is two times of that from a conical nozzle.Field applications also showed that the self-resonating cavitation jets have obvious effectiveness on the plug removal of oil and water injection wells.

The dynamic viscoelasticity and normal rheological behavior of hydrophobic association polymer solution(HAPS) as well as the rheological behavior of HAPS in porous media were measured.The experimental results of dynamic viscoelasticity of HAPS indicate that the loss modulus (G″) and elastic modulus (G') of association polymer solution are higher when the concentration of association polymer(AP) is higher than the critical association concentration.The G″ is larger than the G' when concentration of AP is lower than the critical association concentration,and the G″ is smaller than the G' when the concentration of AP is higher than the critical association concentration.The G″ and G' are free from shear stress in the different concentration of HAPS.Under the experimental shear rate,the macroscopical rheological behaviors of HAPS show shear thinning and shear thickening.In porous media,the rheological behavior of HAPS shows the properties of Newton fluid under the low-speed shear.The shear thinning and shear thickening behaviors could be observed when increasing shear rate.The polymer with a bigger elasticity should be used,and its injecting rate should be higher than the critical viscoelastic flow rate when using hydrophobic association polymer in polymer flooding.In this way,the viscoelasticity of hydrophobic association polymer can be fully utilized to enhance oil recovery.

On the basis of the diffusion equation and Green Function,a new model for productivity test of horizontal well after hydraulic fracturing was derived by the superposition principle of potency.In this model,the influences of geometry,location,azimuth and conductivity of fractures on production rate are considered.In addition,the influential factors and the interference between the multiple fractures are also considered.When the production condition is close to the practical situation,this model can be used to accurately predict the productivity of fractured horizontal well with multiple fractures.In former study,the length,width,distance and conductivity of various fractures were regard as equal,which would result in some deviation.

A new method for evaluating pore structure in heterogeneous reservoir was proposed on the basis of mercury injection data and laboratory experiments of nuclear magnetic resonance.The total pores of rock were divided into spherical pores and cylindrical pores by mercury injection data and optimization algorithm of the sphere-cylinder model with restricted conditions.All pores of rock were rearranged and combined according to the radii of cylindrical pores.It is supposed that the compartment pores were divided by sphere-cylinder model in space,the number of sphere-cylinder model and ideal seepage sections were calculated.The seepage sections show good agreement with the index of reservoir quality.This research shows rock pore structures in figures with the sphere-cylinder model.

The evolvement characters of formation drillability time series were analyzed.A new method for predicting drillability of un-drilled formation under the bit was proposed according to the theory of support vector machine.A prediction model for formation drillability time series was given.This method was applied to predict the formation drillability of Fugu 1 Well in Changqing Oilfield.The comparison of the prediction results with the results of BP neural network indicates that this method is better than BP neural network and has the advantages of high prediction accuracy and excellent generalization.This method is suitable for formation drillability prediction before drilling.

Taking the new polyether polyatomic alcohol SYP-1 as the main agent,the coater,filtrate reducer and shale-control agent of polymer were optimally selected to develop a new drilling fluid.The properties including inhibition,mud filtrate control capacity,rheology,lubricity and formation protection ability of the new drilling fluid were evaluated in laboratory.The functional mechanism of the drilling fluid was briefly investigated.The field tests were made in LN3-6H Well and HD4-23H Well.During the process of drilling,the borehole wall was stable,and the hole diameter was regular.The electric logging,casing running and cementing operation were successful.Laboratory tests and field application indicate that this kind of drilling fluid has the advantages of excellent inhibition,lubricity,anti-sloughing,formation protection properties and convenience for field maintenance and treatment.The successful application demonstrates that the polyether polyatomic alcohol drilling fluid can meet the requirements of drilling in complex formation.

A mathematical model for topology optimization of the tree-type water-injection pipe network was established by taking the minimum investment as the objective function and taking the restrictions to the unique relations between wells and stations,and numbers of connected waterinjection wells as the constraint conditions.The optimization problem was divided into two layers of distribution and geometry.The genetic algorithm and nonlinear optimization were used to solve the problems respectively.The operational process of genetic algorithm was improved,and the fitness function was adjusted.Combined with the simulation annealing algorithm,it adopted the random parent-number fitness-weighted cross and many mutation methods and gave the method of determining initial temperature.The selection operation was also improved.Then a hybrid genetic algorithm was given.This algorithm can improve the speed of convergence and avoid premature convergence.Example shows the efficiency of the algorithm.

The complicated failure of drilling machinery was investigated with the data mining technique.The structure frame of the drilling mechanical failure data mining system is presented.The drilling mechanical failure diagnosis based on neural network was analyzed.A new method for making use of neural network to carry out diagnosis of drilling mechanical failure was proposed.The validity and practicability of the new diagnosis method were proved by the application case history of the data mining system for drilling mechanical failure diagnosis.

A technology for improving the temperature distribution of heat-sensitive oil in wellbore using heat pipe was proposed.Based on the heat transfer theory of two-phase closed thermosiphon and the model of thermal conduction with coupling heat pipe,a theoretical model for calculating the temperature distribution in wellbore with heat pipe was established.The mechanism and technological feasibility of improving fluid temperature distribution in wellbore using heat pipe were analyzed with this model.The applied results of this technology to Chu 32 Well in Huabei Oilfield showed that heat pipe can increase the temperature of fluid in the upper wellbore by absorbing the surplus thermal energy of the fluid in the lower wellbore.At the same time,it can improve the temperature distribution along the wellbore.This technology is significant to the economical production of heavy oil and heat-sensitive oil.

The pitting corrosion damage of pipeline was considered as uniform hole-type damage based on the damage theory.The degradation regularity of apparent yield strength and elastic modulus of damaged pipeline steel was investigated by tension test of specimen with artificial holes.On the basis of diluted solution theory,a model for describing corrosion process of the harmful media within the pipeline and the corrosion damage distribution along the radial direction of the pipeline was derived.The variation regularity of the mechanical properties of corroded pipeline steel with time was studied by corrosion test.Combining the above damage rules with the corresponding variation analyses of stress states and strength,a new approach to predict the remaining life of pitting corrosion damaged pipeline was proposed.

The traditional method for measuring drillability and mechanical properties of rock has the disadvantages of high-cost sampling and long-period testing and is indirectly and difficult in field application.A new method for testing rock drillability is presented.This method takes the detritus returned from bottom hole as the studying object.The fractal mechanism and forming process of broken rock during drilling were studied.The fragment distribution function of broken rock gained from the different depth of well was determined on the basis of laboratory experiment.The fractal dimension of broken rock was calculated.The correlation coefficient of fractal dimension is above 0.95.According to the experimental results of rigidity,intensity and drillability of rocks,a statistical model for combining rigidity,intensity and drillability of rocks with fractal dimension of fragment can be determined.

The global structure analysis and local crack evaluation on the semi-submersible platform servicing in South China Sea were carried out by finite element method and fracture mechanics theory.The fracturing parameters for describing the cracks and their propagation on the local shell plate of the platform were determined.The effects of local shell plate corrosion factor on the fracturing parameters distributed around the crack tip were investigated using ABAQUS software.The global structural strength evaluation to obtain the necessary boundary conditions for the analysis of local fracture was made.The distribution of stress intensity factor along crack front was analyzed by the fracture mechanics.

The generation and development process of the concept of foreland basin were discussed.It is pointed that the current research objects for modern foreland basin theory are confined to converging basins related to the Alpine orogenic belt instead of the diverging extensional geodynamic environment,associated peripheral basins and old foreland basins in the pre-Alpine period and neglecting most of the substances of foreland basins,which is an inborn defect and a hard barrier to stride over in its application.Both the underthrust A and underthrust C are only a visual expression of geodynamic environments,and the transformation between diverging extension and converging compress exists in the whole evolutionary process of foreland basins.The peripheral foreland basins should have three different models.Like other basins,foreland basins change with its development and evolution.There exists no simple or universal structural model for all of the foreland basins.It is an open question to directly and impracticably apply the four units of the "foreland basin system" proposed by Decelles et al,and artificially increase oil-gas resources in foreland basins with the misuse of the concept of foreland basins.Half of the 14 piedmont belts recently overrun as foreland basins in West China did not belong to the foreland basins.

Melut Basin is a large-scale basin of the Cretaceous-Paleogene sediment in the southeastern Sudan.Two strong rifting phases were developed during the Early Cretaceous and Paleocene,and one weak rifting phase was developed in the basin during the Late Cretaceous.Consequently,the main source rocks were deposited in the Lower Cretaceous and the main play was developed in the Paleocene.Based on analogue of seismic reflection characters and sequence stratigraphy,the Lower Cretaceous in the Northern Melut Sub-Basin(NMSB) was deduced as the main source kitchen.The half-graben style of NMSB made the northeastern gentle slope become the most advantageous accumulation area for hydrocarbon.Furthermore,the lower geothermal gradient controlled the critical moment of petroleum system in the Late Eocene,which provided enough hydrocarbons charging into the Paleocene.Accordingly,the pattern of reservoir-forming in Melut Basin was established.This pattern is quite different from adjacent Muglad Basin in Sudan and Bohai Bay Basin in China.Then,a more reasonable estimation of petroleum resources and more scientific exploration strategy in Melut Basin of Sudan were made on the pattern of reservoir-forming,and a Great Palogue Oil Field was successfully discovered by CNPC.

Although the recoverable reserves of oil remaining and production in the mature oil provinces of East China started decreasing in 1985 and 1988 respectively,the rising of oil production in the north-west part of China in recent twenty years has made up for reduction of output in the east part of China.Since 1997,the oil production in Zhujiangkou Basin in sea area has been reduced,and the ratio of reserves to production has dropped to very low point.The oil production in Bohai Basin will rise rapidly,which will not only make up for decreasing of oil production in South Sea,but also make contributions to the oil production boosting in China.The production change in more than twenty years indicated that the north-west and sea areas have become the preliminary strategic replacing areas.The oil production can keep relative stable and slight increasing at least in 15 years.

The sequence stratigraphic characteristics of the Palaeogene in Bohai Sea area were analyzed by the high-resolution sequence stratigraphy theory.The Palaeogene in Bohai Sea area can be divided into four large scale cycles(LSC) and eleven middle scale cycles(MSC).There is a close relationship between the sequence stratigraphic framework and the pool-forming elements of the subtle oil-gas pool in the Palaeogene of Bohai Sea area.The transition point from the base level rising cycle(BLRC) to the base level falling cycle(BLFC) is the location for development of hydrocarbon source rock.The lower part of the BLRC and the upper part of the BLFC are the development locations of sandstone.The MSC boundary and the sand body near the boundary are the good pathways for hydrocarbon migration,which constitutes the complex hydrocarbon migration system in combination with the long-active fault systems.There are six kinds of subtle oil-gas pool in the Palaeogene of Bohai Sea area.These pools appeared in the sequence framework may be predicated.The JZA Gas Pool is taken as an example to briefly illuminate the sequence stratigraphic analysis applied to the exploration for subtle oil-gas pool.

The prospecting degree is low,and the subtle reservoirs are very common in the central part of Junggar Basin.The principles and methods of high-resolution sequence stratigraphy were used to predict the distribution rules of the Jurassic reservoir.Based on drilling data and seismic calibration results,the Jurassic System was divided into four long-term base-level cycles bounded by unconformity and sedimentary transform surfaces.There are mainly three types of short-term base-level cycles,which control the formation of coastal-shallow lagoon sheet sand,mouch bar and subaqueous distributary channel sediments of braided stream delta front.According to stacking patterns of short-term cycles and calibration of logs restrained by key interfaces,a log interpretation model for the Jurassic medium-term base-level cycles was established,and 14 medium-term cycles were distinguished.Under the control of dynamic variation of the accommodation-sediment ratio,the favorable reservoirs were usually developed during the rising stage of the medium-term base levels.The sandstones deposited during descending stage are laterally interconnected,while the lithologic reservoirs can not be formed easily in this stage.The drilling data confirm that the mid-lower part of SQ3 sequence is the main interval for development of lithologic reservoirs.

A set of Triassic-Cretaceous terrestrial detrital rocks from 3000 meters to 4000 meters in thickness were developed in the southern edge of Altyn Mountain in the western Qaidam Basin.There are good exposures of Mesozoic strata in the southern edge of Altyn Mountain.A lot of well-preserved paleocurrent structures such as planar cross bedding,trough cross bedding and climbing bedding were developed in the mid-upper Triassic period and mid-lower Jurassic period.These sedimentary structures reveal that the current in the early Mesozoic went along the direction from northeast to southwest in the Yueyashan and went along two directions from southeast to northwest and from northeast to southwest in the Quanyagou.The later might be related to the short-period uplift of Lishiliang.The paleocurrent direction of the Mesozioc era in Lishiliang was considerably irregular.The paleocurrent analysis reveals that there was a large depression in the Mesozoic between Kunlun Orogen and Alabas Fold.

On the basis of the systematic analytical data of biomarker and stable carbon isotopic composition of oil samples collected from Baise Basin,the distribution and variation of the geochemical indicators for original organic source and depositional environment were revealed.The genesis of oils found in Baise Basin was classified into four types.All oil subsets have obvious differences in carbon number distribution curves of n-alkane,sterane composition,Pr-to-Ph ratio and carbon isotopic ratio and also exhibit a regular distribution geographically.The maturities of oils in the eastern depression of this basin show an increasing trend on the whole from west to east and from depression center towards margin.The spatial and temporal relationship between hydrocarbon generation of source rock and activity episode of faults is mainly responsible for the pattern of maturity variation.The geochemical parameters such as Pr-to-Ph ratio of oils from various regions are closely consistent with those of adjacent source rock,which suggests that the reservoirs are characterized by oil accumulation mechanism in short secondary migration distance.This character could be related to the lack of regional conduit-reservoir rock and the fault's interception and block.Moreover,it is the above factors that made the heterogeneities of source rock to be reflected as the diversified oil types in different region.