The successive petroleum exploration cases of foreign paleo-uplifts were comprehensively researched,and the regional and petroleum geology characteristics of Tazhong Uplift were analyzed.The results show that there are some conditions for forming a large petroleum field in Tazhong Uplift of Tarim Basin.Tazhong Uplift took its shape earlier and developed steadily in the later period.There are many huge to large structures in the Lower Paleozonic deposition and a series of source-reservoir-cap compositions under the seal of Carboniferous mudstone.The unconformity in the Lower Carboniferous was the most important event during tectonic evolution and played the most important role during the formation of hydrocarbon traps.The specialty of tectonic evolution and the varied types of oil pools in the Tazhong Uplift resulted in a regional and widespread composite petroleum system under the regional seal of Carboniferous mudstone.It is suggested that oil and gas exploration in the Tazhong Uplift should be considered as a whole.Some oil pay protective measures should be taken during drilling in order to find big oilfields in the near future.

According to the tectonic evolution,structure of section,sequence relationship and source-reservoir-cap composition of foreland basins,the foreland basins can be divided into two types including epicontinental foreland basin and intracontinental foreland basin.The former includes peripheral foreland basin and retro-arc foreland basin.There are some differences between the two types of foreland basins:(1)The epicontinental foreland basin went through passive continental margin or retro-arc rift stage during tectonic evolution stage,but the intracontinental foreland basin lacked this period.(2) For the texture of sequences,the tectonic-sequence of the epicontinental foreland basin lain on the marine passive continental margin sequence or retro-arc rift sequence,and the intracontinental foreland basin lacked of marine sequence in generally.(3) On the genetic mechanism,the forming of the epicontinental foreland basin was related to the collided orogenic belt or retro-arc orogeny,and the intracontinental foreland basin was related to the rejuvenated orogenic belt.(4) On the characters of hydrocarbon development,the epicontinental foreland basin developed marine and non-marine source rocks,and the intracontinental foreland basin mainly developed non-marine source rocks.The differences of geological characteristics and hydrocarbon potentials between the epicontinental foreland basin and intracontinental foreland basin are obvious.

The Ordovician reservoir in Tahe Oilfield is one of the ancient mantle rock reservoirs.It was rebuilt by multiphase secondary structure-karst effect.The distribution of the reservoir in plane and portrait of reserving body are of strong heterogeneity.In the evolution process of multistage reservoir-forming,the fluid distribution in dimension is complicated and difficult to be described and estimated effectively with the groovy research method of reservoir description and reserve assessment,because of the gradient injection of fluid.Four models for description of small stratum,structure,fracture-karst and fluids were developed,and a geological reservoir model was proposed,on the basis of detailed research on the reservoir characteristics.The conformation of reservoir body in dimension was obtained,according to the class of layer cell per 60 meters.The orderliness of reservoir body distribution in plane was depicted,and the reservoir parameters were researched.The partition of different calculated cells was made out,and the diversification of reserves abundance of every belt and reserves of different reserving bodies were obtained.A set of methods for reservoir description and reserve assessment of Tahe Ordovician carbonate fracture-cave type pool was developed,with combination of karst reserving formation analysis,seismic-logging joint inversion technique,numericalmodeling,reservoir-forming mechanism,reservoir rebuilding and behavior analysis of production testing.These methods have been applied broadly in the development of the Tahe Ordovician pools effectively.The rate of gaining output increases by 5 percent to 8 percent.

Muglad Basin in Sudan is a passive rift basin.It was resulted from the extensional tectonics of the dextral shear stress field in the shear zone of middle Africa.It is different from the active rift basin formed by the uplift of mantle convection.The multi-phase rifting and sagging cycles are obvious in the basin.In the vertical direction,there are three phases of rifts with the strong-weak-strong pattern,respectively.The geothermal gradient in Muglad Basin is lower than that in active rift basin and higher than that in cratonic basin.The main structure stale is half graben.In generally,the basin (mainly in Block 1/2/4) can be characterized by an uplift,two depressions and two slopes.The depressions and uplifts arranged in alternative pattern and have different characteristics in the east and the west parts.There developed many sets of oil source rocks.The Abu Gabra Formation generated in the first rift phase is the principle oil source bed in the basin.The assemblage of Bentiu reservoir rock and Aradeiba regional cap rock formed the chief oil-bearing beds.The tilted antithetic normal fault blocks are the main traps,where the enclose ability of the reservoir and the height of oil column were decided by the throw of the fault and lithology in both sides of the fault.The Muglad Basin has predominant hydrocarbon forming conditions and a great exploration potential.

The development situations of original oil in place (OOIP) in China were analyzed.The affecting factors on OOIP of reservoirs include mainly oil-bearing area and net pay thickness of reservoir.Three uncertainties affecting on OOIP including reservoir sampling limitation,technical uncertainty and commercial uncertainty were discussed.It is suggested that three geological bases for improving estimation quality of original oil in place such as structure,oil-water system and reservoir heterogeneity should be researched further more.

According to the theories of fault-associated folds and salt tectonics,and based on the field work and seismic data interpretation for the western Kuqa Depression,the tectonic styles of the overburden,the salt sequence and the substrate,and their distribution,and formation mechanism were determined.The typical salt tectonic styles include salt cored anticlines,allochthonous salt,salt pillows,salt(fault) welds,salt necking,salt-associated depressions and "fish-tail" structures.The evolution of salt tectonics can be divided into two stages of early inceptive deformation (65~1.64 million years) and late compression deformation (about 1.64 million years).The two kinds of deformation,gravity sliding and layer-parallel compression in the early stage determined structural assemblages of the Kelasu tectonic belt.Deformation and tectonic styles in Qiulitake tectonic belt were caused by compression transmitted though the overburden detachment and were controlled by the thickness of salt layer and the crossed way of back thrust faults,respectively.The petroleum implication of the salt structures was discussed,and potential exploration areas were forecasted,based on some petroleum data.

The genesis,migration,accumulation and pool-forming models of carbon dioxide gas reservoirs in Yangxin-Huagou area were discussed.The data of geochemistry,deep geological background,deep faults and volcanic rock were analyzed.The results show that carbon dioxide mostly originated from inorganic mantle source and magmatic rock,which were primarily accumulated into low-velocity zones within lithosphere with a net of faults as vertical migration pathway.Two shear zones in the extensional basin and two volcanotectonic rift zones of the Paleogene with different pool-forming models and gas reservoirs are the most favorable factors for release and accumulation of carbon dioxide as well as formation of gas reservoirs.The distribution of the gas reservoirs,volcanic rock of the Cenozoic and helium isotope anomaly from inorganic mantle source showed the string-beads form along the principal faults of shear zones and volcano-tectonic rift zones.A gas reservoir assembly of the deep buried hills and medium-deep anticlines or fault-blocks and shallow draping deformational traps developed in the shear zones,and the gas reservoirs associated with igneous mass existed in the volcano-ectonic rift zones.

Ten series of aromatic hydrocarbon compounds including bipheny1,naphthalene,phenanthrene,anthracene,retene,chrysene,benzoanthracene,dibenzofuran,fluorene,dibenzothiophene series from seven lacustrine mudstone samples and three swamp coal samples,as well as five crude samples of the Triassic and the Jurassic in Kuqa Depression were analyzed with GC-MS.It is found that the relative abundances of dibenzofuran series are higher in the coal samples,but lower in the lacustrine mudstone samples.According to the relative abundances of dibenzofuran series,especially dibenzofuran compound in TICs for aromatic hydrocarbons of source rocks and crude oils,the crude oil samples of Sha-3 Well (Cretaceous),Yangtake-5 Well (Eogene and Cretaceous) and Quele-1 Well (Eogene) are possibly derived from coals of the Lower Jurassic Yangxia Formation or the Middle Jurassic Kezilenuer Formation,whereas the crude oil samples of Yingmai-7 Well (Eogene) and Yaha-1 Well (Eogene) may be from the Triassic and Jurassic lacustrine mudstones in Kuqa Depression.The differentiation of coal-generated oils from lacustrine mudstone-generated oils in Kuqa Depression with dibenzofuran series has enlightening and directive significance for further correlations of oil-source rock and oil and/or gas exploration in Kuqa Depression.

On the basis of the Pittman method,a new concept of pore structure parameter of sand reservoir,namely "peak radius of pore and throat",was proposed.The physics meanings of the new concept were determined.The relation of pore structure of sand reservoir with hydrocarbon migration and accumulation indicates that the pore structure parameters of mercury saturation below 20 percent is concerned with secondary migration of oil and gas,and those of mercury saturation over 30 percent is concerned with hydrocarbon and reservoir accumulation.The practical application of this method to Fuyang reservoir in the western Daqing Changyuan area showed that the reservoirs with the peak radius of pore and throat in the range of 0.13 to 1.5μm may be the prospective area for oil and gas accumulation around Qijia-Gulong Depression.

The main types of rocks and reservoir spaces,characters and influence factors of Archeozoic reservoir in the Chengbei 30 buried hills were studied by means of observation on cores,electronic scanning and thin-section analysis.There are four types of crystalling rocks in Archeozoic of the Chengbei 30 buried hills.The most developed fractures are in cataclastic metamorphic migrated biotite feldspar gneiss.The physical properties of those fractures are the best,and their productivities are the highest.The reservoirs under the unconformity between Art and Pt around 250 meters are the valuable ones,and the thickness of reservoirs is in the range of 100 meters to 150 meters.The fractures and micro-cracks are the main reservoir spaces for oil accumulation in the Archeozoic reservoir of the Chengbei 30 buried hills.The dissolving pores,including crystal dissolving pores,inter-crystal dissolving pores and crystal casting pores,and micro-inter-crystal pores are the available reservoir spaces.The main influence factors on reservoir accumulation in Archeozoic reservoir of the Chengbei 30 buried hills include the lithology,cataclasis caused by faulting,magmatization caused by magmatite intrusion,weathering and dissolution in the deep formation.

The depressurization development is a special method for increasing oil recovery rate by using unstable water flooding.The field test results of depressurization development of fractured reservoirs in carbonate buried hill of Renqiu Oilfield carried out during the ninth five-year perion were systematically summarized.The depressurization development mechanism for enhancing oil production is to make the oil-water relationship redistributed as changing driving means and utilizing the differential closure effect of fissures to make the favorable oil displacement actions of elastic force,weight and capillary forces more effective and reduce the seepage flow rate of big fissures and the interference of seepage flow in small-middle fissures,pores and blocks of rocks,which brings the productive potentialities of small-middle fissures,pores and blocks of rocks into play.The opportunities for taking depressurization developing measures and suitable developing speeds for depressurization development were proposed.It is significant for improving developing effects and test research on enhancing recovery ratios in medium-term and late period.

The production mechanism for enhancing recovery of depleted heavy oil reservoir with hot water flooding by adding nitrogen and surfactant was investigated.The operating parameters were optimized,by means of numerical simulation and laboratory experiment.The reasonable operating parameters include hot water injection rate,surfactant concentration,nitrogen-to-liquid ratio,injection scheme and the size of slug.Based on the results of laboratory test and simulation,the recovery performances were predicted,according to the relevant of reservoir characteristics and development status of J90 Block.A field pilot test project was designed and implemented to evaluate the effectiveness of hot water flooding by adding nitrogen and surfactant,after steam simulation in a reservoir with a nine-spot pattern at J90 Block of Liaohe Oilfield.The pilot test showed good recovery performances of this method.Currently,the field test has been extended to nine patterns.It is predicted that this technology may become an effective recovery process following steam stimulation for this type of heavy oil reservoirs.

The correlative relationship between the development indexes of oilfield was established,by the use of functional simulation theory such as differential simulation method and neural network method.The optimal models of oil production composition for different goals including the maximum oil production as stated cost,the minimum cost as stated oil production and the maximum economic benefit as stated oil production and stated cost were established.These models can be used to solve the problems about the optimal compositions for each subentry oil production,usually containing natural production,measure production,oil production of new well in new blocks,oil production of new well in old blocks,and the corresponding workload and other development indexes of oilfield or oil production plant.The satisfactory economic benefit can be obtained in the application of the models to the development programming in several oilfields during the mid-late stage.

An expert system for economic optimization of hydraulic fracturing design was established preliminarily.The key point of the expert system is the utilization of genetic algorithm in the economic optimization of fracturing design.With the genetic algorithm,the optimized design of fracturing plan can be selected from more than one hundred candidates generated by random function.Then,the reproducing and mutating processes were performed on the data of above candidates.Finally,the optimized parameters for hydraulic fracturing design plan can be obtained.Furthermore,the fluctuation range of oil price and interest rate may also be taken into account.Therefore,the new model put forward in the paper is a comprehensive and applicable.A field case verified that the optimized design of fracturing plan determined using the expert system has a higher post-fracturing rate than that using ordinary fracturing design method.

The varying characteristics of composite water cut in the area of polymer flooding and multi factors affecting the results of polymer flooding were analyzed.Taking these factors as inputs and the varying characteristics of the composite water cut as outputs,and taking the known inputs and the outputs of the early production areas as learning samples,a modified model for the three-layer cumulative back propagation (CBP) neural network was established.Some variables of the output layers may be unknowable in the learning samples in this model.Therefore,the all areas with the different production histories can be put into the learning samples,and the unknown points can be predicted.This method can avoid the deviation of the composite water cut in the industrial areas predicted by mode chart method and human correction and used to quantitatively analyze the various factors influencing the dynamic performances of polymer flooding.This model has been successively applied to predict composite water cut,liquid production and oil production of some subsequent production areas.The prediction result may be the good bases for making oilfield development plan.

After employed tertiary infilling,four-spot well pattern has been applied in part of blocks in Changyuan interior of Daqing Oilfield.Due to the close well spacing and complicated oil-water relationship in the reservoir,it is necessary to choose some appropriate fracture parameters during hydraulic fracturing,in order to avoid premature water breakthrough in oil wells.Aiming at the characteristics of horizontal fractures formed in four-spot well pattern by using hydraulic fracturing and according to the geologic features of non-tabulated reservoirs in Sanan Oilfield,a production model for predicting operation of oil and water wells was build up.With the purpose of increase in oil production,oil recovery and economic benefit,some fracture parameters such as radium and conductivity were optimized.The better stimulation and economic benefits have been achieved in Sanan Oilfield.The result can provide theoretical references to the optimization of fracture parameters in integral fracturing stimulation in such kind of oil field.

Virtual prototyping based on integrated products and process development is a new kind of technology for development and assessment of products.The significance and the necessity of virtual prototyping were discussed,and top drive drilling system-virtual prototyping system (TDS-VPS) was developed.The structures and functions of TDS-VPS were introduced.This system is composed of some subsystems including general project design system,general layout design system,module design system,assembly analysis system,running simulation system,performance analysis system.The functional structures of the TDS-VPS include virtual shaping system and simulate system.The data management method of the TDS-VPS was also discussed.

A kind of rotary steering stabilizer used in a common rotary bottom hole assembly to control well path was developed.In order to develop and use this kind of bottom assembly,the mathematical models for 3D mechanical analysis of bottom hole assembly (BHA) with small deflection were proposed.The mathematical models include (1) differential equations; (2) boundary conditions of drill bit,stabilizer,bend angle,diameter change,tangent point and borehole wall; (3) models for calculating lateral forces and deflection angles of bit; (4) models for determining navigation ability and navigattion parameters.As an example,a given rotary steering bottom hole assembly was studied.

Seismic records and sonic log data can all reflect acoustic property of formation.According to seismic wave dynamic mechanics,the reasonable nonlinear mapping relationship between seismic records and log data was established.The model of log data was constructed by using seismic records,on the bases of BP artificial neural network theory.The input layer of BP network is composed of autoregressive coefficient,fractal dimension,maximum Lyapunov index and mutation parameter.The acoustic wave velocity and density of the formation being drilled can be acquired with the log data model,and the elastic property and strength can also be estimated.Based on the nonlinear function curve simulation method,the safe mud weight range model for predicting borehole stability was established and successfully verified in YT101 Well.The prediction model was adapted to predict borehole stability of pre-drilling formation by using the log data of drilled part for the first wild cat well.

The input power of a sucker-rod pumping system was divided into hydraulic horsepower,surface mechanical loss power,down-hole viscous friction loss power,down-hole sliding friction loss power and solution gas expanding power.The influencing factors for each power were determined,and their functional relations were derived.In order to calculate the input power corresponding with different geophysical parameters and liquid properties,different borehole deviations,and parameters of different production and different devices,some mathematical formulas were developed.According to these formulas,a new design method for choosing combination of the production parameters with the parameters of devices was proposed,on the principle of the least energy consumption or the least cost.The new method can be used to determine the most economic combination of parameters for production and devices,and the efficiency of the suck-rod pumping system can be improved greatly.Accordingly,an economical goal for oil production can be achieved.

Using exergy transfer theory and taking driving work as an uniform characteristic item,thermal driving potential fields were divided into driving potential field,driving resistance potential field,driving effective potential field and irrelevant ones.On the basis of that,an exergy transfer model was developed.It is composed of driving potential field ingredient and distribution model,driving exergy vector model and driving resistance structure model.The analysis on thermal driving oil process simulated by electric heating shows that the exergy transfer model can not only essentially describe the driving mechanism of thermal driving oil process,but also provide some new technical information for its time effectiveness analysis.

A mathematical model for accidental gas release in long transmission pipeline was given,on the basis of computational fluid mechanics.It is found that the existing model for describing hole on a pipe is suitable for predicting gas release through a small punctured hole,while the other existing pipe model is suitable to predict the gas release through a complete break of a pipe.In this paper,a new model for the hole diameter that lies between the above two situations was proposed.The calculation results of an example show that when the initial pressure inside the pipe is higher than 1.5 MPa,the mass of gas released during sonic flow is more than 90 percent of the total mass of the released gas.The total average rate of released gas could be substituted by 30 percent of initial released rate.This approximation would become more accurate with increasing the pressure inside the pipe.

The principles of safe and economic transportation temperature in hot oil pipelines and its influencing factors were discussed.The analysis results showed that the allowed shutdown time of hot oil pipeline depended on several factors including environment condition along the transportation pipeline,working state of pipeline and the repairing ability of oil business enterprise.The safe and economic operation temperature in hot oil pipeline is the lowest temperature at the inlet of heating station to satisfy the requirement of permissible shutdown time of pipeline.The safety and economic operation temperature in hot oil pipeline depends upon some factors such as the allowable shutdown time of pipeline,seasons,diameter of pipeline,rheologic characters of crude oil,the environment along the pipeline,and piping heat insulation.The allowable oil temperature of pipeline with large diameter can be lower than that of pipeline with small diameter,while transporting the same oil in the same area.The allowable oil temperature in summer can be lower than that in winter.The condensation point is not the only basis for determining the allowable oil temperature at the inlet of heating station.

The construction,function and specialties of an integrated testing system for full-scale down-hole production tools were introduced.This system can be used to test the different down-hole tools and to research production technologies in laboratory based on simulation of actual production status.The system has the features of full scale,good performance and multiple functions.It is favorable for the test of multiple down-hole tools including compounding tools and for the research of experimental data of the different production technologies including compounding data.The system has been successfully used in Daqing Oilfield.

The sustaining and rapid economic development in China urgently needs to strengthen oil and gas exploration and development to meet increasing oil demand.The situation of oil shortage is becoming more serious in China,and it is very important to enhance petroleum exploration for giant oilfield discovery and increase hydrocarbon reserves and production.The exploration practice and reserves evaluation show that China has so many sedimentary basins with rich petroleum resources and great exploration potential.The investigation for basic geological features of petroleum resources was made,and the potential of residual petroleum resources were analyzed.The petroleum exploration strategy of "elaborate oil exploration in eastern area,enhance petroleum exploration in western area,advance seas exploration,exploit new areas" and relative measures were put forward.

By using the massive statistical results from the third oil-gas resource assessment of the Petro China Limited Company,an improved model including four sub-models of geological evaluation,resources evaluation,economical evaluation and integrated optimum seeking and a set of related methods for integrative evaluation of plays were presented.The model and related methods are applicable to evaluate the plays of petroleum-geological characteristics and can enrich the series of quantitative evaluation techniques for oil-gas exploration in China. Besides,the case study on Liaohe Depression was carried out with this model.Of nineteen plays,seven plays were predicted to be favorable geological settings,four plays unproven oil in place have the reverses over 0.1 billion tons and five plays have potential high income.The nineteen plays were partitioned into three classes by the integrated optimum seeking sub-model.These results can provide valuable references for the exploration prospects of Liaohe Depression in resent years.

The exploration in Bohai Bay Basin evidenced that abundant oil resources are closely in connection with the rich hydrocarbon-generation sag full of organic matter.The terrestrial fault basin characterized by multi-depression center,variable source supply and multi-cycle of infilling evolution developed several oil source beds with different geochemical features and different combination of oil-gas accumulation zones.The multiple oil-gas accumulation zones characterized by different formation and trap types were formed.Some multiple hydrocarbon-bearing systems composed of ulticrossed,superimposed or juxtaposed zones were generated in the space.The complex basin forming system composed of imposed evolution and hydrodynamic setting gave rise to the occurrence of multiple hydrocarbon-bearing systems.The various features of the multi hydrocarbon-bearing systems caused the complexity of oil-gas reservoirs and controlled the occurrence and distribution of multiple hydrocarbon-bearing systems with poly-resource.

The SEC standard for proven reserves has been followed by oil companies listed in the securities markets of the United States.In conclusion,this standard has ten key aspects should be emphasized,including reasonable certainty,existing economic and operating conditions,economic production capacity,gas-oil and/or oil-water contacts and proven oil-bearing area,the reliability of physical data from core analyses and/or log interpretations,improved reserves after enhancing oil recovery,limits of proving developed reserves,limits of proving undeveloped reserves,economic evaluation,application of probability approach.The determination of proved area and proved reserves by improved recovery techniques are important for the use of SEC standards in China,because there is a big gap between China and the western countries about the evaluation standards for determining hydrocarbon-bearing area and enhancing reserves.

Xifeng Oilfield located in thesouthwest of Ordos Basin was discovered in recent two years.The crude oil reserve in this oilfield is about 100 million tons.The major oil pay is Chang 8 of the Upper Triassic period in Yanchang Formation.Up to now,the newly raised total oil reserves including proven oil in place,controlled reserve and predicted reserve have reached 2.1956 billion tons.Yanchang Formation in the Triassic system of Ordos Basin developed aset of clastic rocks from 500 to 1200 meters in thickness,which was deposited by inland lake basin.Yanchang Formation can be divided into ten sections of oil formations.Chang 8 section is of the superior formation and reservoir conditions,and the deep lacustrine mudstone in Chang 7 provided the abundant oil resources.The fluvial and delta sandstone deposited from supply of the southwestern Ordos Basin provided a large area of reservoir.Large scale of lithological traps was developed at the background of regional gentle structure.It was preliminary estimated that Chang 8 section has the extensive prospects of exploration.In the near future,Chang 8 can form reserves scale of 0.2~0.3 billion tons.

The study on the sequence stratigraphy in Jurassic system of the northwestern area of Junggar Basin shows that there mainly developed multiple slope breaks.Those slope breaks can be divided into faulted slope break and bending slope break according to their genetic types and can also be divided into basin margin slope break and inner-basin slope break according to their natural geographical positions.The atectonic movement is the dominant factor for developing the slope breaks,and the scale of slope breaks intimately relates with the size of tectonic movement.The controls of multiple slope breaks on tectonic traps have following features.The atectonic traps were developed near the multiple slope breaks and distributed in beads-shape along the slope breaks.In the longitudinal direction,the development of atectonic traps was characterized by the inheritance.The different slope breaks and their different geographical positions resulted in the different development types of atectonic traps.Any slope break could form different kinds of atectonic traps,owing to its great variation laterally.The existence of multiple slope breaks resulted in the different responses of erosion and deposition in the different geographical positions of Junggar Basin.The source-reservoir-seal assemblage of atectonic traps is fine.The atectonic traps controlled by slope breaks had very favorable oil-bearing conditions.

The technologies of stratum division and correlation using high resolution sequence stratigraphy,the structure interpretation of full three-dimensional seismic data,the acoustic impedance inversion with log and seismic data and prediction of oil and gas with seismic data were comprehensively applied to re-establish the geological model for the east-southern reservoir in Dongxin Oilfield.The laws of reservoir generation were analyzed,and seven roll exploration objects were proposed.These objects can be divided into two types of structural oil pools and lithologic oil reservoirs including seven objects of roll exploration.The first type is the deeper reservoir under the midst of third section in the Shahejie Formation,and the second type is the lithologic pinchout oil reservoir on the background of micro structure and slope.The types of sand body in the studied area include the delta front sheet sand and the deeper water turbidite(haclberry)sand.The former is located between the upper third section in Shahejie Formation and the lower second section in Shahejie Formation.The latter is between the fourth section in Shahejie Formation and the midst of the third section of Shahejie Formation.

Taking Gangxi Oilfield in Huanghua Depression as an example,the isotopic compositions of noble gas in crude oil and their tracing significance were investigated.The ³⁴⁴⁰Ar-to- ³⁶Ar age accumulation effect that the Gangxi oil should be sourced from the Tertiary.Water injection resulted in the contamination of noble gas in the crude oil of Gangxi oilfield.The relations of ³He-to- ⁴²⁰⁴⁰Ar-to- ³⁶Ar ratio with ⁴²⁰Ne ratio can be used to distinguish the water-injected wells and non-injected wells and to predict the effects of water injection.The application of research method for noble gas in crude oil to petroleum geology provides a new way for inferring natural gas and oil source,tectonic backgrounds,geothermal flow value and the effect of water injection in oilfield.

In order to determine a mapping method for sequence stratigraphy lithofacies and paleogeography,the mapping test for sequence stratigraphy lithofacies and paleogeography of the Late Permian reef in Sichuan Basin was carried out.Eight maps of sequence stratigraphy lithofacies-paleogeography were given,on the basis of the isotime surface of each sequence at lower point of marine regression and high point of marine transgression in the Late Permian reef in Sichuan Basin.The sequence stratigraphy lithofacies_paleogeographic map not only reduced the distortion derived from the traditional predominance or compress mapping methods but also promote the prediction of sedimentary and basin evolution laws.

A recognizing method based on logging while drilling and logging information for determine the formation lithology nearby bit in the drilling process of horizontal well was introduced.This method,in terms of logging facies analysis,makes full use of the information while drilling to extract some specific parameters for identifying formation lithology.The collection patterns of formation lithology were established.The data for recognizing rock-lithology nearby the bit were processed by means of gray conjunction analysis.This method has been applied to the practical drilling in three horizontal wells of Mobei Oilfield in Xinjiang area.The more accurate lithology profile could be provided in time.As a result,the geo-steering drilling ability was obviously improved.

The rheological behaviors of hydrolyzed polyacrylamide (HPAM) solution and xanthan gum solution and their rheological behaviors in porous media were measured experimentally.A calculation model for apparent viscosity of polymer solutions in porous media in the presence of both depleted layer effectiveness and visco-elastic effectiveness was established.The oil displacement experiments with two types of polymers were carried out under the conditions of various concentrations and injecting speeds. The results showed that the increase of apparent viscosity or the decrease of the thickness of depleted layer were resulted from the overlap of polymer molecules,which increased the force parallel to oil water interface and reduced the saturation of residual oil and enhanced the displacement efficiencies of polymers.While increasing concentrations or injecting speeds of HPAM solutions,the displacement efficiencies also increased.The displacement efficiency of xanthan gum solution was low,when its concentration was lower than the overlap concentration.The displacement efficiencies of xanthan gum could keep a higher value,as its concentration was higher than the overlap concentration.The displacement efficiency kept stable,when increasing the injecting speeds of xanthan solutions.

Three kinds of water drive experiments including the single model,double model and the combined natural sandstone micro-model were carried out.The oil displacement characters of water drive reservoir with water-sensititve damage and without water-sensitive damage were compared,and the oil displacement efficiencies of water drive under the above conditions were estimated.Compared with the formation water drive reservoir without water-sensitive damage,the injection pressure of water drive in the water-sensitive damaged formation was raised,and the heterogeneity of pore structure became stronger.The injected water resulted in bigger detours,and the displacement efficiency and the sweep efficiency decreased.The oil displacement ways of water drive were mainly piston-types under the two different conditions, and the types of residual oil were mainly clusters.The heterogeneity of porestructure,water sensitivity,injection pressure and the increasing pattern of injection pressure are the chief factors affecting oil displacement efficiency of water drive in Mubo Yan 10 reservoir.It is suggested that the heterogeneity of Mubo Yan10 reservoir should be studied furthermore,and the favorable measures for protecting this reservoir should be adopted in order to enhance oil recovery.The injection pressure should be gradually raised,and the recovery ratio of this reservoir should be enhanced possibly.

The in-situ application results of comb-shape polyacrylamide showed that the comb-shape polyacrylamide can increase the viscosity value of 58 percent to 81 percent more than that of the ordinary Daqing polyacrylamide,and 22 percent to 70 percent more than that of the ordinary polyacrylamide MO-4000 produced by Japan,under the same conditions.The oil displacement efficiency of comb-shape polyacrylamide can increase by two times compared with that of the ordinary polyacrylamide.At the same time,it can decrease the polymer dosage by 30 percent more than the ordinary polyacrylamide.The excellent economy,social and environment benefits of comb-shape polyacrylamide for polymer flooding,alkaline-surfactant-polymer flooding and cross-linking polymer flooding have been achieved.It has become an excellent high-efficiency oil displacement agent and profile modification agent for oilfield exploitation.

The results of the conventional and special experiment on the parameters such as porosity,permeability,capillary pressure,wettability,grain size of cores got from low-resistivity formations of A Oilfield were analyzed.The low-resistivity beds in this oilfield were mainly controlled by some factors including high cation exchange capacity of smectite or mixed illite-smectite,high irreducible water saturation in micro-porosity system,existence of trace pyrite.The porosities of conductive beds ranged from 15.0 percent to 28.2 percent,and the permeability values were less than 0.03μm ².Although porosity exponent was only 0.530,the lithologic constanta was 6.363.The relationship between resistivity index and water saturation showed a non-liner pattern in dual-logarithm coordinate.The saturation exponent ranged from 1.01 to 1.10.The saturation exponents corrected by cation exchange capcity ranged from 1.56 to 1.65.The CT scanning technique and SEM are useful to determinate the microstructure of rocks and the distribution of pores and minerals.

The heavy-oil reservoir in Henan Oilfield is characterized by shallow buried depth,thin oil reservoir and viscosity of crude oil.According to the international and China's screening standards of steam stimulation,most of heavy-oil resources could not be developed by means of conventional steam stimulation.Based on the characteristics of the heavy-oil reservoirs in Henan Oilfield,a series of works of steam stimulation was carried out,including rationally dividing layer series of development,optimizing perforation well section,dynamically adjusting injection-production parameters,assembling stimulation,forcing fluid withdrawal.So,the steam simulation in this kind of shallow and thin heavy-oil reservoirs has achieved successful results in both technology and economy,and a set of perfect recovery program has been set up.In order to further enhance the degree of utilizing heavy-oil resources and the effect of heavy-oil recovery,some new technologies and methods were studied and tested,such as cold heavy-oil production,horizontal fracturing assisted steam flooding technology,hot-water flooding and intermittent steam flooding.The producing reserves rate of heavy-oil resources increased from 8.3 percent to 75 percent by the use of these technologies,and the heavy-oil production of Henan Oilfield was stable in later decade.

Thermal neutron saturation logging (neutron lifetime log or neutron-gamma log) run with high capture cross section tracter has been widely used in many oilfields in China,since the end of 1990's.Boron tracer (boric acid or sodium borate) was used at the initial stage of logging under the operation of log-permeation-log technique.Then gadolinium complex was discovered to be better than boron taken as tracer.Theoretical research and logging operation proved that the thermal neutron capture cross section of gadolinium is much bigger than that of boron.The gadolinium tracer can help to show the abnormality on logging curves more clearly.The weight of gadolinium used for logging operation is far lighter than that of boron.The chemical property of gadolinium is more stable and safer than that of boron,because gadolinium tracer stays as a complex compound.Logs run by neutron lifetime logging tool and neutron-gamma logging tool using gadolinium complex tracer under the operation of log-permeation-log technique have found better application to development of Daqing,Zhongyuan and Nanyang oilfields in China.