There are abundant natural gas resources in the Northeast Asia area.Its prospective gas resource is about 70 trillion cubic meters. This area is a new gas source region where different types of basins dominated with paleo-cratonic inherited basins and late island associated basins were developed. The North China,Tarim and Yangzi areas in China and Siberia in Russia belong to paleo-cratons,and Verhne-yanskoe and Kuqa depressions belong to the foreland basins or cratonic marginal depressions,and the Northeast Sakhalin and the East China Sea are the back-arc basins.The natural gas is distributed primarily in the craton-inherited basins and cratonic marginal depressions or foreland basins,accounting for 80% of the total prospective gas resource.The Tertiary basins associated with the Middle Cenozoic island arc located in the present continent shelf have the resource potential accounting for over 10% of the total.Although gas development in Northeast Asia is still in a low level, this area will become a new important gas resource base in the world. The gas demand in Northeast Asia also shows a strong tendency of increase.

The global exploration phases can be classified into the frontiers,immature and mature regions.The resources assessment will follow some steps:①basin analysis based on tectono-stratigraphic provinces and trend;②petroleum system studies and play evaluation;③play fairway and prospect screening and ranking.The key of the resources assessment is to establish a dynamic geo-economic evaluation system by data processing,detailed and thorough studies to find the scale and location of exploration target,the finding risks,and the commercial value. To pick out the favorable prospects depends heavily on the establishment of a geological concept and modeling,and the prediction of the modeling.There are two sets of outputs for the resources assessment including static and dynamic indexes for benchmarking and screening. The static indexes include net profit,maximum exposure to risk,pay back period of the investment.And the dynamic economic indexes include the net present value and discounted cash flow.Based on the introduction of the resources assessment methods used by the Majors,the resources assessment methods carried out in Tarim Basin by ExxonMobil and in Changbei project of Ordos Basin by Shell are presented. There is a brief review on the Monte-Carlo simulation technology and the Duplo reservoir simulation method.

The traditional net present value(NPV) method is widely used in strategic economic evaluation and investment decision of a project,but it has some defects,because of the limitation of the method and the distinct characters of an oil-gas exploration project(OGEP) such as large investment,long period to recover,complicated technology and high-level risks.So,the true values of an exploration project may be underestimated,and a wrong decision would be got using NPV method.A new method,namely real options method,is introduced.The theorem and the characters of this method are discussed here. An example to apply real options method to the economic evaluation of an OGEP is given.As a new method,real options method brings a great change to people's opinions.The uncertainty of an object can be no longer taken as a negative factor.Instead,the people may focus on how to take the advantages of uncertainty and get more rewards.

The northern area of Qaidam Basin was considered as a compressive basin in the Jurassic and Cretaceous times.In reality,it had involved into a flexural basin as a result of weak compression since the Early-Mid Jurassic.This inference is based upon the restoration study of several main structural cross sections,regional geological data,and analysis of petroliferous circumstances. The Jurassic source rocks still possessed an oil-bearing potential in the Cenozoic time,because they did not reach the threshold of hydrocarbon generation during the Mesozoic burial history.Two periods of strong contractile deformation occurred in the Late Eocene and since the Pliocene respectively were recognized.The deformations had obvious influence on the formation of oil-gas pools.Correspondingly,there existed two types of pools,e.g.primary and secondary pools.The primary pools were developed in traps formed during the first-epoch and previous compression deformation, while the secondary pools only occurred during the second epoch in the shallow-level and fault-bounded fold traps and would be generated only in the regions strongly modified by intensive faults that clearly penetrated into the Pliocene and underlying strata.

The thickness of Cenozoic sedimentary is tremendous,and the sedimentary systems are multiple in Kuqa depression of Tarim Basin.The reservoir petrography property shows that its compositional maturity and textural maturity are lower and various in the different areas and sedimentary environments.In addition,the matrix contents of the different sedimentories are generally high.The secondary pore is the main type of the reservoir pore space,mainly including intergranular dissolution pore,intragranular dissolution pore,ultra-large pore,micro-pore and structural crack.The Paleogene porosity in the southern part of Kuqa Depression is higher than that in the northern part,and it is also higher in the center than that in the eastern and western parts of Kuqa Depression.The permeability of Paleogene reservoir tends to be higher in the south than that in the north,and the change of porosity is not distinct in the eastern and western of Kuqa Depression.The physical properties of the base sandstones of Jidike Formation in the study area show that the porosity in the east is higher than that in the west,and that in the south is higher than that in the north,and that in the circumference is higher than that of the middle part.The general thickness distribution rule of the reservoir exhibits that the Paleogene reservoir is thick and coarse in the east,and it is thin and fine in the west.The thickness and grain sizes of Paleogene reservoir in the south are very lightly different from those in the north.The base sandstone of Jidike Formation is a set of stable and thin sandstone beds for making some tracks in the region of the study area.The development of the reservoir was controlled by sedimentary facies,diagenesis and tectonics.

In recent years,the difficulty and risk have increased with the improvement of exploration and development for the structural and siliciclastic hydrocarbon reservoirs,and with the continuous discovery of the volcanic hydrocarbon reserves widely distributed in the Mesozoic and Cenozoic basins in China.The volcanic-related rock reservoirs as a new field of hydrocarbon exploration and development has greatly attracted the attention and regard of the geologists in the petroleum enterprises worldwide.The summation and study on the research methods,successful experiences and some exploration and development technologies for the volcanic reservoirs abroad and at home are benefit to the hydrocarbon exploration effects.Generally,the research and exploration methods for the volcanic reservoirs mainly include geophysical methods of seismic information recognition,magnetotelluric survey,high-precision gravity-magnetic method,time domain electric-magnetic depth sounding,frequency domain continuous electric-magnetic profile,geophysical logging as well as the volcanic chronology,petrology,petrography and petrochemistry,volcanic-reservoir characteristics and diagenesis,pool-forming and pool-type analysis.

The formation conditions and distribution principles of deep-basin gas reservoir are different from those of the typical hydrocarbon habitat.The formation and conservation of the gas reservoir must meet the force and substance balance conditions.A numerical simulation method for the system of three-dimensional basin was developed in order to derive the data of geology history from the present data.The numerical result is more exact for optimizing the parameters of the initial porosity and compress coefficients.The mathematical model and algorithm were applied to the research of dynamic distribution and prediction of accumulation quantity of deep basin gas.The numerical results fit well with the practice of Turpan-Hami Basin.

The features of fault block types of the crust,well developed deep-fault,Moho uplifting and lithosphere thinned and geothermal flux going up,and extensively developed igneous rocks of mantle source rocks in Bonan subsag show that the deep thermal fluid related to subalkali-alkali magma existed in this area in Paleogene period.In addition,there existed mantle inorganic CO ₂ pool,and the findings of the high hydrothermal altered mineral-wollastonite and low values of hydrothermal altered mineral-NaAICO ₃, ⁸⁷Sr/ ⁸⁶Sr, δ ¹⁸O were found.The metal-rich ions and clay mineral were abnormally evolved.It is proved that the deep reservoir possesses all conditions of dissipation system, and the deep thermal fluid with initial strong acid is one of the most important factors forming secondary pores.The double-diffusive-circula-tive convection mechanism of pulsating deep thermal fluid is expounded in this paper.

A model for the Lower Tertiary framework and sequence system tract of Jiyang subbasin was established with the high-resolution sequence stratigraphy.The study results show that the lowstand sand bodies such as incised channel filling,lowstand wedges and fans controlled by the structural slope-break zones are favorable for forming the subtle reservoirs.The subtle reservoirs controlled by the structural slope break zones with apparent seismic reflection characteristics are apt to be identified and forecasted on the seismic profiles. The methods for subtle reservoir exploration and forecast were discussed, taking a case study of Jiyang subbasin as an example.

Indicator principal component microfacies simulation is a technique for describing lithofacies or microfacies distribution using sequential indicator simulation method based on selection of principal components with discontinuous variables.The method is fast and convenient in operation by using more original information.Based on the geological knowledge about reservoir,a 3D microfacies model of unit S II7+8 fluvial sandbody of study area was developed with the indicator principal component simulation method. Compared with the conventional 2D microfacies model,the 3D model can show the fluvial sandbody constitutes in the vertical direction,and the distribution of flow units in 3D space.The technique is useful for detailed reservoir description and potential study of Daqing Oilfield in the later period of high water cut.

The reservoir sedimentary models of fluvial facies in Guantao group of Gudao and Gudong Oilfields in the eastern Zhanhua sag were studied.The remaining oil distribution in the fluvial facies reservoirs and its control to the formation and distribution of the remaining oil were discussed.The fluvial facies reservoir in this area developed two sizes of heterogeneous sedimentations.The combination of the two heterogeneities is the main factor for controlling the macroscopic and microscopic distribution of the remaining oil in the fluvial facies reservoir.The remaining oil is macroscopically distributed in the pole oil layer,the median and top of the main rhythm,and the units with low seepage,and the areas where the injection-production technology is unperfected.From the microscope,the netlike and spotted remaining oil still exists in the lower watered-out position and a part of blind area with the finer reservoir characteristics.The study result indicates that the sedimentary model is the most important factor for controlling the distribution of remaining oil in the fluvial facies reservoir.

A successful water shut-off pilot test was carried out at a deep production well with high temperature and bottom water in the Carboniferous reservoir of Shixi Oilfield.After the water shut-off treatment had been made in the reservoir for 189 days,the cumulate liquid production decreased by about 3159 tons,and the cumulate oil increment reached about 570 tons.The liquid production per day gradually reduced from 105 tons to 78 tons after treatment for three months.A new method of three-section plugging was used to deal with the harsh reservoir conditions.The temporary plugging agent,main slug (surfited larch tannin extract) and sealing cement were injected into the reservoir separately.The injected temporary plugging agent could seal the zones for about 15 hours,and then the main slug of water shut-off agent gets into the water zones selectively.The formed gel of plugging agent with the surfited larch tannin extract may resist high temperature at bottom hole and have a good thermal stability.The slug of sealing cement could enhance the strength of the water shut-off agent.

The study on the critical oil output and oil recovery with no water in the oil reservoir with edge and bottom water is more embedded at present,but the study on the optimization of drawdown pressure of oil well after produced water is not enough.So,a new method for determining the drawdown pressure of oil well with different water-cut sections is presented.A whole oil reservoir is treated as the studied object on the basis of the systematic well test.According to the raising feature of containing water in oil well,the water cut is subdivided into several sections.The correction between increasing rates of containing water and the drawdown pressure in the different water-cut sections was studied.This method is on lots of production data and has a good maneuverability.An effective application of the method can dig the potentiality of oil reservoir during medium high water cut period and may enhance the oil recovery.A favorable effect of application in the CB,ZS and YA oil reservoirs with edge and bottom water has been obtained.

The connectivity of a low-permeability reservoir has a significant effect on its development.The pulse-testing method has been applied widely in the medium-permeability and high-permeability reservoirs,but it is not favorable to study the communication features of the low-permeability reservoirs.Some new typical curves for the pulse-testing analysis are developed,and the analysis method is improved according to the response features of the pressures in the low-permeability reservoirs.The range of dimensionless time delay is extended from the value below 1.0 to over that.The practical data of the transient pressure acquired from a well group of Daqing Oilfield were interpreted with the new typical curves.The result shows that the new typical curves could meat the needs for interpreting the practical pulse-testing data of the low-permeability reservoirs.It is confirmed that the pulse-testing analysis is an available means for quantitatively evaluating the connectivity of the low-permeability reservoirs.

A new analytical model for pressure decline under the condition of forced fracture closure was developed on the basis of material balance theory and the former corresponding fracture models,such as PKN and KGD models.The effects of back flow of fracturing fluids just at the moment of shut-in and the continue propagation of fractures were considered in the new model. Furthermore,the problem about the leak off of the new propagated fractures was also considered.The condition of natural fracture closure was adaptable in the model.The calculation results indicate that the value of leak off coefficient obtained from the former models is higher than the real value when the forced fracture closure technique is conducted just at the moment of shut-in,while the new model can provide a true value of leak off coefficient and other parameters.The field cases verified that the calculation results with the new model is reliable and may be put into practical application.

The adsorption of asphaltene and resin on quartz sands makes the surface property of the quartz sands transfer from strong water-wet to oil-wet.But the transferring effect is not a function of the concentrations of asphaltene and resin.The oleophilic-site density on rock's surface can be quantified by measuring the concentration difference of heptanol solution,namely measuring the difference between the initial concentration of heptanol solution and the balance concentration due to adsorption on the surface of rock.Quantifying the oil-wet percent of rock's surface can reflect the change of the wettability perfectly.Experimental results show that the heptanol method is realizable to quantify the oil-wet percent.

The evaluation for reliability of long-distance oil pipelines is urgent requirement for pipeline's owner.The traditional methods for evaluating the reliability of oil pipeline are based on the theory of reliability and supposal of failure rate,regarding the pipeline as a system of series connection or parallel connection.The failure rate is used to represent pipeline's reliability.The reliability calculated using statistic data of failure rates is unpractical for design,inspection and maintenance of pipeline's.A new concept of integrated reliability is put forward in consideration of more factors related with design, operation and maintenance of pipeline.A new model is programmed with artificial neural network.The new method for evaluating reliability is more practical than the traditional ones.The approach and steps to establish analysis model are given.

The wall friction induced by oscillatory Maxwell flow in a pipeline was studied. The oscillation of velocity was controlled by Bessel equations,and the analytical solution was obtained using the variable separation method.The effect of oscillatory frequency on the wall friction was analyzed.The results show that the resonance-like characteristic of wall friction is revealed.For some critical values of oscillatory frequency,the wall friction increased dramatically.The effects of the elastic parameters of Maxwell fluids,pipe diameter and oscillatory frequency on the wall friction can be expressed by two dimensionless parameters ( ω and R).In a certain region of parameter ω, there are less numbers of resonance peaks for smaller parameter R in the correlative curve of wall friction with ω.With the increase of R,the positions of resonance peaks move towards left,the number of peaks increased,and the amplitude of peak decreased.When the value of R is over 12,the curve becomes a monotone decreasing curve without any peaks and just like that of Newtonian fluids.This resonance-like characteristic of the wall friction is very useful for increasing the efficiency of oil displacement in the cores.

This paper introduces a new intelligent bit and it's latest development.It gives a minute description of principle and technical design for the new type intelligent bit.The system is composed of four main components:sensor measurement unit,computer data processing and storing,power supply and signal transmission control system.It can complete a lot of intelligent work for the drilling well.Also it makes a prospects to the applied perspective of intelligent bit in drilling engineering for the twenty-first century.

The first order and second moment reliability method for estimating reliability of the mechanical structures with some defects was concisely reviewed.This method defines that the structural reliability index is the shortest distance from the origin to the failure surface in a standard normal coordinate system. An example about reliability estimation of oil and gas pipelines with corrosion defects was given.The results show that the reliability index can be achieved by this method only being iterated for six times.Compared with the Monte-Carlo simulation method,it has a high efficiency and the accuracy of 0.01%. Furthermore,the reliability at different periods and the effective remaining life of oil and gas pipelines could also be determined with the dynamic failure model of structure.

A modified model to simulate the crude properties is presented,and its results correlate well to the PVT curve.The calculation methods for the fluid temperature increment in the submersible electric pump and the temperature gradient along the well bore are also developed.By introducing the techniques for describing and calculating the trajectory of a well bore to the multiphase flow calculation,the problems appeared in calculation for the curved well bore sections were successfully solved.As a result,the distribution of every parameter along the well bore with any shape can be found.On the basis of these,the simulation and analysis on production performance for a well with submersible electric pump were achieved by means of the test data from capillary,producing fluid level and pump characteristic curves.This method has brought a good effect when used in oil fields.

An induction motor for driving a sucker rod pump can be powered by an SCR voltage regulator.The load on the motor is varied all the time.Therefore,the modeling of the above system is quite complicated using traditional modeling methods.But it can be achieved by using a dynamic recurrent Artificial Neural Network (ANN),namely Elman ANN,based on the operation characteristics of the system.A dynamic back-propagation (BP) learning method with an inertia item is applied to ANN training,which has some advantages over the traditional BP method with resonance and slow convergence rate.The trained ANN makes it possible to regulate the voltage cross the motor with the load changes on it.The ANN configuration,the modeling procedure and the dynamic BP learning method were described.The selection methods of the parameters for system modeling were also discussed.The simulation results show that the results of this method have a relative small error that is as good as expected.

In order to measure the load,stress and strain of oil tube,a device for measuring the load was developed,and a test bench for simulating the operation situation of tube was set up.Based on the experimental data,the stress and strain of oil tube were calculated by means of the finite element software ANSYS.The results show that the tube in pumping well is subjected to tensile-tensile fatigue load and situated in the condition of forced vibration with damping,which may be the basic factors resulting in the fatigue fracture of tube.The most dangerous point is at the root of the first engaged tooth of a joint.Generally,the biggest values of stress and strain may exceed the yield limit.Though the stress and strain values are high,the elastic stress and strain amplitudes at the most dangerous points are low,so as the oil tube can go into service for a long time.When non-normal conditions appear,the biggest stress and strain would get into the strengthened phase,and the larger plastic strain amplitude will be produced under the action of a circulating load,which results in the fatigue fracture of oil tube.

The annual oil reserves and oil production proven in east China account for 75% and 90% of the total amounts of the China National Petrochemical Corporation (SINOPEC) respectively.As the exploration maturity-recovery ratio of reserves increase continuously,it is more difficult to maintain the stable production in old oil fields.The recent study shows that there still have greater remaining oil resources and broad remaining exploration space in the eastern matured oil areas.Un-equilibrium exploration maturity and the multiple exploration objective formations showed a great exploration domain in this area.The inherit regularity of formation and accumulation in multiple oil and gas fields leads to a prolonged process of reserve growth.Application of new exploration ideas,new theory and technologies,and detailed geology research will promote the continuous and stable development of oil and gas exploration,wide exploration realm and great resource potential in eastern new exploration areas.The eastern exploration region in China is still the major area of oil production and reserve additions of the SINOPEC during the Tenth and Eleventh Five-Year Plan period.

Sulige gas field in Ordos Basin is the largest natural gas field in China.At present,the gas reserves in Carboniferous-Permian have been proven since the beginning of systematic evaluation and exploration in 2000.Sulige gas field is located in the central part of the basin, where there is the favorable geological conditions for forming natural gas.The source rock widely distributed in Ordos Basin was deposited widely in the paralic environment during the Paleozoic.With the deepening and thermal evolution,organic matters were matured or highly matured,which provides the abundant gas sources.The superimposed fluvial-delta sandstones distributed approximately from north to south have constituted the complex sandstone reservoir body in a large area.Under the background of the gentle west-dip monocline,the fluvial-bay pelitic rocks to the east acted as the barriers laterally,and the various deposition face belt to north part as lithologic tight barrier,and the lacustrine pelitic rocks of the Upper Permian as a good regional seal.As a result,a large-area lithologic trap was formed in Sulige area.High content of quarts in continental facies as well as the dissolution and erosion of volcanic matters were favorable for forming the high-porosity and high-permeability reservoirs.The perfect timing of sources,reservoirs,seals,traps and the conditions of preservation provided a fundamental guarantee for forming and preserving the Sulige gas field.

The foreland basins of the Mesozoic and Cenozoic in mid-western area of China are located in the eastern end of Northern Basin groups of Tethys tectonics.The forming of foreland basin was controlled by the revolution of Tethys Tectonics.Two epochs of foreland basins were developed in mid-western China during the Early Mesozoic and the Late Cenozoic respectively. Foreland basins may be divided into three types and four kinds of responding foreland basins (or thrust belts).All of those foreland basins were controlled by the evolution of Thetys tectonics.Two epochs of foreland basins both underwent the tension tectonics.The tectonics environments of the foreland basins formed the specific geological characteristics for natural gas.Effective resource rock was grown in the tension tectonics settings.Foreland thrust belts were developed in the compression tectonics settings.The foreland was well match with the trapping time and space in the large rowed and belted structural traps.The early foreland basin and thrust belt were altered and superposed by the structures of the late foreland basin.The traps in the main body of the early foreland basin almost were seriously damaged,and the traps in the thrust frontier,fore-deep and fore-bulge slopes and uplift of the early foreland basin could be well preserved.For the late foreland basin,the large structural traps in the thrust belt and fore bulge have some good conditions for pooling gas and will be the key exploration targets recently.

The Ordos Basin,one of the large composite and hydrocarbon-bearing asins,is located in the western part of North China plate. The large-scale oilfield of the Mesozoic has been found in the first cycle of exploration.In the second cycle, the study on the Paleozoic has achieved breakthrough and high-speed progress.The transitional environmental detrital rocks broadly distributed in the Late Paleozoic and the marine environmental carbonaceous halite developed in the Early Paleozoic and Middle Proterozoic are all the excellent hydrocarbon source rocks.The weathering crust of the Caledonian has the advantage of the natural gas accumulation.The western and southern margins of the Ordos Basin are the passive continental margins developed on the basement of the Proterozoic three-fork rift of Qin(ling)-Qi(lian)-He (lan) area and gradually developed as the active continental margins.From the Middle Ordovician (O ₂) to the Middle Carboniferous (C ₂), Qin(lin)-Qi(lian) ocean troughs were subducted and collided to the directions of east and north. Therefore,the Paleozoic foreland basins were formed,and its forebulges were changed into "L-shape" of central paleouplift in the plane.The western margin thrust belts,the south-ern margin thrust belts and the central paleouplift are all the favorable areas for oil and gas exploration of the Paleozoic.

The fault control hydrocarbon theory indicates that the fault is a basic factor for controlling hydrocarbon generation,migration,accumulation,scattering and distribution,and the relationship between faults and hydrocarbon accumulation implies the relationship between branch and fruit or cane and melon.A scientific exploration thought should be to fetch fruits (hydrocarbon accumulations) along branches (faults) or to look for melons (hydrocarbon accumulations) along the canes (faults).The features of fault controlling hydrocarbon in Qaidam Basin are very obvious.The controlling laws of fault for hydrocarbon generation,migration,accumulation,scattering and distribution are also obvious.The faults for controlling hydrocarbon are very active and there is a great potential of oil and gas resources in the middle region of Qaidam Basin.The middle region of the basin has the geological conditions for forming the huge hydrocarbon accumulations,and may be the most important and possible exploration belt.The tectonic belt of E-Bo-Liang (Ⅲ)-Yikeyawuru-Yahu-Tajinaier in Niudong-Yiliping depression and the tectonic traps of Jian-Shishan-Luoyanshan-Chuansiqiu and Hongsan-han in middle southern rift of Qaidam Basin are the first chosen exploration target for a significant breakthrough of oil and gas exploration.

By using oil and gas generation theory,the abnormal phenomena during thermal evolution of hydrocarbon source rock in the deep formation of Dongpu Depression were discussed.It is indicated that the thermal evolution extent of hydrocarbon source rock at abnormally high pressure is not match with its thermal history undergone and is lower than that under the normal pressure condition.The anomalous phenomena occurred only at a certain threshold of the formation pressure factor.When the pressure factor is more than 1.5 in Dongpu Depression,there happens an obvious abnormal phenomenon.The hydrocarbon source rock in deep formation of Dongpu Depression shows that there still has a great source potential and will generate enough oil and gas for forming deep reservoirs.A comprehensive analysis on flow phase of hydrocarbon-bearing fluid,reservoir characteristics and the sealing of cap rock in deep formation shows that there is a good exploration future in the deep formations of Dongpu Depression at the abnormal temperature and pressure.

Himalayan tectonic movement,caused by crash of the Eurasian and Indian plates,is one of the great geological events in the geological evolution history of Ordos Basin.Under the compression of the side and level extrusion created by the uplift of Qingzang plateau,Ordos Basin shows some different features of large-scale uplift,strong erosion,deep sinking around the basin,and the extremely active seismic movements.These tectonic activities affected existence and the development of the basin,mountains and rivers,and the terrain features,and still the new movement of the aged fractures.The various landforms and geologic structures formed by the late tectonic movement were surveyed.The relation between the late tectonic movement and petroleum reservoir was discussed.The study result shows that the distribution difference and non-homogeneity of micro fissuring are the key reasons bringing about the tight reservoir heterogeneous.Applying the seismic pumping mechanism,some new understandings about the hydrocarbon migration and accumulation are presented.

A 3-D and 3-phase (water-oil-gas) model of hydrocarbon secondary migrationis is presented.It is applicable to the exploration area where there exist quite a few wells drilled and seismic sections,and has some distinctive advantages to present the quantity and distribution of hydrocarbon accumulation in the 3-D time and space that 1-D and 2-D models could not reach.This model is mainly based on the principles of continuity equation,flow potential,Darcy's Law,equations of state,and also in view of the major driving forces of sedimentary compaction,hydrocarbon expulsion,fluid potential, buoyancy and capillary pressure, etc.and the effects of lithology,fault,fracture and unconformity on hydrocarbon migration and accumulation.The software of the model performs the true 3-D simulation and true 3-D visualization and can historically supply the various maps for the potentials, pressures, saturations, migration velocities and streamlines of water,oil and gas,as well as the quantity and distribution of hydrocarbon accumulation.Moreover, the three solutions of finite difference,finite element and finite volume are discussed.This model has been successfully applied to Manjar Depression.The simulation results are consistent with the real situation. Some favorable prospects have been proved by recent explorations.

The reservoirs of Funing Formation in the northern slope of Gaoyou Depression are of the fine-grained and moderately sorted sandstones that can be classified as arkoses, lithic arkoses and feldspathic litharenites. Funing reservoir sandstones contain a diagenetic mineral assemblage that recorded the major diagenetic events during burial history. The early calcite was formed at shallow burial, whereas later ferroan carbonates may record a deep diagenetic event. Kaolinite was generated mainly as randomly oriented or vermiform stacks of pseudohexagonal crystals that formed a loosely packed and erratially distributed pore infilling. Chlorite was generated in the deeply buried reservoirs and commonly formed the grain-sized masses. Illite was also generated in the sandstones and formed the grain rims that commonly bridged pores. Authigenic quartz overgrowth and micro crystals contained a variety of organic fluid inclusions that indicated the petroleum filling history. Secondary porosity was created mainly by feldspar, rock fragment and clay matrix dissolution. Based on the diagenetic events related to temperature,the diagenetic stage of reservoirs in Funing Formation was in the period from B-substage of early diagenesis to A-substage of later diagenesis. Reservoir quality was controlled mostly by the sedimentary microfacies and diagenesis. Distributary channel and mouthbar sandbodies commonly have high porosity and permeability, whereas interdistributary and distal sand sheets may have poor petrophisical properties. The reservoir property was controlled by facies in the plane.

When some frequently used exploration decision methods,for example the decision-tree method,are applied to exploration decision-making work,the total costs and profits of the whole exploration process aught to be considered,no matter which stage the exploration is.In that way,the exploration decision-making works are not easy to be done,and furthermore some error decision results often occur.The exploration process can be divided into several stages.Therefore some new decision-making methods should be constructed to fit in with each other.If the target of each stage can be reached completely with the lowest cost,the best result of the whole exploration process can also be reached completely with the lowest cost.In this paper,a new decision-making method is proposed.This method can be used to select some appropriate traps in order to get the largest reserves with the lowest cost.

Results of experiments conducted to determine the hydraulic characteristics of the interface formed between layers of different size particles are reported in this work.In the experiments,300μm and 50μm diameter glass particles were used and the interface was normal to the direction of flow.The pressure gradient and hydraulic conductivity in the vicinity of the interface were measured.The porosity distribution were measured using -ray attenuation technique.A significant reduction is observed in the interfacial porosity and the measured porosity is found to compare well with that calculated from the experimentally determined pressure gradient.

Because the remaining oil distribution is scattered and complex,and there are more influencing factors on multi-layer heterogeneous sandstone reservoir in the late period of high water cut,it is difficult to identify the remaining oil distribution of each layer.A new method for determining the remaining oil distribution in single layer with multiple fuzzy comprehensive evaluation method was developed on the basis of a comprehensive analysis on geology and development factors affecting the remaining oil distribution and the data of geology and production performance in various areas.This method has been successfully applied to research the remaining oil in the tertiary infilling test area of Daqing Oilfield.The core analysis results of a new inspection well in tertiary infilling test area show that the accuracy of identification with above method is over 81.4%.This method is effective to study the remaining oil distibution of single layer in the multi-layer sandstone reservoir.

A delta reservoir of layer 83 in the second member of Shahejie Formation of the Paleogene in the second district of Shengtuo oilfield has developed for 36 years with water flooding.The varying laws and mechanism of the filterate parameters in the process of water flood development of this reservoir were studied by using the data of core analysis and filterate physical simulation.Three models for simulating three filterate parameters were established.The simulation results with the wettability model show that the rock wettability and hydrophilicity are enhanced and the specific surface of rock is depressed with the growing of the combined water cut.The simulation of the porous structure model shows that the radii of pores and throat are enlarged,the connectivity of the pores and the factors for controlling the flow property are improved with the increase of current ecovery and water cut of the oilfield.The model for relative permeability of oil and water shows that the average relative permeability of water phase in the remaining oil was decreasing graduslly.The cross point in normalized plots for relative permeability migrated to right,e.g.the water saturation at the cross point increased.Under the same water saturation,the relative permeability of oil phase increased,and the relative permeability of water phase decreased.The change of filterate parameters is due to the dynamical geology process resulted from the fluid in reservoir development.

A method for determining oil and water saturations in cores by volume-CT scanner was developed on the basis of X-ray hardening treatment,X-ray drifting correction,martix transformation of imagines and position correction of CT images with volume-CT technology.It comes to the conclusion that this volume-CT technology can be used to measure the oil and water saturations in both artificial and natural cores during and after polymer flooding. Experiments indicated that there was a fingering phenomenon in the stage of water flooding,and heterogeneous water sweep channels existed clearly during water flooding.Oil saturation in water channels was obvious lower than that of other areas.The sweep volume was enlarged,and the residual oil was enriched effectively.The oil recovery was enhanced,after polymer slug was injected into the core.The application of volume-CT technology to core flooding shows that polymer flooding not only plays a very important role in improvement of sweep volume,but also enhances oil recovery,in comparison to water flooding.

The sedimentary features of infralittoral turbidite oil reservoir were studied, and the sedimentary models were reconstructed.In combination with flow seepage theory,a vadose model for the turbidite oil reservoir was established.The distribution patterns of residual oil were summarized.The study results show that there is a considerable potential of movable residual oil in the reservoir during the period of extremely high water-cut.The factors dominating the distribution of the residual oil include static barrier and dynamic potential of water. The residual oil is mainly concentrated in the top of normal-cycled sedimentary layer,normal microstructure,variation zone of facies,and regions of force balance and flow stagnation.According to the distribution features of residual oil,the oil concentration degree and actual oil development technology,a series of distinguishing technologies for enhancing oil recovery of reservoir with a high water-cut,including the technologies of horizontal well,unsteady water flooding and profile control,were developed. The notable results in increasing oil production and lowering water percentage have been gained,and the high recovery and recoverable reserve have been obtained by applying these technologies.The study and practice of turbidite oil reservoir during the later period of development of Liangjialou reservoir can provide the important bases for development of such oilfield in high water-cut stage.It also provides references for obtaining a good development effect,high recovery and large economic gain for the similar oil reservoir.

The indoor experiments on cyclic water flooding were made to research the oil expelling and displacement mechanism for increasing oil recovery by using long core model.The main factors affecting the effect of water flooding were revealed and analyzed.The opportunity for implementing cyclic water flooding and the guiding ideologies for optimizing the cyclic water flooding parameters for various petroleum pools were proposed.It is necessary to make fluctuation of formation pressure,bring the pressure of overlying formation and the elastic oil drainage of formation and fluid into play and enhance the action intension of the exchange of fluid between formations in the process of pressure field change for increasing the oil recovery ratio by cyclic water flooding.

Analytical development equation of inflow performance relationships(IPR) under non-Darcy flow was proposed on the base of Wiggins'work.It will be the basis of IPR's application to the low-permeability reservoirs.According to the new equation,the threshold pressure(or its gradient)could be determined from the data of production or the welltest analysis.An engineering application was done in Chang 6 of Jing'an low-permeability reservoir.The results are compared with the data from different sources,such as the data from the experiment and pressure buildup analysis.It shows the new method is simple and can satisfy the precision of engineering analysis.