Based on a comparison from the results of optical characteristics, vitrinite reflectance, elements analysis, concentration of free radicals, infra red spetrum analysis and pyrolysis chromatographic analysis between those from 2 kerogens from paleo-green algae and those from the insoluble organic matter (kerogan-analogous) derived from the pyrolysis of a modern green algae. It is found that the both type I kerogen and kerogen-analogous of Blue green algaes at low maturation stage are characterized by very high O/Cratio(0.25) and very low H/C ratio(0.6). This paper suggests a new idea which is different from type Ⅳ krogens suggested by Tissot. Van Krevelen diagram and the concept of type Ⅳ kerogens cannot be applied to the highly maturated Blue green algae kerogens with these special features; they still have the possibility of hydrocarbon generation along a source specific process of evolution.

In this paper, 10 terrestrial heat flow values have been derived from logging data of 65 wells samples, and heat conductivity from 43 core sam-ples. It is shown that general aspect of the geothermal field is distributed in a ring-like form. An attempt to analyze the factors affecting such a distribution is made also. The Songliao Basin has an excellent geological background of lacustrine sedimentation and rich in oil-producing materials. In addition, a relatively high geothermal field exists in this area. Therefore, it is very favorable to the formation of oil-gas field. The result of analysis has revealed some relations between the forma-tion of oil-gas field and the tectonic structure of Songliao Basin, as well as the relation between the migration and accumulation of oil-gas and the geothermal field.

Immature carbonates with sapropelic organic matter of the Lower Triassic were first discovered at the central uplift of Jurong Basin, and afterwardsthe same carbonates containing sapropelic-humic organic matter(mixed type)were drilled through at Ningzhen rise, southern Jiangsu. These discoveries not only indicate that immature or under-matured carbonates source rocks are distributed widely in this area, but also modify the traditional idea that only gas can be found in the Pz-Mz marine carbonates which have undergone many tectonic movements. In fact, the prospect of oil exploration in this area is quite positive. This paper gives the organic geochemical features of the immature source rock from a wildcat well at Ningzhen rise. Analysis data show that the immaturity of the carbonate source rocks is controlled by the different degree of maturation of the mixed type organic matter under the given geological setting. Compared with mud source rocks containing the same organic matter from the same well, the rocess of maturation of the carbonate organic matter is much slower than that of the mudstone. This is theoretically helpful to find oil pool in the Pz-Mz marine carbonate in southern Jiangsu.

To solve a difficult problem of direct correlation between condensate in a reservoir and bitumen remaining in the source rock-compositionalsegregation caused by their existence in different phases. Taking the Xujiahe Ⅱ condensate reservoir in Zhongba structure of northwestern Sichuan basin as an example and this paper gives a careful study of the characteristics of biomarker distribution in the bitumen from the reservoir, and then it is compared with the biomarkers of related source rocks and condensate in Xujiahe Ⅱ formation. Correlations of reservoir bitumen-source rock and reservoir bitumen-condensate show clearly that the condensate in Xujiahe Ⅱ is come from the upper Xujiahe Ⅰand Xujiahe Ⅲ. The fact that lower molecular weight biomarkers are highly rich in reservoir bitumen and some muddly siltstone shows further that in this local area the reasonable mechanism of migration is that hydrocarbons migrate mainly as gas phase.

In this paper, the pyrolysis kinetics of the hydrocarbon formation in the source rock was studied by using modified Rock-Eval Apparatus with constant heating up rates incressed (at 2, 5, 10, 15, 20℃/min). The immature soure rock samples were taken from Dongpu Depression at a burial depth of 1801 m. The different temperatures at maximum reaction rate (T _max) were obtained from the experiments with different heating up rates. According to these T _max, by regression with a model of maximum reaction rate equa-tion apparent activation energy and pre-exponential factor of this source rock sample were calculated, as 199.6KJ/mol and 2.803×10 ¹³sec ^-1 respecti- vely. Based on these two kinetic parameters, and the rate of subsidence(0.26mm/y)and the geothermal gradient(0.03℃/min)of Donapu Depression, the rate of hydrocarbon formation in the source rocks at different depth were calculated. For example, at a depth of 2768m, the rate of hydrocarbon formation is 0.05(upper threshold); at a depth of 3571m, thi:rate is 0.95(lower threshold). The variation of hydrocarbon generation rate with the burial depth was also obtained. The variation of hydrocarbon generation rate with the burial depth was also obtained. The burial depth was about 3337m where maximum reaction rate occured(hydrocarbon formation peak). The results calculated matches satisfactorily with the actual situation. The characteristics and the reliability of the model were discussed. It is shown that the maximum reaction rate model is a simple and applicable one, and the Rock-Eval Apparatus can be well used for pyrolysis kinetic study of source rocks. The results used in the calculation of hydrocarbon formation fractionof source rock at different burial depth is useful in the evaluation of oil and gas resources and in petroleum exploration as well.

This paper suggests a new technique in the evaluation of the continuity and other development geological parameters of the reservoir formation by using production data(and/or interference well testing data)as a basis combined with other results of geological study. Its application may be helpful to delineate the fault blocks inside an oil field, to estimate reservoir parameters, such as reserves in a single fault block(including the size of the aquifer), average transmissibility of the reservoir and the interwell continuity of the reservoir formations…etc. The generalization of such a technique may give an optimum orientation of the location of new wells to be drilled in case that sufficient conditions have been arrived. To meet the needs of a large scaled engineering problem, a nonlinear programming with complex constraints established already is reduced to a linear programming which can be solved by interation step by step. In order to make this technique more competent, this paper suggests that results of geological study should be used largely to utilize all inforations provided before the selection of an initial guess value. It is expected that this technique may find its wide application in the "roll-over" development of a block faulted oil field.

A two-dimensional, transparent micromodel was prepared according to a micrograph of thin section of a reservoir rock sample by means of the photochemical etching technique. The micromodels exhibts the main features of the pore stucture in an actual reservoir rock. The wettability of this model can be regulated optionaly from strongly water-wet to strongly oil-wet. The roughness of the pore surfaces can be controlled also. The micromodel also can be washed and renewed for subsequent use. The micromodel is used to study the mechanism of oil displacement in second and tertiary oil recovery process and these can be observed visually. The formation of the residual oil and their distribution are studied accordingly A video recording of related phenomena has been carried out and the results of laboratory stu-ies are presented and discussed.

An accurate prediction of the reservoir performance is an inportant basis for the design and adjustment of an oil field development program and an optimum control of its production. Based on the theory of fuzzy control and integrated with the concepts of system theory, information theory and cybernetics a study on the prediction and artificial control ofthe reservoir perfomance is carried out. The reservoir is considered as a fuzzy(vague)system and the fuzzy input/output information is studied by an inverse problem of fuzzy inference of the first kind. Next, thestate structure is described as a fuzzy control relation(R _t)and a fuzzy control prediction method for reservoir behevior indexes is suggested. And optimum control of reservoir performance is discussed. Finally the application of this technique is demonstrated by taking an oil field and a gas well as examples.

Mass transfer is included in the flow of a gas-liquid mixture through porous media with phase change. In this paper, taking the physical and practical condition into account and with a simplification of formula, using a model of ideal porous media and local equalization method. A simple dynamic equation and the relative permeability formula describing the flow of gas-liquid mixture through porous media is derived based on the theories of mass conservation and momentum conservation, and dimen-sional analysis. It is pointed out that description of the flow behavior of such a type by Darcy's law and a conventional relative permeability curves is not satisfactory. The studies show that the equations are useful both theoreticallv and partically.

The three types of decline curves presented by Arps(i.e. Exponential decline, Hyperbolic decline, and Harmonic decline)has been applied extensively in reservoir engineering. They are used to predict future production rate and recoverable reserves of oil and gas reservoirs. However the result their valid prediction can be obtained only when the exact type is identified. Generally three methods of determining are used today to identify the type of decline curve namely: (1) Curve shifting method; (2) Trail and Error method; and (3) Type curve matching method. However, the results obtained by either of these methods are nonunique to some degree. A New method of identify the type of decline curves i.e. the method of dual regression analysis is presented in this paper, which can give a unique result. A program on a PC-1500 pocket computer is presented in this paper.

The helical flow of power-law drilling muds in the drill string was studied both theoretically and experimentally. The analytical expressions of the apparent viscosity distribution, the velocity distribution and the flow ratefor the helical laminar flow were derived. The equation giving the pressure drop, the expressions of the stability parameter K, characterizing the transition from laminar to turbulent flow, and its maximum value K _max were established. Experimental studies with aqueous solutions of CMC and PAM showed that the helical laminar flow of the power law fluid in the pipes is transformed into turbulent flow when K _max=400.

Two parameters L _Sn and L _Gn are presented to describe the sequence distribution of substituents along CMC. The percentage of substituted anhyd- roglucose residues(i.e. substitution index SI)and the degree of substitution in substituted residues can also be obtained from L _Sn and L _Gn through simple calculations. Seven CMC samples of different degree of substitution(DS), SI and L _Sn were prepared and the properties of the drilling mud treated by them were studied. It was found that the fluid-loss of the mud decreased with increasing DS, SI and L _Sn of CMC. The salt-tolerance ofthe mud was enhanced with increasing L _Sn. Preliminary explanations are proposed for the above results.

This paper presents an optimum design method of the concrete anchorage for hot pipeline according to a given thrust force and allowable displacement, and proposes a new shape of the concrete anchorage pier based on theoretical analysis and experimental comparison. A mathmatical model and computer program for determination of anchorage size are established on the basis of optimization theory with the amount of concrete quantity used as objective function and balance of forces, stability against overthrow, adequate strength as constraints. A set of calculated results show that the amount of concrete used for making the anchorage pier designed by the optimization method is significantly less than that designed by the usual method by about 20%～60%.

A practical computer acquisition and transmission system of drilling data is presented in this paper. A Chinese made miciocomputer is used to control acquisition and processiong of drilling data at the drilling site. An IBM PC/XT is used to collect and process drilling data at the drilling company. Data communication between drilling site and drilling company is realized through ultrashort wave radio channels. The primary instrument gives six or eight parameter measurement. A new UPS is used for the system. Reliable hardware and software design ensures stable operation. and the modular structure of the system makes user application, maintenance and expansion possible. Standard data chain and CRC-16 check mode are used in inquiry control by the central station at the drilling company. Different information media, such as display, curve drawing, tabulation, disk record and necessary data processing are provided with Chinese characters function.

The economics of a steam injection project is detemined by its capitalinvestment and operating cost which in turn depends considerably upon the capacity of steam injection system to generate and handle a large volume of high-temperature and high-pressure fluid This paper gives an attempt to apply the principle of queueing theory, integrated with a M/M/C model of stochastic service system, Linear programming technique, and the technique of marginal analysis to optimize the steam injection system, including optimum size and a combination of steam generating stations, optimum number of steam generators in each station, economie ranges and optimum number of wells controlled by each station. The effect of heavy oil prices on the results of project appraisal is also discussed. A discussion on the Shanjiasi thermal recovery project in Shengli Oilfield is presented as an example.

The magnitude of extension of a faulted basin in developing stages can be obtained by means of restoring its palaeostructural cross-section.The extension variation of the depressions in the Bohai basin clearly suggests that the basin was experienced Eocene and Oligocene extension cycles,and the latter involves two subcycles.Chronologically and spacially,the extension was greatly uneven and the source rocks developed in each cycle.For the sedimentary depressions with intensive extension in Eocene and early Oligocene,hydrocarbon was mainly accumulated in Lower Tertiary and basement layers,for those with intensive extension in late Oligocene and slight activities in Neogene,secondary hydrocarbon was trapped mainly in Neogene layers,In accordance with the properties of hydrocarbons in each sedimentary depression,further exploration may greatly widen the prospect of the Bohai basin.

Southeastern China continental margin has undergone a complicated convergence process of the Eurasian plate with the Pacific plate and Tethys plate.With the subduetion of the Pacific plate under the Eurasian plate,the Eastern China continental margin crust was subject to aregional tension stresses that caused the breakdowrn,spreading and subsidence of the back-arc basement and formed a series of intra-arc basins,margin sea basins.and rift basins.The East China Sea basin grew up under the influence of compressional stresses caused by the collision between Luzon and Taiwan in the later stage and a fore-continental basin was formed.

In this paper an experimental technique for investigating geothermal histories of sedimentary basins by analysis of uranium fission tracks in detrital apatites is presented.This method is based on the fact that ²³⁸U fission tracks in minerals can be annealed by heating over a geological period.In the case of apatite the annealing zone occurs between about 70° and 125℃ for a time span in the order of 10 million years(Myr) which is remarkably conforms to the condition favorable for generation of petroleum.The twenty samples analysed were collected from the cores at various depths of exploratory boreholes in the Linqing sedimentary basin.The apatite fission track age T of these samples have been determined by the external detector method,and the distributions of the projected lengths of fossil tracks in these samples have been measured as well.The fission tracks were observed with an optical microscope at a magnification of 1500X.The precision of this method depends mainly on the counts of the fossil fission tracks and the error of the thermal neutron fluence.The obtained relations between the age T and(mean projected length Pof the fossil track relative to the depth of burial) show that T and P are de-creased with increase of depth of burial in a range of 2100-4000 meter,and thus this zone is the apatite fossil fission track annealing zone.The fact that T and Premain fairly constant in 1600-2100 meter range shows that the primary age of the formations penetrated by the borehole is about 85 Myr.The fact fhat all fossil track projected length distributions have a similar form with a peak shows that no strong palaeotemperature fluctuation occured in the region in which the borehole is located,thus this region was in a fairly stable geological state.For large part of the samples r _si>0.8(r _si is a correlation coefficient between spontaneous and induced fission track densities),which also shows that the region was in a stable geological state.The experimental results show that measuring fossil track projected lengths is more powerful to reveal palaeotemperature and is very simple.

An automatic analysis processing of well-logging data for a compre-hensive multi-parameter reservoir evaluation is presented in this paper.Based on this technique,a computer program(DYX) is completed.The program can be used to display various geologicel parameters,evaluation of rock propertics,evaluation of oil-bearing and other information in the fo rm of a continuous map.It provides a base for formation evaluation by well-logging analysis.

The INCOHERENCE function in the GLOBAL program is studied in this paper.The formalation of the INCOHERENCE function is discussed,The meaning of the solution,the significance of the confidence interval and the reduced incoherence are analyzed.The influence of zone parameters,response functions and uncertainties to solution are tested,Finally,some suggestions are proposed for getting good interpretation results in GLOBAL technique.The conclusions of this paper can be applied in the theory and practical application of optimum well logs interpretations.

This paper gives following results.(1) A method is presented to deter-mine total pressure transmissibitity θby pressure build-up data from a well.Its advantage is that only pressure build-up data are required without pressure drawdown testing data,(2) A mehtod is presented to determine cross flow coefficient λ from pressuredrawdown data;(3) Two methods are presented to determine the crossflow coefficient λfrom pressure build-up data.Their advantages are that only data of build-upwell testing is required without pressure drawdown testing data.Thus they are better than the methods now in use.practical examples are given to demonstrate these methods.

This paper suggests an optiamum formulation of dioxy-hexaring liquid sintilator,including PPO(7.5g/1),POPOP(0.6g/1) and naphathalene(1308/1),Its max.water solubilization,the relation between its volume and E%,and the effect of stand-by time on the results of measurement etc.are appraised.In addition,method of sample preparation are discus-sed.A field example of its application is included also.

This paper presents the observational results of the acoustic emission from an in-house hydrofracturing simulation experiment. It points out that propagation of the hydrofracturing crack is not continuous. Source of microfracturing and the distribution of macroc-cracks coincide generally, they all occur in the orientation of maximum horizontal principal stress. Amplitude of acoustic emission is bigger along a direction normal to the linear fracturing source. The amplitude of S wave is bigger in the observed signals. Obvious acoustic emission usually occurs at a fracturing of an integral rock, However, the amplitude of acoustic emission has not on obvious relation to fracturing pressure. These experimental results may be used as a reference to the actual field observations.

Conventional and modern well test analysis methods are successful only in the interpretation of the middle period of well testing data,but they fail to analysis the early period data.By a combination of optimization and grey-system theories a new method is proposed in this paper which is successful in the interpretation of early period well testing data from a heterogeneous reservoir and also for those data from DST.The value of Kh and S obtained agree fairly well with those obtained by using mid-dle period data.Thus,a large quantity of data is restored which has been discarded earlier to get useful informations.

In reference literature(1)Schechter and Gidley established a mathematical model of the reactant concentration C ^P in a single pore to simulate the acidizing process.In order to get the average concentration C ^P,they define a parameter "α" in(1).They assume that "α" depends on the pore geometry,the diffusion coefficient and the reaction velocity constant; but is independent to the time and axial position of the pore.Under some coditions,a formula of C ^P depending on α is given in(1).It is recognized that the method proposed above must prove that α is independent to the time t and axial position of the pore Z,and α can be determined.However,this is impossible.In this paper, C ^P is solved directly from a mathimatical model mentioned above,under some conditions,and thus,an expression of C ^P is obtained.According to the result it is proved that even if a single pore is defined,α still depends on Z andt,and the values of α can spread in an infinite interval.As a result,α can not be detemined.Thus,the method used to solve C ^P in(1) should be modified before its application.

Describing the anisotropy of the formation in terms of Rock-Drilla-bility,a three-Dimensional model for orthotropic formation-isotropic bit interaction is developed through the orthogonal transform,and formulas for the formation force are derived further.The effects of orthotropic formation on bore hole deviation are shown.by a series of caculations and plots.In addition,the serious limitations of Lubinski′s(2)analytical modcl are pointed out in this paper.

This paper analyzes the load which causes the deformation of sucker rod string in a rod pumping well,and establishes the differential equation of bending and gives a power series solution.The number of bending wave and deformation shape of a sucker rod string are discussed.Based on the method stated in this paper,a computer program has been developed to calculate the maximum bending position under any working condition and has been tested and verified at a field scale experimental well at Daqing Oil Field.The position of the roller-wheel coupling can be reasonabl defined,resulting in higher efficiency of the rod pumping operation.

The optimum structual design of a drilling rig foundation made up of bars was studied with sequential quadratic programming for specified structual topology and geometry.A mathematical model was given with its objective of minimizing the structual mass and constraints of local buckling in addition to the usual stress,member size and displacement constraints.The relationship between various parameters of element sections was obtained by curve fitting.Stress constraints were converted into quasi-size constrains to simplify the mathematical model.The sequential quadratic programming was utilized to avoid the complex calculation in sensitivity analysis.An algorithm in incremental form was given under Kuhn-Tucker condition.In order to test the theory and computer program developed,an actual drilling foundation with 176 nodes and 265 elements was calculated in contrast with its original design.The calculation converged after eight iterations and the structual mass was reduced by 12.6 percent.

Floating ring bearing contributes to an increased rotary speed of drill bit,which is the result of reduced friction power loss by the rotation of the floating ring.It is generally believed that the principal parameters are the gaps in the inside and the outside of the floating ring.An experiment of a floating ring bearing unit in a rock bit has been conducted under simulated operating conditions and with the outside gap greater than the inside gap that is commonly used at home and abroad.However,the floating ring was hardly able to rotate.Theoretical analysis of the lubrication state for rock bit under heavy load and low speed has been made in order to find out the suitable gaps.The lubrication state is a mixed or boundary one,so equations of floating ring bearing with full oil film lubrication are not suitable for rock bit's bearings,and the effect of metal contact and elastic deformation on the surface should be consi-dered.The experimental results agree with theoretical analysis that the outside gap of a floating ring should be much smaller than the inside gap to keep the floating ring rotate satisfactorily.The results can be used in the design of floating ring bearing of a rock bit.

An improved heuristic method for Optimum searching of mixed discrete variable problems,i.e.a mixed discrete expanded complex programming method(MDECP)is presented.The definition of‘effective function,in literature is modified by normalization and establishing a buffer region for equality constrained problems.The variable interval discrete technigue in engineering problems are discussed,thus broadening the scope of design.Furthermore,a new principle for check is proposed for a convergence criterion,which uses the maximum mixed sub-gradient defined in this paper rather than the sub-gradient of objective function to seek a local optimum solution.Calculation of a real cases has shown that the number of point-to-point check is greatly decreased and optimum searching is more effective.Finally,an optimum design of chain drive used in oil fields with discrete parameter is made in this paper.

The Mesozoic-Cenozoic sedimentary basins in China are developed in the different geological settings.During Indo-Chinese epoch,nonmarine basins were generated in the north of Indo-Chinese folded belt but remn-ant sea basins developed in the western part of Yangtze area in Southern China as Palaeo-Tethys Ocean became vanished.During Yanshan period and Himalayan period,the old basins were deformed as Meso-and Neo-Te-thys became terminated,and a number of newly-developed basins formed in these different tectonic settings.These settings can be classified into three kinds according to the geodynamic settings of plate or block boundary system,that is,extensional-rifted setting with divergent boundary system; orogenic setting with convergent boundary system,shear-extentional or shear-compressional setting with stike-slip transform boundary system.Rift-rifted basin,mountain front basin and intermountain compie-ssional-depression basin as well as pull-agart basin were generated respectively in these settings.Based on basin structure characteristics,we can group these basins into two classes,namely depression and faulted basin.In fact,faulted basin includes two kinds of strctural types: rifted basin and compressional-faulted basin; pullagart basin belongs to faulted structure.Geodynamic settings of plates or blocks,however,would be different in the different periods.Therefore,the dynamic characteristics of some basins would have changed several times,which can be reflected not only on the changes of their force characteristics,but also on the superimposition of different types of basins at the different stages.This makes that Mesozoic-Cenozoic basins in China have many unique types.The evolution models of these basins can be developed through careful studies,which can lay a foundation for the study of tectonic deformation of lithosphere and the distribution of mineral as well as that of energy resource.

Erlian Basin is a Mesozoic continentians basin developed on the Hersian folding basement.Lower Cretaceous Aershan and Tenggeer Groups and Jurassic formations are the main deposits.Sags in the basin and distributed en lunchen showing the characteristics of action of tensional and torsional force during their formation.Affected by factors such as the structural lines of the basement,boundary conditions and the nonuniformity of the action of the geological forces,the depth of depressions as well as their sizes differ greatly,and show a feature of sectioning and belting distri-bution.Strong tensional and torsional depressions are formed mainly along overlapped areas of NNE-NE and nearly E-W of the basement structural lines,the former depressions being large and deep usually,and the later ones being narrow and shallow.The size of tensional depressions developed on the base of NE-NNE basement sructural lines in the nothern part are greater than those deve-loped on the E-w structural lines in the southern part.As a result of exploratory drilling,5 types of oil reservoirs are discovered.All of them are located in the tensional depression zone.The oil in them being origin-ated from lower cretaceous accounts for 80% of the predicted resources.All the oil and gas are find on the area surrounding the oil-generation sags.However,strong reforming action due to later tectonic movement were occured.Jurassic oil and reservoirs and coaliferous gas reservoirs may be found as more exploration is carried.

The time-temperature compensation relationship as proposed in the previons paker is further proved by a time-temperature plot at the period of oil and gas maturation which is established with the time(t)and temperature(T)data at a measured reflectance R _o=0.5 from drilling cuttings in Pearl River Mouth basin.An empirical formula,logt=(144.16547/T)+0.0721409 is suggested.With this formula,the temperature T required for maturation of oil and gas generadion for various source rock formations during a certen geological time t can be estimated,and then the threshold depth H corresponding to this time t is estimated.Thus by connecting every H points corresponding to different t a curve is obtained representing oil-generating threshold depth of a certen source rock formation during the geological history.It cuts the subsidence et rve of the bottom source rock formation and the point of intersection will represent oil-generation threshold of the source formation(i.e.the beginning of oil generation).Using this method,oil-generation threshold depth of every geological period have been estimated for five suit of souce rock formations in a depression of Pearl River Mouth basin.This depth is very close to those vesults derived from many other data.Moreover,a threshold time analysis for oil generation in various geological period of soue rocks shows a relatively satisfactory result.

This paper discusses systemalically the types of inclutions in carbonate rocks,the distinction between primary and secondery inclutions,and the application of ancient temperature measured by method of "homogenized temperature" in the light of practice.Moreover,it also describes the characteristics of organic inclutions and their variation measured in "homogenized temperature"technigue.Primary and secondery inclutions are of environmental significance because the stages of their formation,order of priority the compositions and homogenized temperature are different.Consequently,distinction between primary and secondery inclutions turns to be a basis for inclution study.This paper introduces the methods of distinction between both inclutions according to morphology of the inclutions in combination with their diagenesis.On the basis of this,the temperature measured by"homogenized method"should obtain its rational interpretation and application.Inclutions in carbonate rock have various features which are closely related to geological environment where they occured and properties of traped fluids.Different liquid gas radio of inclutions and their abundance represent the different environment of the inclution formation.A bundance,colour and variation of organic inclutions not only reflect the quantity to a certain extent,but also the extent of oxidation of the organic matter.This paper gives a primary disccusion and description of the above-ment-ioned points taking the regions of Chishui,Guizhou and Baishai,Guanxi as actual examples.

Geochemical exploration is one of geological prospecting method for oil and gas.An important role has been played by such a technique in finding oil and gas over years.The presence of trace amount of light hydrocarbons in surface soil or in ground water,however,are either the micro-seepage from subfurface hydrocarbon accumulations or other sources due to photodecomposition of organic matters and microorganism activities.This paper gives a discussion on the screening out of significant information from surface geochemical data based on a comprehensive study and computer processing of the data as well as improvement of sampling methods in order to enhance the successful ratio in predicting the potential hydrocarbon deposits.

The velocity ratio of compressional and shear waves in gas saturated rocks is less than that in water saturated ones when their porosities and confining pressures are the same.this paper have proposed an interpre-tation technique for visually identifying gas formation in which measured velocity ratio of compressional and shear waves is shown by a contrast with its background value.A formation is indicated as gas producing when the measured velocity ratio is less than the background one.This method has been tested and verified with neutron and density porosities as well as flushed zone and initial water containing formation porosities.It enhances the ability and accuracy of visual indication gas formation.Field examples are demonstrated.

By a study of factors affecting the result of repeated fracturing of an oil well,this paper presents guidelines in the screening of wells and form-ations to be selected as targets of repeated hydrofracturing and guidlines in the design of fracturing technology.These guidilines have been improved and modified according to the experience of field practice and signigicant well stimulation results are obtained by their application.Other new ideas in the comprehensive geo-technical study presented here may be beneficial to the field practice of other oil fields.

Palmer's P-3D fracturing pressure decline curve analyzing model is established in this paper.The paper also takes the fracture propagation after shut-in according to the criterion of stress intensity factor into cons-ideration and the reason of change of matched pressure with time during shut-in is discussed.In addition,this paper points out that it is important to use corresponding pressure decline analyzing model for different formation conditions.Effective fluid-loss coefficient,fracture geometry parameters and toughness of rocks will be determined by using the met-hod suggested in this paper.

In this paper a theory is given for the interpretation of drawdown and buildup tests,which are given to an individual layer of a multilayer reservoir with crossflow.The crossflow behavior and its effect on drawdown and buildup curves are discussed.It is found that both drawdown and buildup curves have two straight lines with a transition period bet-ween them.The first straight line period is the period when the theory of well test for a single layered reservoir is effective for an indivi-dual layer test in a multilayer reservoir with crossflow.The first strai-ghtline determines the kh product and the skin factor of the test layer.The second straight line determines the total kh product of the reservoir.The vertical permeabilities of the shales between layers can be determined by two method,using the crosspoint of the two straight lines of drawdown or buildup carves and the steady wellbore pressure diffe-rences between the test layer and the shut down layers.

This paper presents a new finite difference method with irregular grids.This method is similar to the conventional finite element method is some aspects,but it can be used in the multi-phase folw reservoir simulator.Comparing with the widely used cartesian coordinate grid,it has the advantages of more flexible approximation of reservoir geometry,and convenient to refine locally.This paper set up the difference equations for the irregular grid system,and describes how to determine the grids automatically,and pre-sents the application of this method in a double porosity medium oil-water two-phase reservoir simulator with bottom water drive.