The petroleum geology of Shan-Gan-Ning basin are multiple in feature. The crust movements of different basement and in different ages provide the background of the formation of various types of oil-gas region. The development of multicycle of regional sidement forms serious suites of source rock, reservoir and cap rock assosiations. The differences in geological structures result in a special oil-gas reservoir sequence inside the basin as well as in adjacent region. The Shan-Gan-Ning basin oil-gas region can be divided into four types: 1. Jurassic Yanan Palaeographic drape region, located in middle west of the basin, developed Jurassic channel sand oil-gas reservoir sequence which lies on the top of erosional surface of Yanchang group. 2. Triassic Yanchang deltaic oil-gas located in east of basin with two kinds of oil-gas reservoir sequence, the lacustrine facies delta foreset sand body and plain distributary sand body. 3. Overthrust structure oil-gas region in west margin of the basin with the oil-gas reservoir sequence controlled by overthrust structure. 4. Paleozoic two-floor texture oil and gas region in north of basin is a complex of the corroded carbonate rock through lower Paleozoic and coal-series oil-gas field through upper Paleozoic which was controlled by basement uplift.

This paper discusses certain problems related to the mechanism of formation of the salt-dome structures and listric normal fault in Zhong-Yuan oil field, North China. In order to explain such mechanism, we have conducted a series of modelling tests related to tectonic phenomena of salt-dome and listric normal fault. The experimental results indicate that formation of salt-dome was controlled by mechanical and physical properties of rock, vertical displacement boundary condition of the basement, and tensile stress field. In our modelling, it has been observed that the development of listric normal fault usually varies with depth. During formation and evolution of salt-dome and listric normal fault, they are subjected from regional tensile, derived from the inplate movement or that between block and plate combined with the shear-tensile stress from the upward gravity gliding of the rock salt formation.

The abundance of organic matter in source rocks has gradually changed in geological time. A new concept of "ancient abundance of organic matter" is presented. The factors affecting the abundance and its calculation method are discussed. The formulae of calculation and several examples are given. The study of ancient abundance of organic matter is very important for the prospecting of oil and gas.

Solid asphalt is widely dispersed over Carboniferous and Permian formations in Wenliu structure of Nanpanjiang depression. It has been discovered that there are six types of occurrence in field survery and six micro-textures in microscope observation. Wenliu asphalts is a type of highly metamorphosed carbonaceous asphalt and anthraxolite according to the physical properties, determined by x-ray diffraction, C ^-, H ^- analysis and the measuring of reflectance. The Permian source rock in the area has reached a postmaturity stage. The precess of asphalt formation and evolution are discussed from the thermal evolution history of that source rock. Properties multistage formation of the asphalts are analyzed also.

The principle of the spectral analysis of actual full waveforms from the Long Spacing Sonic wave (LSS), as well as the main factors affecting this analysis, are discussed and the formula for the estimation of frequency errors is derived also. From these, the variations in the spetrum of each period on the waveforms are analysed and the primary and secondary spectrum values of the compressional, shear and Stoneley waves of some common rocks are given. The continuous primary spectrum of these three types of waves are given The most important is that we work out DASP curve which has been proved to be effective to indicate gas-bearing layers. All results in this paper are based on actual logging waveforms, and all tables and figures are taking from actual field cases.

This paper describes that the lacustrine carbonate of lower Tertiary Shahejie Formation in Bohai Bay is mostly terrigenous elastics-carbonate mixture rock. There is a seris of transition rocks between the terrigenous clastic rock and carbonate. The nomenclature of these rocks is tabulated tentatively.In Bohai Bay the small limited areas of lacustrine carbonate deposition are surrounded by large areas of the terrigenous clastic depositions during lower Tertiary. The terrigenous clastic-carbonate mix is more easily formed in lacustrine setting compared with the shelf of shallow sea. Three kinds of this mixture rock profile are discovered in Bohai Bay. According to the profiles three mixing patterns are put forward and the sedimentary model of terrigenous clasticcarbonate mix is illustrated.

A compositional simulator for multidimensional chemical flooding is established. It takes all the main phenomena in the chemical flooding process (convection, diffusion-dispersion, exchanges among liquid phases and liquid-solid system) and boundary conditions suitable for the oilfield applications into consideration. It can simulate multiphase flow problems in porous media with different geometry. Under the present phenomenalogical knowledge condition, as many parameters as possible are involved in this model. It is different from other chemical flooding simulator by considering the following factors: the appropriate processing of phase equilibrium, the effect of capillary number distribution in space and time, the chemical consumptions, and other laboratory measured data, which make the model describing the real problems more correctly. It can be used to interprete laboratory results, study mechanisms of process, optimise the composition and size of the injected chemical slug etc, and can be used to simulate oilfield chemical flooding process, predict flooding performance and effects of various parameters, and also used to solve practical problems.

This paper discuses the effects of the permeability distribution on the water flooding characteristic curve (the logarithm of cumulative water injection vs cumulative production). A paper published before indicated that the heterogenity of permeability had an effect on the waterflooding characteristic curve and this paper indicated that the permeability distrabution yields remarkable influences on the form of waterflooding characteristic curve but the main characateristics of the curve is not changed. The reservoir and production data of an oil reservoir are used as an example.

Type Curve is a very useful tool in the interpretation of Well test data. Once the optimum match is obtained, the match point and the match curve data, may be used to Calculate formation transmissibility (Kh/μ _o) and formation effective permeability (K), along With Wellbore storage Constant (C) and skin factor (S), but it Can not be used to determine reservoir pressure in the past. In this paper, a method of determining reservoir pressure by match data of the type Curve is presented. Therefore, the application range of the type Curve Will be extended.

A two-dimensional transport equation describing the dispersion and adsorption of chemicals in a solution flowing through a porous medium can be solved numerically by the method of characteristics conbined with the method of finite difference. The characteristics technique is used firstly to obtain the concentration field generated by the convection term, this concentration is called "convection concentration";secondly the method of finite difference is used to obtained the concentration field generated by the dispersion as well as other terms, taking the convection concentration as a known, this concentration is then called "dispersion concentration". Finally, the total concentration in a given time step is yielded by adding the above two concentrations. The effects of dispersion and adsorption on the concentration of the solute are investigated by choosing different parameters in this twodimensional model. The results show that the numerical method introduced in our paper is applicable. The solutions obtained are valuable in many fields of practical interests, such as surfactant, and polymer flooding in enhanced oil recovery operations, the pollution of ground water and other problems.

By applying fuzzy mathematics, four wells in the carbonate reservoir of Wumishan formation of Renqiu oilfield was evaluated. Five items of well logging and four of mud logging data are chosen as evaluation indices. Compa ring with the production testing data, the coincidence of the evaluation result is 88.9%. This is a good result.

The bottomhole pressure difference is an important factor affecting the rate of penetration. Their quantitative relation is necessary both for optimizing drilling parameters and for predicting the rate of penetration. Statistic analysis and standardization is used to determine the effect of bottomhole pressure differentiel on ROP. All parameters other than the pressure differential are standardized by analyzing a large amount of fielb data in order to highlight the effect of pressure differential. A mathematic model is then developed to fit the curves obtainod from the field data. Field data indicate that the effect of bottomhole pressure differential on ROP decreases as the hole depth increases. A model regarding to the factor of the effect of bottomhole pressure differential on ROP versus well depth has been established based on the bit data from Zhongyuan Oilfield. By analyzing these data, it can be clearly seen that the effect of pressure differential on ROP varies with well depth. Therefore, the models generally used without considering well depth are not accurate.

A theoretical analysis is made on directional drilling by catenary technique. The hole deviation at the final depth is greater by several degrees in catenary directional drilling than in the usual way on account of its angle building continuously. The deeper the well, the greater is the deviation. This paper proposes an assumption thar the interaction of the bit and rock can be considered as an elastic embedded end with non-constrained rotation. Moreover, the hole trajectory is simplified as a planar curve in our analysis. A three dimensional. model of buckling of the lower string is proposed for numerical calculation. The necessary conditions to keep the drill bit along the predicted catenary trajectory should be V'(0)=0.and u'(0)=-tgθ. An analytical solution is obtained through Laplace transform. The analysis provides useful information for selecting parameters in catenary directional drilling.

Cubic spline technique is used to simulate directional well trajectories in this paper. The method of using cubic spline interpolation to determine directional well trazectories is disscussed in detail. The coordinates of any point in a directional well trajectory can be calculated. The inclination and azimuth between any two adjacent points in a. well trajectory can also be calculated. The results obtained agree with field measured figures fairly well. This technique can be used in practical field probleus.

In the present paper, the author introduces a new laboratory method to study the formation damage from drilling mud, i. e, a damage radius (r _d)permeability (k) model, unique from those applied at home and abroad. By measuring the dynamic mud filtration under the modelled drilling conditions as well as the observation of mud core damage the damage radius and value of reservoir formation permeability restored can be obtained. The skin effect and production ratio are calcalated to evaluate the mud formation damage, which can be compared with the measured skin effect from field testing. The model provides a new approach to study the formation damage.

The Qinglong Group can be divided into four formations,i.e.Yinkeng Formation,Helongshan Formation,Biandanshan Formation and Dongmaanshan Formation.The first three formations belong to the Lower Triassic and the last one to the Middle Triassic.According to"single factor analysis and comprehensive mapping method",the petrography and lithofacies paleogeography of every formation of Qinglong Group has been studied.The paleogeographical features of Yinkeng Age and Helongshan Age in this region were characterized by shallow water elastic platform,shallow water carbonate platform,deep water slope and deep water basin,with water becoming deeper northwards.In Biandanshan Age,the deep water area gradually narrowed northwards but the shallow water sedimentary area was widened.Meanwhile,the shallow water banks were well developed.In Dongmaanshan Age,the whole Lower Yangtze Sea became a shallow water sedimentary area where gypsum lagoons,restricted sea,dolomite flats,dolo-micrite flats,banks,parabanks and embryonic banks were developed.The deep water basin and slope are beneficial to the preservation and transformation of organic materials.The isopach map of Lower Triassic dark coloured rooks has been drawn showing the distribution of possible source rocks of oil and gas.Oosparite and intrasparite which formed in shallow water banks,postpenecontemporaneous dolomites and structurally fractured limestone may be favorable for reserving oil and gas.Gypsum and anhydrite in Dongmaanshan Formation and dense micrite in all formations may serve as good cap rocks of oil and gas.From the combination of the formation,preservation and cap of oil and gas,it can be seen:(1)The formation,preservation and cap conditions are very good in Changzhuu,Liyang area in the eastern part and Tongling,Guichi,Anqing in the middle part where all the profitable conditions are concentrated;(2)In the western part,the good conditions of petroleum formation exist in the Yinkeng Formation,but the cap rocks are not good enough;(3)It can be inferred that in this region where the deep water deposits and the dark colour rocks are well developed,the primary traps such as Jurong type might be formed if there are structural fractures in rocks.

The 3rd section of the Shahejie.Formation in Longgu Depression is among the thpical sediments of the Paleogene nonmorine half-graben-type basins in East China.There are mainly three kinds of depositional facies.Nearshore subaquatic fans accumulated on the downthrows of major growth faults in deep water environments.They can be divided into three types,which are characterized by the broom7like prograda-tional,the chaotically progradational,and the progradational-retro-gradational configurations,respectively,and have different sedimentologic meanings.Fan delta commonly show the sigmoid progradational configurations.Turbidite fans could either accumulated to form the mounded,the deep-water on lap,and the progradational facies,or be in a diseminated state without typical seismic responses;They usually didn't exist independently,but were related in origin to nearshore subaquatic fans,fan delta,or deep water channels,forming depositional systems.

Members S ₃ ^3-4 of Qiaokou area,Dongpu depression,have reached the mature stage B and over-mature stage of mesodiagenesis.On the basis of deposition,strong diagenesis has resulted low-porosity and low-permeability sandbodies in most of them which can be divided into two types:(1)quartzovergrowth-cemented;and(2)carbonate-cemented.The pore spaces in the reservoirs are charactorized by the predominance of micropore and microfracture,with well developed secondary pore spaces only few layers.During the burial,diagenesis of the sediments,two periods of solution have been undergone,and the resultant secondary porosity in each period was different in scale,quantity and effective preservation because of their different diagenetic environments.There are favorable for the development of secondary pore spaces and may provide good spaces for hydrocarbon accumulation.There are internal relations among diagenetic facies,depositional facies and development of secondary pore spaces.Turbidity-Channel and Stormchannel sandbodies are favorable for the development of secondary pore spaces and may provide good spaces for hydrocarbon accumulation.

Dongpu depression which is rich in oil and gas is a typical salt-lake basin,is made up of well-developed structures and reservoirs,numerous traps and sandbodies,highly-matured source rocks,good conditions for hydrocarbon escape from source rocks,short distance of hydrocarbon migration and existence of secondary porosity in deeply-buried zones are the basis of the formation of oil and gas pools.Oil and gas pools may be divided into structural and stratigraphic types.The former include anticline pools,which may be further classified as contemporaneous faulted-reverse dragged anticline compressively-faulted anticline,arched-anticline formed by the flow of salt and anhydrife and drapped-structure related to buried hills and differential compaction and drape pools.Stratigraphic-type oil and gas pools may be subdivided into primary sandbody lithological pools and stratigraphic unconformity pools.The central uplift zone in the depression,which is an assemblage of a number of substructures and has a variety of traps especially those with characteristics related to salt structures and salt facies changes,is a large composite oil and gas accumulation belt.Proporly combined with sandbodies,the uplift zone involves multiple oil and gas pools dominated by fault block;Wu Zhuangji oil pools which contains a large amount of oil and gas reserves,located at the western slope of the depression,has been discovered.Reverse dragged structural oil and gas pools,stratigraphic-type oil and gas pools and depply-buried natural gas pools are discovered also in the deeply subsided region and steep slope of the depression.

Based on large quantities of analytical data,the characteristics of the distribution of fatty acids,naphthenic acid and phenol in oil field waters and non-oil field waters of various strata in northern Songliao basin are studied and the relationship between the contents of"fingerprint marker"compounds and the accumulation of oil is discussed.Formation water can be closely related to hydrocarbon generation,migration and conservation.Organic,acids are the products from the conversion of organic matter to hydrocarbons Naphthenic acids,fatty acids were formed in source rocksand dissolved in pore water.Hence,the contents of fatty acids,naphthenic acids and phenol in oil field increase towards the boundary of oil trap main source beds and reservoirs on the basis of regional geological survey.Oil and gas accumulation can be predicted by the change in the contents of organic acids and pbenol.Through practice it is proved that they are good indicators for hydrocarbon exploration and are of great importance in searching for oil and gas.

It is a very important task in oil field geology and development to study oil storage sand bodies of different types and reservoir characte ristics.This paper has analized the depositional types of sand bodies in Shengtuo oil field,classified into six kinds of sedimentary sand bodies and described the reservoir characteristics of these sand bodies.Sands and conglomerate bodies of alluvial fan mud and stone stream:mixed with sand,conglomerat and mud,the connection between pores axe not well,so reservoir property is poor and there is less possibility for production;Braided steam sand bodies:Grains axe coarse.Pores texture is fine.The radius of porous channels are large and porous connections are well.The highest permeable beds have permeated all parts of the reservoir so producing capacity is high;Sand bodies of river mouth bar in delta front:Grains are fine and well sorted,pores are small and connect well.permeability is low.The reservoir is thick.Production capacity is great;Turbidity sand body:Grains axe medium size.Lithology is even.pores connect well.High permeable beds are in the middle and lower parts of the reservoir so the reservoir is a high oil production zone.

This paper suggests that a group of related curves between permeability and mercury saturation are established firstlybased on the results of mercury injection and data of laboratory measured permeability(defined as pore-sturcture curves).Then according to permeability values interpreted by logging curve,by graphical or calculational techniques.we determine saturation under the different pressures to give capillary pressure curve of the interpreted permeability value(defined as log pore-structure curve).This method provides a possible way to approach the pore-structure of reservoirs,using log informations.Good agreement has been observed between the capillary pressure curves measured in laboratory and those reconstructed by above procedure in the Maling Oil Field.

The fundamental theory of the flow of heavy oil in a radicallysymmetric reservoir with a well at the center is studied and analytical,semi-analytical and numerical inversions solutions are obtained.A simple and effective method of analysis of well testing results for viscous oil is presented.And some"type curves",which is possible to estimate parameters of formation and viscous oil(e.g.k,φ _c,λ _v,λ _p,and c),is introduced.The method of"type-curve matching"obtained here is quite suitable for high viscosity oil problems.

In hydraulic fracturing,formation may be damaged in two ways,the damage near wellbore by such fluids a.s drilling mud befare fracturing and taae damage behind fracture faces by fracturing fluids after fxacturing.In this paper,a general formula of well productivity ratio has been developed,taking auaunt of the variations of the formation flow capacity and the conductivity of the propped fracture in horizontal fracturing,and has been applied to analyse the practical cases with the damages mentioned above as well as those with the tail-in process.Analyses and discussions axe made an the effects of the damage bath before and after fracturing on the evaluatian of the productivity xatia.A comparison with the electric analog modeling curves gives the conditions under which the presented faxnxulas in this paper can be applied.

The three-dimensional flow theory of turbomachinery was adopted to improve the design of 6D100-150 type water injection pump impeller,which was originally designed by using traditional one-dimensional flow theory.Comparative tests were made with the 3-D impeller and the original one installed in the same diffuser.When the pump speed was reduced to 50%,the single stage pump efficiency with the 3-D impeller was raised from 64.6% to 67.2%,the single stage pump head at the best efficiency point was raised from 33m to 35.25m.Greater improvement will be expected at full pump speed.The traditional pump design should be up-dated with advanced hydraulic calculation and there exists great potential for using the threedimensional flow theory in pump deign.

A new definition of internal surface crack shape in spherical shells was proposed.Using frozen stress photo-elastic method,experimental studies were made of the Stress Intensity Magnification Factor(M _s)for internal surface crack in pressurised thin spherical shells with ratios of wall thickness to inner diameter W/R _i=0.10,0.078,0.067.The variation of M _s with shape a/c anddepth a/W along the crack periphery was obtained.The influence of the dualcurvature of spherical shell on M _s was also studied.An empirical formula of curvature correction factor was presented.

Theoretical investigation of friction characteristics of a mud pump rubber piston was made by using inverse solution of hydrodynamic lubrication,and stable temperature field in the piston was calculated with finite element method.The friction force and temperature field of a 3NB-80 triplex pump piston were measured under actual working condition.The results of both theoretical and experimental investigation showed that the piston was in a mixedlubricating state,and extremely tiny particles in the mud could enter the piston and cylinder contact surface,resulting in abrasive wear.The friction work consumed during relative movement batween piston and cylinder not only remarkably decreased the mechanical efficiency of the pump but also caused considerable temperature rise in the piston.

The macroscopic properties of a homogeneous material can be known in advance from its microscopic test results.But macroscopic and microscopic properties are not the same for the heterogeneous formations whose macros copic nature is to be determined.In this paper,a hypothesis of the formation heterogeneity has been established on the basis of formation drillability analysis;the random character of nonhomogeneous formation drillability has been studied statistisally;the inference of the macroscopic nature has been done by means of the transfer of microscopic properties;and the macroscopic nature of heterogeneous formation drillability has been obtained.The following topics are discussed:microscopic drillability,the criterion of formation homogeneity,the range of the object studied,macroscopic and microscopic range,macroscopic homogeneity and its realization.The application of the hypothesis is discussed with an example.

In this paper heat transfer analysis of water flooding technology in cement underwater tank for storage of high pour point crude oil is described.Heat transfer process in this system is relatively complex.Based on the analysis of the temperature distribution and its variation in the oil tank,a"model of heat transfer in separate regions"is established.The temperature distribution and heat flux of the unsteady state heat transfer are simulated by a finite difference mathematical model.The apparent coefficient of conductivity k _o'of high pour point crude oil in the tank is 0.325T _i ^1/2 The"critical temperature of conductivity" of the oil T _x is 41℃.The temperature distribution and its variation with time in the tank are calculated,and the deviation of calcculated and measured temperatures at the junction points is±1℃.Thus the model can reasonably describe the heat transfer characteristics of the temperatures of the oil,sea water,oil water interface,wall of the tank and its surroundings.Mathematical simulation also gives the variation of heat fluxs of hot oil across the tank cover,tank wall and oil water interface with time.The heat flux of hot oil across the oil water interface accounts for 2.1～3.1% of the total heat flux of oil.Thus the water flooding technology in the underwater tank for storage of high pour point crude oil is practical from the view point of heat transfer.

The Baise residual basin is characterized by the fact that it is an originally big sedimentary basin,and a small residual ones it's with high maturity source bcds,low thresheld depths shallowly buried reservoirs and prolific production in geological conditions,etc.Although the basin is small,it's exploration category is wide.There are various types of reservoirs in the five structural zones of the relatively explorated Tiandong Sag,and oil bearing areas are highly overlapped and connected.The study and analysis of the Baise residual basin gives a certain guids important to the oil and gas exploration in the small Mesozoic and Cenozoic basin in southern China.

The potential of oil and gas resources in depositional type abnormally high pressure zone is good.All the preconditions for its existence are al- most possessed in the lower Tertiary formation in Tsiyang basin.The sealing character of abnormally high pressure zone and origin and migration of oil and gas are closely related.Sonic and seismic well logging data in 450 wells have been used to study the compaction and undercompaction characteristics in the Tertiary sediments.The results show that such data have an important value for the study of origin of the depositional type abnormally high pressure zone,as well as for the evaluation of oil-gas potential within such a zone.

In this paper,the seismic facies and sedimentory facies of the 3rd member of Shahejie Formation in the western Huimin Depression were studied with the data from seismic facies analysis,core analysis,and electric logging analysis.The results show that there are thirteen kinds of seismic facies in the 3rd member of Shahejie Formation,and these seismic facies represent different sedimentary environments and facies.The main types of sedimentary facies may be included in the three categories of sedimentary system,that is,a delta-deep water turbidite fan system,a delta-beach/bar system and a fan-delta system.These systems changed with the evolution of the western Huimin Depression,and are the main locations of sand deposits.In the end of this paper,the favorable oil/gas bearing areas and possible types of oil/gas traps are predicted.

The results of analysis of more than 7000 clay mineral samples from 20 oil bearing basi ns indicated that the characteristics of distribution and controlling factors are different in conventional,salt alkaline lake,coal bearing and volcanic detritus sedimantary basins.The transformation from smectite to illite and kaolinite to chlorite with depth is obvious in normal basins,and such change of clay minerals is governed domminantly by diagenetic process.High illite and chlorite and low kaolinite is the characteristics in salt alkali basins.This is governed by the condition of the aqueous medium,and typical minerals are obviously different under different condition.In coal bearing basins,the clay minerals are characterized by high kaolin ite content.In volcanic detritus basins,the smectite is widely spreaded and it is mainly governed by the source of parent material and the condition of the aqueous medium.

Based on the litholohy analysis,including the methods of thin section,scanning electronic microscope analysis,X-ray energy dispersive spectrum and electric probe analysis,X-ray diffraction analysis,cathodoluminescence analyis etc.The characteristic of sandstone reservoir in Bayanhua group in ErLian Basion has been studied,including the structure of rocks,and the type,amount and occurrence water-sensitive and acid-sensitive cement materials,some of the different measures to preventing the damage of oil-bearing formation have been proposed in this paper.

This Paper has Studied the regularity of the distribution of initial reservoir pressure.A concept of the hight of closure is suggested and a conclusion is reached that the zonal distribution of this initial pressure is governed by the hight of closure in accordance with the abnormal pressure.The relationship between the hight of closure of the reservoir and threshold depth for oil generation is studied also.The migration of hydrocarbons and the time of the formation of the reservoir is predicted.The regularity suggested in this paper is found to be useful for the exploration and development of Gaoshangpu Oil Field and may be applicable to other complex fault-blocked oil field also.

From identified oil recovery factors and the geological and development data of 64 water drive sandstone oil fields in China most part of whose recoverable reserves are recovered,formula for estimating oil recovery factor is derived by means of multivariate stepwise regression technique.Compared with other available formulae,the new one is proved to be an empirical formula with minimum error for estimating oil recovery factor.Based on an analyses of the new formula,as discussion of the main geological and development factors that influence oil recovery factor is presented in this paper also.

In tnis paper,a new model of fluid flow in an infinite multi layered reservoir is established by setting up a new form of well bore boundary condition.Furthermore,an easier handling analytical solution of pressure distrabution in such a reservoir is obtained,and the pressure draw down cuvers are presented.

This Simulator is based on Coats's "In-Situ Combustion Model",The conditions considered in the simulator are: distillation of light components,heat conduction and convection,effects of pressure and temperature on the behavior of fluids,compressibility of fluids and reservoir rocks,capillary pressure,gravity,and heat loss in the wellbore and through the overburden strata.There are direct and iterative solution techniques for selection.This simulator can be used to study multi-dimensional,three-phase,two-com-ponent steamflooding and steam huff and puff problems.

The main factors that affect drilling perameters rate and cost are bit type,bit pressure,rotary speed,hydraulic perameters,mud properties and bottom hole differential pressure,To optimize these parameters,it is necessary to establish a multiple drilling rate equation and cost equation,as well as constraints imposed by drilling technology and equipment conditions.Non-linear programming method can be used for the optimization of each bit run to achieve proper selection of individual parameters and a good match between them.However,for a whole well optimization which is a combination of a series of optimization of bit run multi-interval decision technique should be considered,and special algorithm should be introduced.

Three kinds of strength theory for anisotropic rocks are reviewed: classic Coulomb's shear strength theory,Griffith's crack theory,and empirical theory.Calculation formulas and methods are derived.A comparison of these strength theories is made with the experiments on Casper sandstones and Green River oil shales by the author during his visit to the US.Two minimums in peak strength are present at bedding angle between 0° and 90°.The failure criteria of Hoek-Brown and empirical Mohr-Coulomb are the best ones to predict the peak strength of anisotropic rocks.On account of their complexity,the author presents a new empirical criterion
σ ₁=A _1,2β ⁴+B _1,2β ³+C _1,2β ²+D _1,2β+E _1,2
which is simpler and agrees well with experimental data.