Abundant oil and gas resources in the Bohai Gulf Basin are believed to be accumulated in the relatively complex traps of different origin. There are hundreds of megastructural belts in which oil and gas are accumulated in high-yielding blocks. Due to block-faulting, unconformity and faciea chang, the petroliferous traps of different types different pay horizons form megastruc-tural oilfields which classified as follows: 1. Low buried-hill structural belt. 2. High uplift structural belt. 3. Central anticlinal belt. 4. Strucural-lithologic belt On slope. 5. Structural-lithologic belt in trough. The five types of compsite oil and gas megastructural belts mentioned abofe are distributed at specific locations in the graben and semi-graben basins. As exploration continues and with increasing accuracy of digifal seismic data, more and more composite megastructral oil and gas fields, including giant oilfield an and highly productive oil and gas fields, will be found, It is concluded that in the Bohai Gulf Basin, combination of various types of composite megastrucural oil and gas belts may result in a composite oil and gas basin, and the prospect for increasing hydrocarbon reserves and prospect for increasing hydrocarbon reserves and ptoiuetion will be very bright.

With its abundant hydrocarbon resources, thick source rocks and multiple types of reservoirs and traps, the Bohai Bay area has become a large oil region in China. The different nature of frequent horizontal motion from elevation and subsidence in the geologic past created a tectonic framework with depression and uplift alternately disposed. So far, we have paid more attention to the depressions in guest of oil, but, in the opinion of the author, the margin of the depressions where more oil and gas pools may be found will become more and more important and should be made a new objective for oil exploration in the region. The margin of the Jiyang depression at Chenjiazhuang is cited as an example, giving full description of its favourable geological conditions, difference of origin and the mechanism of its oil and gas aecumulation. It is proposed that more effort should be directed toward the search of oil pools in the drape folds, wedge-outs and basement, particularly in the wedge-outs.

With sedimentary facies as the key and the general rules of oil and gas accumulation as the basis, the author presents his views on where to find subtle oil pools of low permeability in the Yanchang Series. The paper is divided into two parts: 1)For accumulation of oil and gas, stress is laid on sedimentary facies that explains the vertical combination of source-reservoir-cap rccks and the lateral distribution of areas favourable for origination and accumulaticn of hydrccarbons; on the different oil pools formed in different facies zcnes and the relationship of the horizon of oil and gas accumulation with the lithologic properties of sandbodies and of the trapping conditions with lithology and lithofacies. 2)As to where oil is to be found, particular emphasis is laid on the delta in the eastern part of the basin and the tubidity fan in its western part where, in the opinion of the author, oil of commercial value may be found.

Through analysis of the oil pools in the Wuerhe formation in Section 8, the effects of sedimentary facies, formation texture, compaction and post-diagenetic changes on the physical properties and oil saturation of reservoirs with very low permeability there are discussed. It has been pointed that the distribution of oil and gas is controlled by the delta fans; the properties of the reservoirs are worsened by their composite modal textures; and compaction and post-diagenetic changes determine the zonation of authigenic minerals. The resulting reservoirs are primarily of secondary porosity with fine throats and very low permeability. Appraisal of oil potentials has been attempted and ways of exploiting this kind of oil field have been proposed.

The authors have studied the water-drive behavior of L pool in the Laojunmiao oil field, based on the principles pertaining to oil and water flow and in reference to the method of studying displacement curver used by petroleum engineers Tong Xianzhang, Chen Yuanqian, etc. The importance and necessity of intensifying water injection is stressed for an oil field like Laojunmiao with such a long history. Their research indicates that linear relationship exists not only between such variables as W _p, WOR, F _w and N _p, R _o, S _w, but also between and F _w. Formulas have been worked out showing the relationship of factors influencing the water drive production of L pool that may be used for predicting reservoir performance. Feasibility of this method is established by a comparative study.

Using the theory of elastic wave in porous media, a solution for the radial sound field with a local impulse acoustic source in a fluid-filled borehole surrounded by a fluid-saturated porous formation is found. A numerical evaluation of the full waveform curves of the acoustic pressure is given for different porosities and coefficients of permeability K(k/η). The effect of the permeable formation on sound propagation is discussed. The result of analysis shows that the travel time of the refracted arrival of the longitudinal wave has a linear relationship with porosity over a fairly broad range, it has nothing to do with the variations of frequencies and coefficient of permeability. This provides a theoretical basis for the travel time-porosity acoustic logging based on the time-average equation. The variation of amplitude of Stoneley wave is sensitive both to porosity and coefficient of permeability, its strong attenuation is a feature that makes it different from a homogeneous formation. This may be a useful information to acoustic logging.

The convection-diffusion equation is solved by the finite difference method in which the common ion effect is taken into consideration and tfie leakage velocity V1 is supposed to be constant. The stability and conyergence of the difference schemes have been established. The authors have developed the computer programs, made the calculations and drawn up charts for making out the effective acid penetration along the fractures as Shown in Figs. 3-6. The economic indices and errors of the charts are evaluated and the method of their application is described. The charts may also serve as useful tools for studying the mechanism and designing of fracturing and acidization in oil and gas wells.

The paper studies the heave motion of semi-submersible drilling platform acting on the normal sea wave with the linear analysis method. A computer program is worked out and applied in calculation for the South China No. 2 drilling platform for illustration. The results compare well with those from the experiment.

When there is a foam column is the annular space of a pumping oil well there will be no distinct gas—oil interface. In that case, it is difficult to apply the acoustic well-sounding(AWS)method. Based on the principle of mass balance, this paper deals with rules of. motion of the pseudo-fluid level in the annular space in the process of testing the pumping oil well. Through working out the differential equation of motion of the pseudo-fluid level in annular space,P _wbo ^KL(dL/dt)+m/k(e ^KL-1)=(Q ₁-Q ₂TZP _at/AT _at) the depth of the pseudo-fluid level in annular space during the normal operation of the pumping oil well can be determined as following: .

The theoretic correlation of the performance and construction of ttie centrifugal impeller is established by the mathematical method based on the impeller performance in dimensionless form. This can be applied to the design of the impeller sathat optimum efficiency and suctian lift of the impeller can be given.

Thermal treatment of crude oil is one of the effective means for improving the flowability of waxy crude oil at room temperature as has been proved by oru experimental studies of more than ten crude oil samples(including Daqing crude oil)and by our many year’s application in several oil pipelines. Up to now however, the mechaniam of thermal treatment process for waxy crudes has not been well studied. Although it has been recognized that the proportion of the content of paraffin wax and resinasphaltene in the crude oil isthe main cause determining its rheological properties and its thermal treatment behavior, a satisfactory quantitative explanation is still laching. In this paper, based on experimental studies of thermal treatment for two typical waxy crude oil samples and Theological measurement data, the role of composition of crude oil, such as resin-asphaltene, paraffin wax-normal Paraffin and microcrystal wax in determining the efficiency of thermal treatment is discussed. It has been proposed that the ratio of resin-as-phaltene content to normal paraffin content in the crude oil may be taken as an indicator in efficiency prediction of thermal treatment of crude oil, With 0.6～3.0 as the best range to obtain the optimum result.

Biomarkers in Tertiary shales and oils from Subei basin were analysed by gas chromatography and gas chromatographymass spectoscopy. Correlation of biomarkers-steranes, hopanes, 4-methyl steranes, gammacerane, β-carotane, isoprenoid alkanes and methyl hopanes indicates that Ef ⁴ and Ef ² shales contain abundant gammacerane and have predominance of phytane. Ef ⁴ shales are effective source-rock at depth of about 2750 to 3100m. Most Ef ² shales have abundance of β-carotane and gammacerane and higher predominace of phytane than Ef ⁴ shales, but their 4-methyl steranes content is lower. Oil from Ef ² shale and having Pr/Ph〈0.5 and higher content of β-carotane and gammacerane can be expected.

Some achievements in source rock research have been attained in recent years by using pyrolysis technique. The emphasis of this paper is given to the application of pyrolysis data in classifying organic matter and in research of maturity of source rock. A brief illustration is also given to the pyrolysis simulating test of source rock and using the test plots to evaluate quantitatively source rock and calculate primary migration quantity and migration coefficient of oil and gas.

Based on vitrinite reflectance and other index, an attempt in reconstructing paleogeotemperature pattern of Liaohe graben district has recently been conducted for evaluating the oil-generation processes. Results showed that the paleogeothermal gradient and, hence, the paleo-heat flow had been higher during earJy Eogene compared with present-day's ones and experienced a decline by the end of Eogene and rise again since Neogene. The averaged paleotemperature throughout Cz time was similar to that observed at present. Some conclusions can be made as follows: 1. The relatively high paleogeotemperature during Eogene is of great importance to the oil generation of lower strata of Sahejie group in depressions. 2. Sahejie group has been considered to be the key oil-genetic series of Cz sediments in North China Basin. In Liaohe graben district, oil-genetic epoch for Sahejie group in some deep depressions started as early as late Eogene, continuing till present day and leading to higher degree of petroleum maturation. Oil-genetic process of Dongying group is limited to the southern part of Liaohe graben. Epoch of large-scale petroleum occurrence for Dongying group must be traced back to late Neogene, the magnitude and potential of oil generation of Dongying group, however, is much more smaller than that of Sahejie group. Petroleum occurrence in Neogene strata is expected in Liaohe Gulf and seems to be impossible on land. 3. An isobath map of temperature threshold for large-scale petroleum maturation is given and its implications for predication and assessment of oil resouces are discussed.

OiJ-gas fields in carbonate area, for instance in Sichuan province, mostly relate to crevice distribution density in bedrock. This paper will illustrate how to produce a density image on the digital image processing system I~2S 101, by the use of crevice distribution data from field measurement or graphic from remote sensing image interpretation.

The offshore oil and gas pools on the continental shelf of China are characterized by their multiplicity of lithology, reservoir property and types of traps. There are sandstone oil and gas pools in structural traps and sandstone and reef oil and gas pools under great excess reservoir pressure in lithologic traps of Tertiary, oil pools in lithologically trapped volcanic rocks of Jurassic and Cretaceous; and carbonate fractured oil pools in lithostructural traps and strati-structural traps of Carboniferous, Cambrian and Ordovician. The present paper deals largely with the characteristics of log interpretation for sandstone and non-sandstone pools, laying particular emphasis on the method applied for raising the accuracy of interpretation.

Based on data from mercury injection, die casts, electron microscopic scanning, water drive experiments etc. for 50 wells, the pore structures of the different pays in the Malin oil field are classified into 5 types, for each of which a discriminant is established. Experiments show that their water drive efficiency are different from each other,those with strong in-layer interferences are low in efficiency. After regulation of the interferences, the efficiency is improved, and from 13.4 to 31.7% more of the recoverable reserve can be produced.

Average gas pool pressure is currently determined by shutting up of wells which is fraught with difficulties. Wells with super-high pressure or high flow rate can not be closed, and wells in tight pools with low permeability, to be closed for a long time, will incur heavy economic losses. At all events, shut-in of gas wells would seriously affect the producer and the consumer, and it would mean too high a cost just for taking the average formation pressure. To overcome the above, the authors have attempted to introduce a system identification method to compute the average pressure based on records of daily output of gas wells without shutting up the well. It is no doubt economical and practical.

The dimensionless IPR (Inflow performance relationship) Curves for a solution gas drive wells presented by Vogel is a very important tool in predicting productivity. At present, the use of Vogel's equation has been expanded to undersaturated reservoirs P_b) and water producing wells in water drive reservoirs. But Vogel's equation can be only used for an "ideal" well (a well without any negative or positive skin factor) and in a stage of primary production. For real wells (damaged or stimulated wells), Standing has developed a modified form to Vogel's equation and presented a set of dimensionless IPR Curves for different flow efficiencies. Richardson and Shaw presented another modified form of Vogel's equation with a parameter V replacing the constant coefficient in Vogel's equation by taking the degree of recovery into consideration. But they do not give a method to determine the value of V. A general formula of the dimensionless IPR Curves is formulated in this paper by combining the above 3 formula together and is linearized against the bottom hole flowing pressure. A method of determining the parameter V is presented, thus the formula can be solved easily and reasonably giving a practical application to the formula. Two examples presented in this paper illustrate that this formula can be used to determine both the maximum productivity and the production rates of a well under different bottom hole flowing pressures.

The mechanism of microemulsion is studied with particular emphasis on the effect of molecular weight, structure and concentration of hydrocarbons are inclusive of the fatty hydrocarbons from C ₆ to C ₂₃ and some aromatic hydrocarbons. The areas of microemulsion formation as well as the maximun water content of O/W microemulsion are found. Some rules are worked out as theoretical discussions have been attempted, which are belived to be of practical importance to tertiary oil recovery.

An incomplete Cholesky-conjugate gradient method is used to solve the pressure equation of two phase bi-dimension model. Computation shows that the method converges rapidly, it has no need of accelerated parameter and is insensitive to the variation of the calculating parameoers. Compared with the line successive overrelaxation method, the speed of computation has increased by 0.5 to 27.7 times. By using the new method, the two phase bi-dimension model is considerably more efficient, adaptable and reliable.

A Fault Tree of Yu Men Tubing pump is set up and the pump is analyzed for reliability based on the Fault Tree Analysis Theory. An imaginal manual of supervision and maintenance is provided for the technical personnel in production and mintenance to help them in pump failure judgment and handling, pointing out at the same time the direction of improbing the design of this kind of pump.

The paper deals with the optimum design of mast sturcture with givenpti structural arrangemant. The objective is to minimize economic quota of the mast structure. The stress, displacement, member size, local buckling and system buckling constraints of the structure are taken into account. All practical loads on the mast structure such as the wind load, the dead load and the hook load are considered. Two existing mast structures are computed with the planned program and compared with the orignal design.

The choice of optimal parameters for design of pendulum bottomhole assembly with double stabilizers used in vertical hole with very small deflection angle is discussed, based on the continuous beam theory. A design of flexible assembly with double stabilizers(i. e., with a flexible drilling stem between the two stabilizers) is achieved which has the greatest side force that increases with drilling load for deflection prevention. Another design of rigid assembly with double stabilizers(i. e., with a rigid drilling stem between the two stabilizers) is also sought. The new design gives a side force 40～60% higher that of the conventional.

Technology of pipeline transportation of viscous waxy crude oil at home and abroad is reviewed and the trend of development of a unique transportation system to meet the specific need in China is dealt with at some length. It is pointed out that sophistication and diversification are the two main trends of development in oil transportation technology and that the introduction of chemical additives is in vogue worldwide. The author has proposed the key task and some priority topics of research relative to the transportation of heavy crudes with high viscosity and pour point in China.

The saturated hydrocarbon of crude oil in the Western Depression,Liaohe Basin have been analyzed By computerized GC-MS.The hopanes,regular steranes,diasteranes,specifically,25-norhopanes were identified.Heavy biodegradation results in destruction of regular steranes and transformation of regular hopanes to 25-norhopanes.Diasteranes and 25-norhopanes survive heavy biodegradation and they can be used as source fingerprints for biodegraded crudes.The existence of the diasteranes and 25-norhopanes in the "thick oil" shows that the biodegradation plays important part in origin of the "thick oil".

The kinetics of thermal degradation of source rock kerogen is studied by thermal gravity analysis.Models of source rock deposited in salt lake environment of the Dongpu depression is constructed for the purpose.Parameters of the kinetics of thermal degradation for kerogen in source rocks buried at different depth are determined,and method of computing oil and gas derived based on the model is proposed.

The exploration practice in the Beijing-Tianjin area shows that the key point of improving seismic interpretation level in a complex district lies in the high accuracy of seismic work,extraction of available seismic information and the use of the comprehensive interpretation method basing on bo th structure interpretation and seismic stratigraphy.This paper presents the geological interpretation results of analysing the Third member of Shahejie Formation in Beijing-Tianjin Depression by using the method stated above.It describes the seismic facies,sedimentary facies as well as the generation,accumulation and distribution of hydrocarbons,and points out that the lower part of the member is a subaqueous fan and point bar deposit,while the middle part is a fan-delta deposit.According to the thermo-evolution-profile and TTI estimated,it is assumed that the lower part of the member is source rocks with sandstone development and is also a very good reservoir rocks because of having two sets of source rock reservoir and seal rock.Having structures such as Jiuzhou anticline and its down dip and Liuquan fault structure,it is favourable for hydrocarbon accumulation.

Basins of the west Daxinganling have complicated structures frame-works that a central uplift is sandwiched by two downwarps.Supposing the uplift to be an axis,there exists an opposite migration of a group of step fault blocks which have opposite dips,this migration prompted the uprising and the movement of the sedimentary center from the uplift to both sides.Therefore,the grabens near the uplift were formed earlier and have more complete history of development,larger scales,and a better conditions for oil and gas generation than the further ones.At last,we discussed the effect of the slow uprising of Daxinganling upon the basin conditions of oil generation and reservation,then pointed out that the fault grabens west of the uplift is the most promising area.

It is a correct argument that Huayingshan fault zone is a fundamental fault.The zone can be horizontally divided into three distinct parts,i.e.central,southern and northern parts.The central part,known as Xishan-Huaying-shan part,is the main one,and the major fault of the Xishan structure penetrates through the cap rock and extends into the basement.In the belly of the west side of the Huayingshan fault zone,because of the extrusion of the fault zone,many hidden faults and structures have been formed,thus the accumulation condition of oil and gas has been improved.In the east side of the Huayingshan fault zone,the structure moderately folded has better conditions for the accumulation and preservation of oil and gas.Pore,cave and fracture are well developed due to the frequent movement of the Huayingshan fault zone,resulting in an improved accumulation condition of oil and gas.

Water injection for maintenance of reservoir pressure has been employed for 25 years in a conglomerate reservoir of Karamay field.Because of waterflooding the reservoir remains in flow production and the current recovery ratio is close to 47%.The estimated ultimate recovery ratio may reach 45%.Experiences in adjustment of injection-production pattern,means of pressure maintenance and control of injection and withdrawal rate are presented in this paper.

The dynamic system of sandstone oil field using waterinjection development is a non-steady random system which varies with time.A prediction method of oil field performance by the use of system analysis is presented.A case history of D oilfield is exampled to demonstrate the practical value of system analysis for performance prediction of oil field.

A new type-curve is presented for analyzing pressure interference in double porosity system.This type-curve is obtained with both analytic method and difference method giving the same results.Characteristic of pressure interference is discussed and method of interpretation is proposed based on the type-curve.Data from the oil field are interpreted with the curves for illustration.

Based on the behaviour of North China Oil Field,a three phase model of oil,gas and water coning has been developed.The model is used for analysis of Su Qiao oilfield with gas cap and oil ring.A compariston between the different development programmes of this sort of fields is made and factors of influence on the development are calculated.The model played a good part in development of the oil field.

The formula for culcalation of stress and deformation of flexible axle under spiral bending is derived applying the Laplace transform.From actual calculation,it has been found that the main cause of the short life of flexible axle is its inadequate strength.Based on this,we may make improvement to prolong the life of screw drill tool and screw pump.

Five different shapes of fillet weld joint models are listed,using flank angle as the main controlling factor,The states of stress of these models are obtained by applying the elasto-plastic finite element method.The fatigue life of the surface cracks of the weld toe and the central part of the welding bead are calculated.A comparative study of the results obtained is made with those seen in relevant literature,and some conclusions useful to the designing of fillet weld joints of cylindrical oil storage tank,are derived.