The migration and accumulation process of natural gas included the whole geologi cal processes happened after the natural gas expelled from source rock, such as the secondary migration through permeable bed, faults and unconformity surface, the charging to and accumulation in traps and the dissipation through caprock. T he effectiveness of this process could be expressed quantitatively by the net ve locity of natural gas accumulation, i.e. the difference between velocities of th e gas charging into trap and gas losing through coprock in the accumulation and preservation period of a gas accumulation. The natural gas migration and accumul ation process could be classified into high, medium and low effectiveness accord ing to its net velocity of natural gas accumulation. The studies of some typical gas fields with high and low net velocities and the statistic analysis of main large and medium sized gas fields in China had shown that the effectiveness of n atural gas migration and accumulation process was mainly controlled by the diffe rence of excess pressures between source and reservoir, the type and the conduct ibility of conduit system, and the thickness and displacement pressure of the c aprock of a reservoir. In the geological environment of main gas-prone basin in China, the migration and accumulation process of natural gas with high and medi um effectiveness would take place in the areas with the difference of excess pre ssures between source and reservoir over 25 MPa, the thickness of caprock over 4 0 m, the displace pressure of caprock over 15MPa, and with converging conduit sy stem. The above parameters could be used in the prediction of high effective gas field distribution in a basin.
There are three sets of high quality gas source rocks in Tarim Basin, So that it is abundant in generating gas. As the different exploration extent of each stru ctural unit in Trim Basin, and recently there are much of exploration accomplish ment, it is largely necessary to assess the oil and gas resource quantity of tar im basin renewal in case of adopting the new idea, new method and adequately co nsidering the recovery and economic efficiency of resources. The latest result o f oil and gas resource assessment is that the total resource is 123.37 million t ons equivalent, which oil is 59.94 million tons and gas is 79 599.43 million cub es. The gas proved extent of Tarim is so primarily recently that its exploration potential is much more immense. The finding research shows that kuche depressio n is main exploration zone recently; Taxinan depression is the next exploration zone, and Tadong depression is exploration zone later.
Rare is a special deep rock (muddy dolomite, dolomite mudstone, dolomite)-fract ured oil reservoir at Qingxi Oil Field in Jiuxi Basin. In this reservoir which has lower porosity and permeability, fracture becomes major storable-permeable spaces and forms a good “autochthonous source and autochthonous reservoir” so urce-reservoir-seal assemblage. Furthermore, there is a great difference in we lls production, acidization effec,etc. And the fractured formation factors whi ch include structures, lithological characters, diageneses are studied. This stu dy have certain theoretical meanings and practical values.
Principium and method of ascertaining oil-gas pools age with inclusion are intr oduced. Based on homogenization temperature test of inclusion, resuming of hot h istory and hydrocarbon producing history, the infusing degrees and infusing time of Tiandong-19 well, Mo-13 well and Pingchang-1 well are investigated accor ding to inclusion. There are three periods of oil-gas to infuse in Tiandong-19 well and Mo-13 well. Infusing time of three periods of oil-gas in Tiandong-1 9 well are respectively early Trias, early midlle Jurassic and upper midlle Jura ssic. Infusing time of three periods of oil-gas in Mo-13 well are respectively early-midlle Jurassic, midlle-upper Jurassic and upper Cretaceous- early Ter tiary. There are two periods of oil-gas to infuse in Pingchang-1 well. Infusin g time of two periods of oil-gas in Pingchang-1 well are respectively midlle- upper Jurassic and upper Jurassic-early Tertiary. Finally, some questions to be regarded about ascertaining oil-gas pools age with Inclusion are point out.
The conditions of reservoir formation are studied, Oil ＆ gas exploration potent ial are analysed, and the best prospecting plays are evaluated in Daban town sub -depression of Chaiwopu depression under the techniques of effective source roc k theory, reservoir evaluation and reformed basin modeling. It is demonstrated t hat the main source rock in Daban town sub-depression is Upper Permian which be longs to good to intermediate source rock, and has definite resources potential; the main reservoir is also Upper Permian with rather poor petrophysical propert ies, which，in Daban town sub-depression, is a good gas-bearing reservoir as a whole and the main exploration target for hydrocarbon; there are four types of h ydrocarbon reservoirs including structural reservoir, stratigraphic reservoir, l ithologic reservoir, and complex reservoir, and two patterns of reservoir format ion, i.e., self source-lateral expulsion of hydrocarbon, and external source-v ertical expulsion of hydrocarbon; the best plays are Chaiyang fault-fold belt a nd Sangeshan thrust-fault belt.
Sequence stratigraphy frame work controlled the foundation of reservoir and rese r ve distribution. There is an obvious difference in hydrocarbon distribution in d ifferent system tract and different sedimentary sets, but reserves in low system tract play the most important role. In the sequence stratigraphy frame work, th e role and method for each step of exploration is also different from resource pr ediction based on the resource rock evaluation in the initial exploration stage to reservoir discovery based on the trap and reservoir body characterization in the exploration and to remaining reservoir find in the mature field. And in the frame work of baselevel, the distribution of reserve is also not homogeneous. Th e sand at the low location of the baselevel is wide spread and often with large amount of reserves, while sand at the high location is limited and with a few re serves. And also the high location is often become the potitial reserve increasi ng place for its limited sand distribution.
In order to generally evaluate the effect of temperature, effective stress and w ater-saturate to the permeability of tight sandstone, it measured the permeabil ity of tight sandstone at various conditions. It qualitatively analyzed the effe ct of temperature, effective stress and water-saturate to the permeability of t ight sandstone and relationship of them. The experimental result shows that temp erature has greater effect on permeability at lower effective stress level but d ecreases with the increasing of effective stress. Higher of water saturation of sandstone, greater effect of temperature on permeability. The relationship betwe en permeability and effective stress is approximatively exponent but is necessar y to correct at high temperature and water-saturate level. Water-saturate is o ne of key factors that have great effect on permeability and the permeability gr eatly decreases when effective stress increased.
The matrix with low porosity and permeability in the carbonate reservoir in Ying maili area can not provide effective reservoir space, but because of the croppin g out long time or many times, they suffer leach, denudation and karsification n ear surface, so in carbonate the fracture, solution hole and solution cave have developed. They form the paleoweathering crust reservoir. And they mainly distri bute the weathering crust belt beneath the superface of the burial hill. We have worked out the oil and gas coming from the great of lake faces source in Kuche depression pass through the migration pathway which is the unconformity surface of paleontology and Mesozoic group and the carrier bed between the Paleogene Sys tem and cretaceous or the Jurassic and Triassic sandstone. At last they arrive t he carbonate paleoweathering crust reservoir and accumulate beneath the cretaceo us Kapushaliang mudstone.
Through the deposition layering of Chang 1 reservior in Ding 31 wel l area of Youfangzhuang oil field,in terms of the character parameter of rock ph ysics,adopted the method of direct clustering analysis, A, B, C, D four kinds of flow units are classified in Chang 1 reservior of this area, and the geological meaning of them are. analysised. Study results show,type A has strong percolati ng and storing ability, high picking degree, low saturation degree of residual o il; type B has rather strong percolating and storing ability,rather high picking degree, it's the main productive formation of research area; type C has commonl y percolating and storing ability, rather low picking degree, comparatively high saturation degree of residual oil; type D has poor percolating and storing abil ity, is a non-produce formation,poor effect of expoitation.
After discoursing upon the natural gas strata distribution，explore area distrib ution, quality characteristics and coalbed methane distribution, the authors an alysis natural gas resource status and exploration of Sichuan basin. The authors point out that there has a lot of natural gas and coalbed methane in Sichuan ba sin，but the exploration degree is lower, in the strata and exploration areas, t here still have exploration potential, especially，the coalbed methane explorati on and development. The Sichuan economics will increase in the stable situation, and the energy source consumption will also increase. In order to guarantee the natural gas supply ability can support such big energy consumption and the Sich uan economics increase in the coming years, some sustainable development conside rations of natural gas industry in Sichuan basin have been advanced in the paper.
Ake-1 is a commercial gas pool that has made great breakthrough for oil & gas e xploration in the Kashi Sag of the Southwestern Depression, Tarim Basin. On the basis of the component content of natural gas, carbon isotope ratios of methane and ethane, and isotope composition of rare gas, the geochemical characteristics of Ake-1 gas pool were studied in this paper. Natural gas of Ake-1 gas pool b elongs to the typical dry gas. It has predominance methane (80%～91%), low cont ent heavy hydrocarbon (<0.3%) and high content non-hydrocarbon (generally about 20%). There are heavy carbon isotope ratios of methane (-25.2‰～-24.7‰) and e thane (-21.9‰～-21.1‰), and relatively high isotope ratios of rare gases (3He/4He 8.34×10-7, 40Ar/36Ar 1 438). Combined with the geological background, the maturity and source of natural gas from Ake-1 gas pool were discussed by using the results of carbon isotope kine tic modelling. This provided a new thought for evaluating the origin of natural gas. It's suggested that natural gas of Ake-1 gas pool was the evolution produc t of over-matured source Rocks, with the maturity of 2.0%～3.6% RO, and belonged to the mixed gas.
This paper analyzed samples selected from 5 sinian sections developed Molar Toot h carbonates by fluorescent spectroscopic analysis in the Ji-Liao area. These s amples contain 9 kinds lithology and 4 types of Micro-facies developed in the s tudied area and reflected roundly the geochemical features of carbonates and the ir environment significance. Based on the correlation analysis for the testing r esult, systemically discusses the correlativity between oxides of Carbonates, th at is, SiO2, Al2O3and P2O5 is positive correlativ ity with K2O, TFe2O3and TiO2, but is negative with Ca; Na2O is lightly and positively correlated with MgO, Sr and Ba and negative ly correlated with Ca too; Sr and Ba behave positive correlativity with Al2O3, P2O5, K2O, TiO2, moreover,Ba is positively s orrelated with FeO, while Mn is positively correlated with FeO only. The paper a nalyzed the relationship between the contents of oxides and sedimentary environm ent, especially make clear some phenomenon, such as contents of the terrigenous components (for example, K2O) increase, the values of Ca/Mg decline and the content of Sr or the ratio of Sr/Ca adds from the intertidal zone to the deepe r ramp, which indicates the special geochemical environment.
A study on surface and down-hole geochemical exploration techniques has been ca rried out in the Northern Tarim basin, and large scales of surface and down-hoe geochemical explorations have been conducted in this area since the middle of t he 1980s. Oil and gas geochemical exploration results of Tarim Basin accumulated in the past 20 years indicate that there exist obvious geochemical anomalies ov er the known oil/gas reservoirs, and the anomaly patterns are mainly ring-like halos or half rings. Geochemcal exploration in the unknown areas also achieved g ood effects in the aspects of prediction of the prospects, delineation of geoche mical anomalies and evaluation of geochemical evaluation. Quite a lot of geochem ical anomalies delineated in the unknown area have been verified with commercial oil/gas flows by drillings. Down-hole geochemical exploration shows good explo ration results in the aspects of in-situ prediction and identification of oil/g as show layers.
IN a recent on-going development project carried out in Dawanqi shallow oil fie ld, geochemical exploration has been applied, which involves in situ determinati on of free light hydrocarbons (C1-C5)in soil air and absorbed hydrocarbons i n soil samples by means of a thermal release procedure.Due to a high sampling de nsity and a reasonable interpretation of the geochemical data, as good as 94.5% of drilling succeed rate was achieved which leads to a considerable increase of oil out put. It is shown that geochemical methods are highly applicable in the o n-going development for shallow oil fields.
The characteristic fingerprints of three-dimensional fluorescence spectra in we ll-debris and soil samples are described. Determination of well debris and near -surface soil show that the fingerprints not only indicate migration and accumu lation of oil and gas, but also efficiently identify existence of oil and bas fo rmation, and what is more, it can distinguish oil from gas. Therefore, the techn ology of three-dimensional fluorescence spectra fingerprints is a kind of effec tive means in the re-checking of oil wells and the geochemical exploration of o il and gas.
Using two different kinds of methods, i.e thermal alteration index of spore & po llen in palaeontology, orgnic type and the ratio of methane heavy hydrocarbon in acis decomposed gas of in-well chemical exploration, the souce rocks of Cretac eous System in well DB-6 which locates at the southerm part of Songliao basin a re evaluated. According to the study of spore & pollen, the souce rocks of Mings hui formation, Sifangtai formation, Nenjiang formation and Qingshankou formation are mature and have good organic type for oil generating. The 4~5 mbmbers of Ne njiang formation are mature with relatively bad orgnic type, and it is of gas ge nerating tendency. Yaojia formation are high mature with bad organic type, and i t is of gas generating tendency. According to the data of in-well chamical expl oration, the types of souce rock are judged by the ratio of methane to heavy hyd rocarbon in acid decomposed gas, and the results are the same as that from therm al alteration index of spore & pollen and organic type, i.e. the source rocks in 2 member of Nenjiang formation and Qingshankou formation are of relatively high quality.
Progresses on the measuremental techniques corresponding to organic matters, inorganic matters and microbial examination for the samples of gas-oil chemical reconnaissance were reviewed in the paper. It was also pointedout the main problems existed, and then the further research trends on the new approches of sample pretreatment, the extractive extractive technique for trace gas-oil information and microbial detection were discussed.
The basic principle, the major microbial indicators and the typical anomaly patt erns of the surface microbial oil and gas exploration technique are introduced, the historical development course and the current application situation of this technique are generally summarized, and the exploration value of this technique in both undrilled areas and mature producing fields is analyzed through several exploration examples. In undrilled areas, the surface microbial oil and gas expl oration technique can screen out favorable prospects for oil and gas, and can ev aluate the oil and gas potential of seismic structures, and has long been a reli able tool to determine whether a seismic structure is charged of not. In mature producing fields, this technique can map the possible distribution patterns of t he underground oil-gas- bearing reservoirs through microbial reservoir charac terization evaluation, thus can play an import role in the re-exploration of ma ture oil and gas areas.
The oil and gas of borehole geochemistry exploration is the new method for forecasting and evaluation the oil and gas of the reservoir. Analysis of paucity hydrocarbon: take the adsorption silk adsorb hydrocarbon of rock sample . according to the character of hydrocarbon structure and the item of the gas of jar tip and the hydrocarbon of acid analysis and fluorescence .Discovered the oil-gas reservoir and differentiate the oil-gas composing characteristic.
In the low-permeability gas reservoirs discovered in our country, the most are the Ⅲ reservoirs. Sulige is a oversize gas reservoir which has over 5,000 a hun dred million reserves, the reserves of the Ⅲ reservoirs take up 40% of it's tot al reserves. Can the reserves be produced? How much is the length of producing? How much is the contribution to gas productivity? These are the problems that ar e urgent to be solved in gas field developing. It affects the productivity plan of gas field and the decision-making of investment seriously. In this paper, a gas well practical data in Sulige gas field are used to found a geological model of single well, and the producing ability of the Ⅲ reservoirs in low-permeabi lity gas reservoir and the influence factors are simulated entirely. The produci ng ability of the Ⅲ reservoirs in different recovery moment and the contributio n to productivity are analyzed in detail. The Results of the research indicates that many factors are relative to the producing ability of the Ⅲ reservoirs in low-permeability gas reservoir, such as: it's permeability and gas saturation a nd reservoir stress sensitivity, the permeability near the well, the preliminary allocation of gas well, intermittent production or not, and so on. In the paper , the effective measure and the corresponding development strategy to improve th e length of reserves producing are mentioned. It has the important instructional meaning to the productivity planning and the plan design of low-permeability g as reservoir.
Buried hill Y5 gas reservoir with bottom water has a high CO2 content of 92.88 %~99.80%, in which structural fractures and solution cavities are relatively dev eloped. On the basis of testing data of three times, this paper analyzes well te sting characteristics of the reservoir. 1) Through comparison between observatio n results of flowing pressure & temperature gradients and lab analysis, it could be seen that phase behavior of flowing CO2column has obvious difference w ith that of static one. Under the circumstances of above critical conditions of CO2, high-density fluid, including liquid water, gaseous CO2 and hydrates, has been appearing in the well bore. Liquid state CO2 begins to be formed at t he depth of 265.80 m or so, when critical conditions are reached. Influenced by those, pressure loss in well bore is severe comparatively. 2) Per-well gas rate is relatively low and the base of stable production is obviously poor. And, 3) Commingled production of two layers could remarkably reduce gas deliverability. Finally, reasonable initial per-well gas rate are discussed from many aspects, and major measures to increase gas rate are put forward, that is, reducing pollu tion through adoption of acidizing reservoir to dissolve blockage and improve ca pability of gas flow carrying liquid by introduction of slim tubing to increase velocity of flow in the well bore.
近年来,近海多波多分量(一般称为四分量)地震技术发展很快,相继取得了较成功的应用和令人满意的勘探效果。成功的一个主要原因是采集技术(OBC技术)已经基本成熟,能够在近海得到质量较高的地震数据。海上多波多分量地震采集就是在海底应用三分量速度检波器测量速度场的X分量、Y分量和Z分量,并用水听器测量应力场。海上多波多分量地震采集系统主要包括记录子系统、震源子系统、电缆子系统、声学子系统、综合导航子系统和质控子系统。多波采集作业方式以双船(震源船和记录船)、双边放炮作业为主,双船的控制主要由数据连接系统实现。
There are extraordinary active thermal fluids in the mud diapir zone of central depression in Yinggehai basin. Great achievements have been attained presently o n the shallow natural gas exploration in mud diapir zone on the base of the regu larity of gas migration and accumulation controlled by the upward-intrusion of thermal fluid. So far the most GIP is discovered in the shallow exploration area . Changnan Block is one of the areas where are most active upward-intrusion of thermal fluids in the middle-south of the mud diapir zone. It has typical chara cters in seismic sections. In this article, the geophysical characters and uniqu e origin causes of the thermal fluids action are revealed by studing on the prof ile and the plane characters of the mud diapir-thermal fluid seismic smear zone geophysically.
This paper is a summary of researches and practices for 2D seismic exploration in China Southern mountainous districts. Based on the detailed review of seismic and geological conditions, this paper analyzed the difficulties in seismic data acquisitions. Furthermore, an interference wave investigation technique, a flexible survey layouts method and seismic wave excitation are proposed. Better results have been obtained in seismic data acquisition.
The thickness of the turbidite sand-gravel stone reservoir of Tertiary Es3 in complicated fault block reservoir Jin 612, varies largely and distributes u nevenly, its heterogeneity is very strong both laterally and lengthwise. During the oilfield development period，the task of the geologists is to forecast the reservoir properties and its description parameters，to make the reservoir distr ibution and its heterogeneity clear and then decrease the risk of deployment. It 's difficult to fulfill accurately the fine structure near the well and not easy to forecast the distribution of lithology and the lateral variation of the rese rvoir by using routine seismic profile. This paper presents the VSP technology p rinciple, data collection and interpretation in both zero and non-zero offset distance sides. Taking Jin 612-22-36 and Jin 612-8-20 two wells as evidence, the paper presents the application of the VSP data and its effect. This approac h increases the resolution factor of the three dimensional seismic data and thus links the seismic profile and geological horizon, positions the Western and Nor thern faults of block Jin 612 accurately, makes the reservoir distribution both in Northern and Northwestern clear. All these results are helpful to the fault b lock expansion and the well deployment.
As a kind of ripe seismic analysis Technique, AVO has been applied to oil and gas exploration, and great results has been made. AVO also can be used to Natural gas hydrate, a new kind of energy, survey research. AVO simulation of BSR and inner structure of sediments bearing hydrates has been carried out using AVO technique. However, Hydrates are different from oil and natural gas, some problems must be concerned.
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