In the beginning of 21st century, exploration of natural gas has been developing with high speed in China. Increase of proven reserves and new large gas fieldshas been explored more and more. The area of new natural gas proven reserves is mainly located in 5 gas provinces, and the key roles of those are build-up of newprospective areas and deeply exploration around the large gas fields. The 5 gas provinces will be main territories of natural gas exploration in the early 21st century.
Exploration in deep-water hydrocarbon has a fast increase in the world. The water depth for drilling well arrived to 3 050 min 2004. Three giant China oil companies (CNPC, CNOOC, SINOPEC) launch the oil exploration in the deep water region of the South China Sea (SCS). According tothe discoveries in the world, all of them are distributed in the passive continental margin. Three giant sedimentary sequences have been deposited in the basin,those are prorifting, rifting and breakup sedimentary sequences. Source rocks are lacustrine and shore facies, as well as after-rifting drift marine limestoneand shale. The reservoirs are characterized by the deep-water turbidite sandstones, and rifting sandstone. The hydrocarbon reservoirs preserved in the varioustrap in the rifting basin, and some unique deep-water turbidite sandstone, and diapir structures.By the geological analysis of the two deep water regions in the SCS, the same petroleum geological features and richful hydrocarbon exist in the SCS.
Based on the study of the formation mechanism and conditions of abnormal porefluid pressure. The affect of abnormal pore fluid pressure to the seal of gas in each phase was deeply studied. Abnormal pore fluid pressure was considered notto seal gas in free phase directly, it can play an indirect role in sealing gas in free phase through increase of capillary seal ability of mudstone caprock.Abnormal pore fluid pressure was considered not also to seal gas in water-dissolving phase directly, it can play an indirect role in sealing gas in water-dissolving phase through increase of adsorptive fore of mudstone caprock. Abnormal pore fluid pressure was considered not to seal gas in diffusion phasedirectly,it can play an indirect role in sealing gas in diffusion phase through the formation of abnormal gas-bearing concentration of mudstone caprock.
Because the geomechanical environment in the northeastern area of Sichuan basin is complicated and unstable, the combination of structural features formed thereis specific, and exceptionally the planar change of structural features is much more specific. All kinds of structural styles formed there is not formed in onestage of movement but in many stages of movements. This paper summarizes the basic features and the formation and development rule of the structural styles instudy area on the basis of analyzing the transverse structural styles and the sectional structural styles.
In the Early Cambrian, the southern margin of Daba Mt. and Micang Mt. located at the northern margin of Upper Yangze Platform. The reefs and banks whichdeveloped at the margin of carbonate platform, distributed in the area of Nanzheng,Xixiang, Zhengba, Ziyang of Sanxi province and nanjiang of Sichuan.The reefs and banks include cyanobacteria-Archaeocyathus reefs, thrombolite micrite mounds, oncolite biostromes and bioclasic & oolitic banks.The reef building organisms have Archaeocyathus, cyanobacteria. And the biomarks analyses are also proved that the microbial materials are in mud mounds.The reef living organisms have brachiopoda, trilobite, crinoida, sponge. Because of the sea-level change and paleogeographic environment control, the reefs and banks show the cycle sequence, and migrate upper in sequence from the west to the east.
Based on the study of Carboniferous reservoir characteristics in Sanchaping buried structure, it is found that the reservoir space is dominated with dissolvedpore as well as intercrystalline pore and the reservoir belongs to fractured-porous one. It is vertically dominated with the Type Ⅲ reservoir and it is locallydistributed with the Type Ⅱ reservoir(there are two relatively high porosity zones). The major controlling factors of reservoir are dissolution and tectoniceffect. With the help of improved curvature and seismic method, the comprehensive prediction for Carboniferous reservoir was made. The prediction results show that the early-thought area where there is not Carboniferous reservoir does not exist and the favourable reservoir area is distributed with local patch or strip where the next exploration and drilling well deployment are located.
The characteristics of hydrocarbon migration and accumulation system in carbonate formation, eastern Chongqing can be traced from these factors: disturbance ofmulti-tectonics, lithologic character of carbonate formation and existence of abnormal pressure. Besides of permeable formations, plane of unconformity andframework of faults, karst cave is another important type of migration pathway according to the analysis of paleo-karst cave, diagenesis and fault. Buoyancy andhydropower from release of overpressure drive the fluids to migrate in formation. The relationships between hydrocarbon migration stages and tectonic movementsbased on the data of burial history of well and fluid inclusions and the changes of fluid potential in all migration periods indicate that: Under the force of buoyancy and hydropower, hydrocarbon in Silurian and Permian migrated extensively in late Triassic and middle Jurassic. Silurian hydrocarbon was injected intoCarboniferous again when late Yanshan extension movement took place in the end of late Cretaceous. And its accumulation place is Shizhu and other doming zones.Hydrocarbon sourced from Permian formed reservoir in itself. But hydrocarbon reservoir from Triassic destroyed due to the opened framework of faults.
Through analyzing shan 2 number sandbody in the middle-east of Ordos basin, it is thought that the east-west zoning of shan 2 number sandbody is controlled byoriginal differentiation and hydrodynamic force strength. The quartz sandstoneformed by the strong hydrodynamic force has the characteristics of one-high andthree-low that is high quartz, low martix, low-soft lithic-fragment and fewfeldspar in the wastern sand belt, Yulin. But the litharenite formed by the weakhydrodynamic force is different from the quartz sandstone in the eastern sand belt,Shenmu. It has the three-high property of high martix, high-soft lithic-fragment and high feldspar.At the same time the evolution from late Paleozoic islooked upon as main line. It is studied by the applied of the sequencestratigraphy that the distribution of depositional system and feature of basin filling in the isochron stratigraphic framework. It is thought that shan 2 period is a suit of river-delta-lake depositional system. Its sedimentary evolution is represented as the long expanding process of lake and northward recession of alluvial system. Three suits of superposition sandbody that are the retrogressive deposit northward are formed by three periods of lake process in this age. The delta front facies tract is the favorable exploration prospect area in all suits of sandbody.
Upper Paleozoic of Ordos basin is prolific in unconventional natural gas. In thecentral-eastern basin, coal seam in Upper Paleozoic are characterized by thiclayers，high vitrinite content and middle-high coal rank. Influenced by the structural evolution and stress field, cleats are well developed within coal seam andthus the reservoir permeability is high. With the high absorption intensity,stable hydrodynamic field and coal-seam floor and roof, favorable coalbed gas systemis formed. Abundant gas source rocks are develop in the central basin. Compaction process of sandstones is prior to the mass gas expulsion period of gas sourcerocks. Structure movement and hydrodynamics after the formation of reservoirs are relatively stable. Vast deep basin gas traps are formed in combination with these reservoir-forming conditions. Researches on reservoir-forming indicate that areas enriched with coalbed gas in Upper Paleozoic are important gas supplements to deep basin gas traps.
The flower gas pool of the Shiqianfeng formation has become the new exploration area because of it's the less exploration cost.The charactics of the flower gas pool is the highter scaling factor of the lighter sergment, the lower puress of the pool and the coefficient of the pool pressure.At the same time, the flower gas pool was controlled by sandstone reservoir. the flower gas pool of Shiqianfeng formation is the Secondary gas pool.During the Yanshan movement, the formation in eastern Ordos basin was been lifted and eroded，the surpressure lay out the down formation such as the Shihezi formation and Shanxi formation was been released.when the surpressure being released, aboundance of microfissure was been made in the mud which was made the well regional cover，and became the mainly pathway of the gas from source rock to the Shiqianfeng sandstone reservoirs.
By means of the data of drilling, outcrop, logging and high resolution seismal section, combining the conclusion that many scholars have studied on the evolution of tectonics and deposition, using the principles of the high resolution sequence stratigraphy, the article analyzed the characters of the evolution of tectonics in Baoshan basin of the west in Yunnan province, and divided high resolutionstrata sequences. During the evolution of Baoshan basin, it was being in long-lasting extension or in short-dated extrusion because of Xishan tectogenesis, leading to the gradual subsidence, or the sectional and short-term rising, and the fluctuation of the base level inducing the relative changes of accommodation. So the Tertiary strata in Baoshan basin can be recognized three grade Ⅲ-sequence sets which coincide with the evolution stages of basin. Eight grade Ⅲ-sequences can be distinguished in theirs. Based on the principles of base-level cycles and combining the conclusions studied by many scholars on the history of Baoshan Basin's extension and fluctuation, the author takes super-long-term base-level as a period and long-term base-level as a genetic strigraphic unit to discuss controlling function ofsequence charactersitics, stacking pattern, sedimentary system and filling and evolution successions of basin by the change of base-level cycle. It is studiedthat the relation of the basin-level cycle with the belt of sedimentary facies, and Baoshan Basin's high resolution sequence sets is divided.
The West Hollow has been one of the main producing regions of oil gas of Liaohe oil field all the time. Since the seventies, There have already found more than ten oil fields, such as, Huanxiling, Shuguang, Lengjiabao.etc. It has already entered high ripe exploration phase at present. This existing basically. The remaining is mostly the rock oil gas reservoir, leading to make little progress in exploring recent years. Therefore, in this study, begin with study sandstone deposit characteristic, using layers of preface stratigraphy, earthquake attribute discern sand body technological method, strengthening multi-disciplinary organic cooperation, establishing constructed and the rock as equally important in looking for the oil idea,summarizing the law of old liberated area, in order to predicted the distribute of sandstone. This is very important in carrying on the rock oil reservoir distribute characteristic and exploration target optimum.
Lithofacies unit is the single oil sandbody which is more finer than microlayers, which mostly reflects geological characteristic of oil reservoir. Subdivision and contrast are done to meet the demand of tapping remaining oil during middle and later periods of oilfield development. Taking Kexia formation in Wu 2 xi of Karamay oilfield as an example, joint-well sedimentary profile is made according to principle of isochronous contrast and utilizing logging curves and core data, contrast of layers is fulfilled based on contrast of standard well, sedimentary cycle, microfacies and connectivity of sandbody. It is considered that formation S-7 is fan-delta sedimentary, and S+4-7 is main production layer, thick is large and distribution is extensive in the north of the block, connectivity is gradually good, thick becomes thin, area is small, connectivity is poor form north to south and west, the change is great in the horizontal, distribution is scattered. The method is effectivel, and worth popularizing in the refined description of the similar oil reservoir during the development of oilfield.
At present the enclosing capability of cap formation was studied through traditional core analysis in the laboratory. Because of the limitation of experimental expenditure, amount of core hole and coring etc., core analysis has such shortcomings as bad representation, long time needed and high expenditure. In this paper the enclosing capability of cap formation can be appraised by acoustic logging, the study indicates this method has overcome the shortcomings of traditional core analysis, and is good at appraising enclosing capability of cap formation of the Kela 2 gas field. This gas field's cap formation is mainly the first type and forth type cap formation, and the enclosing capability of cap formation is good.
It is very complex compare the coalbed methane conditions between the Daning-Jixian coal field and the Jincheng coal field. For example the deposit environment of Shanxi formation and the thickness change of the coal seams of Shanxi formation are very changeable in very small areas. The structure and hydrogeology are more complex. The boundaries of the of coal pools are complex. Thus the detail features of coal pools should be summarized. The data of coalbed methane exploration is not enough for the coalbed methane development because of few wells which can not control the changes of coal seams and structure.The speed of the exploration and development of coalbed methane is depend on the complex of the thickness change of the coal seams, the structure and hydrogeology, the deposit environment of Shanxi formation.
It is a hotspot question that how are normal oil and gas resources developed with unconventional coalbed methane resources at the same time in the basin with coal，oil and gas resources. Based on physical simulation of adsorption of different coal rank samples from adjacent coal mine of Huimin depression，and combined with measured data of temperatures and pressures of oil and gas wells， deep coalbed methane contents are predicted. The results show that coalbed methane contents of gas coal to fat coal in situ are about 5 ｍ３ perton.
Based on the analysis of desorption velocity and the capable desorption quantity of coalbed methane, we systemically discussed the desorption characteristics of coalbed methane of Panzhuang Coal mine and analyze the relationship between desorption velocity and desorption time, and the relationship between the capable desorption quantity and the burial depth of coal reservoir. In the area, there is quite high capable desorption rate in the middle area of the first mine field, most area of the fifth coal of the second mine field and the north area of the third coal of Panzhuang Coal mine, which is propitious to the exploitation of coalbed methane. In the layer region, the capable desorption rate mostly takes on a negative relationship with the increase of burial depth of coal reservoir, but the data is comparatively discrete.
Recently, commercial coalbed methane production rate has gotten in the Tertiary Powder River basin in USA, which had lower coal rank and lower gas content, but has higher coal thickness and gas abundance; this made us beginning to considering coalbed methane resource in the lower coal rank basin of eastern Inner Mongolia. Tertiary and Cretaceous coal with a resource of 2 trillion cubic meters was the most important coal accumulated period, which has a thick coal seam, lower coal rank, lower gas content. Through the analysis of Northeast China, we could found that it is important to reinforce study on coalbed methane preservation condition, study on forecasting of high permeable and gas-riched area, secondary biogenesis gas and hydraulic conditions.
To improve the recovery ratio of oil and the production benefits of heavy oil reservoirs, Southwest Petroleum Institute and Xinjiang Oil Field cooperated to carry out the mineral field experiments of microbial enhanced oil recovery (MEOR) for heavy oil. In the experiments working bacteria or petroleum bacteria from different places were chose, and the mode of production was individual well injecting-extracting. There were 21 product wells of heavy oil in the two times. Through the influence of working bacteria, the viscosities of heavy oil were decreased greatly. With little or no hot vapor, most test wells had reached for economic productivity. High products investments ratio had been got in the experiments. According to the results of the experiments, the working bacteria selected can obviously degrade heavy oil rich gum and asphaltene. And the mineral field experiments have many advantages, such as little investment, fast returning, greatly profits and so on. Practices have proved that MEOR of heavy oil is worth applying and generalizing in Xinjiang Oil Field.
Gudong shallow gas reservoirs had entered later developing period .As the ratio of total gas produced to OGIP increases，formation pressure decreases year by year，the number of shut down wells increases，sand and water producing are getting serious，and the number of low production wells increases.Through accurate gas reservoir description，the recovery law of various gas sands has been analyzed，and the state of producing，recovering，sealing and remaining of gas reserves has been made clear to improve the development of the reservoir.
The paper studies the flow characteristics of prop-laden fluid in vertical hydraulic fracture. At first, the velocity of fluid flow can be derived from the mechanism of fracture fluid laminar flow and the distributed principle of the fluid pressure in the fracture. And then, the apparent viscosity of prop-laden fluid is calculated reduce based on the kinetic theory of prop-laden fluid together applying Thomas's law. Furthermore, by studying the interaction between the wall of fracture and proppant, we can setup the formula which presents the flow resistance of prop-laden fluid in hydraulic fracture, so that the capability of different proppant concentration and the grain size can be accessed. The paper provides a theoretical method for the further study in prop-laden fluid flow resistance in hydraulic fracture.
Based on the analysis of rare earth elements of the shale rock of the upper Palaeozonic in the Ordos basin, the rare earth elements are enrichment in variegated mudstone and are deficit in melanocratic mud rock. Miner-grain sediment had a high pink and micro-grain one had a very weak. According to the regional distribution of rare earth elements, the source of the northern Ordos basin come form the Yin-shan ancient land, and the source had zonation in east and west area. The sediment differentiation affections control the enrichment of rare earth element. With mudstone particle size become fine form north to south Ordos basin, rare earth elements had a very pink.
different maceral have different chemical constitution. Exinite has the lightest carbon isotopic composition. Inertinite with the heaviest carbon isotopic composition has highest aromatization degree. So the production carbon isotopic composition of different maceral has following rule: semi-fusinoid group＞fusinite＞vitrinite＞exinite. According to the gas productivity of different maceral: exinite＞vitrinite＞semi-fusinoid group＞fusinite, the potential influence of the difference maceral composing of coal formation source rock to carbon isotopic composition between Kuqa depression and Tuha basin has been calculated. The result show the influence is negligible.
The gases can mainly be divided into two groups being with high N2 and high CO2 in the gas shows of Well Yang-1. But, according to the gas analysis and the fact that all gases shows in Nanpangjiang area are with high N2, the high N2gas in Well Yang-1 is actual geological significant. The kind of the gas is featured with high N2 content and heavier isotopic values, the N2 content is from 54.92% to 73.89%, the δ13C1 values are from -33.19‰ to -33.9‰.The gas in Well Yang-1, not being the cracked gas from crude oil and not being the gas derived from the measure strata of Longtan Formation of Upper Permian, is the cracked gas mainly generated from the shaly source kerogen of Middle Devonian. So the main reason why the gas has high N2 and heavier carbon isotopic values is that the gas accumulated in the late stage when the gas was generated from high to over mature Middle Devonian source rock.
A series of alkan-2-ones,alkan-3-ones and alkan-4-ones were found and identificated with mass spectra in a vertical profiles of biogenic gas source rocks in the Quaternary of the Qaidam basin, and the relative contents of different carbon number alkan-2-ones were calculated according to the chart of mass chromatogram of samples. The distribution character of alkan-2-ones、alkan-3-ones and alkan-4-ones is similar in one sample; and there is a great change in the distribution of alkan-2-ones in the vertical profiles. The CPI of alkan-2-ones ranges from 1.20~1.80, and value of L/H ranges from 0.30~1.61. Based on the characteristics of alkan-2-ones distribution and biomarker parameters, and combined with the geological background of the samples, the source of aliphatic ketones in biogeneic gas source rock in the Quaternary of the Qaidam Basin were discussed, we think that the aliphatic ketones derived from biomass in saline-subsaline lacustrine deposits of the Quaternary of Qaidam basin or from the biodegradation of alkanes by bacterial community.
Based on documents home and abroad about nitrogencontaining compound,this paper points out that nitrogen-containing compound has significant use in geochemical research.First,it has unique advantage in studying ondirection and path of hydrocarbon migration.Also,it is successful used in manyother ways,such as maturity and oilsource correlation research.
The experiment of combination and dissociation process of methane hydrate researched by computerized tomography (CT) is expatiated on in this article. It was proved that CT could identify the combination and dissociation process of methane hydrate distinctly. The dynamic process of methane hydrate can be recorded by CT images which reflect the density information. It was shown in this experiment that there was a paroxysmal beginning at the early time of combination which began at the interface between water and methane and the early resultant was loose and with low density which would become denser. And the methane hydrate became loose and released the gas during dissociation process.
When the temperature is above zero centigrade, methane hydrate decomposition can be regarded as a gas-solid reaction without solid production layer. From crystal dissolution angle, the paper studied on hydrate particle shrinking problem.The paper related particle radius to reaction time with a differential equation and thus built a particle shrinking model of methane hydrate decomposition. Dynamics analysis was done by use of experimental data from the literature, which indicated that interface chemical reaction was the control of the process. Global reaction velocity constant and the activation energy of methane hydrate decomposition. The results from the model match the experimental data perfectly showing that the model is of high reliability.
The hydrate has a peculiar cagelike crystal structure, 1m3 of hydrate can envelop 150～180m3 of natural gas. The new method of natural gas storage and transportation in hydrate form has the advantages of safety reliability and low cost and can replace the conventional methods for natural gas storage and transportation——the method by pipeline and that by liquefaction, and especially it is suitable for developing offshore gas fields and the small gas fields in remote area, gibing rise to scientists' attention. In this paper the capital costs of four forms for natural gas transportation have been compared, and the results have shown that the costs of an NGH chain is the lowest than of others, and it should be a new way of gas transportation. Some technical problems that needs to be solved in the performance of gas transportation in the form of NGH are put forward.
Based on the databases of SCI, INSPEC and DII of information Platform of ISI Web of Knowledge and Derwent Analytics Software, this article compared and analyzed the articles of natural gas hydrate science in Science Citation Index (Expanded) from 1995 through 2005 from different aspects. Then it discussed the status and trends of international natural gas hydrate research and development by comparing thse output of articles and patents of different institutions on bibliometrics.
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