The hydrocarbon generation conditions of Carboniferous and low Triassic large and middle scale gas fields in eastern part of Sichuan basin have been studied adopting the petroleum system and the gas reservoir geochemical method in this paper. The two suits of dull muddy rocks in Low Silurian and upper Permian is respectively the hydrocarbon source rocks for the Carboniferous and low Triassic gas fields in eastern part of Sichuan basin.Here, the gas concentration is mainly controlled by Kaijiang Paleo-uplift formed in Indosinian-Yanshan periods. The traps formed in Himalaya period may adjust the reservoir forming and control the present distribution of gas fields.
Due to pervasion diffusibility of gas, obturation factors of gas is very importance in rift-basin with tension tectonic suffering more tectonization. A lot of difference types gas pools have been explored in north region of Jizhong sag, China northern, besides having excellent source rocks of generating gas hydrocarbon, and yet relation of obturation factors of gas. The paper generally discussed obturation factors (cover) assembling gas, expatiated main research results.The capillary pressure obturation standard of gas pool be founded in the region, withⅠ-Ⅱ types cover being good and better, Ⅲ-Ⅳ types cover being middling，for them being capable of obturating gas pools. The displacement pressure values from coal covers, Bengxi-Sanxi group of Carboniferous-Permian, can be more then 5 MPa, belong to Ⅱ-Ⅲ types of being better cover. The displacement pressure values of mud-rock covers, Ek-Es3 of Lower Terrtiary, commonly can be more then 0.5 MPa, the most value is the 2.83 MPa, with containing nor-coMPaction zone, being primary source rocks stratum. Therefore, superpressure-obturation-action and hydrocarbon-obturation-action are more important, covers of Ek-Es3 are to belong better covers. Factors of rocks and diagenesis: The obturation capability of cover is depressed along with increase of arenaceous rocks; thick single mud rocks can debase pervasion action of gas. The rocks of middling extent of diagenesis has the most excellent capability of obturation, in other word, with being early diagenesis B phase-late diagenesis A phase. Factors of stratum and tectonic: lower amplitude traps are better obturation action of gas then higher amplitude. Obturation acton of fault be engendered by character and scale of fault as well as stratum contact between ascend and lift stratum, but some small size late fault is destruct action to obturation after produced gas pools.
Gaoshiti-Moxi structure belt is the important exploration area of Sinian Dengying formation. The laser fluorescence, inclusion enclave and isotope technologies etc are used to obtain the gas migration and gather information. Though the trap evolvement and reservoir characters are analyzed, and reservoiring model of is made. The Gaoshiti-Moxi was a palaeohigh area after Caledonian movement, through the Indosian, Yanshanian and early Himalayan movement the palaeohigh area was keeping. The belt is big trap after later Himalayan movement. There are three gas-bearing formation types of cavern, pore space and fractural interval, it can be divided into two gas-bearing units that are Sinian top unit and dengying 2 formation unit. Combining with hydrocarbon simulation study, the main phase of oil generation for source rocks is early-middle Jurassic, the main phase of gas generation is early Cretaceous, The Gaoshiti Moxi is evolving anticline gas reservoir. The Gaoshiti-Moxi structure belt is favorable to migrate and assemble oil and gas, so it benefit to exploration.
Based on studying development, geochemical and generation gas characteristics of sourcerock and development, seal characteristics of caprock of deep strata in Xujiaweizi region. This paper studied the match relation between sourcerock and caprocks in time and space and their controlling to farmation of gas reservoirs in this region. The time match relation between K1d2 or K1q1+2mudstone caprocks and K1sh+ycsourcerock in Xujiaweizi region is good, but former is better than the latter. It is the important cause that there is more gas distribution under K1d2 mudstone caprock than that under K1q1+2 mudstone caprock. The space relation between K1d2 orK1q1+2mudstone caprock and K1sh+yc sourcerock is best in the centre of Xujiaweizi depression. This is the important cause that gas distributes from basement rock to K1q1+2 in the three structures of Shengping, Wangjiatun and Changed in Xujiaweizi depression.The quality matching relation between K1d2 caprock and K1sh+yc sourcerock is better than that between K1q1+2caprock and K1sh+yc sourcerock. This is the another important cause that there is more gas distribution under K1d2 caprock than that under K1q1+2 caprock. The center of Xujiaweizi depression is the most favorable area for gas to accumulate and form gas reservoirs from the matching relation between caprock and sourcerock.
Based on contrast of distribution, organic type and abundance of Xujiahe formation, Upper Triassic between Chishui area and other areas in Sichuan Basin, and with analysis on the main geo-chemical characteristics of gas from Xujiahe formation, this article discovered the source characteristics of Xujiahe formation, discussed the origin of natural gas found in the Formation, and forecasted the direction of following exploration.
Random simulation modeling and determinate simulation modeling were used in the paper for Su 6 well region and the whole field. In accordance with the major problem with the strong heterogeneity of Lower Paleozoic carbonate reservoir in Sulige gas field，the geological research and gas reservoir description results in Sulige gas field were quantitatively transformed by taking random simulation modeling as the major method，therefore a set of geological models，including structural model，petrophysical model and fluid distribution mode1 of Sulige gas field were set up. Based on these models，the risk assessment of reserves may be carried out；the relation between gas well productivity and geological condition can be summarized；the bases of optimizing well sites may be determined ;and the grid parameter fields can be provided for gas reservoir numerical simulation.
According to the outcrop observing and the core describing as well as lots of data analyzing, it indicated that front-delta deposition is the main sedimentary system of Chang 6 in Ansai district. The distributary channel deposits, the inter-distributary deposits and the sands are the main sedimentary microfacies in the studied area while the point bar isn't development. The distributary channel deposits is the main reservoir sands. The evolution and the distribution of the microfacies in every number have been studied. The accumulation of oil and gas are controlled by microfacies. The distributary channel deposit of Chang 6 is the good reservoir, and also is the direction of the developing in Ansai oil field.
Reservoirs are influenced by incumbency rock pressure, sideways pressure and porosity pressure at primitive stratum. This stress state is called primitive effective-stress. After the primitive effective-stress be considered, the law of stress sensitivity still follow the negative exponential attenuation. Compare to no consideration of primitive effective-stress, the descend degree of permeability is more little, so the stress sensitivity is weaker. But the law can suit to the fact, and have practical meaning for actual production.
During the sedimentary of Majiagou formation, the wide area of the eastern Ordos basin were controlled by the middle palaeohigh and the marginal deep, lied in the surrounding of the continental margin basin .The solution roles are faint very much, the filled roles are intension very much, the strong heterogeneity are exhibited on the space distribution. The characteristics of development are controlled by sedimentary surrounding, palaeogroove and palaeohydrodynamic condition on the macrocosmic, controlled by the pore styles and the filled intension and the filled styles on the microcosmic. Sedimentary rocks are decided by the sedimentary surrounding, which is the substantial base of the reservoir development; the plane distribution of the residual solution platform are controlled by palaeogroove; the difference of the filled intension are controlled by the compacted released water. The filled styles of pore and core include mainly dolomite and calcite. the dolomite react on construction, the calcite react on destroy roles. The filled region of the dolomite and the calcite mixed and the physiognomy of mini-karst are piled up, the region is the main domain of the Ordovician explored in the future.
Carboniferous strata are important exploration field in the southwestern Tarim basin. Oil-gas resource is very rich, exploration work is insufficient. Combined geochemistry index, the article analyses some characteristic factors, i.e., which can reflect sediment environment independently. The characteristic factors are thickness, fabric form, lithofacies, lithology ratio andlithology characteristic. On the basis of research of the oil-gas geologic conditions, the most favorable areas for oil-gas exploration are indicated, i.e., the western end of Bachu uplift, Mazatake-Haimi-Luosi faulted zone, the northern edge of Meigeqi slope and the overthrust plate of southern edge. And the article brings forward the correspondence countermeasures.
Presently the T1j22 stratum have become the important stratum of oil and gas exploration in Dachiganjing structural belt of east Sichuan, through comprehensive researches of reservoir sedimentary feature、 reservoir physical property、reservoir influential factor and reservoir prediction, we find that the T1j22 reservoir pore spaces were dominated by crystal-to-crystal pores and corrosion pores, and the reservoir type was defined as fracture-pore type. The reservoirs were classified in four types, and in this area reservoirs mainly belong to type Ⅲ，however, in the stratum profile, type Ⅰand type Ⅱ were few distributed, and formed 1～2 high porosity section. The reservoir physical property were primarily dominated by sedimentary facies、corrosion and dolomization. Through reservoir prediction, it indicated that the reservoir in Mainan structure and Mopan-Laowan buried structure which located in short limb and bottom wall were finely developed ,this two areas were the primary area for the further exploration and drill site design in Dachiganjing structural belt.
According to figure of faults distribution in the bottom of Minghuazhen formation of nanpu sag, self-similarity of fault spatial distribution has been examined by using fractal theory and the fractal dimension of capacity. Correlation coefficients are between 0.99 and 1, which suggests that faults are fractal structure. The fractal dimension of capacity(D0) in different areas have been calculated and its isoline map is drawn. Author find that the three of four oilfield are located in the areas where the fractal dimension of capacity are larger than 1.18, which show that the distribution of the fractal dimension relates to the distribution of oilfield. So Beipuxi fault zone, nanpu fault zone and getuo fault zone are ascertained as the favorable areas.
Research results of regional geology and petroleum geology of Weibei sag suggest that there are good formation conditions for tight gas reservoir in structure, sedimentary, source rock, reservoir rock, caprock and trap conditions in Weibei sag. The sandstones under the depth of 3 000 m of the second member of Kongdian formation in north sag are the most favourable for the formation of tight gas reservoirin Weibei sag. Based on the compassion researches in regional geology and petroleum geology between Weibei sag and Dongpu sag which are similar in tectonic basis and petroleum geology each other, the formation conditions for tight gas reservoir in Weibei sag are different from that in Dongpu sag. The differences of the formation conditions for tight gas reservoir between Weibei sag and Dongpu sag are source rock, reservoir rock and caprock. The formation conditions for tight gas reservoir in Dongpu sag are better than that in Weibei sag.
Based on comprehensive study of micro-facies and stratigraphy sequence, the integrated analysis of seismic multi-parameters is an effective method for subtle-trap identification, comparison and evaluation at present time. Building an iso-time model with the boundary of sequence is the foundation of this method. Multi-parameters of seismic include the following contents, seismic-facies classification in little time-window within the boundary of stratigraphy sequence may quickly approach to favorable oil-gas target. The seismic-facies should be identified with well-log and comparison with pre-known target. Using impedance and well-log parameters inversion may ascertain the reservoir type of target. The analysis of seismic attributes may validate the reliability of reservoir inversion, on the other hand, they may forecast the possibility of oil-gas in reservoir. Potential energy trend analysis of fluid may demonstrate in large scale how about the target position. Oil-gas detection based on seismic information decomposition may distinguish which type of fluid is permeated in the target. Using 3D visualization may straightly understand where the target is and how about the range of reservoir, which may additional help the researcher to choose the position and track of will-be-drilled well. In this paper, the authors take the XN region of JH Basin as an example to show how the multi-parameters analysis of seismic to work in subtle-trap identification, comparison and evaluation. The fact shows that method is an effective and practical way in subtle reservoir exploration.
At present, a lot of the theoretical models or equations of calculating formation fracture pressure are presented and used, but there are few statistical models that can obviously reflect the formation fracture pressure and the logging rock mechanics parameter variety. In this paper, based the relation of formation fracture pressure and rock mechanics parameter, the four parameters which have a close connection to formation fracture pressure and are regarded as independent variable (input parameter), such as Young's modulus, bulk modulus, poison's ratio and depth etc. are selected. And by the BP neural network and multi-regress analysis technique, some reasonable statistical models of formation fracture pressure are established by making full use of formation fracture pressure data of carbonate formation, and the prediction study is developed. All research shows, the form of multi-regress analysis is simple and visual, and easy to use, but the error is not lesser. The BP neural network model is complex, and it's model is difficult to set up, but the estimate's formation fracture the pressure error is little, the precision is high. The two kinds of statistical model are still practical and feasible approaches to calculate formation fracture pressure.
Watering out of gas wells influences the deliverability of gas wells and the recovery of gas reservoirs severely. During the development of gas reservoirs, it is key to identify early water influx for producing without water and developing actively. Presently, there are many methods such as water monitoring, pressure monitoring, well test and so on. In this paper, the applicability of the methods is presented respectively: the method of water monitoring can be used only after producing water of gas well, the method of P/Zplot is used at the stage of nonlinear relationship between P/Z and cumulative gas production, the methods of well test can be used with abundance well test data, water influx calculation has its uncertainty. And then, it is given that analyzing all information on water invasion synthetically is the only way to reducing the risk of identifying early water influx of gas reservoirs based on its complexity and the applicability of the methods.
Firstly, the converse of fuzzy integrated evaluation is solved and the importance of every factor for wells and layers choice of fracturing and acidizing is aware. Then when one factor is absent, the degree according with the field practice that is calculated by constant weight evaluation method(CWEM) is compared with the degree calculated by variable weight evaluation method(VWEM). It is showed that results calculated by VWEM are more accurate than results calculated by CWEM. Thirdly, when one different factor is absent. Different results calculated by VWEM are compared with each other. it is discovered that more important factor is absent, The degree according with field practice is more bad.
According to the chemical composition, carbon isotope, hydrogen isotope and noble gas isotope researches, the deep gas of Bonan sag displayed the characteristics of normal accompanying gas with crude oil, with high contents of heavy hydrocarbons. The genesis of the deep gas may not be high mature to over mature source rocks. The characteristics of carbon and hydrogen isotope composition show that the deep gas of Bonan sag mixed by biogenic gas, thermgenic gas and coal-formed gas. The noble gas (He) isotope of the deep gas from Bonan sag indicated that the accompanying gas with crude oil in the sag is typical crust type gas, without clear mantle type gas. Based on the low frequency of deep fault activity, Bonan sag provided a advantaged geologic area for deep oil and gas accumulation.
Pyrrolic nitrogen compounds are used as tracers for investigating oil migration of Daluhu oilfield in Dongyin depression. The results of analyses on some prarmeters of pyrrolic nitrogen compounds in oils indicate that migration effects are obvious. It is suggested that oils likely move from north to south.
The Hongyanchi formation and Lucaogou formation of Upper Permian are main prospecting target of Well Chaican 1 Ce 1 in Chaiwopu Sag. The formation of Hongyanchi has a low abundance of organic matter with a TOC content almost less than 0.4%, for most samples, the main type of organic matter belongs to type Ⅲ and less are belongs to type Ⅱ, and the vitrinite reflectance amount to about 1.58%, which shows organic matter has evolved to higher stage of maturity. The formation of Lucaogou has a lower abundance of organic matter with a TOC content less than 0.4%, the type of organic matter mainly belongs to type Ⅲ and much less are belongs to type Ⅱ, the vitrinite reflectance amount to about 1.67%, which shows organic matter has evolved to higher stage of maturity, too. As a result, all the organic matter has passed the principal stage of oil formation, and can only produce very limited amount of condensate and wet gas at most.
Once hydrates block gas production system，it is difficult to eliminate blockages，often influence run，bring accident indeed. To gas gathering pipelines, It's very important to advance to prediction the beginning location of hydrates formation to inject inhibitor. This study is purport to safely, high efficiency in Gas gathering pipelines. ; In this paper，a hydrate formation thermodynamic model for predict hydrate formation conditions has been formulated based on numerical analysis,chemical engineering thermodynamics，heat transfer theories, etc. By combining the model and dynamics of gas production system，the beginning location of hydrates formation of hydrate formation has been predicted. Hydrate plug forecast software(GGP-NGH 1.0) whose language is Visual Basic has been developed that furnish the foundations for predicting hydrate blocking problems of gas gathering pipelines.
Marine sediments on the continental slope of the NE South China Sea have appropriate thickness, methane-generating potential, and occur in a suitable pressure temperature regime to host gas hydrate. Evidence for gas hydrate, the bottom simulating reflector (BSR), is observed to the south of Taiwan on reflection seismic records, and can be used to suggest that gas hydrates are widely distributed. The tectono-sedimentary framework south of Taiwan bears directly upon methane generation and the likelihood of the presence of significant gas hydrate deposits.The distribution of contourite, slump block, and the fronts of delta or fans is highly consistent with the distribution of BSR in both areas, so that they are the most favorable facieses for gas hydrate accumulation.
Coalbed methane reservoir simulation is the method currently available to determine operating strategies and estimate ultimate field recovery. Reservoir simulation follows the steps in performing a conventional reservoir simulation study. These steps involve selecting simulator, establishing simulation model, performing sensitivity analyses, adjusting history matching parameters and forcasting production. Coalbed methane is an unconventional natural gas. Based on the geology model of desorption-diffusion-Darcy flow，coalbed methane reservoir simulation has its own characters. Systemic reservoir simulation has been performed in Xinji test area of coalbed methane. The establishment of simulation model and history matching have been emphasized in the article. Simulating coalbed methane reservoirs is based on the establishment of simulation model, in Xinji test area which consists of determining the area of simulation and boundary conditions，designing the simulation grid, handling fluid PVT data，reservoir description data and recurrent data and so on. History matching is the process of calibrating a simulation model to past performance of wells. By history matching a reservoir model that describes the real reservoir has been created in Xinji test area. Whether the thick sandstone adjacent to No. 5 and 6 coal seam contributes to gas production is analysed. Then suggests aimed to the behavior of the production wells has been put forward. At last the history match data has been used to predict production rates of wells.
In this paper,the pressure behavior of the flow problem with deformed double porosity is studied, not only considering the double porosity and absorption of coal seams but also the deformation of medium. The new mathematical models of pseudosteady state flow problem with deformed double porosity are built by introducing the permeability module. The dependence of permeability on pore pressure makes the flow equation strongly nonlinear. The numerical solutions for pseudosteady state flow models are obtained by using Newtonian iterative method in an infinitely large system and the finite closed system. The change rules of pressure are discussed when the parameters of the models change. The plots of type pressure curves are given, and the results can be provided to theoretical basis and well-test method for oil field.
Through the study of the geological characteristics of coalbed methane in Wangying-liujia district, The mechanical properties of syncline and its controlling of coalbed methane is analyzed. It is illustrated that the syncline is the main controlling factor: the permeability and gas content of the superstratum of syncline is much lower, so it closes over the underlayer of syncline whose permeability and gas content is higher. Therefore, prospecting and exploitation of coalbed methane should be carried through seams in which lies in underlayer of syncline.
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