The gas industry in China shows excellent developing trends: firstly, from count ry poor in natural gas to the one rich in it. In 2005, the gas output has reache d near 500×108 m3; secondly, the theory of natural gas exploration develops from monism(oil type gas-generating theories) to dualism(oil-type and coal-f ormed gas-generating theories); thirdly, the increasing gas output calls for st rengthening in natural gas exploration and development. During the past more tha n 20 years, the natural gas geological theories have developed much: The coal me asure source rocks mainly generate gas with minor oil; the identification index with high credibility and accuracy on various natural gases have been set up; th e studies on the controlling factors of great gas field formation, by quantifica tion or semi-quantification; the carbonate with TOC content about or lower than 0.2% can hardly be regarded as sources rocks and the TOC content of effective c arbonate source rocks must reaches or more than 0.5%. Not only the abiogenic gas exists in the nature, but also can it form gas pools. Several CO2 gas pools h ave been found in eastern basins of China. And the first abiogenic alcane gas re servoir in the world has been.
Xiangshan Science Conferences of No.239, the topics is natural gas resources in china and its development strategies, was hold in Beijing on November 2 to 4,2004. The situatioo of the natural gas resources, the opportunities of development and strategies of natural gas industries were discussed by the scientists who attend the meeting, based on natural gas resources, exploration and development technologies of natural gas and development strategies of natural gas in China.
The flowing groundwater in coal measure can affect the c oalbed gas content largely. Both in horizontal and vertical directions, that in the area with stronger hydrodynamics, the gas content in coal is lower. However, in areas with weaker hydrodynamics, or stagnant area, the coal usually has high gas content. In coal mine production, the area with active groundwater has litt le gas outburst or no outburst. In the excavation area with weak or stagnant hyd rodynamics, the gas outburst usually happed with large amount of released gas. A ccording above, the stagnant water controlling is put forward.
Based on physical simulates of methane-solubility in water of different minefields and coalbed water, gas-dissolving in the lignite re servoir of Hailaer basin in Neimenggu municipality were calculated. Based on triaxiality compress experiments of three-phase medium coal rocks, i.e. coal ma trix, gas and water, integrated into state equation of ideal gas and Malueta law , free gas in the lignite reservoir were calculated. Based on isothermal methane -adsorbing experiments under equilibrium moisture, gas-adsorbing in the lignit e reservoir were estimated. At last, taking Hailaer basin as an example, total g as content in the lignite reservoir were predicted.
Some different comments of tectonics in Kuqa area are presented, which will prof it exploration and exploitation of natural gas. It is usual viewpoint that the a rea is always in compressed tectonic background since late stage of Oligocene. I t is adverted that Cenozoic stratum is not only involved by nappe tectonics, but also remodeled by NS extensional tectonics. There are five class of extensional tectonics: Fault-block Tectonics, which develops in the after part of compress ed geologic body; Antithetic extensional tectonic (antithetic normal fault); Lat eral extensional tectonic (lateral normal fault); Inverse extensional tectonic ( negative inversion-tectonics); Taphrogenic extensional tectonic (normal graben) , which develops in the uplift of compressed geologic body. The geologic body ha ppens fold and thrust early because of extrusion and fault-block later because of stretch in the same area, and thrust in the foreside because of extrusion and normal fault in the backside because of stretch on the same time. The extension al tectonics exists in the margin of basins in northwest China, which is usually negated, and develops together with nappe tectonic.
Mixed water dolomization is the basis of platform fringing oolitic beach reservoir of Feixianguan group. With the petrologic analysis of dolomite, the geochemistry analysis as well as the speculation of temperature and depth, it is proved that dolomization came into being in mixed water. The authors summarize the dolomization genetic model of oolitic beach reservoir. The mixed water dolomization is mainly controlled by frequent change of the sea level.
Yingqiong basin and Baiyun sag of Pearl River Mouth basin are rich in gas resour ces and diverse in gas origin, with varied exploration fields and greater resour ces base. So far, biogenic and biogenic-undernatured transition gas have been d iscovered in the basin, besides shallow and mid-deep gas reservoirs predominate d by matured and high-matured humic gas(coal-formed gas).With sizable reserves and higher production capacity, these biogenic and biogenic-undernatured tran sition gas have a great resources base and exploration potential. A breakthrough of biogenic gas exploration in this area is just round the corner providing tha t prospecting strength and comprehensive research depth are enlarged.
The abnormality of marine carbonate petroleu m system indicated in source providing,bearing system,pool-forming process,syst em composition, types of oil-gas pool, location of accumulation and other field .The feature of easy to diffuse and abnormality of petroleum accumulation indica tes that they are unsuitable for the traditional study and exploration methods.I n this paper we examine a new thought on carbonate petroleum system study which include several respects as providing province study, bearing province study, c losing province study, pressure province, geochemistry province study and arrang ement study.Based on this,the petroleum system could be classified and the promi sing regions could be determined practically.
There are large areal clastic reservoirs in the Permian,Triassic and Jurassic i n eastern part of southern margin of Junggar basin. The sedimentary environment changed frequently and the anisotropy of the reservoir is apparent. Field observ ation and (cast) thin-section analysis indicate: The intergranular dissolved po re is the main pore type and the throat type is mainly of sheet,tortuous sheet a nd bundled tubes. The result of the successive research indicates: The type of r eservoir in Jurassic is mainly ofⅠandⅡ,and in Triassic is mainly of Ⅱ and Ⅲ, the reservoir in Permian is mainly of Ⅲ.
The basic petroleum geological cond ition analysis is the premise for oil-gas exploration, but the particularity an alysis is the key point for finding the most effective cut-in way for oil-gas exploration. The particularity of subtle traps formation and subtle reservoirs m ainly show in the following points: the property of Tuha basin and structure cha racteristics- a long and narrow multi-recycle stacked basin; sedimentary syste m-two directions (north and south) short sediment sources sedimentary systems; the geological background of subtle reservoir-lower generation and upper reserv oir, structural slope character of south slope; subtle traps for oil-gas occurr ing-fault connected with source rock and lateral fault must be existing; subtle reservoir-space accumulated with oil-gas of subtle traps are small, sandstone s for oil-gas reservoir are thin and reserves of single trap are small. Accordi ng the conditions mentioned above, the subtle reservoirs exploration of Shengbei depression must be clinging to stated structural background, and the south wing of Shengbei structural zone, a crossover region of north and south sediment sou rces, is an available area for subtle traps developing and subtle reservoirs exp loration.
Recognizing the water saturation in tight gas reservoirs directly affects reserv es evaluation and development measurement of the gas reservoirs. Sealed coring a nd log interpretation show there is an ultra-low water saturation in tight gas reservoirs in northern Ordos basin, the initial water saturation in tight gas re servoirs is between 20% and 30%, which is far below the irreducible water satura tion. This article believe that the mechanism of forming ultra-low water satura tion in tight gas reservoirs is the result of the process of removing water duri ng hydrocarbon generating, then proving the conclusion by an experiment. The eff ects of isolation of mudstone, the variation of relative permeability between wa ter and gas in gas and water transitional zone, the continual gas accumulation i ncreasing the pressure in tight gas reservoirs are main issues for sustaining ul tra-low water saturation.
By applying of sequence stratigraphy principle, connecting with the data of outc rop and core, the strata in Yanchang formation in Ansai district have been divid ed into S1, S2, S3 and S4. Beside the S4 which lost the highstand system tract ( HST), the others possess the lowstand system tract (LST), the transgressive syst em tract(TST) and the HST. Every system tract is made of different stratigraphic pattern. The sequences in studying area control the assemblage of source, reser voirs and caps and the distribution of reservoirs as well as the performance of reservoirs. So Chang 7 that lie in the maximum flooding surface is the main sour ce rock. Chang 9, Chang 4+5 and Chang 1 that lie in the TST either have the abil ity of producing oil or can became the caps. Chang 6, Chang 3 and Chang 2 that b elong to the LST possess good reservoirs. Chang 8 lie in the LST will became the next exploration aim.
Using the basin modeling technology based on the method of petroleum system, Aut hors have simulated and analyzed the dynamic geological process of petroleum sys tem in Luyi depression which was composite and reconstructed. There are favorabl e conditions of secondary generating hydrocarbon to Carboniferous-Permian resou rce rocks in Luyi depression. The hydrocarbon resource rocks had passed through the two fastigiums of generating hydrocarbon, which are Yenshan period and Himal ayan period. The key period of accumulation is Himalayan period. In the end, the exploring targets have been predicted.
Member 2 in Shanxi formation of Permian system in Yulin gasfield is the mainly gas reservoir,was deposited in a braided river of delta enviroment.The reservoir sandstone mainly is quartzose sandstone, lithic quartzo se sandstone and little lithic sandstone,The reservoir sandstone is typical of l ow porosity and low permeability.This article was based on core observation,and use thin section observation,scanning transmission electron microscope observati on,cathodoluminesconce and physical property,takes research and analysis,indicat es that the sandstone of member 2 in Shanxi formation in Yulin gasfield went thr ough the compaction,cementation,metasomasis,solution and fillition of clayimpuri ty during the diagenesis,and now it is in the late diagenesis stage. The porosit y of the reservoir sandstone of member 2 in Shanxi formation,its statistical por osity composition being protogenetic intergranular remainder porosity of 44.7%,s econdary porosity of 55.3%,which indicates that the diagenesis has the greatest.
On according the newest three earthquake preserve explaining fruit and drilling data of South Songliao basin in Yaoyingtai Changling sag area, analysis the rup ture structure character. On according analyse report of character and rock mine , analysis reservoir character. The circle closed of Yaoyingtai is made up of positive faultage which near the S outhnorh groups tend towards is divided up vary construct, the west brae cinctu re, the middle part rift valley, the east horst, each formations cincture is dis membered into different construct by hypo-stage faultage. In Yaoyingtai area, t he mostly oil system contains of sandstone reservoir of Quantou group, Yaojia gr oup and Qingshangkou group, Inside the borough, the average permeable of reservo ir sample is 3.18×10-3 μm2 ; the average hole degree is 13.13%; the av erage Oiliness saturation is 18.80%; the average containing water saturation is 20.24%; In Yaoyingtai area, the stratum of Quantou group, Yaojia group and Qings hangkou group make for Southnorh direction, lean to west, the obliquity of strat um isabout 4°~8°, the whole directs the east and drives up all along takes on delay slope odd inclined conformation.
Sebei gas field is the fourth one in China. Its pay-zone is unconsolidation Qua ternary fine-silty and dirty sandstones, alternating with gas and water layers, with severe sand production. Grain size of the sand is very fine, so sand contr ol here is very difficult, it is cosmopolitan puzzle. We have succeeded in appl ying a series of techniques of comprehensive sand control using fiber-complex p ack. The technique uses formation pretreatment (soft fiber, its branched chain w ith electric charge adsorbs on fine siltstones and forms big aggregations of fin e siltstones.). special fibers and resin-coated sand complex to stabilize pack. Using high pressure pack to form the fiber complex annularity of well and to in crease productivity, It bypasses near well bore damage. This combined rehabilita tion technique enables screenless sand control completion. The technique was app lied in Se 7-1-4 well; the results are remarkable. After the sand control tre atment, sand was not found even the gas production rate is 2 1 times that of be f ore. This paper presents lab study, operation design, well selection principle, field operation and result analysis about the sand control techniFormation que.
In this paper, the mechanism of the phenomena of streaming along the pore-wall with condensate oil is analyzed, using the mechanism of bound water membrane.
As a special type of oil and gas reservoirs, the developm ent difficulty of condensate gas reservoir is more complexed than the other oil and gas reservoirs because of the unique fluid phase ch aracteristics, and so the development process consider not only the recovery pre sent of reserves of natural gas but also the condensate oil's. Taking the develo pment program study of condensate gas reservoir with a small oil ring of Baolang area of Xinjiang province as a case history, the problems needing to be firstly considered and resolved during the process of development plan study of condens ate gas reservoir are summed up, and such development strategies are put forward , that is, the development of such kind of condensate gas reservoir should cente r the benefits and focus on proving the deliveribility and development pattern o f gas reservoir and the program should apply arranging wholy and implementing st eply.
The Fluid-solid coupling method is usually adopted both at home and aboard, in the numerical simulation of deformable media gas reservoirs. Though totally feas ible in theory, The Fluid-solid coupling method meets very great difficulty in practical applications, due to the uncertainty of rock deformation type and the complexity of the solution of the model. The accurate numerical simulation of de formable media gas reservoirs is realized by the introduction of the relationshi p curve of dimensionless permeability and dimensionless pressure. The results of laboratory testing can be utilized directly in this method and it is very simple.
Molecular nitrogen is one of most common non-hydrocar bon components in natural gas reservoirs. The origin of molecular nitrogen in na tural gas can be classified to be three types, according to its origin, that is, atmospheric nitrogen resource, bio-genesis resource and deep crust and upper- mantle resource correspondingly. Based on the nitrogen preserve, distribution an d some geochemistry properties, and combined with the volcanic history of Tarim basin, the genesis of molecular nitrogen in natural gas has been comprehensively analyzed in the paper. The study shows:① the gas pool in the shallow part (suc h as Cretateous), the average relative abundance of nitrogen is lower 5 percent, and its main origin is from atmospheric nitrogen, and its exploration risk coef ficient is relatively lower;② the middle part (such as Carboniferous, Permian), its origin of nitrogen is relatively complex, which main resource is from the d eep mantle or bio-genesis. The average relative abundance of nitrogen is about 20 percent, and its exploration lies in between; ③ the deep part gas pool (such as Ordivician), the average relative abundance of nitrogen is variable, thepoor
-nitrogen gas pool, its main resource is from bio-genesis, while the rich-nit rogen gas pool, its main resource is from the deep mantle and is related with th e metamorphic rock, its exploration risk coefficient is relatively higher.
It is importan to analyze the continuity of fluids in rese rvoirs in developemnt geology. The condition of the continuity of reservoirs is relate to not only the location of production well and the perforated interval b ut also the location of input well and the efficiency of injection of water. The techniques of the fignerprints of gas chromatograms and spectrophotometry have been applied to the vertical and lateral continuity of the reservoirs. The indu strial scale oil was found by penetrating at shallow zone (305 m) in well S1-26 -1. The result of testing once at shallow zone suggested that there was merely oil trace, not industrial scale oil. So it is doubted that the industrial scale oil come from the mid-deep level because of the leaky casings. The results of s tudy on the continuity of oil between well S1-26-1 and near this well show tha t the oil of well S1-26-1 come from the shallow zone.
With the development in modern testing and analyzin g techniques, carbon isotopes have been used widely in oil and gas geochemistry. Recent advances in carbon isotope studies are summarized in this paper, which i nclude identification of source rock type and forming-environment, the genetic type of natural gas, maturity of natural gas, the correlation of oil-gas-sourc e, the alteration of oil and gas, the retracing of second migration of oil and/o r gases, the mixing of different natural gases, the application in reservoir geo chemistry. Some questions in application of carbon isotope in oil and gas geoche mistry are also discussed.
This paper deeply discussed the excellent chara cteristics of S transform (ST). By replacing the basic wavelet in the ST with ac tual seismic wavelet which was extracted from seismic data, the general S transf orm (GST) was achieved in the seismic data analysis. The general“three instanta neous” attribute (namely general instantaneous amplitude, frequency and phase) can be extracted from single frequency complex seismic trace which is produced b y S transform. When the reservoir was filled with gas or oil, the reflected seis mic energy would be attenuated in high frequency and be enhanced in low frequenc y. Therefore, Hydrocarbon can be detected through the low-frequency instantaneo us energy spectrum based on GST. Moreover, this method had succeed in several ar eas such as Indonesia, Tarim and Junggar.
3D prestack depth migration is an ideal seismic data imaging technique for the area where there o ccur very complicated geologic structure and severe lateral velocity variation.3 D prestack depth migration imaging technique have been applied to CX gas field,a nd bring satisfactory effect.The main steps of 3D prestack depth migration can b e described in the following points:①Design time model by picking up velocity h orizons in time section;②Construct interval velocity-depth model by using the interval velocities which have been obtained layer by layer with the use of cohe rent inversion and stacking velocity inversion methods;③Improve geologic model through residual velocity analysis;④Achieve the 3D prestack depth migration after finite difference algorithm.
At present, seismic data interpretation, velocity analysis, time-depth conversi ons usually are completed on one interpretative software. As we know, every inte rpretative software application has its advantages and disadvantages. Only using one kind of interpretative software in complicated structure area can't meet th e needs of each work assignment. We analyze the advantages and disadvantages of two mapping modules CPS-3 and Z-Map Plus in GeoQuest and Landmark respectively . The functions of the velocity analysis module InDepth have been perfected and data transmission between CPS-3 and Z-Map Plus was achieved. With in a complic ated structure area of inconsistent datum plane between seismic section and velo city spectrum, a new method of time-depth conversion has been used to make the structural map. A 3D velocity field of high accuracy is found and time-depth co nversion is completed on a datum plane of velocity spectrum to make the structur al map by combining CPS-3 and Z-MAP Plus. Three dimensions visual software Ea rth Vision is applied to display final structural map. This method was applied a nd achieved success in the C area.
Wavelet analysis is a new method of mathematics, because of its good local behavior in time domain and in frequency domain, it is better for processing the highly random varying signals than classic Fourier analysis. This paper discussed the compression of seismic data by 2-D wavelet packet transform.
On the basis of induction phenomenon during gas hydrates formation，the definiti on of the induction time was summarized and discriminated. The methods both in t heory and experiment were concluded and summarized. The factors of the water mol ecule, the gas composition, the disturbance and the driving force, which were re ported affecting the induction time, were analyzed. It is expected that the unam biguous concepts of induction time and the rules of the factors affected in indu ction time will have an active effect on research work in the following days.
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