Porous-grain–upper-boundary model and its application to Tarim Basin carbonates

Most of the carbonates in the Tarim Basin in northwest China are low-porosity and low-permeability rocks. Owing to the complexity of porosity in carbonates, conventional rock- physics models do not describe the relation between velocity and porosity for the Tarim Basin carbonates well. We propose the porous-grain-upper-boundary （PGU） model for estimating the relation between velocity and porosity for low-porosity carbonates. In this model, the carbonate sediments are treated as packed media of porous elastic grains, and the carbonate pores are divided into isolated and connected pores The PGU model is modified from the porous-grain-stiff-sand （PGST） model by replacing the critical porosity with the more practical isolated porosity. In the implementation, the effective elastic constants of the porous grains are calculated by using the differential effective medium （DEM） model. Then, the elastic constants of connected porous grains in dry rocks are calculated by using the modified upper Hashin-Shtrikman bound. The application to the Tarim carbonates shows that relative to other conventional effective medium models the PGU model matches the well log data well.

Fuzzy Comprehensive Evaluation Model for Water Resources Carrying Capacity in Tarim River Basin,Xinjiang,China

This paper explores the method of comprehensive evaluation of water resources carrying capacity and sets up an evaluation model applying the fuzzy comprehensive evaluation method. Based on the data of nature,society,economics and water resources of the Tarim River Basin in 2002,we evaluated the water resources carrying capacity of the basin by means of the model. The results show that the comprehensive grades are 0.438 and 0.454 for Aksu and Kashi prefectures respectively,where the current water resources exploitation and utilization has reached a relative high degree and there is only a very limited water carrying capacity,0.620 for Kizilsu Kirgiz Autonomous Prefecture,where water resources carrying capacity is much higher,and in between for Hotan Prefecture and Bayingolin Mongo-lian Autonomous Prefecture. As a whole,the comprehensive grade of the Tarim River Basin is 0.508 and the current water resources exploitation and utilization has reached a relative high degree. Thus,we suggest that the integrated management of the water resources in the basin should be strengthened in order to utilize water resources scientifically and sustainably.

LAND COVER CHANGES AND LANDSCAPE DYNAMICS ASSESSMENT IN LOWER REACHES OF TARIM RIVER IN CHINA

The Tarim River Basin, located in the typical arid region, is one of the key regions of LUCC research in China and plays an important role in maintaining the sustainable development of the western China. In recent years,the ecological environment of the Tarim River Basin has degraded greatly. In the lower reaches, in particular, the riverbed has been dried up for more than 20 years, which accelerated the desertification and has been a great threat to people′s lives. Taking the section of the Tarim River between Qiala Lake and Taitema Lake as a typical region, an investigation on land cover changes was carried out with the support of remote sensing information of 1988 and 2000 respectively. The changes of land cover in this region were obtained: 1) Cropland tended to increase. 2) Urban or Built-up Area in 2000 was 324.4ha more than that in 1988. 3) Waters expanded by 3476.51ha. 4) Woodland and Grassland decreased, while Barren Land increased by 3824.9ha. The total amount of land use/land cover change between 1988 and 2000 is small,which is only 0.355% of the total area. It shows that the developmental pace of the lower reaches of the Tarim River is relative slow. Based on these results, the authors assessed the landscape dynamics of this region and pointed out that the degree of desertification was strengthened and the landscape dominated by sand land was further characterized by salt desert.

Characteristics of Wind Erosion and Deposition in Oasis-desert Ecotone in Southern Margin of Tarim Basin,China

The oasis-desert ecotone is a fragile ecological zone that is affected both by oasis and desert conditions. To understand the impact of the differences in wind power, and the influence of wind erosion and deposition on the ecotone, meteorological data and con- temporaneous wind erosion and deposition data were collected on the southern margin of Tarim Basin with serious sand-blown hazards. The wind velocity, average wind velocity, sand drift potential （DP）, resultant sand drift potential （RDP）, and sand transportation rate decrease significantly and successively across four landscape types with increasing vegetation coverage （VC）. Flat surfaces and areas of shifting sandy ground experience intense wind erosion with fast movement of mobile sand dunes; semi-fixed sand areas experience ex- tensive wind deposition but only slight wind erosion; and fixed sand areas experience only slight wind erosion and deposition. Volume of wind erosion on bare newly reclaimed farmland is up to 6.96 times that of bare shifting sandy ground. Wind erosion volume per unit area and VC follow an exponential function relationship in natural conditions, while wind deposition volume per unit area does not conform to any functions which has close relationship with vary topography and arrangement patterns of vegetation besides for VC. The results indicate that the volume of wind erosion has a close correlation with VC, and different types and distribution patterns of topog- raphy and vegetation also profoundly influence the wind deposition volume in the field, and underground water tables in different land- scape types control the plant community distribution. Keywords： wind erosion; wind deposition; oasis-desert ecotone; vegetation coverage （VC）; topography; Cele County

The effect of slight to minor biodegradation on C_6 to C_7 light hydrocarbons in crude oils: a case study from Dawanqi Oilfield in the Tarim Basin,NW China

Light hydrocarbons （LHs） are one of the main petroleum fractions in crude oils, and carry much infor- mation regarding the genetic origin and alteration of crude oils. But secondary alterations--especially biodegrada- tion--have a significant effect on the composition of LHs in crude oils. Because most of the LHs affected in oils underwent only slight biodegradation （rank 1 on the biodegradation scale）, the variation of LHs can be used to describe more the refined features of biodegradation. Here, 23 crude oils from the Dawanqi Oilfield in the Tarim Basin, NW China, eleven of which have been biodegraded to different extents, were analyzed in order to investigate the effect of slight to minor biodegradation on C6--C7 LHs. The study results showed that biodegradation resulted in the prior depletion of straight-chained alkanes, followed by branched alkanes. In slight and minor biodegraded oils, such biodegradation scale could not sufficiently affect C6- C7 cycloalkanes. For branched C6--C7 alkanes, generally, monomethylalkanes are biodegraded earlier than dimethylalkanes and trimethylalkanes, which indicates that branched alkanes are more resistant to biodegradation, with the increase of substituted methyl groups on parent rings. The degree of alkylation is one of the primary controlling factors on the biodegradation of C6-Cv LHs. There is a particular case： although 2,2,3-trimethylbutane has a rela- tive higher alkylation degree, 2,2-dimethylpentane is more resistant to biodegradation than 2,2,3-trimethylbutane. 2,2- Dimethylpentane is the most resistant to biodegradation in branched C6-C7 alkanes. Furthermore, the 2-methylpen- tane/3-methylpentane and 2-methylhexane/3-methylhexane ratios decreased steadily with increasing biodegradation, which implies that isomers of bilateral methyl groups are more prone to bacterial attack relative to mid-chain iso- mers. The position of the alkyls on the carbon skeleton is also one of the critical factors controlling the rate of biodegradation. With increasing biodegradation, Mango＇s LH parameters K1 values decrease and K2 values increase, the values of n-heptane and isoheptane decrease, and the indices of methylcyclohexane and cyclohexane increase. LH parameters should be applied cautiously for the biodegraded oils. Because biodegraded samples belong to slight or minor biodegraded oils, the values of n-heptane and isoheptane from Dawanqi Oilfield can better reflect and determine the ＂Biodegraded＂ zone. When the heptane value is 0-21 and the isoheptane value is 0-2.6, the crude oil in Dawanqi Oilfield is defined as the ＂Biodegraded＂ zone

Application of sequence stratigraphy to Triassic terrestrial strata in Tahe area of Tarim Basin

Based on a synthetic geological study of drilling,well logging and seismic data,core observations and geochemical analysis,it is recognized that Triassic sedimentary facies in the Tahe area of Tarim Basin include braided river deposits filling erosional valleys,and sublacustrine fan,canyon and delta facies.Braided river deposits filling erosional valleys are dominated by coarse-grained lithic quartz sandstone with oblique bedding,and represent the most important sedimentation type of sandstone in the study area.Sublacustrine fan and canyon facies are mainly distributed in the Middle Oil Member.Most delta sediments are deposited in highstand system tract(HST),Because of frequent changes in base level,delta sediments are commonly eroded and rarely preserved.Sedimentary cycles are clearly reflected by lithology,sedimentary structures and well logging data,and are closely related to the changes in lacustrine level.In accordance with the basic principle of sequence subdivision,seven type-I boundaries can be recognized in Triassic strata and six type-I sequences are subdivided correspondingly.In general,lowstand system tract(LST) is well developed within stratigraphic sequences and forms the main body of reservoir sandstone in this area;highstand system tract(HST) and transgressive system tract(TST) are often eroded by upper sequences or missed,Although various factors have different influences on terrestrial sequence stratigraphy,the classical sequence stratigraphy theory proposed by VAIL can be applied to terrestrial strata.

Forming mechanism of hydrocarbon reservoirs in Yingshan Formation of Yuqi block in Akekule arch,Tarim Basin

The reservoir conditions,oil and gas charge history and accumulation phases were studied for Yingshan Formation of Yuqi block,and an oil and gas accumulation model was established by using the techniques of reservoir prediction,fluorescence thin section and fluid inclusion analysis under the guidance of the theories of oil and gas accumulation.The results indicate that the main rock types in Yingshan Formation are micrite and calcarenite.The carbonate reservoirs are of cave,fracture-pore and fracture types,and their physical properties are intermediate;there are at least four oil/gas charges,i.e.late Hercynian,Yanshanian,early Himalayan and middle Himalayan(Cenozoic).The most important charge periods are late Hercynian,early Himalayan and middle Himalayan;the oil and gas accumulation model is self source-lateral expulsion of hydrocarbon-multistage accumulation,or hydrocarbon sourced from and preserved in the same old rocks-long term expulsion of hydrocarbon-multistage accumulation.

Spatio-temporal Variability of Soil Water at Three Seasonal Floodplain Sites: A Case Study in Tarim Basin,Northwest China

The floodplain -egetation of the Tarim River in Northwest China is strongly influenced by irrigated agriculture. The abstrac- tion of river water disturbs; the natural dynamics of the floodplain ecosystem. The human impact on the hydrological system by bank dams and the irrigation of cotton plantings have caused adverse changes of the Tarim River and its floodplains, so the current stocks of the typical Tugai vegetation show significant signs of degradation. Field studies of soils and statistical analysis of soil moisture data have shown that the vitality of the Tugai vegetation is primarily determined by its position to the riverbank and the groundwater. There exist complex interactions between soil hydrological conditions and the vitality of the vegetation. But the availability of water is not only influenced by the groundwater level and seasonal flood events. The spatial distribution of stocks at different states of vitality seems also to be decisively influenced by physical soil properties. Our results show that the water supply of plant communities is strongly in- fluenced by the soil texture. Spatial differences of soil moisture and corresponding soil water tensions may be the decisive factors for the zonafion of vegetation. Physical soil properties control the water retention and rising of capillary water from deeper soil layers and the phreatic zone and may supply the root systems of the phreatophytic vegetation with water. Keywords： soil moisture;soil texture; soil water tensions; Tarim River; water retention

Dual influence of the rejuvenation of Southern Tianshan and Western Kunlun orogen on the Cenozoic structure deformation of Tarim Basin,northwestern China:A superposition deformation model from Bachu Uplift

Based on new high-resolution seismic profiles and existing structural and sedimentary results, a superposition deformation model for Cenozoic Bachu Uplift of northwestern Tarim Basin, northwestern China is proposed. The model presents the idea that the Bachu Uplift suffered structure superposition deformation under the dual influences of the Cenozoic uplifting of Southern Tianshan and Western Kunlun orogen, northwestern China. In the end of the Eocene （early Himalayan movement）, Bachu Uplift started to be formed with the uplifting of Western Kunlun, and extended NNW into the interior of Kalpin Uplift. In the end of the Miocene （middle Himalayan movement）, Bachu Uplift suffered not only the NNW structure deformation caused by the Western Kunlun uplifting, but also the NE structure deformation caused by the Southern Tianshan uplifting, and the thrust front fault of Kalpin thrust system related to the Southern Tianshan orogen intrudes southeastward into the hinterland of Bachu Uplift and extends NNE from well Pil to Xiaohaizi reservoir and Gudongshan mountain, which resulted in the strata folded and denuded strongly. In the end of the Pliocene （late Himalayan movement）, the impact of Southern Yianshan orogen decreased because of the stress released with the breakthrough upward of Kalpin fault extending NE, and Bachu Uplift suffered mainly the structure deformation extending NW-NNW caused by the uplifting of Western Kunlun orogen.

Hydrocarbon charging histories of the Ordovician reservoir in the Tahe oil field, Tarim Basin, China

The Ordovician reservoir of the Tahe oil field went through many tectonic reconstructions, and was characterized by multiple hydrocarbon chargings. The aim of this study was to unravel the complex charging histories. Systematic analysis of fluid inclusions was employed to complete the investigation. Fluorescence observation of oil inclusions under UV light, and microthermometry of both oil and aqueous inclusions in 105 core samples taken from the Ordovician reservoir indicated that the Ordovician reservoir underwent four oil chargings and a gas charging. The hydrocarbon chargings occurred at the late Hercynian, the Indo-Sinian and Yanshan, the early Himalaya, the middle Himalaya, and the late Himalaya,respectively. The critical hydrocarbon charging time was at the late Hercynian.

THE IMPACT OF HUMAN ACTIVITIES ON GROUNDWATER RESOURCES IN THE SOUTH EDGE OF TARIM BASIN, XINJIANG

In the modern times, the population growth, development of industrial andagricultural production and the petroleum exploitation, brought about the unceasing expansion ofartificial oasis and abrupt increase of water demand. The artificial hydraulic irrigationengineering took the place of the natural river system, the reservoirs took the place of naturallakes, which in turn enhanced the space-time redistribution of surface water based on the naturalevolution, and so did groundwater: The groundwater recharge reduced 26. 2% in 46 years from 1950 to1995 in the southern piedmont flood plain of Tarim Basin due to mean yearly population increase rateof 27. 7 per thousand and associated with the water use rate increasing from 24. 6% to 58. 4%. Atthe same time the artificial water system seepage give primary play to groundwater recharge, whichis up to 57. 6% whilst that of the natural system reduce to 33.7%. As a result, groundwater leveldrop 3 - 5m widespread except some irrigation area and surroundings of plain reservoir. Spring waterdischarge also reduce about 37. 6% and discharge zone continuously move away to the north with thevalue of 0. 5 - 1. 2km in the past 40 years.

DH1井试井资料早期评价

以塔里木盆地塔北隆起中段背斜构造上的一口DH1予探井为例,介绍了用试井资料,结合有关资料,对所测试层段进行了较全面的解释评价,如地层参数计算、动储量计算和动态予测。并且用均质理论模型对解释结果进行检验,利用节点分析有关曲线提出该井的射孔孔密、油管内径、油管长度的建议,以期达到最佳的开采条件。

Braid-Delta Deposits from a Broad Shallow-Marine Setting: the Middle Member of the Kalpingtag Formation in the Central Tarim Basin

During the early Silurian, a transgressive and vast shallow sea with flat sea-floor covered the central Tarim Basin (the Tazhong area). The depositional environment of the middle member of the Kalpingtag Formation is controversial. In order to provide a basis for the prediction of reservoir sand, the sedimentary facies are recognized according to abundant core observations and de- scriptions combined with well-log analysis, isograms, seismic interpretations and regional sedimentary background. The middle member of the Kalpingtag Formation, which shows a retrograding sequence, is interpreted as braid-delta deposits influenced by mi- nor tidal reworking. The sources of clasts are from the southern uplift. The subaqueous braid-delta deposits in the study area have some characteristics quite different from the common deltas that generally deposit in marginal seas. Four facies grouped to a delta front association are recognized, ranging from distributary-channel (Facies A), front bar (Facies B), sand sheet (Facies C) and inter- distributary bay (Facies D). The distributary channels construct the sandbody framework of the delta front. Front bar deposits, which are fine-grained with low depositional dips, display a near-continuous sand strip around the entire periphery of the delta. Sand sheet deposits are mainly found in front of Facies B, gradationally contacting with the prodelta. The interdistributary bay is essentially the uppermost unit capping the channel sequence and generally made up of laminated and massive mudstones. The delta front deposits display extensive sheet-like bodies contrasting with the characteristic wedge shapes of common subaqueous delta bodies. The bi- modal cross-stratification and mud drapes in the fine- to medium-grained sandstone in the distal area are inferred to reflect high-energy tidal processes.

The complex nonlinear systems with fractal as well as chaotic dynamics of annual runoff processes in the three headwaters of the Tarim River

This paper attempted to identify fractal and chaotic characteristics of the annual runoff processes in headwaters of the Tarim River.Methods of fractal analyses were used to explore several aspects of the temporal changes from 1957 to 2002.The main findings are as follows:(1) The annual runoff processes of the three headwaters of the Tarim River are com-plex nonlinear systems with fractal as well as chaotic dynamics.(2) The correlation dimensions of attractor derived from the time series of the annual runoff for the Hotan,Yarkand and Aksu rivers are all greater than 3.0 and non-integral,implying that all three rivers are chaotic dynamical systems that are sensitive to initial conditions,and the dynamic modeling of their annual runoff process requires at least four independent variables.(3) The time series of annual runoff in each river presents a long-term correlation characteristic.The Hurst exponent for the period of 1989 to 2002 suggests that we may expect to see an increasing trend in the annual runoff of the Aksu and Yarkand rivers in the years after 2002,but a decreasing tendency for the Hotan River in the same period.

Sediment record of environmental change at Lake Lop Nur (Xinjiang, NW China) from 13.0 to 5.6 cal ka BP

Lake Lop Nur is located in the eastern part of the Tarim Basin in Xinjiang,northwestern China.A 220-cm-long sediment core was collected from the center of the ear-shaped depression forming the basin and dated with AMS^(14)C.Grain size,total organic matter(TOC),total nitrogen(TN),and TOC/TN(C/N)analyses were used to reconstruct climatic conditions from 13.0 to 5.6 cal ka BP.The results showed fi ve main climatic stages.Zone I(13.0–11.3 cal ka BP)was a wet–dry environment,whereas Zone II(11.3–8.9 cal ka BP)consisted of a primarily wet environment.Zone III(8.9–7.7 cal ka BP)was subdivided into Zone IIIa(8.9–8.2 cal ka BP)that indicated lake constriction and dry climate,and Zone IIIb(8.2–7.7 cal ka BP)in which the proxies indicated wet conditions.In Zone IV(7.7–6.6 cal ka BP),the climate presented a bit wet conditions.In Zone V(6.6–5.6 cal ka BP),abundant glauberite is present in the sediment and silt dominates the lithology;these results indicate the lake shrank and the overall climate was dry.Abrupt environmental events were also identifi ed,including six dry events at 11.0,10.5,9.3,8.6,8.2,and 7.6 cal ka BP and one fl ood event from 7.8 to 7.7 cal ka BP in the Early–Middle Holocene.

The Maximum Ice Age Glaciation between the Karakorum Main Ridge (K_2) and the Tarim Basin and its Influence on Global Energy Balance

A modern research approach and working techniques in hitherto unexamined areas, produced the following results: 1). The tongues of deca- kilometre long Karakorum glaciers belong to temperate ice-streams with an annual meltwater output. The short Aghil glaciers on the contrary are continental, arid and cold. 2). The present-day oscillations of the Karakorum glaciers are related to their own mass, and are contrary to and independent of the actual climate. Only the short glaciers, with steep tongue fronts, show a present-day positive balance. 3). C- dated Late Glacial moraines indicate14 a 400~800 m thick valley glacier at the former confluence point of the K2-, Sarpo Laggo- and Skamri glaciers. 4). From the evidence of transfluence passes with roches moutonnées, striae and the limits of glacial polishing, as well as moraines and erratics, a High Glacial at least 1200 m thick ice-stream network between the Karakorums and the Kuen Lun north slopes was reconstructed. The Shaksgam and Yarkand valleys were occupied by glaciers coming from west Tibet. The lowest-lying moraines are to be found in the foreland down to 2000 m, indicating a depression of the High Glacial (LGM) snowline (ELA) by 1300 m. 5). The approximately 10,000 measurements of the radiation balance at up to heights of 5500 m on K2 indicate that with incoming energy near the solar constant the reflection from snow- covered ice is up to 70% greater than from rock and rock waste surfaces. 6).These results confirm for the very dry western margins of Tibet an almost complete ice sheet cover in an area with subtropical energy balance, conforming with the Ice Age hypothesis of the author which is based upon the presence of a 2.4 million km2 Tibetan inland ice sheet. This inland ice developed for the first time when Tibet was uplifted over the snowline during the early Pleistocene. As the measured subtropical radiation balance shows, it was able to trigger the Quaternary Ice Ages.

Desertification and Blown Sand Disaster in China

Approximately 331 million ha, one-third of China＇s total land, is prone to desertification processes, leading to natural disasters and economic losses. In this study, the situation, tendency, their influences and their risk governance of desertification and blown sand disaster in China were examined using satellite images, field photographs, field data and a literature review. The desiccated areas in Lop Nor and the lower Heihe River fluvial plain covered about 50,000 km2 and 40,000 km2, respectively. In Ejina, about 100 species of vegetation became extinct. The rate of wind erosion in China was between 1,000 tons/km2/year and 2,000 tons/km2/year. There were 12 sand deserts and sandy lands, occupying a total of 710,000 km2. Salinized soils occurred across 99.1 million ha. The two main sand and dust storm-prone areas in China were the Tarim Basin and its surroundings, and the Alxa Plateau and its surroundings. From 1981 to 2007, the annual average frequency of sand and dust storms varied from 1 d to 37 d with a general increase from southeast to northwest. Since 1978, China has implemented a number of ecological construction projects that have reduced desertification from 1999 to 2004 and from 2005 to 2009, and the number of dust and sand storm days from 9.3 d between 1954 and 1959 to 4.4 d between 2000 and 2007. The results could improve understanding of desertification and blown sand disasters in China and provide valuable experiences for global desertification control.

Reservoir characteristics of Donghe well No.1 in Tarim Basin

Based on the techniques of X-ray diffraction analysis, identification of the thin sections of core cast, phys- ical analysis and scanning electron microscopy analysis, this paper studied the reservoir characteristics of the Carboniferous strata in Donghe well No.1 of Tarim region. The results show that the reservoir lithology is mainly the fine-grained quartz sandstone with ferrocalcite and pyrite, mud cement-based, the permeability concentrated in 5-40 × 10-3 μm2, a small part of the high permeability up to 150-327 ×10-3 μm2 and porosity ranged from 10% to 20%. The most part of the reservoirs is low perme- ability with a small part of the layer in moderate-high permeability. The types of reservoir space include intergranular pores, intra particle-molding pores, micro-pores and cracks, which mainly are intergranular pores with the pore diameter of 15-200 μm, 95.5μm on average. And the types of the throats are comolex with the main tvne of constricted l：hroats in this area and large contribution to the permeability.

Permian sequence stratigraphy of shallow water basin in Tarim Basin

Based on analysis of drilling, logging and field profile data, six sequence boundaries in Permian are identified in Bachu and Tazhong regions of Tarim Basin. All sequence boundaries are of type I sequence bound- aries, and are characterized by down cut. According to the six sequence boundaries, the Permian in this area can be divided into 5 third-order sequences, and all the sequences correspond with classic sequence model of Vail. Sequence Psq4 indicates lake transgressive system tract （TST） and highstand system tract （HST）. Se- quences Psql, Psq2, Psq3, Psq5 indicate low stand system tract （ LST）, transgressive system tract and high- stand system tract. LST is deposited by incised channel infilling with features of fluvial facies. TST is deposited by shore-shallow lake and semi-deep lake. HST is deposited by semi-deep lake, shore-shallow lake and delta. In addition, volcanic rocks are present on the top part of HST in sequence Psq3. Incised channel infilling and deltaic deposits were mainly distributed on western slope of Tadong uplift.

Geological characteristics and shale gas distribution of carboniferous mudstones in the Tarim Basin,China

Extant research on Paleozoic mudstone is well developed in the Tarim Basin, while the research on Carboniferous mudstone is relatively weak. Through systematic study of lithology, geochemical characteristics,reservoir characteristics and gas–bearing properties of Carboniferous mudstone in the Tarim Basin, this study aims to provide a geological basis for the Paleozoic shale gas exploration and development, favorable zone optimization, and resource potential evaluation in the Tarim Basin. The results show that the sedimentary environments of organic-rich mudstone in the study area were mainly basin facies and slope facies. Lithology is dominated by black carbonaceous mudstone, followed by calcareous mudstone, siliceous mudstone, and siliceous rocks. Mudstone is mainly developed in the Kalashayi Formation,which is located in the Bachu and Markit slope belt, with the cumulative thickness of 30–200 m. The organic carbon content is commonly more than 0.4%, and the organic matter types are type II and type III. Thermal evolution degree is widely distributed from a low mature to over mature stage, and different tectonic units have a greater difference. The contents of quartz plus feldspar are between 12% and 82.5%, with an average of 45.8%. Thecontent distribution of clay mineral is from 12% to 57%,with an average of 38.2%. Carbonate minerals(mainly siderite) content is below 50%. The brittle mineral content of the mudstone is approximately 65%, with a strong compressibility, and the mudstone has the material basis of forming crack and natural fracture. Microscopic pores in micro–nanometer level are well developed in the mudstone, including micro bedding joint, microcrack,interbedded pores of clay mineral, nanoscale intragranular or edge pores in the massive organic matter, bioclastic micropores, and mineral dissolution pores, etc. According to the standards provided by the Ministry of Land and Resources in China, the Kalashayi Formation in Bamai Area is a favorable area for shale gas development.