Table of Content

01 January 2019, Volume 39 Issue 1 Previous Issue    Next Issue

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

Discovery, Distribution and Exploration Practice of Large Oil Provinces of Above?Source Conglomerate in Mahu Sag ZHI Dongming1a, TANG Yong1b, ZHENG Menglin1b, GUO Wenjian1b, WU Tao1b ZOU Zhiwen2 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180101 Abstract ( 223 )   PDF (300KB) ( 497 )   Save Combining the data of geophysics, geology and drilling, the paper systematically summarizes the discovery process of large oil provinces in Mahu Sag. Based on reservoir dissection and the study of reservoir?cap assemblages in the upper Wuerhe formation and Baikouquan formation, the reservoir forming model has been perfected, which could guide the overall breakthrough of Baikouquan formation and upper Wuerhe formation in sedimentary fans of Xiazijie, Karamay, Zhongguai and Xiayan, and 2 large oil provinces such as Baikouquan formation in the northern Mahu sag and the upper Wuerhe formation in the southern Mahu sag have been discovered. It is considered that the favorable conditions of large oil province forming in Mahu sag consist of the large?scaled slope tectonic setting during the deposition of the upper Wuerhe formation and Baikouquan formation, the high?quality alkalin?lacustrine source rocks in the Lower Permian Fengcheng formation, the continuous superimposed conglomerate bodies distributed on the 2 unconformity surfaces and the high?steep faults and so on. Based on which, a new hydrocarbon accumulation model of lithological reservoir groups which is made up of multistage retrogradational conglomerate bodies in large and continuous distribution is established. The discovery of the large oil provinces and the establishment of the hydrocarbon accumulation model in Mahu sag can provide guidance and references for the exploration in the strata of Middle Permian and deep Carboniferous?Lower Permian in this area Related Articles | Metrics

Basic Characteristics and Highly Efficient Hydrocarbon Generation of Alkaline?Lacustrine Source Rocks in Fengcheng Formation of Mahu Sag WANG Xiaojun1, WANG Tingting2, CAO Jian2 2018, 39 (1):  1-1.  doi: 10.7657/XJPG201801002 Abstract ( 168 )   PDF (300KB) ( 374 )   Save Ancinet alkaline?lacustrine source rocks have been recently discovered in the Lower Permian Fengcheng formation of the Mahu sag in the northwestern margin of Junggar basin. To improve the theory of hydrocarbon generation for this special type of source rocks, the paper studies the basic characteristics of the alkaline?lacustrine source rocks. The compositions of Fengcheng formation are very complicated and dominated by the mixtures of terrigenous debris, carbonates and volcanic materials, which is called alkaline?lacustrine dolomitic diamictite. The bio?precursor of the Fengcheng source rock is characterized by algae and bacteria, the bacterial activity increases with the increase of alkalinity of depositional environment. As a result, the content of organic matter in altered armorphous bodies increases. The organic matter richness of the Fengcheng source rocks has reached moderate to good quality and the kerogen type of the rock is mainly Type I to II1, indicating good hydrocarbon generation potential. The second member to third member of Fengcheng formation form a complete alkali evolution cycle. The second member of Fengcheng formation has reached the peak of the alkali evolution, during which carbonate content is the highest, the bio?precursors are almost amorphous bodies with great hydrocarbon generating potential. The hydrocarbon generation of the source rock is characterized by multistage and high efficiency，with the hydrocarbon generation ratio being almost two times as much as conventional lacustrine source rocks， which lays a foundation for the formation of the 2 "hundred?mile" oil zones in the northwestern margin of Junggar basin and still indicates great exploration potential in the future Related Articles | Metrics

Sedimentation Model and Exploration Significance of Large?Scaled Shallow Retrogradation Fan Delta in Mahu Sag TANG Yong1, XU Yang2, LI Yazhe2, WANG Libao2 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180103 Abstract ( 127 )   PDF (300KB) ( 635 )   Save The upper Wuerhe formation of Permian and Triassic Baikouquan formation in Mahu sag and its adjacent areas are a set of near?source coarse deposits under the background of depression basin that are large?scaled shallow retrogradation fan?delta deposits under the background of gentle slope, and 13 lithofacies and 7 sedimentary microfacies are identified based on core observation. Multiple fan deltas are developed on the slope of the sag, and the fan bodies connect with each other. The formation of this kind of large?scaled shallow retrogradation fan delta is closely related to 3 geological conditions. The first is that continuously uplifting periphery ancient mountains and stable river systems provided sufficient provenance for each fan during deposition; the second is that there was a good paleogeographic background such as large basin, shallow water and gentle slope; the third is that continuous lake transgression and multi?stage slope?break are significant conditions for large?sized superposition and merging of sand bodies. A sedimentary model of large?scaled shallow retrogradation fan delta is established, which provides guidance for petroleum prospecting and reserves estimation in Mahu sag Related Articles | Metrics

Hierarchical Architectural Element Analysis for Sandy Conglomerate Deposits of Baikouquan Formation, Mahu Sag ZHANG Changmin, LIU Jiangyan, PAN Jin, ZHU Rui 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180104 Abstract ( 71 )   PDF (300KB) ( 50 )   Save Enormous petroleum resources have been discovered in the Lower Triassic Baikouquan formation of Mahu sag, Jungaer basin since the year of 2010, but reservoir evaluation and efficient development are difficult due to the complicated internal structure and serious reservoir heterogeneity of the sandy conglomerate in Baikouquan formation, so profound analyses on sedimentary genesis and architectural structure of the sandy conglomerate are needed. The paper utilizes hierarchical architectural element analysis method to delineate the architectural structure of the sandy conglomerate in Baikouquan formation of Mahu sag. Based on the detailed description of cores of 1,922 m long obtained from 82 wells, the paper presents a multi?attribute lithofacies denomination program which is dominated by 4 attributes i.e., rock grain size, sedimentary structure, color and grain support mode and 227 lithofacies are identified in the sandy conglomerate of Baikouquan formation. According to core, logging and seismic data, depositional interfaces of 11 orders are classified in the studied interval and architectural structural elements of 11 orders are identified correspondingly, and the corresponding architectural structural elements with lithofacies and sedimentary microfacies are analyzed. Taking the 9th order architectural structural element as a basic unit, the evolution processes of the sedimentary systems in Huangyangquan fan and Xiazijie fan are characterized through well?tie correlation constrained by seismic data. It is considered that the Baikouquan formation in both Huangyangquan fan and Xiazijie fan belongs to coarse?grain sandy conglomerate deposits and takes river as the main transportation force. The depositional system of Huangyangquan fan is of relatively small scale and has more characteristics of alluvial fans and fluvial fans; the depositional system of Xiazijie fan is of large scale and has more characteristics of river fans. From the first member to the third member of Baikouquan formation, the depositional system gradually changed from alluvial and fluvial fans to fan delta with the rise of water level of lake. Medium?fine conglomerate with low content of matrix is good lithofacies, seasonal channel deposits and underwater distributary channel deposits are favorable sedimentary microfacies, the second member of Baikouquan formation is the most favorable interval for oil accumulation Related Articles | Metrics

Tectono-Depositional Setting and Its Evolution during Permian to Triassic around Mahu Sag, Junggar Basin HE Dengfa1, WU Songtao1, ZHAO Long2, ZHENG Menglin2, LI Di1, LU Yu1 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180105 Abstract ( 145 )   PDF (300KB) ( 114 )   Save Mahu sag in Junggar basin is proved to be rich of oil and gas, and famous for its Permian and Triassic oil and gas pools in sandy conglomerate fans. To discuss the tectono?depositional setting for the development of fan bodies is an important clue to explore the coupling among the tectonic, the climatic, and the geomorphic processes, is a foundation for appraisal of petroleum exploration potential, and an accelerator for petroleum exploration and development. Based on the newly-acquired drilling and geophysical exploration data, the paper is to disclose the tectono?depositional setting during Permian to Triassic Period from a point of view of sedimentary source to sink concept. The study result shows that the Mahu sag is a depression of Carboniferous to Quaternary built upon the pre?Carboniferous folded basement. The Permian to Triassic saw its dominant period of sedimentary filling, and underwent such evolution processes as the post?orogenic extension during Late Carboniferous to Early Permian, the compression and thrusting during Middle Permian to Middle Triassic, and intra?cratonic depression in Late Triassic, during which alluvial fan, fan delta, and lake sedimentary systems were mainly developed. The episodic and breaking?forward thrusting, the priority transportation pathways made up of tear faults and lateral transfer zones and the arid environment controlled the large?scale fan delta systems in and around Mahu sag. It is an integrated petroliferous system with the Fengcheng formation mudstones in the extensional alkaline lacustrine facies as the excellent hydrocarbon source, the overlying fan deltas as the favorable reservoirs, and the Upper Triassic thick mudstone as the regional cap rock. The Mahu sag is of great potential for oil and gas, and has a board prospect for multi-layer stereoscopic exploration Related Articles | Metrics

Tectonic Setting and Environment of Alkaline Lacustrine Source Rocks in the Lower Permian Fengcheng Formation of Mahu Sag ZHANG Yuanyuan, LI Wei, TANG Wenbin 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180106 Abstract ( 176 )   PDF (300KB) ( 312 )   Save Mahu sag is one of the most prolific oil?gas sags in the Junggar basin. The high?quality lacustrine source rocks in the Lower Permian Fengcheng formation are considered as the oldest alkaline lacustrine deposits, which provides the resource foundation for the formation of hundreds of miles oil province in northwestern margin of Junggar basin. Based on the investigations of regional geology, sedimentology, mineralogy and petrology, Fengcheng formation is inferred to be developed in the post-orogenic extensional fault depression which is found on the Paleozoic basement in the western Junggar basin. The formation is overall a set of fan delta?lacustrine deposits with the depocenter in the center of Mahu sag. Abundant alkaline minerals are observed in the Fengcheng formation, including reedmergnerite, northupite, shortite, searlesite, eitelite, wegscheiderite and nahcolite etc., which indicates a representative alkaline lacustrine facies with high salinity, distinct from other common saline-lake deposits. The presence of shortite, wegscheiderite, reedmergnerite and searlesite confirms that the alkaline lacustrine source rocks of the Fengcheng formation were deposited in a closed and high salinity lacustrine environment highly effected by deep hydrothermal fluids, not due to evaporation, which is also strongly associated with volcanic activities under the extensional fault depression setting Related Articles | Metrics

Diagenesis in Alkaline Environment and Its Influences on Reservoir QualityA Case Study of Middle-Lower Permian Clastic Reservoirs in Northwestern Margin of Junggar Basin SHAN Xiang, GUO Huajun, ZOU Zhiwen, LI Yazhe, WANG Libao 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180107 Abstract ( 62 )   PDF (300KB) ( 138 )   Save Based on the data of cast thin section, SEM, Electronic probe, X-ray diffraction and petrophysical properties etc., the paper detailedly studies the petrologic features and diagenesis of the Middle-Lower Permian clastics in the northwestern margin of Junggar basin, based on which, the influence of the diagenesis in alkaline environment on accumulative properties of reservoirs is discussed. The results show that the diagenesis in alkaline environment is commonly noted in the Middle-Lower Permian strata, such as tephra hydrolysis, tephra albitization, formation of zeolites and chlorite and so on. Various associated pores including alkaline dissolved pore of tephra, albitized associated pore and intercrystalline micropore in clay minerals are developed in alkaline environment. The influences of diagenesis in alkaline environment on the Middle-Lower Permian clastic reservoirs mainly include strong impaction of reservoir fluids resulted from alkaline fluids, i.e., high reservoir compaction ratio in alkaline fluids, which is unfavorable for primary pore preservation; high authigenic mineral content of reservoir under the diagenesis in alkaline environment and local cementation with large pore reduction amounts; high pore increase efficiency due to the corrosion of alkaline fluid. Alkaline dissolved pore in tephra can be the important accumulation space Related Articles | Metrics

Rock Mechanical Characteristics and Fracture Propagation Mechanism of Sandy Conglomerate Reservoirs in Baikouquan Formation of Mahu Sag LIU Xiangjun1, XIONG Jian1, LIANG Lixi1, YOU Xincai2 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180108 Abstract ( 110 )   PDF (300KB) ( 397 )   Save Taking the rock of the sandy conglomerate reservoirs of Baikouquan formation in Mahu sag as the study objects, the mechanical characteristics and fracture propagation mechanism of the sandy conglomerate reservoirs with different lithologies are studied through various rock mechanical experiments. Based on which, a 2D model containing true gravels is established by using numerical modeling method, the dynamic process of fracture propagation in the sandy conglomerate are investigated, and the influence of gravel strength on fracture propagation mechanism is discussed. The results indicate that rock mechanical parameters of the sandy conglomerate are seriously heterogeneous, resulting in the obvious differences of mechanical characteristics in sandy conglomerates with different lithologies, among which the mechanical strength of fine conglomerate is higher than that of coarse conglomerate; the differences between gravel and matrix compositions have significant influence on rock mechanical characteristics of the sandy conglomerate; the failure mode of the sandy conglomerate is dominated by splitting failure in uniaxial compression and that is dominated by splitting failure, single shear failure and dual shear failure etc. in triaxial compression; gravel particles have shielding effect on the extension of fractures and the fracture propagation during rock failure process in the sandy conglomerate mainly contains 3 types such as going?through gravel, bypassing gravel and embedded in gravel. The strength of gravels and the matrix reflects the mechanical properties of glutenite. The larger the strength difference between gravel and matrix is, the stronger the shielding effect of the gravels is, the stronger the received resistance of fracture will be, causing that the fracture propagation would transfer from going through gravel to bypassing gravel Related Articles | Metrics

Lower Limits of Reservoir Physical Properties and Controlling Factors of Baikouquan Formation in the Northern Slope of Mahu Sag GUO Huajun, SHAN Xiang, LI Yazhe, ZOU Zhiwen, WANG Libao 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180109 Abstract ( 96 )   PDF (300KB) ( 244 )   Save Based on the comprehensive application of the data on formation test, core analysis and logging interpretation, the low limits of physical properties of effective sandy conglomerate reservoirs in the Lower Triassic Baikouquan formation of the northern slope of Mahu sag are determined by using the distribution function curve method and formation test method, and regression analysis method is used to match the lower limits of physical properties with depth. Based on which, lithofacies, sedimentary microfacies and diagenesis are analyzed by using the differences of reservoir physical properties. The results show that the lower limits of effective reservoir physical properties exhibit a trend of gradual decrease with the increase of depth in the study area; the development of effective reservoirs is mainly controlled by sedimentary microfacies and lithofacies, and weakly influenced by diagenesis. Microfacies of underwater distributary channel and braided channel are the most favorable areas for effective reservoir development, and tabular cross?bedding and trough cross?bedding are the most favorable lithofacies for effective reservoir development; the sandy conglomerate in the study area is mainly in the A stage of the middle diagenetic period, the secondary pores result from feldspar dissolved by organic acid which is liberated from thermal evolution of organic matter, which can improve reservoir physical properties, the effective reservoirs with the diagenetic faices of weak?compaction?weak?corrosion and unstable component corrosion are the most developed Related Articles | Metrics

Hydrocarbon Accumulation Model of Lithological Reservoirs in Baikouquan Formation of Wellblock MH?1 on the Southern Slope of Mahu Sag WU Jun, BAI Yu, YU Xing, REN Benbing 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180110 Abstract ( 86 )   PDF (300KB) ( 216 )   Save The controlling factors of hydrocarbon accumulation in the Lower Triassic Baikouquan formation of Wellblock MH-1 on the southern slope of Mahu sag are very complicated. Inverse oil-water relations of oil and gas zones located on the lower structural positions and aquifers located on the higher structural positions, unclear reservoir controlling factors and undefined reservoir forming rules are the bottleneck problems constraining petroleum exploration in the area. The distributions of main channels of fan body, facies boundary and subfacies of fan delta front are determined based on the detailed study on paleogeomorphology. The spatial distribution of good quality reservoirs are predicted by using pre?stack elastic parameter inversion. 5 period superimposed sand bodies with poor lateral connectivity developed in the Baikouquan formation of Wellblock MH?1 forms a lithological trap group. The SW trending reverse fault was the main path for primary oil and gas migration during the late Indosinian movement. A hydrocarbon accumulation model of “ one sand body is one reservoir” is established for the Baikouquan formation in Wellblock MH-1, the distribution of favorable accumulation area is predicted and breakthrough has been gained in the 2 appraisal wells, which can verify the model and provide theoretical guidance for further petroleum exploration in the wellblock Related Articles | Metrics

Diagenesis and Diagenetic Facies of the Reservoir in the Lower Wuerhe Formation of Eastern Mahu Sag XU Lin, CHANG Qiusheng, ZHANG Ni, WANG Wei, ZHU Tao 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180111 Abstract ( 100 )   PDF (300KB) ( 288 )   Save Based on the analysis of core, rock thin section, cast thin section, SEM and X-ray diffraction data, it is considered that the diagenesis of the lower Wuerhe formation of Middle Permian in the eastern Mahu sag includes compaction, cementation and dissolution, among which compaction and cementation resulted in poorer petrophysical properties, and the dissolution, especially the dissolution of feldspar and laumontite allowed the improvement of the reservoir physical properties. The comprehensive analysis of type and evolution of the diagenesis shows that the diagenetic evolution of the lower Wuerhe formation is mainly at the Stage A of middle diagenesis period in the study area, partial reservoirs with relatively large burial depth are at Stage B of middle diagenesis period or at Stage A of late diagenesis period. According to diagenesis, cement content and pore type, the lower Wuerhe formation is classified into 6 diagenetic facies such as weak compaction diagenetic facies of mud-poor medium-coarse sandstone—fine conglomerate, dissolution diagenetic facies of analcite—laumontite?cemented medium to coarse sandstone—conglomerate, calcite?cemented diagenetic facies of shaly sandy conglomerate, weak?dissolution diagenetic facies of analcite—laumontite cemented sandy conglomerate, silicon—albite cemented diagenetic facies of dolomitic sandy conglomerate and heulandite?cemented diagenetic facies of mud?rich sandy conglomerate, among which the weak compaction diagenetic facies of mud-poor medium-coarse sandstone—fine conglomerate is the most favorable, dissolution diagenetic facies of analcite—laumontite cemented medium to coarse sandstone—conglomerate is secondly favorable and the poorest facies is heulandite?cemented diagenetic facies of mud?rich sandy conglomerate Related Articles | Metrics

Variations of Reservoir Pressure during Shale Gas Production CHEN Yixi, ZHANG Yiping, LI Bobo, SHI Zhengpu 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180112 Abstract ( 85 )   PDF (300KB) ( 166 )   Save Shale gas reservoirs are characterized by developed microfractures and complex pore structures. To study the influences of natural fractures and hydraulic fractures on reservoir pressure during shale gas production, the paper observes dynamic characteristics of reservoir pressure, considers the multi?scale effects of shale gas reservoirs, establishes a mathematical model for seepage flow of shale gas on the basis of the dual media?discrete fracture model, and uses finite element analysis method to obtain numerical solution. The result shows that during shale gas production, reservoir pressure is mainly influenced by fracture amount, aperture and connectivity status. At the early stage of shale gas production, the seepage flow of free gas in fractures is the dominant and reservoir pressure reduces significantly; at the middle and late stages of shale gas production, the adsorbed gas desorbs in the shale gas reservoir, which plays a leading role in the seepage flow, and the reservoir pressure drops slowly Related Articles | Metrics

Dynamic Pressure Characteristics of Unconventional Fractures during Multi?Staged Fracturing in Horizontal Wells WANG Jinghui1a, MEI Minghua2, LIANG Zhengzhong1a, WANG Huajun2, LIU Juan1b 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180113 Abstract ( 62 )   PDF (300KB) ( 208 )   Save To solve the problem of well test interpretation of fracture asymmetry during fracturing in the complicated strata, based on the basic theory of point source function, a mathematics model for well test interpretation of finite conductivity vertical fractures was established, then a well test interpretation model of the unconventional fracture during multi-staged fracturing in horizontal wells was obtained by using pressure drop superposition principle, and the semi-analytical solution of the model was obtained with integral transformation. The fractures were discredited numerically, and combined with the semi?analytical solution and Duhamel principle, bottom hole pressure and pressure derivative curves considering the wellbore storage and skin effects were mapped on the basis of Stehfest numerical inversion. The results showed that the model included wellbore storage stage, bilinear flow stage, early linear flow stage, first radial flow stage, second linear flow stage, transitional flow stage and systematic radial flow stage; asymmetric factor mainly had an influence on time length in the bilinear flow stage; fracture perveance mainly affected the characteristics of downhole pressure and pressure derivative curves in bilinear flow stage and early linear flow stage, and the greater the flow conductivity was, the more unobvious the characteristic of downhole pressure derivative curves in the bilinear flow stage would be Related Articles | Metrics

OVT Domain Based Prediction Technology for Low Permeability Sandy Conglomerate Reservoirs WANG Bin1,2, YIN Lu1, CHEN Yongbo1, TENG Tuanyu1, LI Dezi1 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180114 Abstract ( 89 )   PDF (300KB) ( 240 )   Save The sweet spot of the sandy conglomerate reservoir in Baikouquan formation on the eastern slope of Mahu sag, Junggar basin is characterized by serious lateral superimposition, small thickness and strong heterogeneity. It is difficult to accurately predict this kind of reservoir with conventional data. OVT domain prestack seismic attribute analysis technology which takes azimuthal anisotropy analysis as the core can fully use the geological and fluid information contained in prestack datasets and do reservoir prediction more efficiently. But due to the influences of unstable energy, unbalanced density and relatively low signal noise ratio on original OVT domain gathers, the gather quality is not very good. Therefore, the paper introduces a new method which can use dynamic analysis to find the advantageous azimuth of gathers, do stacking of partial gathers and finally improve imaging quality and resolution of seismic data. The processed seismic data is used to predict the sweet spot reservoir distribution in the eastern Mahu area. The predicted area of the sweet spot reservoir is about 140 km2, which provides basis for well deployment and reserves estimation in the eastern Mahu area Related Articles | Metrics

Using NMR Logging to Determine Fluid Properties in Low Permeability Conglomerate Reservoirs: A Case Study from the Lower Triassic Baikouquan Formation in Mahu Sag ZHANG Nia, WANG Weia, WANG Zhenlina, ZHAO Yanweib, XU Lina 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180115 Abstract ( 71 )   PDF (300KB) ( 132 )   Save The Triassic Baikouquan formation in the Mahu sag of Junggar basin are characterized by complex lithology and large variations of electrical parameters. Conventional logging methods can’t be used to effectively identify fluid properties in low permeability conglomerate reservoirs. NMR experiments show that T2 spectrum of water saturated rock sample is distributed ahead of the lateral relaxation time of 100 ms, but the actual NMR T2 spectrum of the layer at the corresponding depth is still distributed behind the lateral relaxation time of 100 ms, which reflects the signal of oil. According to the shape of the T2 spectrum and taking the lateral relaxation time of 100 ms as the marker to identify oil and water, sensitivity parameters and fluid identification chart are established. The result of fluid property identification in the reservoir of the study area by using the NMR method is consistent with the result of formation test, and good application effects has been gained during production. Related Articles | Metrics

Application of NMR Technology in Evaluation of Low Permeability Conglomerate Reservoirs :A Case Study from the Lower Triassic Baikouquan Formation in Mahu Sag MAO Rui1, XU Lin1, FANG Tao2, WANG Zhenlin1 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180116 Abstract ( 91 )   PDF (300KB) ( 548 )   Save The low permeability conglomerate reservoir in the Lower Triassic Baikouquan formation of Mahu sag, Junggar basin is characterized by complex reservoir lithology, complicated clay minerals and serious heterogeneity, so it is difficult to accurately characterize the effective porosity of the conglomerate reservoir with current logging methods. Considering that the clay mineral content is the controlling factor of reservoir physical properties, the paper uses the difference between neutron logging porosity and NMR logging porosity and clay mineral content obtained from core analysis to establish a clay mineral content characterization model; then uses clay bound water porosity and clay mineral content obtained from core analysis to establish a clay bound water porosity characterization model, based on which the effective porosity can be obtained by NMR porosity minus clay bound water porosity. The actual application of the method in 19 exploration wells in the study area shows that the relative error of effective porosity is only 6.8%, indicating that good effect has been gained by using the method, which could provide a new technological means for effective porosity evaluation with NMR logging data Related Articles | Metrics

Re-Cognition of the Jurassic Source Rocks in Sikeshu Sag CHENG Changling 2018, 39 (1):  1-1.  doi: 10.7657/XJPG20180117 Abstract ( 109 )   PDF (300KB) ( 254 )   Save The oil-source correlation shows that the oil and gas in the southern flank of Chepaizi swell in the western margin of Junggar basin are mainly from the Jurassic source rocks in the Sikeshu sag and the neighboring areas. Re-evaluation of hydrocarbon resources is significant for understanding the exploration potential of Sikeshu sag and the neighboring areas. Based on the data of outcrop, seismic and drilling, the palaeogeomorphology of the Sikeshu sag and Chepaizi swell during Jurassic sedimentary period is restored in Junggar basin, and the Sikeshu sag and Shawan sag are verified as relatively independent sedimentary units during Jurassic Period. 3 sub-sags developed in the Sikeshu sag are the favorable areas for source rock development. Based on the source rock index analysis of outcrop sample, core and cuttings and combined with seismic data, the development areas of effective source rocks are determined. The calculated hydrocarbon resources of the source rocks in Jurassic Badaowan formation of Sikeshu sag by using a differential pressure model reach 2.8 × 108 t, which provides abundant material basis for oil and gas exploration in the Sikeshu sag and the neighboring areas Related Articles | Metrics