Tahe Area Research Articles

Differential fault-fluid alterations and reservoir properties in ultra-deep carbonates in the Tarim Basin, NW China

The development of high-quality carbonate hydrocarbon reservoirs in the ultra-deep (7000–10000 m) Lower Paleozoic strata of the Tarim Basin was substantially related to tectonic evolution, strike-slip faults, and diagenetic fluids. Detailed studies of the influences of tectonic evolution and strike-slip faults on the properties of diagenetic fluids and the development mechanisms of ultradeep carbonate reservoirs under the control of both faults and fluids are required to identify high quality reservoirs. In this study, end-member geochemical indicators of meteoric water, hydrothermal fluid, and formation fluid were constructed based on typical diagenetic mineral and geochemical data obtained from representative wells. Meteoric karst associated with strong tectonic uplift was the main diagenetic event along strike-slip faults in the Tahe area. The Shunbei area was generally affected by buried formation water, and locally by weak meteoric water or hydrothermal fluids. The Tazhong, Shunnan, and Gucheng areas were predominantly affected by strong hydrothermal fluids along strike-slip faults associated with strong volcanic activity, while some wells, such as TZ12, reveal the influence of thermochemical sulfate reduction (TSR). Differences in fault fluid types and properties resulted in differential development of ultra-deep carbonate reservoirs among the different areas. In the Tahe area, meteoric water alteration along faults formed karst fracture-cavity reservoirs. In the Shunbei area, fault-cavity carbonate reservoirs were formed by strong strike-slip faults, whereas fluid alteration was weak. Hydrothermal dissolution reservoir in the Tazhong area, hydrothermal silicification reservoir in the Shunnan area, and hydrothermal dolomitization reservoir in the Gucheng area are developed, respectively.

The spatial and geological characteristics of fault- and paleokarst-controlled carbonate-hosted reservoirs in the Tabei Uplift, Tarim Basin, China

Seismic interpretation and characterization of Middle Ordovician carbonates of the northern Tarim Basin in China reveal a series of deep-seated, sub-vertical conjugate strike-slip faults, together with sets of apparently layer-bound fractures striking parallel or orthogonal to the faults. Detailed stratigraphic analysis, well logging response interpretations (including formation microscanner images), coupled with core sample and thin section observations highlight vertical and lateral partitioning of fracturing and dissolution processes. Fracturing and dissolution development are most intense in grain-supported host rocks (grainstones, packstones) deposited in relatively shallow water conditions. Reservoir pore spaces vary systematically from north (Tahe) to south (Shunbei), which can be attributed to their proximity to a major regional angular unconformity with overlying Upper Devonian to Carboniferous sequences. Larger-scale dissolved fracture-cavity reservoirs are developed in the northern Tahe area due to the combined effects of faulting, surface karstification, and river system development close to the base Carboniferous erosion surface. Farther south, where the rocks lie farther from the paleoerosion surface, reservoir space is characterized by smaller, more structurally controlled open cavities bounded by fault slip surfaces, breccias, and open fractures. The observed interactions between paleokarstification intensity, tectonic controls, and host rock lithological layering—and their control over the observed reservoir complexity—are likely to occur in carbonate reservoirs worldwide.

Petrochronology and petrogeochemistry of the Tamulangou Formation in Tahe area, northern Da Hinggan Mountains NE China: Geological implication

Petrochronology and petrogeochemistry of the Tamulangou Formation in Tahe area, northern Da Hinggan Mountains NE China: Geological implication

Genesis, Distribution, and Characterization of a Paleokarst Subsurface River System in the Tahe Area, Tarim Basin, Western China

Summary Subsurface river systems constitute one of three major paleokarst types that make up Ordovician reservoirs in the Tahe area of the Tarim Basin. The total length of the river system is approximately 400 km, and the reserves associated with this karst type are more than 200 million tons. However, it is manifested that 47% of drilled wells have not encountered river paleokarst, while 50% of wells that have encountered river paleokarst are fully filled due to the poor understanding of the paleokarst of this region, resulting in a significant variation of production capacities. In this study, we propose a detailed data integration approach with outcrops, drilling, logging, seismic profiles, and dynamic data to delineate the complex paleokarst river system in the Tahe area. The karst geological theory with reservoir characterization is combined in particular. The workflow of clarifying the main controlling factors, architecture types, and development distribution modes of the subsurface river system is established. Fill material type, sequence of fill structure, and fill controlling factors are also revealed. A quantitative characterization method of the subsurface rivers is established adopting predictions based on seismic data and high-resolution geostatistical and geological modeling. The Ordovician reservoirs in the Tahe area comprise three paleokarst river systems with different characteristics. Karst paleogeomorphology is the main control over the overall flow direction and plane distribution of the subsurface rivers. Changes in the surface of the phreatic zone are crucial in controlling the vertical layers and scale of the rivers. The combined action of faults plays a decisive role in controlling the anastomosing pattern of the rivers. Single-branch channels, reticulated channels, and structural corridors in single-layer or multilayer styles are the main subsurface river types. Trunk channels, branch channels, hall caves, and inlets/outlets are dominant structures in the architecture of the river system. Sand-mud, breccia, and chemically precipitated materials are the most common fill types. Three typical sequences of fill structure and four spatial combination modes exist in the subsurface river system. The morphology and fill characteristics of rivers are predictable using seismic attributes, such as frequency division energy, frequency division inversion, and coherent energy gradient. 3D models are constructed by multivariate control multipoint geostatistical method, which can characterize the strong heterogeneity characteristics of subsurface river systems. This complex paleokarst system enables remarkable results for the adjustment of the reservoir development plan through quantitative characterization.

Characteristics of Chaotic Weak Reflection in Carbonate Fracture-Cavity Reservoirs: A Case Study of Ordovician Reservoirs in Block 10 of the Tahe Oilfield, Tarim Basin, China.

The identification of carbonate reservoirs is a critical task in oil and gas exploration. Chaotic weak reflection is an important type of reflection characteristic in carbonate reservoirs. Widespread distribution of chaotic weak reflection has been observed in the Ordovician Yijianfang Formation in the Tahe area. However, there is still a lack of systematic research on the distribution, characteristics, reservoir space, and reservoir types of chaotic weak reflection in the Tahe area. To address this issue, this study conducted a comprehensive analysis of multiscale data and found that chaotic weak reflections are distributed within 100 ms below the top interface of the Middle Ordovician. Seismic profiles exhibit a "string of pearls" with a "tail" or "pearl-like" widening feature. On well logs, all three porosity curves exhibit localized peaks, with increases in acoustic (AC) and compensated neutron (CNL) and decreases in density (DEN), while the deep and shallow lateral resistivity (RD, RS) curves show positive amplitude differences. In the FMI, they are represented by dark sinusoidal curves and dark small patches. Based on these response characteristics, two types of reservoir spaces are identified for chaotic weak reflections: high-angle vertical fractures and caves with heights less than 7 m, which can form independent reservoirs or fracture-cavity complexes. Three types of reservoirs are distinguished: fracture, cavity, and cavity-fracture types.

Middle to Upper Ordovician stable carbon isotope stratigraphy and sedimentary facies in the Shunbei and Tahe areas, northern-central Tarim, China

The Shunbei area, located in northern-central Tarim (Northwest China), represents a new, important area for petroleum and gas exploration. This study presents high-resolution, conodont biostratigraphically controlled stable carbon isotope data from 540 samples of four deeply buried (∼7000–8000 m) wells in the Shunbei area and its nearby Tahe area spanning the Middle to Upper Ordovician for detailed chemostratigraphic correlations. Additionally, thin sections are obtained from the two studied areas for sedimentary facies analysis. The δ13C data from Shunbei area correlate well with the results from Tahe area and other outcrops in northwestern Tarim. The major global δ13C excursions of the mid-Darriwilian Isotopic Carbon Excursion (MDICE, ∼+1‰) and the Guttenberg Isotopic Carbon Excursion (GICE, ∼+1‰) are recognized from the upper Yijianfang and the Lianglitag formations respectively. Two minor (∼+0.5‰) δ13C positive peaks from the Yingshan Formation of the Shunbei area are comparable to lower Darriwilian strata of platform facies in Tarim, providing a potential tool for correlating lower Darriwilian hydrocarbon reservoirs, such as the Yingshan and Yijianfang formations in the Tarim Basin. A major sedimentary gap is detected in the lower Qiaerbak Formation of the Shunbei area and the upper Yijianfang Formation of the Tahe area, indicating an erosional event occurred in the early Sandbian which could be correlated with the globally tectonic-active interval during the Darriwilian–Sandbian transition. The completely preserved MDICE and GICE in the Shunbei area, as well as its relatively deeper-water sedimentary environment in comparison with the Tahe area, collectively suggest that the Shunbei area is of significance for further geochemical studies on the Middle and Late Ordovician environments and their resources.

Analyzing the Formation and Evolution of Strike-Slip Faults and Their Controlling Effects on Hydrocarbon Migration and Charging: A Case Study of Tahe Area, Tarim Basin

The Ordovician strike-slip faults system in the Tahe area of the Tarim Basin provides an important opportunity for using 3D seismic data to document the structural characteristics, formation, and evolution of strike-slip faults and their relationship with oil and gas. With high-resolution 3D seismic data, the strike-slip faults are interpreted, classified, and described using the seismic coherence technique. The geometric characteristics, active periods, formation, and evolution process of strike-slip faults are analyzed, and the relationship between strike-slip faults and hydrocarbon accumulation and charging is discussed in this research project. On the map, the primary strike-slip faults on the east and west sides of the Tahe area are relatively sheared to each other, showing an “X” type conjugate fault, and the secondary strike-slip faults are scattered. In the cross-section, the primary strike-slip faults are inserted downward into the Cambrian basement and up to Devonian, and “Single line”, “Y”, “Flower”, and “Parallel lines” structures are observed. Bounded by the top of Ordovician, the deep and shallow parts are vertically segmented, with different structure styles. The switch of the structural style of strike-slip faults is attributed to principal stress. A deep “positive flower” shape of faults was developed in the mid-Ordovician period under the effect of compressive stress. Meanwhile, a shallow “negative flower” shape of faults was developed from the late Ordovician to the mid-Devonian period under tensile stress. The “Compound Flower” shape of deep “positive flower” shape and shallow “negative flower” shape formed by compressive and tensile activities has a wider fracture range, which leads to deep fluid migration and shallow karstification. There are two combinations of deep Ordovician strike-slip faults in the section: “Lower single branch-upper flower type” and “lower single branch-upper single branch type”. The primary faults of the former insertion into the Cambrian basement are associated with homologous secondary faults, while the latter has no derived secondary faults. It has an important impact on reservoir reconstruction and distribution, and the reservoir is controlled by faults. Strike-slip faults not only control the channel of oil and gas migration, but also the horizontal and vertical distribution of oil and gas. The closer the carbonate reservoir is to the primary fault, the more likely it is to form a high yield area. There are four types of oil and gas charging models controlled by strike-slip faults. In the area where the structure is high and the strike-slip faults are sheared relatively to each other, the larger the scale of faults, the more conducive it would be to oil and gas migration and accumulation. Among them, the charging model related to the primary fault has higher oil and gas migration efficiency. This research contributes to analyzing the relationship between strike-slip faults and oil and gas as well as playing a significant role in applications of oil and gas exploration in practical works.

Applicability Analysis of Pre-Stack Inversion in Carbonate Karst Reservoir

Although pre-stack inversion has been carried out on reservoir prediction, few studies have focused on the application of pre-stack for seismic inversion in fractured-cavity carbonate reservoirs. In carbonate rock, complicated combinations and fluid predictions in karst caves are remain unclear. Post-stack methods are commonly used to predict the position, size, and fillings of caves, but pre-stack inversion is seldom applied in carbonate karst reservoirs. This paper proposes a pre-stack inversion method for forward modeling data and oil survey seismic data, using both points to indicate the application of pre-stack inversion in karst caves. Considering influence of cave size, depth, and filler on prediction, three sets of models (different caves volume; different fillings velocity of caves; complicated combination of caves) are employed and inverted by pre-stack inversion. We analyze the pre-stack results to depict Ordovician oil bearing and characterize caves. Geological model parameters came from actual data of the Tahe oilfield, and seismic data were synthesized from geological models based on full-wave equation forward simulation. Moreover, a case study of pre-stack inversion from the Tahe area was employed. The study shows that, from both the forward modeling and the oil seismic data points of view, pre-stack inversion is applicable to carbonate karst reservoirs.

GANSim‐3D for Conditional Geomodeling: Theory and Field Application

AbstractWe present a Generative Adversarial Network (GAN)‐based 3D reservoir simulation framework, GANSim‐3D, where the generator is progressively trained to capture geological patterns and relationships between various input conditioning data and output earth models, and is thus able to directly produce multiple 3D realistic and conditional earth models from given conditioning data. Conditioning data can include 3D sparse well facies data, probability maps, and global features, such as facies proportion. The generator only includes 3D convolutional layers, and once trained on a data set consisting of small‐size data cubes, it can be used for geomodeling of 3D reservoirs of large arbitrary sizes by simply extending the inputs. To illustrate how GANSim‐3D is practically used and to verify GANSim‐3D, a field karst cave reservoir in Tahe area of China is used as an example. The 3D well facies data and 3D probability map of caves obtained from geophysical interpretation are taken as conditioning data. First, we create training, validation, and test datasets consisting of 64 × 64 × 64‐size 3D cave facies models integrating field geological patterns, 3D well facies data, and 3D probability maps. Then, the 3D generator is trained and evaluated with various metrics. Next, we apply the pretrained generator for conditional geomodeling of two field cave reservoirs of size 64 × 64 × 64 and 336 × 256 × 96, respectively. The produced reservoir realizations prove to be diverse, consistent with field geological patterns and field conditioning data, and robust to noise in the 3D probability maps. Each realization with 336 × 256 × 96 cells only takes 0.988 s using 1 GPU.

Differential structure of Ordovician karst zone and hydrocarbon enrichment in paleogeomorphic units in Tahe area, Tarim Basin, NW China

Based on a large number of drilling, logging, seismic and production data, the differential structures of karst zone and hydrocarbon distribution in different paleogeomorphic units of the Tahe area, Tarim Basin, are discussed by analyzing the karst drainages and flowing channels. The karst paleogeomorphy of Ordovician in Tahe area is composed of watershed, karst valley and karst basin. The watershed has epikarst zone of 57.8 m thick on average and vadose karst zone of 115.2 m thick on average with dense faults, fractures and medium—small fracture-caves, and 76.5% of wells in this area have cumulative production of more than 5×10 4 t per well. The karst valleys have epikarst zone, vadose karst zone and runoff karst zone, with an average thickness of 14.6, 26.4 and 132.6 m respectively. In the runoff karst zone, the caves of subsurface river are mostly filled by fine sediment, with a filling rate up to 86.8%, and 84.9% of wells in this area have cumulative production of less than 2×10 4 t per well. The karst basin has no karst zone, but only fault—karst reservoirs in local fault zones, which are up to 600 m thick and closely developed within 1 km around faults. Different karst landforms have different water flowing pattern, forming different karst zone structures and resulting in differential distribution of oil and gas. The watershed has been on the direction of oil and gas migration, so medium—small sized connected fracture-caves in this area have high filling degree of oil and gas, and most wells in this area have high production. Most caves in subsurface river are filled due to strong sedimentation and transportation of the river, so the subsurface river sediment has low hydrocarbon abundance and more low production oil wells. The faults linking source rock are not only the water channels but also the oil-gas migration pathways, where the karst fractures and caves provide huge reservoir space for oil and gas accumulation.

A multidisciplinary approach applied to paleokarst zones of the Tahe area, China: compositional scheme and reservoir quality—case study

A multidisciplinary approach applied to paleokarst zones of the Tahe area, China: compositional scheme and reservoir quality—case study

Formation of hoodoo-upland on Ordovician karst slope and its significance in petroleum geology in Tahe area, Tarim Basin, NW China

Based on a large number of geological and geophysical data, the formation, fracture-caves types and hydrocarbon distribution of hoodoo-upland on the Ordovician karst slope in the Tahe area, Tarim Basin, are discussed by analyzing faults and strata thickness. The hoodoo-upland was made of high peaks and narrow valleys in the Ordovician karst slope during the Early Hercynian karst period, which were distributed along the NNE positive flower structure and had inherited evolution. The fault-fractures and fracture-vugs complex were extremely developed, with a thickness of 100 m. The cumulative oil production of 60% oil wells was more than 20×104 t per well in the hoodoo-upland, where the residual thickness of the Ordovician Yingshan Formation was greater than karst depressions. Caves formed by the shelter of collapsed breccias were developed in the valleys. They were 1.6 to 13.5 m high, with a filling rate of 51.6%. The positive flower structure under the settings of strike-slip compression controlled the early formation of the hoodoo-upland on the karst slope, resulting in the differences of drainage distribution and karstification. Compared with the water-rich karst valley, the hoodoo-upland with lean water suffered weaker karstification, had thicker residual stratum, and was higher in terrain. In rainy season, the meteoric water flew and corrode along the cracks, forming a complex network of fractures and caves. Combined with inherited uplift and the effective match of the NNE deep faults, oil and gas continuously charged into the reservoir space in the upland, forming the hoodoo fracture-cave reservoir with vertically quasi continuous distribution, high hydrocarbon abundance and high production.

Origin, hydrocarbon accumulation and oil-gas enrichment of fault-karst carbonate reservoirs: A case study of Ordovician carbonate reservoirs in South Tahe area of Halahatang oilfield, Tarim Basin

Abstract Based on comprehensive analysis of tectonic and fault evolution, core, well logging, seismic, drilling, and production data, the reservoir space characteristic, distribution, origin of fault-karst carbonate reservoir in Yueman block of South Tahe area, Halahatang oilfield, Tarim Basin, were studied systematically. And the regular pattern of hydrocarbon accumulation and enrichment was analyzed systematically based on development practice of the reservoirs. The results show that fault-karst carbonate reservoirs are distributed in the form of “body by body” discontinuously, heterogeneously and irregularly, which are controlled by the development of faults. Three formation models of fault-karst carbonate reservoirs, namely, the models controlled by the main deep-large fault, the secondary fault and the secondary internal fault, are built. The hydrocarbon accumulation and enrichment of fault-karst carbonate reservoirs is controlled by the spatiotemporal matching relation between hydrocarbon generation period and fault activity, and the size and segmentation of fault. The study results can effectively guide the well deployment and help the efficient development of fault-karst carbonate reservoirs of South Tahe area, Halahatang oilfield.

Integrating Geochemical and Geophysical Information to Improve Geological Mapping in Northeast China: A Data Transferring Technology for Characterization and Classification

In mainland China, there are large surface areas covered with shallow overburden (Regolith thickness < 100 m). Geological mapping is difficult here as there is not enough exposed bedrock. In this paper, we transfer geochemical and geophysical data to characteristics, and use it in geological mapping to identify the underlying bedrock. Above all, we define the “represent area of one geochemical sample” as one “statistical unit”. All geophysical data in each unit (hundreds of data) are analyzed generating statistical parameters, such as mode, interquartile range, frequency, skewness, and kurtosis, which are combined together to describe the characteristics of rocks in this area. As for the geochemical data in each unit, some rock-forming elements are screened to build new parameters, such as SiO2, Na2O + K2O, CaO, Al2O3, FeO + MgO. All geophysical and geochemical parameters are regarded as characteristics of one unit. The merged array is normalized so that all the parameters have uniform weight and the comparability between different parameters is improved. Then, K-means clustering method is used to classify all the samples in a research area. As the K-value is very difficult to estimate, it is necessary to conduct further experiments with different K-values, determine and explain the relationship between different classifications, and then identify the best classifications. Using the field information as a reference, one or more classifications are judged as one geological body. The method in this paper is practiced using the Tahe area, located within a typical shallow overburden area in Northeast China, as a case study. We used seven elements of 334 geochemical samples and 41.222 geological samples. K-values of 6, 7, 8, and 9 are calculated. We were successful in identifying geological bodies, and gained a new understanding on the scope of some rocks types. It is believed that the method proposed in this paper is highly efficient, easy to conduct, and can provide more detailed and comprehensive information than traditional methods.

Three-Dimensional Geophysical Characterization of Deeply Buried Paleokarst System in the Tahe Oilfield, Tarim Basin, China

Paleokarst reservoirs are the major type of the Ordovician carbonate reservoirs in the Tahe Oilfield. Due to the strong heterogeneity in distribution, it is a real challenge to detect the spatial distribution of paleokarst reservoirs, especially those deeply buried more than 5500 m in the Tahe area. Based on the abundant core samples, this paper first described the structure of paleocaves drilled by well. Second, after time–depth conversions, the results from drilled wells were tied to three-dimensional (3D) seismic datasets, and then the threshold of host rocks and caves in wave impedance were identified. Third, the seismic-scale mapping and visualization of the paleokarst reservoirs were achieved by tracing the distribution of paleocaves. This approach was applied in the well T403 area, and the structure of the paleokarst, especially the runoff zone, was interpreted. 3D structure and spatial distribution of the paleokarst system was demonstrated by plane, vertical, and 3D models. Additionally, according to the hydrology genetic relationships, the paleocaves in the runoff zone were divided into sinkholes, main channel, and branch channel. The approach of a 3D geophysical characterization of a deeply buried paleokarst system can be applicable to Tahe and other similar paleokarst oilfields, which will guide hydrocarbon exploration in paleokarst reservoirs.

Automatic Velocity Model Building Technology

The automatic velocity model building technology is a new velocity model building method researched all by ourselves, it had been supported by China Ministry of Geology and Mineral Resources and SinoPec petroleum corporation from 1992 to 2004. We have got Chinese Patent in 2004 after over ten years study. After that, we applied this technology successfully in several workareas of China with different geology conditions, such as foothill complex surface and subsurface structure in the southern part of Tianshan Mountain?carbonate platform edge in Tahe area and marine carbonate rock in southern China etc. This technology includes two main procedures: High Density CDR Velocity Analysis and Constrained Interval Velocity Inversion.

碳酸盐岩油藏生产过程中的动态应力场变化规律——以塔河地区TP326CH井为例

碳酸盐岩油藏生产过程中的动态应力场变化规律——以塔河地区TP326CH井为例

中度火干扰对兴安落叶松林土壤呼吸的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 中度火干扰对兴安落叶松林土壤呼吸的影响 DOI: 10.5846/stxb201705311005 作者: 作者单位: 东北林业大学林学院,东北林业大学林学院,东北林业大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 中央高校基本科研业务费专项资金项目（2572015DA01）；国家自然科学基金项目（31470657） Effects of fire disturbances on soil respiration in Dahurian Larch (Larix gmelinii) forests Author: Affiliation: Faculty of Forestry,Northeast Forestry University,Faculty of Forestry,Northeast Forestry University,Faculty of Forestry,Northeast Forestry University Fund Project: Fundamental Research Funds for the Central Universities (2572015DA01); National Natural Science Foundation (31470657) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过测定中度火干扰后塔河地区兴安落叶松（Larix gmelinii）林生长季土壤呼吸（Rs），并进一步探究火干扰后影响土壤呼吸变化的主要环境因子。选择在塔河林业局火烧4年后兴安落叶松林中度火烧迹地设置样地，选择临近未过火区域设置对照样地。土壤呼吸通量用LI-8100进行测量，土壤异养呼吸（Rh）采用壕沟法进行测量。火烧迹地与未火烧对照样地生长季土壤呼吸速率平均值分别为（3.67±1.03）μmol CO2 m-2 s-1，（4.21±1.25）μmol CO2 m-2 s-1。火烧迹地土壤呼吸速率显著降低（P<0.05）。生长季土壤呼吸组分的动态变化表明，土壤呼吸速率的降低是因为土壤自养呼吸（Ra）显著降低导致的（P<0.05）。温度是控制这一地区生长季土壤呼吸变化的主要环境因子。与对照样地相比，火烧迹地土壤呼吸的变化与土壤温度具有更强的相关性。塔河地区兴安落叶松林火烧迹地和未火烧对照样地Q10分别为5.85±1.06，4.25±1.19，火干扰后Q10显著增加（P<0.05）。研究结果表明：在全球气候变化的背景下火干扰后中国塔河地区兴安落叶松林生态系统对温度的变化更为敏感。本研究结果将为研究中国塔河地区火干扰后碳循环变化提供数据支持。 Abstract:This study investigated the increasing seasonal soil respiration (Rs) in the Dahurian Larch (Larix gmelinii) forests after fire disturbance in the Tahe area, and identified the main environmental factors influencing soil respiration changes after fires. Plots that had been under fire disturbance over four years in the Tahe forestry bureau were selected for this investigation, and the nearby unburnt area was selected for the control plots. The Rs was measured by using an Li-8100, and the trench method was used to measure the soil heterotrophic respiration (Rh). The mean Rs of post-fire plots and unburnt control plots was (3.67±1.03)μmol CO2 m-2 s-1 and (4.21±1.25)μmol CO2 m-2 s-1, respectively. The Rs in the post-fire plots was significantly lower than that in the unburnt control plots (P < 0.05). We quantified the Rs component changes after fire disturbance. The decrease in Rs was mainly due to a significantly decreased autotrophic respiration (Ra) rate (P < 0.05). Soil temperature was the dominant environmental factor influencing soil respiration variability in this area. Compared with the unburnt control plots, the Rs in the post-fire plots had a much stronger correlation with soil temperature. The temperature sensitivity index (Q10) of Rs in the post-fire plots and unburnt control plots was 5.85±1.06 and 4.25±1.19, respectively. The Q10 value significantly increased after fire disturbance (P < 0.05). In view of the global climate change, the results of this study demonstrate that the Dahurian Larch (L. gmelinii) forest ecosystem in the Tahe area of China is sensitive to temperature change. Our findings provide scientific basis for research on carbon cycling after fire disturbance in the Tahe area of China. 参考文献 相似文献 引证文献

碳酸盐岩油藏生产过程中的动态应力场变化规律——以塔河地区TP326CH井为例

碳酸盐岩油藏生产过程中的动态应力场变化规律——以塔河地区TP326CH井为例

Reservoir characteristics and controlling factors of Silurian Lower Kepingtage Formation in Tahe area, Tarim Basin, NW China

With the breakthrough of exploration in Well TP16-1, the lower Kepingtage Formation becomes a key target for petroleum exploration of deep clastic reservoir in Tahe area. In this paper we focused on the research of the reservoir characteristics and its controlling factors in two sub-member formations (S1k 1 1 and S1k 1 3 ). Based on X-ray diffraction, conventional physical properties data (porosity and permeability) and reservoir storage space data (casting thin section and scanning electron microscope), we determined that the S1k1 Formation belongs to extra-low porosity and permeability reservoir, although the upper S1k 1 3 Formation shows relative better physical characteristic than the lower S1k 1 1 Formation. The development of storage space in the study area is controlled by sedimentary microfacies, diagenesis process. Reservoirs in S1k1 Formation are mainly located in channel (S1k 1 1 sandstones) and sand flat (S1k 1 3 sandstones). The sand flat sediments with a more coarse grain size compared with the channel. In diagenesis, compaction is the major controlling factor for reducing the porosity, followed by cementation. Dissolution of diagenesis is the major controlling factor in enhancing the reservoir porosities. Compared with channel (S1k 1 1 ) sandstones, sand flat sandstones (S1k 1 3 ) have better reservoir quality for its weaker compaction, cementation and stronger dissolution. On the basis of sedimentary characteristics (grain size and subfacies), physical property (porosity and permeability) and reservoir storage space, we divide the S1k1 reservoir into three categories (I, II and III). Type I reservoir is high quality reservoir. It is mainly distributed in the south area of S1k 1 1 and S1k 1 3 reservoir. Type II is moderate reservoir. It is located in the middle of S1k 1 1 reservoir and in the north of S1k 1 3 reservoir. Type III is the poor reservoir. It is only located in the north of S1k 1 1 reservoir.