2016 Vol. 35, No. 2

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Current situation and trend of marine data buoy and monitoring network technology of China
WANG Juncheng, WANG Zhongqiu, WANG Yiming, ZHENG Yi, LIU Shixuan, LI Yunzhou
2016, 35(2): 1-10. doi: 10.1007/s13131-016-0815-z
Marine data buoy can provide a long-term, continuous, real-time, reliable data of ocean observation in a variety of complex marine environment. It is one of the most reliable, most effective and important means of ocean monitoring technology. In this paper, the classification, main theory and technology system of marine data buoy are summarized. The typical technological breakthrough of the development of marine data buoy in recent years is summarized. The composition and application of marine monitoring network in China was introduced, and the gap between the technology of China's marine data buoy and the international advanced countries is compared. Combined on the situation and demand of China's current situation and needs, the development trend of marine data buoy and buoy monitoring network are expected.
Quality control methods for KOOS operational sea surface temperature products
YANG Chansu, KIM Sunhwa
2016, 35(2): 11-18. doi: 10.1007/s13131-016-0807-z
Sea surface temperature SST obtained from the initial version of the Korea Operational Oceanographic System (KOOS) SST satellite have low accuracy during summer and daytime. This is attributed to the diurnal warming effect. Error estimation of SST data must be carried out to use the real-time forecasting numerical model of the KOOS. This study suggests two quality control methods for the KOOS SST system. To minimize the diurnal warming effect, SSTs of areas where wind speed is higher than 5 m/s were used. Depending on the wind threshold value, KOOS SST data for August 2014 were reduced by 0.15℃. Errors in SST data are considered to be a combination of random, sampling, and bias errors. To estimate bias error, the standard deviation of bias between KOOS SSTs and climatology SSTs were used. KOOS SST data yielded an analysis error standard deviation value similar to OSTIA and NOAA NCDC (OISST) data. The KOOS SST shows lower random and sampling errors with increasing number of observations using six satellite datasets. In further studies, the proposed quality control methods for the KOOS SST system will be applied through more long-term case studies and comparisons with other SST systems.
Verification of an operational ocean circulation-surface wave coupled forecasting system for the China's seas
WANG Guansuo, ZHAO Chang, XU Jiangling, QIAO Fangli, XIA Changshui
2016, 35(2): 19-28. doi: 10.1007/s13131-016-0810-4
An operational ocean circulation-surface wave coupled forecasting system for the seas off China and adjacent areas (OCFS-C) is developed based on parallelized circulation and wave models. It has been in operation since November 1, 2007. In this paper we comprehensively present the simulation and verification of the system, whose distinguishing feature is that the wave-induced mixing is coupled in the circulation model. In particular, with nested technique the resolution in the China's seas has been updated to (1/24)° from the global model with (1/2)° resolution. Besides, daily remote sensing sea surface temperature (SST) data have been assimilated into the model to generate a hot restart field for OCFS-C. Moreover, inter-comparisons between forecasting and independent observational data are performed to evaluate the effectiveness of OCFS-C in upper-ocean quantities predictions, including SST, mixed layer depth (MLD) and subsurface temperature. Except in conventional statistical metrics, non-dimensional skill scores (SS) is also used to evaluate forecast skill. Observations from buoys and Argo profiles are used for lead time and real time validations, which give a large SS value (more than 0.90). Besides, prediction skill for the seasonal variation of SST is confirmed. Comparisons of subsurface temperatures with Argo profiles data indicate that OCFS-C has low skill in predicting subsurface temperatures between 100 m and 150 m. Nevertheless, inter-comparisons of MLD reveal that the MLD from model is shallower than that from Argo profiles by about 12 m, i.e., OCFS-C is successful and steady in MLD predictions. Validation of 1-d, 2-d and 3-d forecasting SST shows that our operational ocean circulation-surface wave coupled forecasting model has reasonable accuracy in the upper ocean.
Case study on the three-dimensional structure of meso-scale eddy in the South China Sea based on a high-resolution model
XIA Changshui, JUNG KyungTae, WANG Guansuo, YIN Xunqiang, GUO Jingsong
2016, 35(2): 29-38. doi: 10.1007/s13131-016-0805-1
Meso-scale eddies are important features in the South China Sea (SCS). The eddies with diameters of 50-200 km can greatly impact the transport of heat, momentum, and tracers. A high-resolution wave-tide-circulation coupled model was developed to simulate the meso-scale eddy in the SCS in this study. The aim of this study is to examine the model ability to simulate the meso-scale eddy in the SCS without data assimilations The simulated Sea Surface Height (SSH) anomalies agree with the observed the AVISO SSH anomalies well. The simulated subsurface temperature profiles agree with the CTD observation data from the ROSE (Responses of Marine Hazards to climate change in the Western Pacific) project. The simulated upper-ocean currents also agree with the main circulation based on observations. A warm eddy is identified in winter in the northern SCS. The position and domain of the simulated eddy are confirmed by the observed sea surface height data from the AVISO. The result shows that the model has the ability to simulate the meso-scale eddy in the SCS without data assimilation. The three-dimensional structure of the meso-scale eddy in the SCS is analyzed using the model result. It is found that the eddy center is tilted vertically, which agrees with the observation. It is also found that the velocity center of the eddy does not coincide with the temperature center of the eddy. The result shows that the model has the ability to simulate the meso-scale eddy in the SCS without data assimilations. Further study on the forming mechanism and the three-dimensional structure of the meso-scale eddies will be carried out using the model result and cruise observation data in the near future.
Global parameter estimation of the Cochlodinium polykrikoides model using bioassay data
CHO Hong-Yeon, PARK Kwang-Soon, KIM Sung
2016, 35(2): 39-45. doi: 10.1007/s13131-016-0806-0
Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide (a.k.a algal bloom) model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%-50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required. As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.
Spatiotemporal heterogeneity of phytoplankton diversity and its relation to water environmental factors in the southern waters of Miaodao Archipelago, China
ZHENG Wei, LI Fen, SHI Honghua, HUO Yuanzi, LI Yan, CHI Yuan, GUO Zhen, WANG Yuanyuan, SHEN Chengcheng, LIU Jian, QIAO Mingyang
2016, 35(2): 46-55. doi: 10.1007/s13131-016-0811-3
To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter (73), moderate in autumn (70), but lower in summer (31) and spring (27). The species richness index in autumn (5.92) and winter (4.28) was higher than that in summer (2.83) and spring (1.41). The Shannon-Wiener diversity index was high in autumn (2.82), followed by winter (1.99) and summer (1.92), and low in spring (0.07). The species evenness index in autumn (0.46) and summer (0.39) was higher than that in winter (0.32) and spring (0.02). On the basis of principal component analysis (PCA) and redundancy analysis (RDA), we found that dissolved inorganic nitrogen (DIN) and chemical oxygen demand (COD) in spring, COD in summer, pH in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis (CA) based on key environmental variables.
A model to assess fundamental and realized carrying capacities of island ecosystem: A case study in the southern Miaodao Archipelago of China
SHI Honghua, SHEN Chengcheng, ZHENG Wei, LI Fen, WANG Xiaoli, CHI Yuan, GUO Zhen, QIAO Mingyang, GAO Liyuan, DING Dewen
2016, 35(2): 56-67. doi: 10.1007/s13131-016-0808-y
Research on carrying capacity, aiming at maintaining the limited ability of the Earth's life supporting system to sustain human development, requires a comprehensive and ecosystem-based approach to monitor and assess the localized sustainability of coupled social and ecological systems. A definition termed the ecosystem-based carrying capacity of island (EBCCI) was developed in this paper of which the indices of fundamental and realized carrying capacities of island (FCCI and RCCI) were highlighted to emphasize the inter-dependencies between social systems and ecological systems. In order to avoid the difficulties and uncertainties of direct assessment, the related assessment model was established on the basis of synthetic evaluation of inherent and external factors affecting the EBCCI. The southern Miaodao Archipelago (SMA) located in the intersection of the Bohai Sea and the Yellow Sea, China, was taken as a typical example to acquire integrated recognition of the island ecosystem and its carrying capacity so as to discuss its sustainable development. The index scores of FCCI and RCCI in the SMA were 0.818 5 and 0.712 9 out of 1.0, respectively, with acceptable uncertainties. The results showed a relatively well capacity to sustain progress and relatively well realization of the carrying capacity of island ecosystem, owing to a well capacity of ecologically regulating, general performance of both ecologically supporting and resource provisioning, and a relatively high level of social supporting system. The study implied that it was critical to optimize the inter-dependencies and to sustain the relative balance between social systems and ecological systems so as to improve the RCCI and further facilitate the sustainability of SMA. The approach proposed in this paper provides a powerful tool which is well applicative to the regional level of an oceanic island or archipelago to study the sustainable development and can be further popularized to the coastal zone.
Upper limits for chlorophyll a changes with brine volume in sea ice during the austral spring in the Weddell Sea, Antarctica
LI Zhijun, LI Runling, WANG Zipan, HAAS Christian, DIECKMANN Gerhard
2016, 35(2): 68-75. doi: 10.1007/s13131-015-0740-6
During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples, and 311 chlorophyll a (Chl a) and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.
Temporal variations of dimethylsulfide and dimethylsulfoniopropionate in the southern Yellow Sea in spring and autumn
YANG Jian, YANG Guipeng, ZHANG Honghai, ZHANG Shenghui
2016, 35(2): 76-87. doi: 10.1007/s13131-015-0780-y
Temporal distributions of dimethylsul.de (DMS) and dimethylsulfoniopropionate (DMSP) were studied in the southern Yellow Sea (SYS) during April and September 2010. The mean concentrations (range) of DMS, dissolved and particulate DMSP (DMSPd and DMSPp) in the surface waters in spring are 1.69 (0.48-4.92), 3.18 (0.68-6.75) and 15.81 (2.82-52.33) nmol/L, respectively, and those in autumn are 2.80 (1.33-5.10), 5.45 (2.19-11.30) and 30.63 (6.24-137.87) nmol/L. On the whole, the distributions of DMS and DMSP in spring are completely different from those in autumn. In the central part of the SYS, the concentrations of DMS and DMSP in spring are obviously higher than those in autumn, but the opposite situation is found on the south of 34°N, which can be attributed to the differences in nutrients and phytoplankton biomass and composition between spring and autumn. Besides, the seasonal variations of water column stability and the Changjiang diluted water also have significant impact on the distributions of DMS and DMSP in spring and autumn on the south of 34°N. DMS and DMSPp concentrations coincide well with chlorophyll a (Chl a) levels in the spring cruise, suggesting that phytoplankton biomass may play an important role in controlling the distributions of DMS and DMSPp in the study area. Annual DMS emission rates range from 0.015 to 0.033 Tg/a (calculated by S), respectively, using the equations of Liss and Merlivat (1986) and Wanninkhof (1992). This result implies a signi.cant relative contribution of the SYS to the global oceanic DMS fluxes.
Integrated bioremediation techniques in a shrimp farming environment under controlled conditions
SONG Xianli, YANG Qian, REN J. Shengmin, SUN Yao, WANG Xiulin, SUN Fuxin
2016, 35(2): 88-94. doi: 10.1007/s13131-016-0812-2
This study investigated the integrated bioremediation techniques for a shrimp culture system to reduce unconsumed feed and the contents of suspended solids (SS), nutrients and organic pollutants using barracuda, clamworm, scallop, large algae and a biofilter. A multi-pool internal circulation system was designed to test the effectiveness of the techniques in the laboratory. The experimental result has shown that Argopecten irradians, Gracilaria lemaneiformis and the biofilter efficiently reduced the contents of SS, dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in the breeding wastewater. The amount of unconsumed feed was significantly reduced by barracuda and clamworm, but there was an increase in the contents of SS, DIC and DOC in the water due to disturbance by the barracuda and clamworm. The capacity of macroalgae to extract inorganic nitrogen was insufficient. However, the balance of the nitrogen fixation rate of macroalgae and the biological exhaust nitrogen rate within the system should be fully considered. The use of the biofilter alone was not optimal for the remediation of organic matter in shrimp effluent so that auxiliary foam separation technology is needed to improve the ability of the system to remove macromolecules. This study provides a basis for the further development of remediation techniques to reduce the environmental impact of shrimp aquaculture.
Mangrove forest degradation indicated by mangrove-derived organic matter in the Qinzhou Bay, Guangxi, China, and its response to the Asian monsoon during the Holocene climatic optimum
MENG Xianwei, XIA Peng, LI Zhen, LIU Lejun
2016, 35(2): 95-100. doi: 10.1007/s13131-015-0778-5
The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum (HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous, and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope (δ13Corg) and the molar ratio of total organic carbon to total nitrogen (C/N). The percentage of mangrove-derived organic matter (MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.
Major and trace element composition of surface sediments from the Southwest Indian Ridge: evidence for the incorporation of a hydrothermal component
LI Zhenggang, CHU Fengyou, JIN Lu, LI Xiaohu, DONG Yanhui, CHEN Ling, ZHU Jihao
2016, 35(2): 101-108. doi: 10.1007/s13131-015-0678-8
Hydrothermal materials in deep-sea sediments provide a robust tracer to the localized hydrothermal activity at mid-ocean ridges. Major, trace and rare earth element (REE) data for surface sediments collected from the ultraslow spreading Southwest Indian Ridge are presented to examine the existence of hydrothermal component. Biogenic carbonate oozes dominate all the sediment samples, with CaO content varying from 85.5% to 89.9% on a volatile-free basis. The leaching residue of bulk sediments by ~5% HCl is compositionally comparable to the Upper Continental Crust (UCC) in SiO2, Al2O3, CaO, MgO, alkali elements (Rb, Cs) and high field strength elements (Nb, Ta, Zr, Hf, Ti). These detritus-hosted elements are inferred to be prominently derived from the Australian continent by means of eolian dust, while the contribution of local volcaniclastics is insignificant. In addition, the residual fraction shows a clear enrichment in Fe, Mn, and Ba compared with the UCC. Combining the positive Eu anomaly of residual fraction which is opposed to the UCC but the characteristic of hydrothermal fluids and associated precipitates occurred at mid-ocean ridges, the incorporation of localized hydrothermal component can be constrained. REE mixing calculations indicate that more than half REE within the residual fraction (~55%-60%) are derived from a hydrothermal component, which is inferred to be resulted from a diffuse fluid mineralization. The low-temperature diffuse flow may be widely distributed along the slow-ultraslow spreading ridges where crustal faults and fissures abound, and probably have a great mineralization potential.
The effect of sea surface temperature increase on the potential habitat of Ommastrephes bartramii in the Northwest Pacific Ocean
XU Jie, CHEN Xinjun, CHEN Yong, DING Qi, TIAN Siquan
2016, 35(2): 109-116. doi: 10.1007/s13131-015-0782-9
In the Northwest Pacific Ocean, the squid jigging fisheries from China, Japan and other countries and regions have targeted the west winter-spring cohort of neon flying squid (Ommastrephes bartramii) from August to November since the 1970s. This squid is a short-lived ecological opportunist with a life-span of about one year, and its population is labile and recruitment variability is driven by the environment or climate change. This variability provides a challenge for ones to forecast the key habitats affected by climate change. The catch data of O. bartramii from Chinese squid jigging fishery and the satellite-derived sea surface temperature (SST) data are used in the Northwest Pacific Ocean from August to November of 1998 to 2004, the SST preferences of O. bartramii corresponding to high values of catch per fishing day (CPUE) are determined and monthly potential habitats are predicted using a histogram analysis of the SST data. The possible changes in the potential habitats of O. bartramii in the Northwest Pacific Ocean are estimated under four climate change scenarios based on the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change, i.e., 0.5, 1, 2 and 4℃ increases in the SST because of the climate change. The results reveal an obvious poleward shift of the potential habitats of O. bartramii in the Northwest Pacific Ocean.
Application of a Bayesian method to data-poor stock assessment by using Indian Ocean albacore (Thunnus alalunga) stock assessment as an example
GUAN Wenjiang, TANG Lin, ZHU Jiangfeng, TIAN Siquan, XU Liuxiong
2016, 35(2): 117-125. doi: 10.1007/s13131-016-0814-0
It is widely recognized that assessments of the status of data-poor fish stocks are challenging and that Bayesian analysis is one of the methods which can be used to improve the reliability of stock assessments in data-poor situations through borrowing strength from prior information deduced from species with good-quality data or other known information. Because there is considerable uncertainty remaining in the stock assessment of albacore tuna (Thunnus alalunga) in the Indian Ocean due to the limited and low-quality data, we investigate the advantages of a Bayesian method in data-poor stock assessment by using Indian Ocean albacore stock assessment as an example. Eight Bayesian biomass dynamics models with different prior assumptions and catch data series were developed to assess the stock. The results show (1) the rationality of choice of catch data series and assumption of parameters could be enhanced by analyzing the posterior distribution of the parameters; (2) the reliability of the stock assessment could be improved by using demographic methods to construct a prior for the intrinsic rate of increase (r). Because we can make use of more information to improve the rationality of parameter estimation and the reliability of the stock assessment compared with traditional statistical methods by incorporating any available knowledge into the informative priors and analyzing the posterior distribution based on Bayesian framework in data-poor situations, we suggest that the Bayesian method should be an alternative method to be applied in data-poor species stock assessment, such as Indian Ocean albacore.
An estimation of genetic parameters of growth traits in juvenile turbot (Scophthalmus maximus L.) using parental molecular relatedness
HU Yulong, GUAN Jiantao, MA Yu, KONG Jie, WANG Weiji
2016, 35(2): 126-130. doi: 10.1007/s13131-015-0643-6
The estimation of genetic parameters has played an important role in animal selective breeding for growth traits. Recently studies show that molecular markers can be incorporated into genetic evaluations. In order to improve the performance of an incomplete pedigree (i.e, only parents are known) in the genetic evaluations, 12 microsatellite markers have been applied in the estimation of the genetic parameters for body weight in a farmed population (n=1 890) of juvenile turbot (Scophthalmus maximus L.). A new relatedness called parental molecular relatedness (PMR) is estimated based on results of genotyping of 48 parents (31 males, 17 females) with microsatellites markers. The feasibility of PMR in estimation of genetic parameters is verified by comparison with pedigree related (PR) which is obtained from a complete pedigree. The results demonstrate that a high correlation (0.872) between them is found. Heritabilities are estimated using the PMR (0.52±0.13) and PR (0.55±0.22) with the same animal model. A cross-validation shows that the predictive abilities of models using the PMR and the PR are identical (0.81). From that, a conclusion can be made that PMR and PR predicted genetic values equally well in a population of juvenile turbot. Therefore PMR can be applied as an alternative of the PR when only parents are known. However, for a better performance, more markers and more families should be included in a further study.
An evaluation of multiple annealing and looping based genome amplification using a synthetic bacterial community
WANG Yong, GAO Zhaoming, XU Ying, LI Guangyu, HE Lisheng, QIAN Peiyuan
2016, 35(2): 131-136. doi: 10.1007/s13131-015-0781-x
The low biomass in environmental samples is a major challenge for microbial metagenomic studies. The amplification of a genomic DNA was frequently applied to meeting the minimum requirement of the DNA for a high-throughput next-generation-sequencing technology. Using a synthetic bacterial community, the amplification efficiency of the Multiple Annealing and Looping Based Amplification Cycles (MALBAC) kit that is originally developed to amplify the single-cell genomic DNA of mammalian organisms is examined. The DNA template of 10 pg in each reaction of the MALBAC amplification may generate enough DNA for Illumina sequencing. Using 10 pg and 100 pg templates for each reaction set, the MALBAC kit shows a stable and homogeneous amplification as indicated by the highly consistent coverage of the reads from the two amplified samples on the contigs assembled by the original unamplified sample. Although GenomePlex whole genome amplification kit allows one to generate enough DNA using 100 pg of template in each reaction, the minority of the mixed bacterial species is not linearly amplified. For both of the kits, the GC-rich regions of the genomic DNA are not efficiently amplified as suggested by the low coverage of the contigs with the high GC content. The high efficiency of the MALBAC kit is supported for the amplification of environmental microbial DNA samples, and the concerns on its application are also raised to bacterial species with the high GC content.
Research Notes
Evaluation of abundant hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin, South China Sea
LIU Zhen, SUN Zhipeng, WANG Zisong, ZHANG Wei, LI Tingan, HE Weijun, LI Fengxia, CAO Shang, LIU Jingjing, LIN Lu
2016, 35(2): 137-144. doi: 10.1007/s13131-015-0784-7
It has been confirmed that the key source rocks of Qiongdongnan Basin are associated with the Yacheng Formation, which was deposited in a transitional marine-continental environment. Because the distribution and evolution patterns of the source rocks in the major depressions are different, it is important to determine the most abundant hydrocarbon-generation depressions in terms of exploration effectiveness. Based on an analysis of organic matter characteristics of the source rocks, in combination with drilling data and seismic data, this paper establishes a model to evaluate the hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin. First of all, by using the method of seismic-facies model analysis, the distribution of sedimentary facies was determined. Then, the sedimentary facies were correlated with the organic facies, and the distribution of organic facies was predicted. Meanwhile, the thickness of source rocks for all the depressions was calculated on the basis of a quantitative analysis of seismic velocity and lithology. The relationship between mudstone porosity and vitrinite reflectance (Ro) was used to predict the maturity of source rocks. Second, using the parameters such as thickness and maturity of source rocks, the quantity and intensity of gas generation for Yacheng and Lingshui Formations were calculated. Finally, in combination with the identified hydrocarbon resources, the quantity and intensity of gas generation were used as a guide to establish an evaluation standard for hydrocarbon-generation depressions, which was optimized for the main depressions in the Central Depression Belt. It is proposed that Lingshui, Ledong, Baodao and Changchang Depressions are the most abundant hydrocarbon depressions, whilst Songnan and Beijiao Depressions are rich hydrocarbon depressions. Such an evaluation procedure is beneficial to the next stage of exploration in the deep-water area of Qiongdongnan Basin.