Revision of P-wave velocity and thickness of hydrate layer in Shenhu Area,South China Sea

To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sediments of five drilling wells, which causes P-wave velocity to approximate the propagation velocity of sea water(about 1500 m s-1). This also affects the identification of the hydrate layer and results in the underestimate of its thickness. In addition, because there could be about a 5 m thick velocity ramp above or below the hydrate layer as interpreted by acoustic and resistivity logging curves, the recalibrated thickness of this layer is less than the original estimated thickness. The recalibrated P-wave velocity of the hydrate layer is also higher than the original estimated velocity. For the drilling well with a relatively thin hydrate layer, the velocity ramp plays a more important role in identifying and determining the thickness of the layer.     

Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7℃, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water drilling through hydrate formation, the drilling fluid with low temperatures should be given priority. The drilling process should be kept under balanced pressures, and the drilling time should be shortened.     

木里冻土区天然气水合物成藏特征

为探讨木里冻土区天然气水合物的烃类来源及成藏特征,应用地球化学反演方法,根据碳同位素和成熟度的关系,分析烃类的成因和来源,结合水合物赋存特征、地层埋藏史等研究水合物成藏特征。结果表明:木里冻土地区天然气水合物的烃类气体以油型气为主,浅部混有少量煤成气;前者主要来源于石炭统和下二叠统烃源岩,侏罗系烃源岩贡献较小。水合物成藏空间分布非均质性较强,纵向上不同层段的气体来源和充注特征具有较大差异,上部层段烃类成熟度较低,来源于早期常规油气藏破坏后逸散气体,混有少量水合物分解甲烷;中部层段甲烷具有"多阶"充注特征,有原油裂解气贡献,底部发育油气优势运移路径;下部层段烃类主要来源于深部烃源岩层(早二叠系和石炭系),具有"多阶"充注特征。水合物形成前的常规油气藏演化和水合物形成后的保存条件,是研究区天然气水合物成藏和展布的主控因素。     

3D seismic analysis of the gas hydrate system and the fluid migration paths in part of the Niger Delta Basin,Nigeria

Comprehensive qualitative and semi-quantitative seismic analysis was carried out on 3-dimensional seismic data acquired in the deepwater compressional and shale diapiric zone of the Niger Delta Basin using an advanced seismic imaging tool. The main aim of this work is to obtain an understanding of the forming mechanism of the gas hydrate system, and the fluid migration paths associated with this part of the basin. The results showed the presence of pockmarks on the seafloor and bottom simulating reflectors (BSRs) in the field, indicating the active fluid flux and existence of gas hydrate system in the area. In the area of approximately 195 km² occupying nearly 24% of the entire study field, three major zones with continuous or discontinuous BSRs of 3 to 7 km in length which are in the northeastern, southern and eastern part of the field respectively were delineated. The BSR is interpreted to be the transition between the free gas zone and the gas hydrate zone. The geologic structures including faults (strike-slip and normal faults), chimneys and diapirs were deduced to be the main conduits for gas migration. It is concluded that the biogenic gases generated in the basin were possibly transported via faults and chimneys by advection processes and subsequently accumulated under low temperature and high pressure conditions in the free gas zone below the BSR forming gas hydrate. A plausible explanation for the presence of the ubiquitous pockmarks of different diameters and sizes in the area is the transportation of the excessive gas to the seafloor through these mapped geologic structures.     

Heat calculation and numerical simulation in steam mining of permafrost gas hydrate

Steam mining method was injecting hot steam into the borehole to heat the hydrate strata at the same time of depressurization mining,which could promote further decomposition and expand mining areas of gas hydrate. Steam heat calculation would provide the basis for the design of heating device and the choice of the field test parameters. There were piping heat loss in the process of mining. The heat transfer of steam flowing in the pipe was steady,so the heat loss could be obtained easily by formula calculation. The power of stratum heating should be determined by numerical simulation for the process of heating was dynamic and the equations were usually nonlinear. The selected mining conditions were 500-millimeter mining radius,10 centigrade mining temperature and 180 centigrade steam temperature. Heat loss and best heating power,obtained by formula calculation and numerical simulation,were 21. 35 W/m and 20 kW.     

Estimation of potential distribution of gas hydrate in the northern South China Sea

Gas hydrate research has significant importance for securing world energy resources, and has the potential to produce considerable economic benefits. Previous studies have shown that the South China Sea is an area that harbors gas hydrates. However, there is a lack of systematic investigations and understanding on the distribution of gas hydrate throughout the region. In this paper, we applied mineral resource quantitative assessment techniques to forecast and estimate the potential distribution of gas hydrate resources in the northern South China Sea. However, current hydrate samples from the South China Sea are too few to produce models of occurrences. Thus, according to similarity and contrast principles of mineral outputs, we can use a similar hydrate-mining environment with sufficient gas hydrate data as a testing ground for modeling northern South China Sea gas hydrate conditions. We selected the Gulf of Mexico, which has extensively studied gas hydrates, to develop predictive models of gas hydrate distributions, and to test errors in the model. Then, we compared the existing northern South China Sea hydrate-mining data with the Gulf of Mexico characteristics, and collated the relevant data into the model. Subsequently, we applied the model to the northern South China Sea to obtain the potential gas hydrate distribution of the area, and to identify significant exploration targets. Finally, we evaluated the reliability of the predicted results. The south seabed area of Taiwan Bank is recommended as a priority exploration target. The Zhujiang Mouth, Southeast Hainan, and Southwest Taiwan Basins, including the South Bijia Basin, also are recommended as exploration target areas. In addition, the method in this paper can provide a useful predictive approach for gas hydrate resource assessment, which gives a scientific basis for construction and implementation of long-term planning for gas hydrate exploration and general exploitation of the seabed of China.     

Estimation of potential distribution of gas hydrate in the northern South China Sea

Gas hydrate research has significant importance for securing world energy resources, and has the potential to produce considerable economic benefits. Previous studies have shown that the South China Sea is an area that harbors gas hydrates. However, there is a lack of systematic investigations and understanding on the distribution of gas hydrate throughout the region. In this paper, we applied mineral resource quantitative assessment techniques to forecast and estimate the potential distribution of gas hydrate resources in the northern South China Sea. However, current hydrate samples from the South China Sea are too few to produce models of occurrences. Thus, according to similarity and contrast principles of mineral outputs, we can use a similar hydrate-mining environment with sufficient gas hydrate data as a testing ground for modeling northern South China Sea gas hydrate conditions. We selected the Gulf of Mexico, which has extensively studied gas hydrates, to develop predictive models of gas hydrate distributions, and to test errors in the model. Then, we compared the existing northern South China Sea hydrate-mining data with the Gulf of Mexico characteristics, and collated the relevant data into the model. Subsequently, we applied the model to the northern South China Sea to obtain the potential gas hydrate distribution of the area, and to identify significant exploration targets. Finally, we evaluated the reliability of the predicted results. The south seabed area of Taiwan Bank is recommended as a priority exploration target. The Zhujiang Mouth, Southeast Hainan, and Southwest Taiwan Basins, including the South Bijia Basin, also are recommended as exploration target areas. In addition, the method in this paper can provide a useful predictive approach for gas hydrate resource assessment, which gives a scientific basis for construction and implementation of long-term planning for gas hydrate exploration and general exploitation of the seabed of China.     

Simulating the effect of hydrate dissociation on wellhead stability during oil and gas development in deepwater

It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development (OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson’s ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.     

Accumulation and exploration of gas hydrate in deep-sea sediments of northern South China Sea

The large deep-sea area from the southwestern Qiongdongnan Basin to the eastern Dongsha Islands,within the continental margin of northern South China Sea,is a frontier of natural gas hydrate exploration in China.Multiform of deep-sea sedimentations have been occurred since late Miocene,and sediment waves as a potential quality reservoir of natural gas hydrate is an most important style of them.Based on abundant available data of seismic,gravity sampling and drilling core,we analyzed the characteristics of seismic reflection and sedimentation of sediment waves and the occurrence of natural gas hydrate hosted in it,and discussed the control factors on natural gas hydrate accumulation.The former findings revealed the deep sea of the northern South China Sea have superior geological conditions on natural gas hydrate accumulation.Therefore,it will be of great significance in deep-sea natural gas hydrate exploration with the study on the relationship between deep-sea sedimentation and natural gas hydrate accumulation.     

Downward shift of gas hydrate stability zone due to seafloor erosion in the eastern Dongsha Island,South China Sea

New acquired and reprocessed three-dimensional(3 D) seismic data were used to delineate the distribution and characterization of bottom simulating reflections(B SRs) in the Chaoshan Sag,in the eastern part of Dongsha Island,South China Sea.Three submarine canyons with different scales were interpreted from the 3 D seismic data,displaying three stages of canyon development and are related with the variation of BSR.Abundant faults were identified from the coherence and ant-tracing attributions extracted from3 D seismic data,which provide the evidence for fluid migration from deeper sediments to the gas hydrate stability zone(GHSZ).The uplift of Dongsha Island created a large number of faults and leads to the increased seafloor erosion.The erosion caused the cooling of the seafloor sediments and deepening of the base of the gas hydrate stability zone,which is attributed to the presence of paleo-BSR and BSR downward shift in the study area.Hence,methane gas may be released during the BSR resetting and gas hydrate dissociation related with seafloor ero sion.     

Application of seismic interferometric migration for shallow seismic high precision data processing: A case study in the Shenhu area

The stability of submarine geological structures has a crucial influence on the construction of offshore engineering projects and the exploitation of seabed resources. Marine geologists should possess a detailed understanding of common submarine geological hazards. Current marine seismic exploration methods are based on the most effective detection technologies. Therefore, current research focuses on improving the resolution and precision of shallow stratum structure detection methods. In this article, the feasibility of shallow seismic structure imaging is assessed by building a complex model, and differences between the seismic interferometry imaging method and the traditional imaging method are discussed. The imaging effect of the model is better for shallow layers than for deep layers because coherent noise produced by this method can result in an unsatisfactory imaging effect for deep layers. The seismic interference method has certain advantages for geological structural imaging of shallow submarine strata, which indicates continuous horizontal events, a high resolution, a clear fault, and an obvious structure boundary. The effects of the actual data applied to the Shenhu area can fully illustrate the advantages of the method. Thus, this method has the potential to provide new insights for shallow submarine strata imaging in the area.     

Sensitivity analysis of the DeNitrification and Decomposition model for simulating regional carbon budget at the wetland-grassland area on the Zoige Plateau,china

Although mathematical models (e.g., DeNitrification and DeComposition (DNDC) provide a powerful tool to study regional carbon budget, it is still difficult to obtain accurate simulation results because there exists large uncertainties in modeling regional carbon budget. Through the investigation on the sensitivity of model output parameters to the input parameters, sensitivity analysis (SA) has been proved to be able to identify the key sources of uncertainties and be helpful to reduce the model uncertainties. However, some input parameters with discrete values (e.g., land use type and soil type) and the regional effect of the sensitive parameters were rarely examined in SA. In this paper, taking the Zoige Plateau as a case area, we combined the one-factor-at-a-time (OAT) with Extended Fourier Amplitude Sensitivity Test (EFAST) to conduct a SA of DNDC for simulating the regional carbon budget, including Gross Primary Productivity (GPP), Net Primary Productivity (NPP), Net Ecosystem Productivity (NEP), autotrophic respiration (Ra), soil microbial heterotrophic respiration (Rh) and ecosystem respiration (Re). The result showed that the combination of OAT and EFAST could test the contribution of the input parameters with discrete values to the output parameters. In DNDC model, land use type and soil type had a significant impact on the regional carbon budget of the Zoige Plateau, and daily temperature was also confirmed to be one of the most important parameters for carbon budget. For the other input parameters, with the change of land use type or soil type at regional scale, the sensitive parameters of carbon budget would vary accordingly. The SA results would provide scientific evidence to optimize DNDC model and they suggested that we should pay attention to the spatial/temporal effect of SA and try to use the appropriate data in simulation of the regional carbon budget.     

Distinct BSRs and their implications for natural gas hydrate formation and distribution at the submarine Makran accretionary zone

To investigate the nature of gas hydrates in the Makran area,new high-resolution geophysical data were acquired between 2018-2019.The data collected comprise multibeam and two-dimensional multi-channel seismic reflection data.The multibeam bathymetry data show East-North-East(ENE) ridges,piggy-back basins,canyon and channel systems,and the morphology of the abyssal plain.Continuous and discontinuous bottom simulating reflectors(BSRs) occur in the piggy-back basins on most of the seismic profiles available.The BSRs cut the dipping layers with strong amplitude and reversed polarity.Discontinuous BSRs indicate a transition along a dipping high-permeable sand layers from gas-rich segment to the gas hydrate-bearing segment and sugge st alternating sediments of fine and relatively coarse grain size.Double BSRs are highly dynamic and attributed to slumps occurring in the study area.The BSRs induced by slumps are located both at deep and shallow depths,responding to the temperature or pressure variation.For the first time,BSRs are observed in the abyssal plain of the Makran area,being associated with anticline structures,which do not show large spatial continuity and are strongly conditioned by structural conditions such as anticlines and fluid migration pathways,including deep fault,gas chimney,and high-permeable sedimentary layer.Our results may help to assess the gas hydrate potential within the piggy-back basins and to determine the most promising target areas.Moreover,results about the abyssal plain BSR may help to locate hydrocarbon reservoirs in the deep ocean.     

川东南南川地区构造变形与页岩气富集

南川地区自下古生界海相页岩成气以来,遭受了强烈的构造改造作用,致使页岩气富集规律复杂。为揭示南川地区中新生代构造变形对页岩气富集的制约,通过构造精细解析,以及对演化时序和页岩气富集主控因素的分析,构建了结构模式,恢复了中新生代构造演化过程,厘定了页岩气富集主控因素,进而分析了构造样式与页岩气富集模式的响应关系。研究表明,南川地区整体构造变形自东向西逐渐减弱,存在北段强烈冲断褶皱-断展-断滑、南段强烈冲断褶皱-断滑两种前展式结构模式。中燕山期,主体NE向构造发育,平桥、东胜构造形成,至中燕山期末期,受金佛山隆起以及南川-遵义断层的作用,南段发生构造叠加与改造,早期NE向构造演化为北倾单斜,并在南川-遵义断层东侧发育近南北向阳春沟背斜。受差异构造变形作用,北段断褶带发育背斜型富页岩气构造样式,外缘带为单斜型构造样式,而南段构造叠加带则发育单斜型和背斜型构造样式。页岩气整体保存条件受构造变形方式制约,北段页岩气保存条件由东向西逐渐变好,而南段页岩气保存条件较为复杂,其中北段的低角度单斜、宽缓背斜、较宽缓背斜3类构造样式为有利的页岩气富集构造。      

Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs

The origin and migration of natural gas and the accumulation of gas hydrates within the Pearl River Mouth Basin of the northern South China Sea are poorly understood. Based on high-resolution 2D/3D seismic data, three environments of focused fluid flow: gas chimneys, mud diapirs and active faults have been identified. Widespread gas chimneys that act as important conduits for fluid flow are located below bottom simulating reflections and above basal uplifts. The occurrence and evolution of gas chimneys can be divided into a violent eruptive stage and a quiet seepage stage. For most gas chimneys, the strong eruptions are deduced to have happened during the Dongsha Movement in the latest Miocene, which are observed below Pliocene strata and few active faults develop above the top of the Miocene. The formation pressures of the Baiyun Sag currently are considered to be normal, based on these terms: 1) Borehole pressure tests with pressure coefficients of 1.043–1.047; 2) The distribution of gas chimneys is limited to strata older than the Pliocene; 3) Disseminated methane hydrates, rather than fractured hydrates, are found in the hydrate samples; 4) The gas hydrate is mainly charged with biogenic gas rather than thermogenic gas based on the chemical tests from gas hydrates cores. However, periods of quiet focused fluid flow also enable the establishment of good conduits for the migration of abundant biogenic gas and lesser volumes of thermogenic gas. A geological model governing fluid flow has been proposed to interpret the release of overpressure, the migration of fluids and the formation of gas hydrates, in an integrated manner. This model suggests that gas chimneys positioned above basal uplifts were caused by the Dongsha Movement at about 5.5 Ma. Biogenic gas occupies the strata above the base of the middle Miocene and migrates slowly into the gas chimney columns. Some of the biogenic gas and small volumes of thermogenic gas eventually contribute to the formation of the gas hydrates.     

孤东地区走滑作用对油气成藏的控制

通过陆地和海域地震资料重新整合,重新厘定孤东地区主控断层性质,结合构造物理模拟实验及孤东地区石油地质条件,分析断层性质对油气分布的控制作用。结果表明:孤东、垦东断层具有明显的右旋走滑作用,并派生右行左阶增压叠置和拉张释压马尾扇构造样式。增压叠置区位于孤东低凸起,油气聚集分布,为主要成藏区,以浅层成藏为主,潜山不成藏;拉张释压马尾扇区位于孤东断层尾端,油气分布较少,为主要失利区。两种构造样式的相互结合共同控制孤东地区油气的运移与分布。该结果为研究走滑派生构造特征地区的油气分布特征提供参考。     

Sensitivity and uncertainty analysis of regional marine ecosystem services value

Marine ecosystem services are the benefits which people obtain from the marine ecosystem, including provisioning ser-vices, regulating services, cultural services and supporting services. The human species, while buffered against environmental changes by culture and technology, is fundamentally dependent on the flow of ecosystem services. Marine ecosystem services be-come increasingly valuable as the terrestrial resources become scarce. The value of marine ecosystem services is the monetary flow of ecosystem services on specific temporal and spatial scales, which often changes due to the variation of the goods prices, yields and the status of marine exploitation. Sensitivity analysis is to study the relationship between the value of marine ecosystem services and the main factors which affect it. Uncertainty analysis based on varying prices, yields and status of marine exploitation was carried out. Through uncertainty analysis, a more credible value range instead of a fixed value of marine ecosystem services was obtained in this study. Moreover, sensitivity analysis of the marine ecosystem services value revealed the relative importance of different factors.     

辽河盆地东部凸起太原组页岩气聚集条件及有利区预测

从辽河盆地东部凸起太原组泥页岩发育的沉积背景、地球化学条件、储集物性及含气性等方面分析页岩气聚集的基础条件,采用多信息叠合法对该区太原组页岩气富集有利区进行预测.结果表明:太原组地层发育潮坪、沼泽及泻湖相,富有机质暗色泥页岩、碳质泥页岩,单层厚度大,分布面积广,连续性好,有机碳平均质量分数为3.3%,有机质类型以Ⅲ型为主的混合型,生烃潜力较大,热演化程度高,处于大量生气的阶段;泥页岩脆性较好,孔隙和裂缝发育,含气性好,具备页岩气聚集的地质、地球化学条件及储集物性条件,有利于页岩气的生成、富集及后期储层改造.根据页岩气富集的多种因素分析结果,认为王家南部地区页岩气聚集条件和储集性能较优越,是辽河盆地东部凸起太原组页岩气勘探开发的有利区域.     

Tidal analysis in the venturi-shaped area between Zhenhai and Shenjiamen in the East China Sea

In order to better understand the general tidal features in the venturi-shaped area between Zhenhai and Shenjiamen in the northern coastal region of Zhejiang Province in the East China Sea, the tidal data were obtained from both the three permanent tide stations of Zhenhai, Dinghai and Shenjiamen, and four temporary tide stations of Mamu, Chuanshan, Guoju and Liuheng, along with the current speed being observed at Luotou Waterway. Results from harmonic analysis show that: (1) The area was dominated by shallow water tides with irregular semi-diurnal features, and the smallest tidal range occurred in the area near a crossing line between Zhenhai and Dinghai stations, indicating that a tidal node existed in the southern Hangzhou Bay; (2) Formulae, HS2/HM2 >0.4 and gM2-(gK1+gO1)=270° (where H and g are harmonic constants), could be used as judging criteria for high and low tidal level diurnal inequalities; (3) The duration difference between ebb and flood tides could be roughly assessed by the ratio of HM4 vs. HM2; and the larger the ratio is, the bigger the duration difference is. At the same time, the duration period could be assessed by 2gM2-gM4, the epoch difference between M2 and M4 tidal constituents. If 2gM2-gM4 <180°, then the ebb duration is longer than the flood duration; if 180°< 2gM2-gM4 <360°, the result is reversed; (4) Taking Dinghai station as a center point, the highest tidal levels and the average high tidal levels, as well as the average tidal ranges at all stations became higher and larger both southeastwards and northwestwards, while the lowest tidal levels and the average low tidal levels appeared to be lower both southeastwards and northwestwards; and (5) The tidal patterns were not all in line with the tidal current patterns. As a conclusion, the smallest tidal range occurred in the narrow part of the venturi-shaped area. Along the both sides of the area, the highest tidal level and tidal range became higher and larger, while the lowest tidal level became lower with the increase of the distance from the narrow throat area. This is somehow different from the theory that the tidal level increases gradually when it moves towards the top narrow area of a V-shaped bay or estuary.     

DNAPL场地污染通量升尺度预测的敏感性分析

重非水相液体(DNAPL)污染问题日益严重。为评估DNAPL污染场地的环境风险, 常采用升尺度模型推估DNAPL污染源区溶解相的质量通量(溶解通量)。由于升尺度模型中的参数较多, 调查成本较高, 因此需筛选模型中的关键参数, 指导实际污染场地设计合理的观测数据采集方案。首先对升尺度模型中6个参数(地下水平均流速q、标准化浓度C₀/Ceq、离散状DNAPL质量比例GF₀、初始时刻离散状DNAPL贡献的通量比例f_g、拟合参数β₁及β₂)开展全局敏感性分析, 识别其中关键参数, 进而采用局部敏感性分析定量化关键参数的变化对通量预测的影响。研究结果表明, 参数q、C₀/Ceq、GF₀和f_g对通量预测有较大影响。q和C₀/Ceq在整个衰减过程中敏感性均相对较高, GF₀和f_g随着衰减过程的进行, 敏感性不断增高, 分别在衰减中后期和后期达到峰值; 对于不同结构的污染源区, q或C₀/Ceq增大时, 通量的增幅基本不变。随着污染源区中离散状DNAPL和池状DNAPL间的质量比例(GTP)增大, GF₀或f_g增大时, 其对通量预测的影响不断增大或减小。因此在预测溶解通量时需将调查成本重点应用于q和C₀/Ceq; 在合理设计污染源区修复方案时, 应重点调查GF₀; 在预测污染源区寿命时, f_g为重要调查对象; 对于所有结构的污染源区, q和C₀/Ceq均为重要调查对象, 对于GTP较大的污染源区, 应将调查成本重点应用于GF₀, 对于GTP较小的污染源区, 应重点调查f_g。