Dynamic Field Division of Hydrocarbon Migration,Accumulation and Hydrocarbon Enrichment Rules in Sedimentary Basins

Hydrocarbon distribution rules in the deep and shallow parts of sedimentary basins are considerably different, particularly in the following four aspects. First, the critical porosity for hydrocarbon migration is much lower in the deep parts of basins: at a depth of 7000 m, hydrocarbons can accumulate only in rocks with porosity less than 5%. However, in the shallow parts of basins (i.e., depths of around 1000 m), hydrocarbon can accumulate in rocks only when porosity is over 20%. Second, hydrocarbon reservoirs tend to exhibit negative pressures after hydrocarbon accumulation at depth, with a pressure coefficient less than 0.7. However, hydrocarbon reservoirs at shallow depths tend to exhibit high pressure after hydrocarbon accumulation. Third, deep reservoirs tend to exhibit characteristics of oil (-gas)-water inversion, indicating that the oil (gas) accumulated under the water. However, the oil (gas) tends to accumulate over water in shallow reservoirs. Fourth, continuous unconventional tight hydrocarbon reservoirs are distributed widely in deep reservoirs, where the buoyancy force is not the primary dynamic force and the caprock is not involved during the process of hydrocarbon accumulation. Conversely, the majority of hydrocarbons in shallow regions accumulate in traps with complex structures. The results of this study indicate that two dynamic boundary conditions are primarily responsible for the above phenomena: a lower limit to the buoyancy force and the lower limit of hydrocarbon accumulation overall, corresponding to about 10%-12% porosity and irreducible water saturation of 100%, respectively. These two dynamic boundary conditions were used to divide sedimentary basins into three different dynamic fields of hydrocarbon accumulation: the free fluid dynamic field, limit fluid dynamic field, and restrain fluid dynamic field. The free fluid dynamic field is located between the surface and the lower limit of the buoyancy force, such that hydrocarbons in this field migrate and accumulate under the influence of, for example, the buoyancy force, pressure, hydrodynamic force, and capillary force. The hydrocarbon reservoirs formed are characterized as "four high," indicating that they accumulate in high structures, are sealed in high locations, migrate into areas of high porosity, and are stored in reservoirs at high pressure. The basic features of distribution and accumulation in this case include hydrocarbon migration as a result of the buoyancy force and formation of a reservoir by a caprock. The limit fluid dynamic field is located between the lower limit of the buoyancy force and the lower limit of hydrocarbon accumulation overall; the hydrocarbon migrates and accumulates as a result of, for example, the molecular expansion force and the capillary force. The hydrocarbon reservoirs formed are characterized as "four low," indicating that hydrocarbons accumulate in low structures, migrate into areas of low porosity, and accumulate in reservoirs with low pressure, and that oil(-gas)-water inversion occurs at low locations. Continuous hydrocarbon accumulation over a large area is a basic feature of this field. The restrain fluid dynamic field is located under the bottom of hydrocarbon accumulation, such that the entire pore space is filled with water. Hydrocarbons migrate as a result of the molecular diffusion force only. This field lacks many of the basic conditions required for formation of hydrocarbon reservoirs: there is no effective porosity, movable fluid, or hydrocarbon accumulation, and potential for hydrocarbon exploration is low. Many conventional hydrocarbon resources have been discovered and exploited in the free fluid dynamic field of shallow reservoirs, where exploration potential was previously considered to be low. Continuous unconventional tight hydrocarbon resources have been discovered in the limit fluid dynamic field of deep reservoirs; the exploration potential of this setting is thought to be tremendous, indicating that future exploration should be focused primarily in this direction.

Features and dynamic mechanisms of Cenozoic tectonic migration and its impact on the hydrocarbon accumulation in the northern South China Sea

The northern continental margin of the South China Sea(SCS) is located within the tectonic system of Southeast Asia, an area with a great deal of tectonic migration due to the regional tectonic movements. The available geological and geophysical data of the area are comprehensively analyzed in order to demonstrate the typical migration patterns of the Cenozoic tectonics in the northern SCS caused by the episodes of the Cenozoic tectonic movement. Furthermore, the lateral variation characteristics of the strata and the different evolution patterns of the main basins' features are assessed. It primarily focus on:(1) the Cenozoic episodic rifting from north to south in the continental margin of the northern SCS;(2) the rifting and depression time of the main basins progressively become younger as one goes from north to south, signifying that the migration of both the tectonics and the sediments within the northern SCS travelled from north to south during the Cenozoic; and(3) the lateral tectonic migration on the direction of EW is not regular in total, but in some local areas the trending of the tectonic migration is from west to east. The analysis of the tectonic migration features of the northern SCS, in combination with the regional tectonic evolution background, indicates that the observed remote lagging effect, resulted from the India-Eurasia plate collision, is the main dynamic mechanism involved in the tectonic migration within the northern SCS. The tectonic migration has significant influence on both the organization of petroleum deposits and on the hydrocarbon accumulation within the basins in the northern SCS; comprehensive understanding of this dynamic system is of great reference value in predicting the hydrocarbon accumulation and has the potential to have an enormous impact in discovering new deep reservoirs for the future oil-gas exploration.

Hydrocarbon migration and accumulation along the fault intersection zone-a case study on the reef-flat systems of the No.1 slope break zone in the Tazhong area, Tarim Basin

Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality (2-3 orders of magnitude at the intersection zone) and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.

A Study of the Migration and Accumulation Efficiency and the Genesis of Hydrocarbon Natural Gas in the Xujiaweizi Fault Depression

摘要：为了在 Xujiaweizi 调查迁居和烃天然气的累积效率，并且为它的开始的分类提供新证据，指责消沉，在一个封闭系统的一个来源岩石热分解实验被设计并且执行了。基于这，为描述从有机物的产生和碳同位素分别在这期间处理的气体的运动模型被建立，校准然后外推到由联合 Xushen-1 的热历史数据很好的地质的条件。结果显示在 Xujiaweizi 差错消沉的煤措施是典型高效率的煤气的来源，从他们产生的天然气有高迁居和累积效率，并且因而，大规模天然气累积发生在区域。在 Xujiaweizi 差错消沉的高度 / 过去成熟的煤措施与高 13C1 价值产生 coaliferous 气体(>?20%) 在迟了的阶段，使碳成为器官的链烷气体的同位素作文反常地重。另外，通过天然气的 caprock 混合和驱散能导致否定的碳同位素顺序(13C1 > 13C2 > 13C3 > 13C4 ) 器官的链烷，气体，和驱散罐头也导致器官的链烷气体的反常地重的碳同位素作文。至于无机的 nonhydrocarbon 气体水库的发现，它能是仅仅服务一补助证据而非烃气体是无机的一条直接证据。作为结果，作为无机的气体在 Xujiaweizi 差错消沉分类烃天然气需要更充分的证据。

Artificial Neural Network Model of Hydrocarbon Migration and Accumulation

Based on the dynamic simulation of the 3 D structure the sedimentary modeling, the unit entity model has been adopted to transfer the heterogeneous complex passage system into limited simple homogeneous entity, and then the traditional dynamic simulation has been used to calculate the phase and the drive forces of the hydrocarbon , and the artificial neural network(ANN) technology has been applied to resolve such problems as the direction, velocity and quantity of the hydrocarbon migration among the unit entities. Through simulating of petroleum migration and accumulation in Zhu Ⅲ depression, the complex mechanism of hydrocarbon migration and accumulation has been opened out.

Hydrodynamic Evolution and Hydrocarbon Accumulation in the Dabashan Foreland Thrust Belt,China

在 Dabashan 低岬有二出戏构造的带：上面并且更低的戏。更低的戏经历了当上面的戏有一个沉积水动力学阶段时，水动力学从 Sinian 上演到新生代的一个沉积水动力学阶段，二个埋葬水动力学阶段，二个构造水动力学阶段和二渗入，一个埋葬水动力学阶段，二个构造水动力学阶段和阶段渗入水动力学阶段从对新生代二叠。两沉积的水，包括的烃，和深披风液体的广泛的流动在中间迟了的三叠纪的 Indosinian 造山运动在碰撞造山运动期间在 Chengkou 差错发生了，并且液体流动在在中间迟了的侏罗记的 intracontinental 造山运动期间是复杂的。除了这些运动，，大气的水的渗入和运动在封面阶层 decollement 发生在 Chengkou 差错构造的带，广泛的沉积的水流动(包括的烃) 主要在 Zhenba 和 Pingba 差错发生了。在阶段期间快速高举并且从白垩纪的发掘到新生代，液体流动主要被高度差别引起的大气的水和导致严肃的流动的渗入描绘，而构造过程引起的沉积的水流动是相对不太重要。沉积的水流动在在中间迟了的三叠纪的 Indosinian 造山运动的碰撞造山运动期间对在烃移植和累积的更低的戏更重要，但是它的影响在上面的戏上是相对细微的。一方面，水动力学在在中间迟了的侏罗记的 intracontinental 造山运动期间调整了，改革或炉破坏了在更低的戏的油水库；在另一方面，它驱使大量烃旁边地并且垂直地移居并且为烃累积是有利的。主要从白垩纪调整并且破坏油水库到新生代的渗入水动力学。

Paleoporosity and critical porosity in the accumulation period and their impacts on hydrocarbon accumulation—A case study of the middle Es3 member of the Paleogene formation in the Niuzhuang Sag, Dongying Depression, Southeastern Bohai Bay Basin, East Chi

Similar reservoir sandbodies and fault conduit systems in the sandstone reservoirs in the middle Es3 member of the Niuzhuang Sag have been problematic for a long time. The following problems remain unsolved: 1) The distribution of sandstone porosity is inconsistent with the hydrocarbon accumulation. The oil sandstones have low porosity instead of high porosity. 2) Sandstones, which have the same properties, have different levels of oiliness, and the sandstones with almost the same properties show different degrees of oil-bearing capacity. This study analyzes the condition of reservoirs in the research area during the accumulation period in terms of paleoporosity estimation and discusses the critical porosity of the sandstone reservoirs during the same period. The following conclusions can be drawn from the results. 1) Although reservoir properties are low at present and some reservoirs have become tight, the paleoporosity ranging from 18% to 25% is greater than the critical porosity of 13.9%. As the loss of porosity is different in terms of burial history, the present porosity cannot reflect porosity during the accumulation period. Similarly, high porosity during the accumulation period does not indicate that the present porosity is high. 2) The present reservoir location is consistent with the distribution of high paleoporosity during the accumulation period. This result indicates that high porosity belts are prone to hydrocarbon accumulation because of the dominant migration pathways generated as a result of property discrepancies under similar fault conduit conditions. Consequently, the hydrocarbon mainly accumulates in high porosity belts. Paleoporosity during the accumulation period is found to be a vital controlling factor. Therefore, high paleoporosity sandstones in the middle Es3 member of the Niuzhuang Sag have great potential for future exploration.

The characteristics of unconformity surface at the bottom of the Paleogene and its significance in hydrocarbon migration in the Sikeshu Sag of the Junggar Basin, Northwest China

The unconformity surface at the bottom of the Paleogene, located in the Sikeshu Sag of the Junggar Basin, Northwest China, is one of the most important hydrocarbon migration pathways and characterized by 3 layers of upper coarse clastic rock, lower weathering crust and leached zone. The upper coarse clastic rock displays features of higher density, lower SDT and gamma-ray logging while the weathering crust in the lower part displays opposite features. The formation water is of NaHCO 3 type but at lower mineralization degree. The QGF indices are generally between 2.19 and 3.77 and the GOI parameters vary from 1% to 5%. From the southeast to the northwest of the sag, the content of saturated hydrocarbon increases from 30.81% to 53.74% while that of non-hydrocarbon and asphaltene decreases. The Pr/nC 17 decreases from 0.65 to 0.47 while the Ph/nC 18 decreases from 0.66 to 0.27, and the content of benzo[c] carbazole declines while the benzo[a] carbazole amount and (alkyl carbazole)/(alkyl+benzo carbazole) ratio both increase. These revealed that the hydrocarbons migrated from the sag to the ramp region along the unconformity surface.

THE PEPC EVOLUTION OF THE EAST CHINA SEA BASIN AND ITSHYDROCARBON ACCUMULATION

Evidence from such diverse fields as geology,seismology and geophysic exploration indicate that the "backarc spnding"and"terrane matching" models can not be reasonably used to explain the evolutionary feature of the East China Sea (ECS) Basin. A new model,the persistent extending-pulsative compressing (PEPC) model,is proposed by the authors. An active persistently extension oceanward took place at the margin of the continental lithosphere,because of its inhomogeneous composition,texture and thermal state, and was conttolled by deep-seated (mantle) geological processes.The extension is the main cause for the formation and evolution of the ECS Basin.The northwestward movement of the Philippine Sea lithosphete provides the basin with a compre8sion.The compression is short in time but powerful in force strength, i. e. in a pulsative form, relatively to the above-mentioned extension. The PEPC model plays a new role in comprehencing the laws of hydtocarbon accumulation and prospecting for oil /Ras fields in the ECS Basin.There are several source- reservoir-caprock associations related closely to the multiperiodic persistent extending-pulsative compressing.The Paleocene and Eocene are the main mature source rocks and the Oligocene to Miocene are the potential source rocks in the Shelf Basin.Commonly the persistent extension is favourable to the formation of the hydrocarbon areas, but the pulsative compression causes them to be destroyed.

A unified model for the formation and distribution of both conventional and unconventional hydrocarbon reservoirs

The discovery and large-scale exploration of unconventional oil/gas resources since 1980s have been considered as the most important advancement in the history of petroleum geology;that has not only changed the balance of supply and demand in the global energy market,but also improved our understanding of the formation mechanisms and distribution characteristics of oil/gas reservoirs.However,what is the difference of conventional and unconventional resources and why they always related to each other in petroliferous basins is not clear.As the differences and correlations between unconventional and conventional resources are complex challenging issues and very critical for resources assessment and hydrocarbon exploration,this paper focused on studying the relationship of formations and distributions among different oil/gas reservoirs.Drilling results of 12,237 exploratory wells in 6 representative petroliferous basins of China and distribution characteristics for 52,926 oil/gas accumulations over the world were applied to clarify the formation conditions and genetic relations of different oil/gas reservoirs in a petroliferous basin,and then to establish a unified model to address the differences and correlations of conventional and unconventional reservoirs.In this model,conventional reservoirs formed in free hydrocarbon dynamic field with high porosity and permeability located above the boundary of hydrocarbon buoyancy-driven accumulation depth limit.Unconventional tight reservoirs formed in confined hydrocarbon dynamic field with low porosity and permeability located between hydrocarbon buoyancy-driven accumulation depth limit and hydrocarbon accumulation depth limit.Shale oil/gas reservoirs formed in the bound hydrocarbon dynamic field with low porosity and ultra-low permeability within the source rock layers.More than 75%of proved reserves around the world are discovered in the free hydrocarbon dynamic field,which is estimated to contain only 10%of originally generated hydrocarbons.Most of undiscovered resources distributed in the confined hydrocarbon dynamic field and the bound hydrocarbon dynamic field,which contains 90%of original generated hydrocarbons,implying a reasonable and promising area for future hydrocarbon explorations.The buried depths of hydrocarbon dynamic fields become shallow with the increase of heat flow,and the remaining oil/gas resources mainly exist in the deep area of“cold basin”with low geothermal gradient.Lithology changing in the hydrocarbon dynamic field causes local anomalies in the oil/gas dynamic mechanism,leading to the local formation of unconventional hydrocarbon reservoirs in the free hydrocarbon dynamic field or the occurrence of oil/gas enrichment sweet points with high porosity and permeability in the confined hydrocarbon dynamic field.The tectonic movements destroy the medium conditions and oil/gas components,which leads to the transformation of conventional oil/gas reservoirs formed in free hydrocarbon dynamic field to unconventional ones or unconventional ones formed in confined and bound hydrocarbon dynamic fields to conventional ones.

Thermodynamic Modeling of Fluid-Bearing Natural Gas Inclusions for Geothermometer and Geobarometer of Overpressured Environments in Qiongdongnan Basin, South China Sea

It is a very difficult problem to directly determine fluid pressure during hydrocarbon migration and accumulation in sedimentary basins. pVt modeling of coupling hydrocarbon fluid inclusion of its coeval aqueous fluid inclusion provides a powerful tool for establishing the relationship of formation pressure evolution with time. Homogenization temperature of fluid inclusion can routinely be measured under microthermometric microscopy. Crushing technique has been employed to obtain the composition of fluid inclusions, and the commercial software VTFLINC easily and rapidly completes the construction of p t phase diagram. The minimum trapping pressure of hydrocarbon fluid inclusion would be then determined in the p t space. In this paper, three samples of YC21 1 1 and YC21 1 4 wells at YC21 1 structural closure, Qiongdongnan basin, South China Sea, were selected for the pVt modeling practice, and the formation pressure coefficient (equals to fluid pressure/hydrostatic pressure) changing trend with time has primarily been established. The modeling results also indicate that the reservoirs of Lingshui and Yacheng formations in YC21 1 structure are within a very high potential system and would have undergone a discharging of thermal fluids through top seal rupture, which depicts that there is a very high risk for natural gas exploration in this area.

Tight sandstone gas accumulation mechanisms and sweet spot prediction, Triassic Xujiahe Formation, Sichuan Basin, China

The prediction of continental tight sandstone gas sweet spots is an obstacle during tight sandstone gas exploration. In this work, the classic physical fluid charging experimental equipment is improved, the combination of the gas migration and accumulation process with the pore network numerical simulation method is investigated, and application of the permeability/porosity ratio is proposed to predict the gas saturation and sweet spots of continental formations. The results show that (1) as the charging pressure increases, the permeability of the reservoir increases because more narrow pore throats are displaced in the percolation process;and (2) based on pore network numerical simulation and theoretical analysis, the natural gas migration and accumulation mechanisms are revealed. The gas saturation of tight sandstone rock is controlled by the gas charging pressure and dynamic percolation characteristics. (3) The ratio of permeability/porosity and fluid charging pressure is proposed to predict the gas saturation of the formation. The ratio is verified in a pilot and proven to be applicable and practical. This work highlights the tight sandstone gas migration and accumulation mechanisms and narrows the gap among microscale physical experiments, numerical simulation research, and field applications.

Control effect of fluid entry pressure on hydrocarbon accumulation

The micromigration of oil-drive-water and gas-drive-water in oil and gas fields was studied,by using core slices and micro-experimental technology,and the migration processes and characteristics of oil and gas in pores and throats were observed,as well as entry pressures of oil/gas migration.Research shows that entry pressures of both oil-drive-water and gas-drive-water increase obviously as porosity decreases,and the statistical regularity observes the power function variation.However,there is a complex changing relationship between porosity and different entry pressure values of the two replacement processes,forming three curve sections,each representing a different accumulation significance.When the porosity is over 10%-12%,the difference between oil-drive-water and gas-drive-water entry pressures is small.Both oil and gas can migrate and accumulate in this kind of reservoir.The probabilities of oil and gas reservoir formation are nearly equal,forming conventional oil/gas pools.When porosity is between 5% and 10%-12%,the difference between the two is obvious,which indicates that this kind of reservoir can seal oil,but can also be a reservoir for gas,easily forming unconventional hydrocarbon pools(deep-basin gas pools).When porosity is less than 5%,the difference is indistinct and the entry capillary pressures show the same sealing function for oil and gas.In this condition,both oil and gas pools are difficult to form.Experimental results give a rational explanation for the difference of accumulation probability between deep-basin gas and deep-basin oil,and also for the mechanism of tight sand acting as cap rock.

Numerical simulation of the dynamic migration mechanism and prediction of saturation of tight sandstone oil

Quantitative characterization of tight sandstone oil migration and accumulation is an emerging research frontier in the field of oil and gas exploration.In this study,a conceptual model containing multiple basic geological elements is developed,and a nonlinear seepage numerical model for tight sandstone oil migration and accumulation is established.The effects of the slip effect,overpressure driving force,buoyancy,and capillary force on the migration and accumulation of tight oil are examined.The results showed that(1)the differences in oil migration and accumulation between tight and conventional reservoirs are reflected in the growth mode of oil saturation,distribution characteristics of oil and water,and extent of the effect of the formation dip angle;(2)the slip effect has a significant impact when the average pore throat radius is less than 150 nm and the overpressure driving force and capillary force are the main mechanical mechanisms controlling oil migration and accumulation in tight sandstone,while the coupling effect of buoyancy,capillary force,and overpressure driving force controls the upper and lower limits of oil saturation.Finally,a dimensional and dimensionless identification chart for rapidly predicting the oil saturation of tight sandstone is proposed and verified using the measured data.This study provides a basis for analyzing the migration and accumulation mechanisms of tight sandstone oil and a new approach for predicting oil saturation.Additionally,we developed digital and visual analysis methods for the migration results,enriching the expression of the dynamics of hydrocarbon accumulation.

Group classification of mixed oils in central Junggar Basin,Northwest China and their migration

The produced oils in central Junggar Basin are commonly mixed in origin.In this paper,in order to reveal this complexity and thereby provide valuable clues to the study of oil source and formation mechanism,genetic groups of the mixed oils were classified and their migration/accumulation was investigated.Based on the artificial oil mixing experiments,some representative biomarkers of the mixed oils showed varying tendencies according to mixing ratios of the oils.Hence,these biomarkers are useful for determining the origin of the mixed oils.According to the criteria,oils in the area were divided into four basic groups,i.e.,the Lower Permian Fengcheng oil,the Middle Permian Lower Wuerhe oil,the Jurassic source derived oil,and the mixed oil(including the Lower and Middle Permian mixed oil and the Permian and Jurassic mixed oil).Oil migration and accumulation were discussed in combination with the geological background.

Re-recognition of “unconventional” in unconventional oil and gas

Taking the Wufeng–Longmaxi shale gas in the Sichuan Basin as a typical example,based on the new progress in exploration and development,this study re-examines the"unconventional"of unconventional oil and gas from two aspects:oil and gas formation and accumulation mechanisms,and main features of oil and gas layers.The oil and gas of continuous accumulation and distribution from integrated source and reservoir is unconventional oil and gas,and the study focusing on shale oil and gas in comparison with conventional oil and gas has made progress in five aspects:(1)Unconventional oil and gas have source-reservoir-in-one and in-situ accumulation;according to the theory of continuous oil and gas accumulation,the accumulation power of oil and gas is overpressure and diffusion;for conventional oil and gas,the source and reservoir are different formations,the trapping accumulation is its theoretical foundation,and the accumulation power is characterized by buoyancy and capillary force.(2)The unconventional oil and gas reservoirs are mainly formed in the low-energy oxygen-anaerobic environment,dominantly semi-deep to deep shelf facies and the semi-deep to deep lake facies,simple in lithology,rich in organic matter and clay minerals;conventional oil and gas mainly occur in coarse-grained sedimentary rocks formed in high-energy waters with complex lithology.(3)The unconventional oil and gas reservoirs have mainly nano-scale pores,of which organic matter pores take a considerable proportion;conventional oil and gas reservoirs mainly have micron-millimeter pores and no organic matter pores.(4)Unconventional shale oil and gas reservoirs have oil and gas in uniform distribution,high oil and gas saturation,low or no water content,and no obvious oil and gas water boundary;conventional oil and gas reservoirs have oil and gas of complex properties,moderate oil and gas saturation,slightly higher water content,and obvious oil,gas and water boundaries.(5)Organic-rich shale is the main target of unconventional oil and gas exploration;the sedimentary environment controls high organic matter abundance zone and organic matter content controls oil and gas abundance;positive structure and high porosity control the yields of shale wells;bedding and fracture development are important factors deciding high yield.

Model of Fault Controlling Petroleum Accumulation in Linshang Fault Zone,Huimin Depression

Fault controlling petroleum accumulation is mainly reflected in hydrocarbon migration and sealing in accumulation periods.By fault activity rate analysis and fuzzy comprehensive sealing evaluation in different places of Linshang Fault Zone(LFZ),LFZ controlling petroleum accumulation shows a lot of spatiotemporal differences:(1) main branch of

渤东凹陷新生代伸展-走滑叠合断裂时空差异演化模式及控藏效应

以三维地震精细解释为基础,通过构造剖面恢复,系统分析了渤东凹陷新生代伸展-走滑叠合断裂的时空差异演化特征及控藏作用。研究结果表明:(1)渤东凹陷新生代广泛发育以NNE向为主干、NE向为派生、NW向为叠加的伸展-走滑叠合断裂体系,可划分为强伸展-弱走滑断裂和强走滑-弱伸展断裂2类;整体具有深浅分层、南北分段的特征,纵向上,古近系主要发育强伸展-弱走滑断裂,断裂大而稀,新近系—第四系主要发育强走滑-弱伸展断裂,断裂小而密;平面上,同一断裂在不同段的构造组合样式存在差异。(2)研究区新生代伸展-走滑叠合断裂的演化主要表现为北部断裂活动强度“早强晚弱”,中部断裂继承性持续发育,南部断裂活动强度“早弱晚强”;演化模式分为初始断陷(孔店组—沙四段沉积期)、强烈断陷(沙三段—东营组沉积期)和走滑坳陷(馆陶组—平原组沉积期)3个阶段,初始断陷阶段,NNE—NE向强伸展与弱走滑叠合,NE向强伸展-弱走滑断裂为主控,NW向先存断裂活化,分割凹陷;强烈断陷阶段,NNE—NE向强伸展与弱走滑叠合,NNE向强伸展-弱走滑断裂变为主控,NW向断裂活动减弱或停止;走滑坳陷阶段,NNE向强走滑与弱伸展叠合,断裂不控制沉积,但对地层展布具有调整作用。(3)研究区伸展-走滑叠合断裂的发育演化与油气成藏密切相关,整体具有“早期伸展控源、晚期走滑控运、多期叠加控圈”的特征,东部斜坡带是油气运聚的有利区。

白云凹陷深层压实作用和超压成因讨论及其对深层流体运聚的影响

珠江口盆地白云凹陷含有丰富的油气资源,勘探潜力巨大。深层目的层发育强烈的超压,文中对白云凹陷深层的超压成因及压实作用进行研究;利用三维地震资料和地球物理测井资料对白云凹陷深层的超压详细了解,利用综合压实曲线方法和盆地模拟技术对钻、测井资料进行处理,分析深层的异常压力成因。以分区块、分层位的原则总结压力分布规律和异常高压产生的原因,并利用流体势的评价手段对白云凹陷深层油气的运聚进行预测,为白云凹陷下一步的勘探部署提供依据。研究认为:白云凹陷发育超压的区块主要有主洼中心、主洼东、主洼西南、北坡(以超压发育规模排序);深层超压发育在珠海组及以下地层,不同层位超压成因的贡献亦不相同。其中,恩平组超压成因主要为压实作用增压和生烃增压、而珠海组异常压力主要来源则是压实作用增压与传递型超压。不同区块的欠压实作用不同。此外,受地热等因素影响,各区块发育的化学压实作用不同。由于主洼发育较强的超压,气势较大,东洼和西洼等小洼陷在晚期也形成了气势高值区;主洼-北坡、主洼-西南部和主洼东由于地势较高而形成了明显的气势低值区。恩平组气势梯度较大的区域逐渐向斜坡带和低隆起上扩张,有利于油气晚期向北坡和主洼东部等地区运移。

柴达木盆地英雄岭构造带新生代隆升过程与油气成藏效应

英雄岭构造带是柴达木盆地内部最大的正向构造单元,构造带及周缘蕴育了丰富的油气资源。针对构造带地质结构认识不清、初始隆升时间认识不统一、形成过程和机制不明确等问题,通过构造解析、构造演化、构造模拟、埋藏史与生烃史恢复等手段,以钻井和连片三维地震数据为基础,以时间为主线,以构造活动期次为节点,以主干地震剖面为纲,以具体构造为目,从几何学和运动学方面揭示英雄岭构造带三维空间结构和形成过程。研究表明:英雄岭构造带空间上具有南北分带展布、东西分段相接、垂向上下分层叠置的特征;新生代以来构造带演化经历了古近纪断坳、新近纪早期初始隆升和新近纪晚期—第四纪调整定型3个阶段,演化过程具有自南向北、自西向东逐次扩展的特点,构造演化与油气成藏紧密相关;青藏高原隆升背景下特殊的盆地边界条件、内部结构和应力场变换可为英雄岭构造带成藏模式建立和下一步有利勘探方向选择提供参考。