A pull-apart basin (PAB) is a releasing zone constrained by strike–slip faults. A PAB partly appears as a unique basin type typically dominated by the basin sidewall and cross-basin faults. However, the structural characteristics of different subsidiary faults derived from strike–slip motions are currently poorly understood in PABs. Under the control of different bend strike–slip faults, this study examines the formation and evolution of PABs reconstructed from wet clay with high water content (68%) as the experimental material. It was reported that (1) a PAB shows the single asymmetric half-graben architecture in the profile and rhombus in the plane, regardless of the bend type of the strike–slip fault; (2) the subsidiary fault area density increases with increasing fault displacement in PABs and might be impacted by the nature of the wet clay; (3) as the strike–slip fault displacement increases, the subsidiary fault number initially increases and then begins to decrease with large fault formation; and (4) T-faults are the most numerous faults in PABs, followed by Riedel shear faults. R′- and P-shear faults account for a small proportion and are unstable. The proportion of Riedel shear faults gradually decreases from the underlapping strike–slip faults to the overlapping strike–slip faults, accompanied by an increase in the corresponding R′-shear faults. The primary control factor affecting the proportion of subsidiary faults is the stress component. Re-recognition of subsidiary faults in the PABs is significant for interpreting strike–slip faults and the study of hydrocarbon migration.

以经典层序地层学为基础,综合钻井、地震、测井曲线等资料,对渤海石臼坨凸起陡坡带展开层序地层的研究.渤海石臼坨凸起南部陡坡带层序划分为沙河街组和东营组,其中沙河街组特征比较明显且发育完整.沙河街组时期分为沙河街四段、沙河街三段和沙河街一二段共 3 段.研究结果表明,渤海石臼坨凸起南部陡坡带沙河街组主要发育湖泊-三角洲沉积体系,且水体逐渐增加,扇三角洲不断向石臼坨凸起南部陡坡带西南方向推进,辫状河三角洲向石臼坨凸起东南方向推进.

Hydrocarbon source rock is one of the key factors controlling oil/gas accumulation in petroliferous system of a sedimentary basin. Focusing on the challenges facing hydrocarbon source rock prediction in basins or lows with relatively low exploration maturity, sparsely distributed drilling wells and insufficient source rock index, we take the underexplored areas in northern Zhu Ⅰ Depression in the Pearl River Mouth Basin (PRMB) as an example to systematically analyze the source-to-sink system and predict source rocks from the perspectives of “searching for lake (deep-to-semi-deep lake)”, “recognizing mudstones (deep-to-semi-deep lacustrine mudstones)”, and “identifying hydrocarbon (hydrocarbon source rock prediction and evaluation)”. First, the original basin features and location of the paleo-lacustrine basin are illustrated by restoring multi-stage tectono-palaeogeomorphology to “find the lake”; and the deep-to-semi-deep lake is identified in the underexplored area together with preliminary selection of potential lows with well-developed hydrocarbon source rocks in combination with analyses including “identifying the lacustrine basin boundary by seismic progradational reflection, determining the scope of the deep-to-semi-deep lake by slope break system, illustrating paleo-environment characters by biochemical index, and defining the lacustrine basin scale by tectonic intensity”. The results indicate that five lows formed during the Wenchang depositional period , and five lows formed during the depositional period of the lower Enping Formation have the potential of developing deep-to-semi-deep lacustrine mudstones. Second, the reconstruction of source-to-sink system and the geological analysis of deep-to-semideep lacustrine mudstone development are conducted through analyses of paleo-provenance, paleo-environment and depositional systems, as well as tectono-palaeogeomorphology features; various configuration elements simulation results of the source-to-sink system show that basins characterized by medium sediment supply intensity, fine-grained source materials, high lake level, large accommodation space and under-equal or equal compensation are favorable for the deposition of mud-rich lacustrine facies. Finally, based on data of exploratory wells encountering high-quality hydrocarbon source rocks in mature exploration areas, we analyze four types of deep-to-semi-deep seismic facies and their geologic backgrounds corresponding to hydrocarbon source rock intervals, establish the “hydrocarbon source rock facies (seismic facies of hydrocarbon source rocks)” of the mature exploration areas. Coupled with the systematic summary of hydrocarbon-enrichment factors in main hydrocarbon-rich lows of the Zhu Ⅰ Depression, we assess and rank the high-quality hydrocarbon source rocks in the underexplored areas with multiple factors and from multidimensional points of view. The research results also indicate that the first-order potentially hydrocarbon-rich lows include LF22, HF33, and HZ24 (with the lower and upper Wenchang Formation as source rocks), as well as the LF7 and HF10 (with the lower Wenchang Formation as source rocks); the second-order potentially hydrocarbon-rich ones are HZ5 and HZ11 (with the lower Enping Formation as source rocks), with the hydrocarbon source rock prediction and evaluation results of some lows having been testified in practical exploration.

Rifted lake basins usually have their sedimentary filling controlled by the intensity of tectonic activities, sea level fluctuation and sediment flux. The distribution of sand bodies in these basins are also controlled by slope-break zones and paleovalley systems. It is of great significance to explore the configuration relationship between the slope break zones and paleovalley systems for oil and gas exploration in rifted lake basins. The Pearl River Mouth Basin is the most important petroliferous basin in the South China Sea. The less explored Haifeng 33 Subsag in the basin is selected to study the factors controlling the development of sedimentary systems so as to support the mapping of reservoirs and deployment of oil and gas exploration. Based on 3-D seismic data and logging data of the subsag as well as on the basis of regional structural interpretation, this paper analyzes the types and development characteristics of the slope-break zones and the paleovalleys of the Paleogene Wenchang Formation in the subsag, and clarifies the control of the slope-break zones and paleovalleys on sediment filling. The results show that there are three types of slope-break zones in the study area: fault slope-break zone, flexure slope-break zone and sedimentary slope-break zone. The paleovalleys are mainly V-shaped, U-shaped, W-shaped and single fault groove types, among which the V-shaped and U-shaped valleys are more in number and more concentrated in-plane distribution. The slope-break zones control the boundary of denudation and provenance, thus mobilizing the sediments in a certain direction for a certain distance within certain space. Different sedimentary systems are believed to be developed in different periods under the influence of these zones. Serving as transport channels, paleovalleys control the direction of sediment transport, location of sediment discharge as well as scale of depositional system. It is concluded that slope-break zones together with paleovalleys determine the types, scales, development and evolution of depositional systems.

Hydrocarbon source rocks, as a main geologic factor of petroliferous systems in a sedimentary basin, play a key role in the accumulation of oil and gas and the formation of hydrocarbon accumulations. This study, which focuses on difficulties in prediction of hydrocarbon source rocks in basins or sags with low exploration degree and insufficient hydrocarbon source rock indicators, taking the Wenchang Formation of northern Zhu I Depression, Pearl River Mouth Basin as an example, proposed a hypothesis of "finding lakes and hydrocarbon source rocks". Detailed steps include, first, determination of the lacustrine basin boundary according to analysis of seismic foreset facies, determination of the depositional area based on the compilation of strata residual thickness maps, determination of the lacustrine basin shape according to deciphering slope break belt system, determination of the fluctuation of paleo-water depth according to biogeochemical indicators of mature exploration areas, determination of the lacustrine basin scale based on analyses of tectonics intensity and accommodation space, which prove the existence of the lacustrine basin and identify the range of semi deep-deep lake; second, further analyses of tectonopalaeogeomorphology, paleo-provenance, palaeoclimate and paleo-water depth to reconstruct the geologic background of the original basin and semi-deep-deep lacustrine facies, to determine the distribution of semi-deep/deep lacustrine sediments in combination with studies of logging facies, core facies, seismic facies and sedimentary facies, and to rank the sags' potential of developing hydrocarbon source rocks from controlling factors of source-to-sink system development; third, on the basis of regional sedimentary facies analysis, through identification and assessment of seismic facies types of semi-deep/deep lacustrine basins in mature areas, establishing "hydrocarbon source rock facies" in mature areas to instruct the identification and depicting of hydrocarbon source rocks in semi-deep/deep lacustrine basins with low exploration degree; fourth, through systematical summary of hydrocarbon-rich geological factors and lower limit index of hydrocarbon formation of the sags already revealed by drilling wells (e.g., sag area, tectonic subsidence amount, accommodation space, provenance characteristic, mudstone thickness, water body environment, sedimentary facies types of hydrocarbon source rocks), in correlation with corresponding indexes of sags with low exploration degree, then the evaluation and sorting of high-quality source rocks in areas with sparsely distributed or no drilling wells can be conducted with multi-factors and multiple dimensions. It is concluded that LF22 sag, HZ10 sag and HZ8 sag are II-order hydrocarbon rich sags; whereas HZS, HZ11 and HZ24 are the III-order hydrocarbon-generating sags.

目前陆相湖盆构造活跃期沉积的层序地层研究比较成熟,而对于坳陷湖盆萎缩期的层序地层研究多处于探索阶段.本论文以沉积学、层序地层学、地震沉积学为理论基础,结合计算机数值模拟技术,应用研究区钻测井、地震资料,以旋回为主,界面为辅,研究渤海黄河口地区新近纪古湖泊、古气候变迁及湖平面变化影响下的层序地层响应特征.在新近系共识别出5个三级旋回,根据旋回划分结果并结合关键界面特征分析划分了SB00、SB01、SB02、SB0、SB21、SB2六个三级层序界面、五个最大水进面.据此将新近纪馆陶组和明化镇组共划分为5个三级层序、10个体系域,三级层序自下而上分别对应于馆陶组下段、馆陶组上段、明化镇组下段下部、明化镇组下段上部、明化镇组上段地层.

This paper presents revision of the Neogene chronostratigraphic framework of the Huanghekou area in the Bohai Bay Basin, northern China, on the basis of integration of palaeomagnetic data and Neogene seismic stratigraphy. The modern Lake Dongting was selected for analyses of bottom sediments, water depth and elemental composition. Four elements, namely Al, V, Ni and Ga with R 2 value larger than 0.7, were chosen to establish a quantitative relationship (F P) between elemental composition and water depth of bottom sediments. A water depth of ~2.4 m was identified as an accumulation depth of Candoniella albicans, which is used to derive environmental variable (Φ) of formula F P. Candoniella albicans is also found within the Neogene well W10 in the Huanghekou area. Considering 2.4 m as D value in formula F p and measured element values at different depths of W10, Φ values were obtained at different depths. The quantitative palaeowater depths of each drilling well were estimated for the first time in this area by considering elemental composition of chip samples of four drilling wells in the Huanghekou area, which are directly iterated to the F F. Palaeowater depth reconstruction of the Neogene in the Huanghekou area indicates an initial deepening trend and a later shallowing trend during the evolution, with average and deepest bathymetry at ~2.3 and ~4.8 m, respectively. Frequent fluctuations of palaeowater depth control the sand dispersal pattern in a shallow delta during the lower part of the Lower Member of Minghuazhen Formation.

综合利用地震、测井和录井资料,恢复了L工区沙三段的构造-古地貌,并分析了构造-古地貌对沉积体系的控制作用.沙三段沉积时期,同沉积断裂较少,且规模较小,差异沉降相对较弱,受不同走向断层的控制,总体上其构造-古地貌可划分为14个构造-古地貌单元,3个凸起带、西北部1个稳定剥蚀带、西南部1个深洼带、3个浅洼带、3个斜坡带、2个水下低凸起带及分散在斜坡带上的沟谷(如图2).受构造-古地貌控制,在斜坡带及浅洼带识别出辫状河三角洲、滨浅湖混合滩、滨浅湖钙质滩坝及滨浅湖砂质滩坝,在靠近控凹断层的深洼带识别出扇三角洲.辫状河三角洲、扇三角洲及滨浅湖砂质滩坝砂岩丰富,可形成地层-岩性圈闭,是油气勘探的重要区域.

Accurate estimation of diffuse attenuation coefficients in the visible wavelengths K d(λ) from remotely sensed data is particularly challenging in global oceanic and coastal waters. The objectives of the present study are to evaluate the applicability of a semi-analytical K d(λ) retrieval model (SAKM) and Jamet’s neural network model (JNNM), and then develop a new neural network K d(λ) retrieval model (NNKM). Based on the comparison of K d(λ) predicted by these models with in situ measurements taken from the global oceanic and coastal waters, all of the NNKM, SAKM, and JNNM models work well in K d(λ) retrievals, but the NNKM model works more stable and accurate than both SAKM and JNNM models. The near-infrared band-based and shortwave infrared band-based combined model is used to remove the atmospheric effects on MODIS data. The K d(λ) data was determined from the atmospheric corrected MODIS data using the NNKM, JNNM, and SAKM models. The results show that the NNKM model produces <30% uncertainty in deriving K d(λ) from global oceanic and coastal waters, which is 4.88-17.18% more accurate than SAKM and JNNM models. Furthermore, we employ an empirical approach to calculate K par from the NNKM model-derived diffuse attenuation coefficient at visible bands (443, 488, 555, and 667 nm). The results show that our model presents a satisfactory performance in deriving K par from the global oceanic and coastal waters with 20.2% uncertainty. The K par are quantified from MODIS data atmospheric correction using our model. Comparing with field measurements, our model produces ~31.0% uncertainty in deriving K par from Bohai Sea. Finally, the applicability of our model for general oceanographic studies is briefly illuminated by applying it to climatological monthly mean remote sensing reflectance for time ranging from July, 2002- July 2014 at the global scale. The results indicate that the high K d(λ) and K par values are usually found around the coastal zones in the high latitude regions, while low K d(λ) and K par values are usually found in the open oceans around the low-latitude regions. These results could improve our knowledge about the light field under waters at either the global or basin scales, and be potentially used into general circulation models to estimate the heat flux between atmosphere and ocean.

The time and space evolution of sequence architecture and depositional systems has attracted much attention in the geological field. Meanwhile, due to the recent excellence, the Oligocene lacustrine rift basin takes a key position during geological research in Huanghekou depression of Bohai Bay Basin in east China. However, the systematic researches of the depositional sequence of Dongying formation in Huanghekou depression appear little, thus this study aims that using many seismic lines, complemented by well logs and cores to thoroughly analyze the time and space allocation of depositional sequence of Huanghekou depression and its major controlling factor, base-level change, in a typical rift lacustrine basin. The Oligocene Dongying formation in this article will be divided into three composite sequences on the basis of unconformities on basin margins and correlative conformities in the basin center. Every sequence is composed of a regional depositional cycle from transgression with an onlapping lacustrine expanding systems tract (EST) to regression with a prograding highstand systems tract (HST). And five sequences can be further identified by subordinate discontinuous boundaries in Huanghekou depression. The evolution of depositional systems is associated with base-level change within sequences. In Lower and Middle Dongying formation (ESTSQ3, HSTSQ3, ESTSQ2), depositional systems are dominated by braid river delta and sandy beach-bars. During the late period of Dongying formation (HSTSQ2, SQ1), depositional systems are characterized by meandering river delta or braid river delta deposits. And base-level change is one of major controlling factors, of which the shape and scale control the development of the depositional sequences. Base-level changes, via affecting the A/S, directly control the depositional states and determine the unique depositional sequences structure: in the northern steep slope, multiple meandering river deltas systems exist. In the middle of the depression, the large areas of beach bars can be found. And the depositional system is continuously developed with the large-scale braided river delta in the southern gentle slope.

The Huanghekou Sag, as an important oil-bearing zone, is located in the southeastern part of the Bohai Bay basin. It has higher values for petroleum exploration-especially in Neogene. The Neogene was a depressional lacustrine period and was characterized with both tectonically stable and gentle topography. Thus it is difficult to identify and subdivide sequences using the traditional method. Based on the practical geologic setting and current data of the Neogene of Huanghekou Sag, using the new method to set up the isochronous sequence stratigraphic framework. By analyzing climate cycle, drilling well and logging cycle, seismic cycle and the identification of unconformity of seismic and drilling well and logging data, the Neogene was divided into 5 third-order sequences and 10 systems tracts. In different sequence sets and systems tract, which was controlled by climate, ratio rate between sedimentary being supplied and accommodated, the sand body scale was different.

The sublacustrine fan,an important deposition of Paleogene in Huanghekou Sag,is characterized by both good physical character of reservoir and oil-bearing property,thus it of higher value for petroleum exploration.Through studying the formation mechanism,the main control factors,the lithology,logging curve features and seismic reflectance signature in the lower Member 3 of Shahejie Formation in Huanghekou Sag,it was found that the oil-bearing sand bodies in the Area A belonged to two kinds of sublacustrine fan deposition formed under semi-deep-lake to deep-lake environment.Deposition of the deep-water turbidite sublacustrine fan corresponded to low stand system tract;deposition of the slump turbidite sublacustrine fan corresponded to transgressive system tract and high stand system tract,which was formed by slumping delta front sand.Viewed from spatial distribution,the deep-water turbidite sublacustrine fan was mainly developed in the second-order fault downthrown of the basin,while the slump turbidite sublacustrine fan was distributed in the abrupt slope which located in the south of study area,and the extent of the fan in the front of fan delta was greater and longer than that in the north.The sublacustrine fan was controlled by faulted-topographic break and sedimentary-slope break.As a matter of fact,different tectonic background,lake level changes and provenance could result in different position,shape and size of sublacustrine fan.

The lake-floor fan, as an important deposition of Paleogene in Huanghekou Sag, is characterized with both good physical character of reservoir and oil-bearing property, thus it has higher values for petroleum exploration. The lower Member 3 of Shahejie Formation, rich in sandstone, can be divided into lowstand system tract, extensive system tract and highstand system tracts based on seismic reflection signature, and core and logging data clearly. The sand bodies in the study area belonged to two kinds of lake-floor fan deposition formed under semi-deep-lake to deep-lake environment: deposition of the deep-water turbidite fan corresponded to lowstand system tract; deposition of the slump turbidite fan corresponded to extensive system tract and highstand system tract, which was formed by slumping fan delta front sand. Viewed from spatial distribution, the deep-water turbidite fan was mainly developed in the second-order fault downthrown of the basin, while the slump turbidite fan was distributed in the abrupt slope which located in the south of study area. The complex of lake-floor fan consists of various sediments’gravity flow deposits, including:(1)turbidity current deposit with characteristics of Bouma sequences; (2)mud-bearing sandy debris flow deposits with characteristics of dominated sand and mixed by mud; (3)sand-bearing muddy debris flow deposits with characteristics of dominated mud and mixed by sand; (4)gritty debris flow deposits with characteristics of massive gravel accumulation;(5)sandy slump deposits with characteristics of deformed sedimentary structure. During lower water level period(LSTs3L), most of the study area were erosion or sediment pass-by areas, and terrigenous clastic matters were directly transported into deep-water area under the second-order faulted belt, and then formed the deep-water turbidite fan. During higher water level period (ESTs3L, HSTs3L), the slump tuibidite fan, which resulted from various sediments’gravity flows, mainly developed in front of fan dalta in south. The sandstones of the lake-floor fan are the main reservoirs of oil in the northwestern part of the Huanghekou sag.

By studying the lithology,sedimentary texture,structural attitude,logging curve features and seismicreflectance signature in Member 3 of Shahejie Formation in Huanghekou Sag,Bohai Bay Basin,we found thatthe oil-bearing sand bodies in the study area belong to slump turbidite fan deposition formed the under semideeplake and deep lake environment. Slump turbidite fan facies include inner fan,middle fan and outer fan subfacies.The inner fan is mainly composed of slumping sediments and debris flow. The middle fan is dominated by debrisflow and turbidity flow sediments. The outer fan is mainly composed of turbidity flow sediments. Based on theregional geology background,the formation mechanism and the main controlling factors of the slump turbidite fanare discussed in the paper. This kind of fan is usually surrounded by dark grey and dark mudstones formed underreduction environment of the deep lake and semideep lake,and they are more easily to form the lithologic trap. Sothe slump turbidite fan is advantageous for oil-gas migration and accumulation and is also important target of oil andgas exploration in the steep slope belt of the faulted lake basin.

A study of hydrocarbon charge history was carried out in JZ25 area,Liaodong Bay waters,by using homogenization temperature of fluid inclusions.The results indicate that the area had experienced two stages of hydrocarbon charge.The first one happened during the period prior to a secondary outgrowth of quartz and mainly in form of liquid-hydrocarbon inclusions of low abundance and low maturity.The second stage happened during the period after the secondary outgrowth of quart and organic inclusions of high abundance were mainly distributed along the micro-fractures that cut through quartz grains and their outgrowth rims or in the dissolution pores of feldspar grains.Hydrocarbon reservoirs in JZ25 area is considered to be formed mainly during the second stage,which is 23-21 Ma from nowadays.An analysis of excess pressure system and hydrocarbon pathway of source rocks in third member of the Shahejie Formation in the study area was then performed based on the above understanding.A model illustrating hydrocarbon migration controlled by both reservoirs and faults was also established and served as an important guidance for the exploration of large-scale hydrocarbon reservoirs in JZ25 area.