Research progress and key research directions of shale oil in lacustrine rift basins

The Lunpola Basin in central Tibet is a Cenozoic lacustrine rift basin with widespread organic‐rich shale and oil shale depositions. Forty‐nine samples were collected from the Lunpola section to evaluate the controlling factors of trace‐element enrichment and mineralogical composition in the lacustrine rift basin. Minerals identified in the Lunpola section include abundant quartz, calcite, and clay minerals; minor quantities of feldspar, dolomite, siderite, and mirabilite; and trace amounts of aragonite, magnesite, salt, pyrite, hematite, zeolite, barite, amphibole, gypsum, anhydrite, anatase, galena, sphalerite, apatite, chromite, zircon, and monazite. The Lunpola shale and oil shale are enriched in trace elements B, Cr, Ni, Mo, and U, in comparison to the upper continental crust. Three processes were probably responsible for the geochemical anomalies found in the Lunpola Basin, including the detrital material input, lake water, and hydrothermal activities. Mineralogical and geochemical data show that the lake water is the dominant influences on the elevated trace element concentrations in the shale and oil shale. The depletion or enrichment of trace elements in sediments from the lacustrine rift basin is governed by general processes (e.g. anoxic environment). Additionally, hydrothermal fluids also cause remobilization of some trace elements in the Lunpola lacustrine rift basin. Copyright © 2017 John Wiley & Sons, Ltd.

Impact of input, preservation and dilution on organic matter enrichment in lacustrine rift basin: A case study of lacustrine shale in Dehui Depression of Songliao Basin, NE China

Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry

Rifting plays an important role in accommodation variations in rift basins. However, fluvial discharge as another important factor affecting lacustrine rift sequence stratigraphy is not well explored. In this work, seismic and well data are used to investigate the stratigraphic features, rift activity, and effect of fluvial discharge in the Nanpu Sag, Bohai Bay Basin. The syn‐rift deposition of the Dongying Formation (28.5–23.8 Ma) is divided into four sequences (SQ1, SQ2, SQ3, and SQ4), and the rift‐related subsidence rate along two parallel boundary faults is calculated. The results indicate that the rift activity weakens from SQ1 to SQ4 and that the two parallel boundary faults consist of a total of four fault segments. As the fault segmented, three propagation folds formed intrabasin highs on which the Beipu, Laoyemiao, and Gaoliu outlets developed. Well logs and 3D seismic data show that from SQ1 to SQ3, retrogradational stacking patterns occur in Beipu, Laoyemiao, and the hanging‐wall ramp, while progradational stacking patterns occur in the Gaoliu outlet. In SQ4, the sequence stacking patterns are progradation‐dominated. By evaluating channel erosion and sediment supply, the fluvial discharge can be estimated, and the result indicates that the Gaoliu outlet has the strongest fluvial discharge from SQ1 to SQ3 with strong channel erosion, and in SQ4, the fluvial discharge of each outlet is comparable and relatively low. The high fluvial discharge of the Gaoliu outlet from SQ1 to SQ3 is considered to be the primary reason for the lake level rise in the intervals between the pulses of rift activities. Sequence stacking patterns and depositional trends in our study intervals are not in line with the rift subsidence rate; this indicates that rifting is not the only factor controlling the rift sequence stratigraphy and variations in the accommodation of lacustrine rift basins. While the Gaoliu outlet has predominant fluvial discharge from SQ1 to SQ3, progradational parasequence sets deposit in the Gaoliu outlet. In contrast, the retrogradational parasequence sets occurred in the Beipu outlet, Laoyemiao outlet, and the hanging‐wall ramp. As the fluvial discharge of the Gaoliu outlet decreased in SQ4, the fluvial discharge in each outlet became low, and the stacking patterns were dominated by progradation. Consequently, this research suggests that fluvial discharge is a significant factor controlling the accommodation creation in lacustrine rift basins, and a sequence model which gives a full consideration of fluvial discharge is constructed for lacustrine rift basins.

Research Article| February 01, 1990 Development of coarse-grained facies in lacustrine rift basins: Examples from East Africa Christopher A. Scholz; Christopher A. Scholz 1Department of Geology, Duke University, Durham, North Carolina 27706 Search for other works by this author on: GSW Google Scholar Bruce R. Rosendahl; Bruce R. Rosendahl 2Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149 Search for other works by this author on: GSW Google Scholar Deborah L. Scott Deborah L. Scott 3Department of Geology, Duke University, Durham, North Carolina 27706 Search for other works by this author on: GSW Google Scholar Author and Article Information Christopher A. Scholz 1Department of Geology, Duke University, Durham, North Carolina 27706 Bruce R. Rosendahl 2Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149 Deborah L. Scott 3Department of Geology, Duke University, Durham, North Carolina 27706 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (2): 140–144. https://doi.org/10.1130/0091-7613(1990)018<0140:DOCGFI>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Christopher A. Scholz, Bruce R. Rosendahl, Deborah L. Scott; Development of coarse-grained facies in lacustrine rift basins: Examples from East Africa. Geology 1990;; 18 (2): 140–144. doi: https://doi.org/10.1130/0091-7613(1990)018<0140:DOCGFI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Detailed studies of high-resolution and multifold seismic reflection data from the two largest East African rift lakes, Malawi and Tanganyika, reveal a complex suite of coarse-grained depositional facies. These facies occur within specific regions of the controlling half grabens that compose the rift lakes. Sand-prone environments include subaqueous channels and small drowned fluvial complexes. Channel systems range from large erosional canyons to deep-water turbidite channel-levee systems. Lowstand and highstand deltas of axial and shoaling-side rivers are volumetrically important coarse-grained facies. Fan deltas develop along the base of major border faults during lake lowstands; subaqueous talus fan deposits occur along the base of the border faults during lake highstands. Lowstand deltas are the best-preserved progradational facies in these rift lakes. In addition to simple tectonic control, drastic tectonically or climatically induced lake-level change significantly regulates the production of coarse-grained lacustrine synrift deposits. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Lacustrine rift basins are ideal continental settings for understanding organic matter (OM) accumulation mechanisms, because lacustrine deposits are most sensitive to variable climatic and palaeoenvironmental conditions. The Lunpola Basin is a Cenozoic lacustrine rift basin with widespread oil shale depositions that provide a valuable example of triggering factors that controlled OM accumulation. In the investigated interval of the basin, high Si, Ti, Zr, Th, Al and rare earth element concentrations suggest high clastic fluxes during the oil shale deposition. These high clastic fluxes could be attributed to warm and humid climates due to high values of ln(Al2O3/Na2O) and C‐value (Ʃ (Fe + Mn + Cr + Ni + V + Co)/Ʃ (Ca + Mg + Sr + Ba + K + Na)). The Lunpola shales and oil shales were deposited in saltwater environments under enhanced dysoxic to anoxic conditions with high palaeoproductivity. In the Lunpola Basin, climate warming can be subdivided into two different stages based on C‐value and ln(Al2O3/Na2O) variations. Each stage is consistent with an increase in the primary productivity of the palaeolake. Thus, a model for climate‐induced OM enrichment in lacustrine rift basins is proposed, which indicates that climate and primary productivity are the key factors controlling OM accumulation.

Characteristics of sedimentary differential response for multi-episode rifting cycles in lacustrine rift basin: A case study of the Palaeogene Baxian sag in the Bohai Bay Basin

Seismic interpretation and geological evaluation of hydrocarbon source rocks in volcanic-rich continental lacustrine rift basins: A case study of the Lower Cretaceous Yingcheng Formation from the Changling Fault Depression in the Songliao Basin, NE China

Deep-water gravity flow deposits in a lacustrine rift basin and their oil and gas geological significance in eastern China

Abstract:Daihai Lake, a modern lacustrine rift basin, located in Inner Mongolia, North China, serves as an important modern analog for understanding deltaic depositional processes in an active rift setting. Two of the deltas (Yuanzigou delta and Bulianghe delta) on the margins of Daihai Lake were surveyed to compare and contrast stacking patterns using aerial photographs, field trenching and sediment sampling. Shallow cores and trench data collected from the margins of Daihai Lake indicate that a variety of depositional processes have been active since Daihai Lake formed. Two 3‐D sedimentation models which employ chronostratigraphic correlation technique were generated. The chronostratigraphic sedimentation models predict and represent the architectures and sand‐body continuity of sediments. Stratigraphical coincidence of the broad sheeted drifts and channel erosion suggests a coupling between downslope and alongslope processes. Distributary mouth bars are prevalent in the front of deltas on steeper slopes due to the dominance of down‐slope flows. On the contrary, the along‐slope currents favor the development of distal bar deposits with sheeted sandbodies on gentle depositional slopes. This study provides an insight into the architecture of complex sedimentary facies associated with highlighting key differences between downslope flows and alongslope currents. The distribution of sand within these deltas is of particular interests, with applications in understanding the architecture of hydrocarbon reservoirs formed in lacustrine rift basin.

The Xihu sag, which is the largest petroliferous sub-basin of the East China Sea Shelf Basin, formed in a continental back-arc setting. The Oligocene Huagang Formation consisting of a fluvial–lacustrine succession deposited during the compressional stage is the prime hydrocarbon-bearing interval in the Xihu sag. A third-order sequence-stratigraphic framework has been built, and component sand-body characteristics were investigated based on seismic attribute analysis and well-log correlation. Two overall upward-fining sequences, and an internal low-accommodation systems tract (LAST) (fluvial successions characterised by amalgamated fluvial channel sand bodies interlayered with rare overbank deposits) and high-accommodation systems tract (HAST) (intervals dominated by overbank or lacustrine deposits) have been identified. The thick, multi-storied channel-fill sandstone bodies deposited along the central depression belt, capped by extensive overbank or lacustrine mud deposits, characterise each sequence and form favourable reservoir–seal associations. Proximal-to-distal changes in lithofacies associations were also analysed. The sequence-stratigraphic and lithofacies analysis suggest the existence of an axial, large-scale river channel system in the Oligocene Xihu sag. On the basis of the restoration of basin geomorphology and seismic facies analysis, the depositional architectures of the axial paleodrainage system have been reconstructed. Overall, the Huagang sequences represent the sedimentary evolution of a large-scale fluvial system sourced from axial and lateral supply areas, to form river deltas into an interior-draining basin-centre lake. Two major fluvio-lacustrine transgression–regression cycles have been recorded. During the transgression cycle, the fluvial morphology was dominated by braided fluvial style; whereas during the regression cycle, the fluvial morphology was characterised by a combination of multiple fluvial channel styles in the LAST, from upstream to downstream low-sinuosity braided, high-sinuosity braided and anastomosing fluvial channel patterns were distributed and then replaced by large-scale lake flooding in the HAST. The braided channel centre, paleobathymetric lows of channel networks and delta-front bodies are sand-prone units. The fluvial sedimentation was governed by multiple parameters: tectonics, paleogeomorphology and climate fluctuations. This integrated study on fluvial sedimentation and evolution of the Oligocene drainage system enable us to propose a conceptual model depicting fluvial channel styles and component sand-body architecture in lacustrine rift basins with axial plus transverse sediment supplies. This model can serve as a reference to illustrate channel-sand-body and associated reservoir architecture in similar types of drainage systems in terrestrial basins.

Genesis and depositional model of subaqueous sediment gravity-flow deposits in a lacustrine rift basin as exemplified by the Eocene Shahejie Formation in the Jiyang Depression, Eastern China

Formation of zoned ankerite in gravity-flow sandstones in the Linnan Sag, Bohai Bay Basin, eastern China: Evidence of episodic fluid flow revealed from in-situ trace elemental analysis

Abstract: Steep and Gentle Slope Depositional Systems in Lacustrine Rift Basins - A Case study of the Huagou Sag in the Bohai Bay Basin: Facies Composition and Geological Controls&amp;nbsp;

Oils from two lacustrine rift basins in east China are thoroughly investigated using geochemical method to understand controls on alkylphenol occurrence and distribution in oils. Oils in the Lujiapu Depression, Kailu Basin are derived from the Cretaceous source rocks, and those in the Dongying Depression, Bohai Bay Basin, from the Tertiary source rocks. All oils are experienced relatively short distance of migration and have similar maturity in each basin. Differences in homologue distributions from different oilfields are most likely caused by organic facies variation of source rocks. The oils in the Lujiapu Depression are characterized by high proportion of C3 alkylphenols (prefixes refer to the number of alkylcarbons joined to the aromatic ring of the phenol molecule) and low proportion of cresols and C2 alkylphenols compared to oils from the Dongying Depression. Alkylphenol isomer distribution is possibly affected by depositional environment especially for C3 alkylphenols. Dysoxic freshwater environment is favorable for the formation of propyl or isopropyl substituted C3 alkylphenols, while highly reducing saline water is more suitable for trimethyl substituted C3 alkylphenols. Variations in alkylphenol concentrations within a petroleum system are controlled mainly by secondary migration processes with alkylphenol concentrations decreasing along migration direction. Interestingly, coupled with geological factors, a subtle change of alkylphenol concentrations can be applied to differentiate carrier systems. When oil migrates through sandy beds, concentrations of total alkylphenols decrease dramatically with migration distance, while such change is less significant when oil migrates vertically along faults. However, most isomer ratios potentially related to migration distance are not as effective as those alkylcarbazoles in migration diagnosis due to complicated affecting factors.