HC Migration Research Articles

Paleozoic and Mesozoic hydrocarbon foci of generation and assessment of their role in formation oil deposits of the Pre-Jurassic complex of Western Siberia

The following problem is solved by the present research: the probable sources of Paleozoic hydrocarbon deposits are determined on the basis of modeling the hydrocarbon foci of generation Paleozoic-Mesozoic oil source formations (for example, the southeast of Western Siberia, Tomsk Region). The research area is the lands Ostanino field group: the Selveikin area of deep drilling, the Ostaninskoye and Gerasimovskoye oil and gas condensate fields. Pre-Jurassic strata with oil source potential, including the Paleozoic Larinskaya (S1lr), Mirnaya (D13mr), Chuzikskaya (D2cz), Chaginskaya (D3cg) and Kehoregskaya (C1kh) formations, as well as Jurassic Bazhenovskaya (J3bg) and Tyumenskaya (J1-2tm ) formations, and, accordingly, the reservoirs of the weathering crust and bed-rock Paleozoic reservoirs are the objects of study. The subject of analysis was selected in accordance with the concept of the geothermal regime of the subsoil, as a leading factor in the implementation of the generation potential of the parent sediments. The research methods are digital paleotemperature modeling and historical-geological analysis. The results and conclusions concerning the fundamental problems of “Paleozoic oil” are obtained. 1. Source of the Paleozoic oil deposits can be both the Domanic type rocks of the Paleozoic formations and the Jurassic oil source formations. Thus, both upward vertical interstratal HC migration and downward HC migration can take place. Therefore, the two concepts of “main source” are compatible and should not be considered, as often, orthodoxly alternative. 2. The domanicoid rocks of the Paleozoic formations are most likely the source for Paleozoic gas and gas condensate deposits. 3. Paleozoic formations the roof of the bed-rock Paleozoic (on the Ostankinskaya group of fields – C1kh and D3cg) can be only the source of the «Paleozoic oil» and gas deposits in the Pre-Jurassic oil and gas complex. 4. Bazhenov formation – J3bg may be the “Jurassic” source of oil deposits in the Pre-Jurassic oil and gas complex. The results were obtained and conclusions were drawn concerning the applied (search) aspects of the problem: 1. Results additionally substantiate the author’s search criterion for the oil and gas content of the Paleozoic – these are anomalous geophysical and petrophysical characteristics of the Jurassic section. 2. The absence of hydrocarbon deposits in the Jurassic section is most likely a negative sign of the Paleozoic oil and gas content. 4. The low density of the modern heat flow (less than 40 mW/m2) is most likely a negative sign of oil deposits in the Paleozoic. 3. High paleotemperatures in terms of VR (more than 175oC) are most likely a negative sign of oil and gas deposits in the Paleozoic. 4. Reasons have been obtained to state that oil deposits in the Paleozoic cannot be richer than oil deposits in the Jurassic.

Results of Modeling of Generation and Accumulation Hydrocarbon Systems in the Sedimentary Basins of the Sea of Okhotsk

The paper presents the results of modeling of generation and accumulation hydrocarbon systems in the sedimentary basins of the sea of Okhotsk. The results of modeling HC migration showed that the most likely zones of hydrocarbon accumulation are the side parts of sedimentary basins. The anticline zones located on the border of two or more basins have the most favorable conditions. These areas, in general, are among the most promising in terms of hydrocarbon prospecting. However, such zones are characterized by complex conditions for the formation and preservation of deposits due to the non-synchronous evolution of adjacent sedimentary basins. This leads to uncertainties when assessing their prospects at the regional research level, for example, when predicting the type of fluid in deposits. For example, Vostochno-Shmidtovsk (East Schmidt) anticline zone is located on the border of two large centers of oil and gas generation: Severo-Sakhalinsky (North-Sakhalin) and Deryugin basin. The results of numerical modeling of the regional level allowed us to establish that HC migration towards the anticline zone occurs from the East (from the Deryugin basin) and the West (from the Severo-Sakhalinsky (North-Sakhalin) basin). The type of fluid in the predicted clusters is controlled by the type and maturity of the organic matter of the generation centers.

Oil shows geochemistry and fluid inclusion thermometry of Mid Cretaceous carbonates from the eastern Basque Cantabrian Basin (N Spain)

Abstract Surface liquid and solid hydrocarbons are common in Cretaceous carbonate exposures throughout the Basque Cantabrian Basin (N Spain). This study investigates the oil shows that appear in the upper Albian-lower Cenomanian reefal limestones cropping out in the eastern margin of the basin in order to assess potential source rocks and common characteristics with other oil occurrences in the basin. Specifically, the study focuses on (i) the petrography and fluid inclusion thermometry of the host rock and cements, and (ii) geochemistry of the hydrocarbons including biomarkers and isotopes. Geochemistry results indicate that the studied oils, in a way similar to previously reported hydrocarbons from the eastern Basque Cantabrian Basin, were generated from marine carbonate source rocks deposited in a hypersaline environment. However, their isotopic signatures are notably different, and thus discard a common source rock. Moreover, the studied oils are notably different from those reported elsewhere in the basin, both in the western and northern parts. The petrography of the calcite cements and the fluid inclusion thermometry suggests a scenario of condensates to light oils HC migration trapped in burial calcite cements at a minimum temperature of 174 °C. The generation, migration and entrapment of these oils took likely place between Turonian and Campanian time in close association with the elevated heat flow resulting from the rift extension. Following this stage, a second entrapment of heavy to asphaltene-rich oils occurred at 72 °C, likely during the Late Cretaceous to early Cenozoic uplift related to the early stages of inversion of the Basque Cantabrian Basin. The elevated temperature of the oil entrapment suggests the occurrence of abnormal geothermal gradients in the eastern Basque Cantabrian Basin during the middle Late Cretaceous, which is ultimately associated with the opening of the Bay of Biscay.

Coupling stratigraphic and petroleum system modeling tools in complex tectonic domains: case study in the North Algerian Offshore

In the eastern Algerian offshore basin, 3D basin modeling applied for facies prediction and petroleum potential assessment shows that most favorable zones for reservoir development and hydrocarbon occurrence are located at a maximum distance of 60 km from the coastline. The lack of well data in this area is partly compensated by a large data set of geophysical and geological (GG they represent important constraints for 3D dynamic modeling. Facies distribution model is constrained by sequence and environment evolution through time that is defined from onshore outcrops. 2D structural reconstitution and thermal modeling were also undertaken with ArcTem software. The structural interpretations highlight the occurrence of north-verging ramps during the Quaternary which played an important role in HC generation and migration. Three source rocks have been considered for maturation modeling with Temis Flow software, Burdigalian, Langhian, and Tortonian. They are found to be in gas window in the deep areas and locally in oil window at shallower structured zones. The modeling results indicate that the main fluid discharge was focused toward the southern border of the offshore basin where recent thrust faults (parallel to the margin) are located. In order to test the role of these faults in terms of hydrocarbon migration and trapping, two scenarios are considered according to whether they were sealed or not. In both cases, the 2D/3D simulations depict overpressures (2,000–4,000 psi) in the pre-salt sedimentary package. However, the hydrocarbon charge is most efficient with the sealing faults for the lower Langhian and lower Messinian reservoirs. The hydrocarbon potential depends mostly on the lateral extension of seals, their sealing capacity and the organic carbon (TOC) content of potential source rocks. Besides, the sea drop of about 1,000 m during the Messinian salinity crisis has induced depressurization that caused oil and gas seepage from Miocene reservoirs.

Relics of mud volcanoes in the sedimentary cover of the South Caspian Basin

The paper is devoted to one of the phenomena in young sedimentary basins related to their disequilibrium and the consequent formation of subvertical sedimentary structures. We propose the term “sedimentary plume” for such structures. The paper presents descriptions of the probable forms of sedimentary plumes, as well as their reflection in seismic data, age, stratigraphic features, and formation conditions. Their formation is likely related to processes of the deconsolidation of sedimentary piles because of phase transitions. According to this concept, the formation of hydrocarbon pools is attributed to a series of sequential processes including the convective dislocation of matter along with the floating of unconsolidated clay bodies, phase transitions and conjugated processes of the HC generation, migration, and accumulation.

Identification and numerical modelling of hydrocarbon leakage in the Lower Congo Basin: Implications on the genesis of km-wide seafloor mounded structures

We present a combined approach of interpretation of 2D seismic-reflection data and numerical modelling of hydrocarbon generation and migration across the southern slope of the Lower Congo Basin, in order to investigate the factors controlling timing and distribution of hydrocarbon leakage in this area. We identified three main families of past and present-day leakage features: (1) Mid-Upper Miocene seismic chimneys concentrated basinwards and ending up on buried pockmarks, (2) Plio-Pleistocene chimneys, rather clustered to the east of the study area and ending up in seafloor pockmarks, and (3) fewer scattered chimneys identified within the Miocene sequences ending up in shallow enhanced reflectors (“Flat spots”). Stratigraphic and structural elements seem to control the distribution of these features. At least two major events of leakage occurred during the Middle–Late Miocene and intermittently during the Pliocene-Present. External factors as sediment supply are associated to the Miocene leakage event, whilst internal structural elements probably triggered the Pliocene to present-day leakage. A major seabed morphological feature, represented by a margin-paralleled belt of more than 1-km-wide mounds, was identified above growth faults to the east of the study area. Data-constrained 2D HC generation and migration modelling suggests a genetic link between these structures and vertical migration/leakage of thermogenic methane sourced from either currently mature Oligo-Miocene source rocks or secondary cracking and further expulsion from over-mature Upper-Cretaceous source rocks. Hence, the mounds are likely to represent a lineation of methane-derived carbonate build-ups. Despite the natural limitations of a 2D migration model, when combined and calibrated with observations from seismic data, it can be used as a valid tool to assess petroleum migration routes in sedimentary basins. To the best of our knowledge, this is the first integrated approach combining both seismic observations and numerical modelling carried out in the Angola basin.

Sedimentology and hydrocarbon habitat of the submarine-fan deposits of the Central Carpathian Paleogene Basin (NE Slovakia)

The Central Carpathian Paleogene Basin accommodates a subsiding area of the destructive plate-margin. The basin history comprises marginal faulting and alluvial fan accumulation (E 2); transgressive onlap by shoreface sediments and carbonate platform deposits (E 2); glacio-eustatic regression induced by cooling (Terminal Eocene Event); forced regression, tectonic subsidence and growth-fault accumulation of basin-floor and slope fans (E 3); decelerating subsidence, aggradation and sea-level rising during the mud-rich deposition (O 1); high-magnitude drop in sea-level (Mid-Oligocene Event), retroarc backstep of depocenters and lowstand accumulation of sand-rich fans and suprafans (O 2–M 1); subduction-related shortening and basin inversion along the northern margins affected by backthrusting and transpressional deformation (O 2–M 1). The basin-fill sequence has poor (TOC≤0.5%) to fair (TOC<1.0%) quality of source rocks. Maturity of OM ranges from initial to relic stage of HC generation. Paleogene rock-extracts display a good correlation with scarce trapped oils. The presence of solid bitumens and HC-rich fluid inclusions indicates overpressure conditions during HC generation and migration. Potential HC reservoirs can be expected in porous lithologies (scarp breccias), in basement highs and traps related to backthrusting, fault-propagation folding and strike–slip tectonics.

ABSTRACT: Structural framework and inversion kinematics of the Bawal Graben , west Natuna Sea: Implications for sediment dispersal and HC migration

ABSTRACT: Structural framework and inversion kinematics of the Bawal Graben , west Natuna Sea: Implications for sediment dispersal and HC migration

Abstract: HC Migration in Thrusted Area Using Basin Modeling Application to the Bolivian Sub Andean Zone

Abstract: HC Migration in Thrusted Area Using Basin Modeling Application to the Bolivian Sub Andean Zone

State of the Art: Appraisal of HC Generation and Migration: ABSTRACT

State of the Art: Appraisal of HC Generation and Migration: ABSTRACT

Understanding of HC migration in sedimentary basins (present state of knowledge)

Great advances were made during the decade of 1975–1985 in the understanding of HC migration by establishing that the main mechanisms were polyphasic flow, whatever its stage, and that migration in solution in water and/or by molecular diffusion was insignificant, except for methane, ethane and benzene. Research is now focusing on points which still have not been satisfactorily answered such as: 1. (1) Behaviour of source-rocks during HC expulsion: the main driving force for fluid expulsion has been recognized to be excess fluid pressure within the source-rock with respect to its surrounding environment of permeable beds. The pressure build-up is due mainly to accommodation by the fluids of part of the mechanical stresses which are exerted on the rock (mainly sedimentary load but also stresses developed by tectonics), to thermal expansion of water, and to HC formation from kerogen in response to increasing temperatures. However, it is not clear whether or not petroleum expulsion proceeds preferentially along oil-wet networks (kerogen or oil-wet mineral surfaces). Nor it is not clear whether or not microfracturing, provoked by an internal fluid pressure higher than allowed by the mechanical strength of source-rocks, is necessary for HC expulsion. 2. (2) Modifications of the compositions of HC phases (e.g. “oil” versus “gas”, or the distribution of biomarkers during migration,) and losses of hydrocarbons along the migration pathways. Although careful observations of natural sample series, and also experimentation, have been done, no clear picture has emerged for the moment. However, compositional effects seem to be due more to changes in thermodynamic conditions along migration pathways, which provoke inter alia hydrocarbon phase separation (retrograde condensation), than to differential retention by mineral surfaces. It is likely that, while careful observations on a large variety of source-rock samples are needed to more clearly understand source-rocks functioning, progress in understanding HC migration will come increasingly from modeling and experimentation. Models, which mathematically simulate natural processes, are necessary to help the human mind in handling such complex phenomena and therefore are of precious help to focus research on the most important points. They replace migration in its geological and historical dimensions with numerical or conceptual tools, while observation only describes the present state. Models are also the tools by which knowledge on migration can be applied to exploration problems. However quantitative applications of models require numerous and precise geological data that are difficult to gather at early stages of exploration. In the field of experimentation, it will be easier to design crucial experiments, now that HC migration mechanisms are better understood. Thanks to experimentation, it should also be possible to validate models. However, so as to reach such aims, substantial progress has to be made in the technology of experimental systems.