Showing papers on "Petroleum reservoir published in 2011"
TL;DR: In this article, the authors presented seismic observation of pipe anomalies from offshore Nigeria, outcrops of blow-out pipes from Rhodes, Greece, and geophysical modelling of an acoustic pipe.
178 citations
Journal Article•
TL;DR: Based on the field emission SEM and the nano CT reconfiguration technique, it was the first discovery of nano-pore in research of unconventional tight sandstone and shale gas reservoir in China, whose diameter is less than one micron as discussed by the authors.
Abstract: The oil and gas reservoirs have been divided in three types: Millimeterpore,micropore and nanopore.The diameter of pore throat in conventional reservoir is generally larger than one micron.The diameter of nano-pore in shale gas reservoirs ranges between 5 and 160 nanometers in North American,mainly from 80 to 100 nanometers.Based on the field emission SEM and the nano CT reconfiguration technique,it was the first discovery of nano-pore in research of unconventional tight sandstone and shale gas reservoir in China,whose diameter is less than one micron.The nano-pore in tight sandstone gas reservoirs is mainly of grain micropore,authigenic mineral intragranular pore and microfracture,throat is sheetlike,bended platy,has poor connectivity and its diameter ranges between 10 and 1000 nanometers,mainly from 300 to 900 nanometers.The nanopore in shale gas reservoirs is mainly of organic matter nanopore,grain nanopore and authigenic mineral intragranular pore,and its diameter ranges between 5 and 300 nanometers,mainly from 80 to 200 nanometers.The nanopore is main body of connectivitive reservoir space in tight reservoirs.The discovery of nano-pore system within oil and gas reservoir has changed the traditional understanding that the micron-pore is exclusive.It also provided the significant scientific value with understanding geological characteristics of conventional oil and gas local accumulation,unconventionally continuous petroleum accumulation,develop petroleum accumulation mechanism and increase the potential of resources.
148 citations
TL;DR: This paper used contact mode atomic force microscopy (AFM) to image the internal pore surfaces from fresh outcrop sandstone and from reservoir sandstone that had been cleaned with strong solvents, the traditional treatment method for samples used in core plug testing.
113 citations
TL;DR: In this article, the authors analyzed three major hydrocarbon bearing intervals in the Lunnan lower bulge for their stable carbon isotopes and molecular biomarkers and concluded that the recently discovered deep (6500m) eastern Lungu giant Ordovician gas condensate pool with an estimated reserve of 723 million bbl oil equivalent is a secondary hydrocarbon accumulation derived from the mixing of an early formed oil and a late formed gas.
108 citations
TL;DR: In this paper, a geothermal reservoir model is presented, in which a thermo-poroelastic finite element module is coupled to a fracture geomechanical module, which describes fracture closure as a function of effective stress and the changes in parameters, such as effective permeability, porosity and discrete fracture apertures.
91 citations
TL;DR: In this paper, the authors focus on the problem of predicting subsidence accurately enough so that rational design decisions can be made, mitigating or reducing the incidence of casing shear arising from subsidence or thermal reservoir stimulation, understanding and analyzing thermal production processes in viscous oil reservoirs, monitoring of deformations in and around reservoirs being subjected to complex processes.
Abstract: Petroleum geomechanics deals mainly with coupled problems requiring simultaneous consideration of changes in temperature, pressure, stress, and chemical potential (THMC). Major current challenges in this domain include: accurate delineation of in situ physical properties and conditions (T, [σ], p), especially for naturally fractured reservoirs; wellbore wall stability predictions in swelling and fractured shale strata; modeling and monitoring of multiple-stage hydraulic fracturing used for development of resources in low-permeability rocks; controlling or exploiting sand ingress into producing wellbores; predicting subsidence accurately enough so that rational design decisions can be made; mitigating or reducing the incidence of casing shear arising from subsidence or thermal reservoir stimulation; understanding and analyzing thermal production processes in viscous oil reservoirs; monitoring of deformations in and around reservoirs being subjected to complex processes; and, a newer development, using the deep sedimentary basin environment for the permanent and secure disposal of fluid and granular wastes. Given the importance of fossil fuel energy in our industrial societies (>80% of all primary energy provision), the rewards for better engineering are significant.
77 citations
TL;DR: The Dabei gas field of the Kuqa thrust basin this article is the only known coal-derived hydrocarbons field in the world with a vertical distribution of liquid oil and gas pools.
66 citations
TL;DR: The results of previously performed stimulation treatments in the geothermal research well GtGrSk4/05 at Gros Schonebeck, Germany are presented in this paper, where the stimulation treatments included multiple hydraulic stimulations and an acid treatment.
64 citations
TL;DR: Based on gammacerane/C31 hopane and C28/(C27 +C 28 +C 29) sterane ratios, three of the fifteen crude oils from the Tazhong Uplift correlate with Cambrian-Lower Ordovician source rocks, while the free and inclusion oils in oil-containing carbonates from the Tahe oilfield correlate mainly with Middle-Upper Ordovicians source rocks as mentioned in this paper.
58 citations
TL;DR: In this paper, a comprehensive study was performed to characterize, for the first time, the mud, water, and gases released from onshore mud volcanoes located in the southern margin of the Junggar Basin, northwestern China.
45 citations
TL;DR: In this paper, the storage capacity in such combined reservoirs can be assessed by a material balance method, which considers different trapping states of CO 2 in oil reservoirs and aquifers.
TL;DR: A Pennsylvanian reservoir architecture and facies evolution diagram combines data on key reservoir facies and targets, including their dimensions; the relative location of the facies tracts within each depositional system; the overall system architecture; and each stage's potential for diagenetic modification.
Abstract: The Permian Basin of west Texas and New Mexico is the largest petroleum-producing basin in the United States. In this area, multiple episodes of Paleozoic faulting, uplift, and erosion occurred, including those events related to the Marathon-Ouachita orogeny (Hercynian orogenic cycle 350–250 Ma). Within Paleozoic rocks in the Permian Basin, the Pennsylvanian succession is the second most oil-productive system, next to the Permian. This succession has been viewed historically as sedimentologically and stratigraphically complex because of the interplay of deposition, coinciding with icehouse climatic conditions during a second-order global transgression, and presumed active tectonism.New paleodepositional systems maps for the Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian stages of the greater Permian Basin are presented. This study integrates varied data, including outcrop, drill core, geophysical (seismic and gravity), wireline log, biostratigraphic, and reservoir quality. Systems maps depict the spatial and temporal distribution of sediment source areas, shallow-water to basinal carbonates, alluvial to open-marine siliciclastics, shales, and areas of uplift.A Pennsylvanian reservoir architecture and facies evolution diagram combines data on key reservoir facies and targets, including their dimensions; the relative location of the facies tracts within each depositional system; the overall system architecture; and each stage's potential for diagenetic modification. A unified depositional system model provides continuity between the paleodepositional systems maps and summarizes the entire Pennsylvanian facies proportion evolution within eight provinces of the Permian Basin. The depositional systems information is referenced to second- to fourth-order eustasy curves and tectonic input. The reservoir evolution diagram and paleodepositional maps used in conjunction with the unified systems model provide the reader with the most current and extensive integration of data on the Pennsylvanian geologic history in the greater Permian Basin from a sedimentologic and petroleum reservoir systems perspective. Insights into facies distribution, the overall development of the basin and its subbasins, tectonic episodes, identification of potential new play types and exploration targets, and new depositional and sequence-stratigraphic architectural models are presented in this article.
TL;DR: In this article, thermal conductivity of both dry and fully water (brine solution, 5g/l NaCl concentration) saturated rocks have been measured for 35 sandstone core samples obtained from both Hungary and Egypt.
TL;DR: A general three-dimensional numerical model for single phase, slightly compressible flow through fractured porous media is described, based on a discrete fracture representation, and the hydrodynamic response of a fractured aquifer is investigated.
TL;DR: Arctic Alaska is one of the most prolific petroleum provinces in North America with total known resources (cumulative production plus proved reserves) of c. 28 BBOE as discussed by the authors, which constitutes a significant part of a displaced continental fragment, the Arctic Alaska microplate, that was probably rifted from the Canadian Arctic margin during formation of the Canada Basin.
Abstract: The Arctic Alaska petroleum province encompasses all lands and adjacent continental shelf areas north of the Brooks Range–Herald Arch orogenic belt and south of the northern (outboard) margin of the Beaufort Rift shoulder. Even though only a small part is thoroughly explored, it is one of the most prolific petroleum provinces in North America with total known resources (cumulative production plus proved reserves) of c . 28 BBOE. The province constitutes a significant part of a displaced continental fragment, the Arctic Alaska microplate, that was probably rifted from the Canadian Arctic margin during formation of the Canada Basin. Petroleum prospective rocks in the province, mostly Mississippian and younger, record a sequential geological evolution through passive margin, rift and foreland basin tectonic stages. Significant petroleum source and reservoir rocks were formed during each tectonic stage but it was the foreland basin stage that provided the necessary burial heating to generate petroleum from the source rocks. The lion9s share of known petroleum resources in the province occur in combination structural–stratigraphic traps formed as a consequence of rifting and located along the rift shoulder. Since the discovery of the super-giant Prudhoe Bay accumulation in one of these traps in the late 1960s, exploration activity preferentially focused on these types of traps. More recent activity, however, has emphasized the potential for stratigraphic traps and the prospect of a natural gas pipeline in this region has spurred renewed interest in structural traps. For assessment purposes, the province is divided into a Platform assessment unit (AU), comprising the Beaufort Rift shoulder and its relatively undeformed flanks, and a Fold-and-Thrust Belt AU, comprising the deformed area north of the Brooks Range and Herald Arch tectonic belt. Mean estimates of undiscovered, technically recoverable resources include nearly 28 billion barrels of oil (BBO) and 122 trillion cubic feet (TCF) of nonassociated gas in the Platform AU and 2 BBO and 59 TCF of nonassociated gas in the Fold-and-Thrust Belt AU.
TL;DR: In this paper, the effect of CO2 on carbonate rocks was studied by carrying out Brazilian tests on Lixhe and Austin chalks, and the tensile strength of both salt water and CO2-salt water exposed samples were observed to decrease with sample porosity.
TL;DR: In this paper, the authors focused on one of the marine oil fields in the Southwest Iran, where the main aim was to predict accurate porosity and make 3D porosity cube.
TL;DR: In this article, a pore-scale representation of a dolomite reservoir rock is presented, containing several orders of magnitude in pore sizes within a single rock model.
Abstract: A continuum-based pore-scale representation of a dolomite reservoir rock is presented, containing several orders of magnitude in pore sizes within a single rock model. The macroscale rock fabric from a low-resolution x-ray microtomogram was combined with microscale information gathered from high-resolution two-dimensional electron microscope images. The low-resolution x-ray microtomogram was segmented into six separate rock phases in terms of mineralogy, matrix appearances, and open- versus crystal-filled molds. These large-scale rock phases were decorated (modeled) with geometric objects, such as different dolomite crystal types and anhydrite, according to the high-resolution information gathered from the electron microscope images. This procedure resulted in an approximate three-dimensional representation of the diagenetically transformed rock sample with respect to dolomite crystal sizes, porosity, appearance, and volume of different matrix phases and pore/matrix/cement ratio. The resulting rock model contains a pore-size distribution ranging from moldic macropores (several hundred micrometers in diameter) down to mudstone micropores (1 m in diameter). This allows us to study the effect and contribution of different pore classes to the petrophysical properties of the rock. Higher resolution x-ray tomographs of the same rock were used as control volumes for the pore-size distribution of the model. The pore-size analysis and percolation tests performed in three dimensions at various discretization resolutions indicate pore-throat radii of 1.5 to 6 m for the largest interconnected pore network. This also highlights the challenge to determine appropriate resolutions for x-ray imaging when the exact rock microstructure is not known.
31 Dec 2011
TL;DR: An integrated geologic and geophysical study of the Bakken Petroleum System, in the Williston basin of North Dakota and Montana indicates that dolomite is needed for good reservoir performance in the Middle Bakken; regional and local fractures play a significant role in enhancing permeability and well production, and it is important to recognize both because local fractures will dominate in on-structure locations; and the organic-rich Bakken shale serves as both a source and reservoir rock as discussed by the authors.
Abstract: An integrated geologic and geophysical study of the Bakken Petroleum System, in the Williston basin of North Dakota and Montana indicates that: (1) dolomite is needed for good reservoir performance in the Middle Bakken; (2) regional and local fractures play a significant role in enhancing permeability and well production, and it is important to recognize both because local fractures will dominate in on-structure locations; and (3) the organic-rich Bakken shale serves as both a source and reservoir rock. The Middle Bakken Member of the Bakken Formation is the target for horizontal drilling. The mineralogy across all the Middle Bakken lithofacies is very similar and is dominated by dolomite, calcite, and quartz. This Member is comprised of six lithofacies: (A) muddy lime wackestone, (B) bioturbated, argillaceous, calcareous, very fine-grained siltstone/sandstone, (C) planar to symmetrically ripple to undulose laminated, shaly, very fine-grained siltstone/sandstone, (D) contorted to massive fine-grained sandstone, to low angle, planar cross-laminated sandstone with thin discontinuous shale laminations, (E) finely inter-laminated, bioturbated, dolomitic mudstone and dolomitic siltstone/sandstone to calcitic, whole fossil, dolomitic lime wackestone, and (F) bioturbated, shaly, dolomitic siltstone. Lithofacies B, C, D, and E can all be reservoirs, if quartz and dolomite-rich (facies D) or dolomitized (facies B,more » C, E). Porosity averages 4-8%, permeability averages 0.001-0.01 mD or less. Dolomitic facies porosity is intercrystalline and tends to be greater than 6%. Permeability may reach values of 0.15 mD or greater. This appears to be a determinant of high productive wells in Elm Coulee, Parshall, and Sanish fields. Lithofacies G is organic-rich, pyritic brown/black mudstone and comprises the Bakken shales. These shales are siliceous, which increases brittleness and enhances fracture potential. Mechanical properties of the Bakken reveal that the shales have similar effective stress as the Middle Bakken suggesting that the shale will not contain induced fractures, and will contribute hydrocarbons from interconnected micro-fractures. Organic-rich shale impedance increases with a reduction in porosity and an increase in kerogen stiffness during the burial maturation process. Maturation can be directly related to impedance, and should be seismically mappable. Fractures enhance permeability and production. Regional fractures form an orthogonal set with a dominant NE-SW trend, and a less prominent NW-SE trend. Many horizontal 1 direction to intersect these fractures. Local structures formed by basement tectonics or salt dissolution generate both hinge parallel and hinge oblique fractures that may overprint and dominate the regional fracture signature. Horizontal microfractures formed by oil expulsion in the Bakken shales, and connected and opened by hydrofracturing provide permeability pathways for oil flow into wells that have been hydro-fractured in the Middle Bakken lithofacies. Results from the lithofacies, mineral, and fracture analyses of this study were used to construct a dual porosity Petrel geo-model for a portion of the Elm Coulee Field. In this field, dolomitization enhances reservoir porosity and permeability. First year cumulative production helps locate areas of high well productivity and in deriving fracture swarm distribution. A fracture model was developed based on high productivity well distribution, and regional fracture distribution, and was combined with favorable matrix properties to build a dual porosity geo-model.« less
01 Jan 2011
TL;DR: A center in the present paper is referred to as an area or region which may include one or more hydrocarbon accumulations as mentioned in this paper, where a gas accumulation center is an area in which natural gas generated from cracked oil accumulated.
Abstract: A center in the present paper is referred to as an area or region which may include one or more hydrocarbon accumulations. A hydrocarbon generation center is referred to as an area containing high quality source rock which was subjected to thermal maturation. A gas generation center is an area in which an oil pool or accumulation was present, and oil was thermally cracked to generate gas. A gas accumulation center is referred to as an area in which natural gas generated from cracked oil accumulated. A gas preservation center is referred to as an area or region where the present natural gas pool/pools is/are located.As one of the oldest petroleum reservoir rocks in the world, the upper Sinian Dengying Formation (Upper Proterozoic) in the Sichuan basin was deeply buried, and its paleo-oil pools (gas generation centers) underwent complex transformation into paleo-gas pools (gas accumulation centers) and the present gas pools (gas preservation centers) as a result of multiphase tectonic activities. The paleo ...
TL;DR: In this paper, a good understanding of the effect of rock and porefluid properties on seismic waves is needed for the characterization of a subsurface hydrocarbon reservoir from a seismic data set.
Abstract: A good understanding of the effect of rock and pore-fluid properties on seismic waves is necessary for the characterization of a subsurface hydrocarbon reservoir from a seismic data set. Information about the rock and fluids in the reservoir can be obtained, for example, through well logging and laboratory tests with samples cored from the wellbore. Together with seismic data, this information can be extrapolated for the entire dimension of the reservoir to provide valuable quantitative estimates for production. Additionally, this information can be extrapolated in time for monitoring the spatial redistribution of fluids during production. Making such space and time extrapolations more accurate using seismic data is the main goal of rock physics. For that, identifying and understanding the physical processes taking place in a reservoir rock at different scales is an important step and the subject of our article.
01 Jan 2011
TL;DR: In this article, an integrated geomechanical study for CO2 geological storage has been conducted to evaluate the feasibility of injecting and storing CO2 in the M4 depleted carbonate gas reservoir.
Abstract: The M4 Field is located north of Central Luconia Province in the Sarawak Basin, East Malaysia. The reservoir is approximately 2000 m below sea-level where the water depth is approximately 120m. An integrated geomechanical study for CO2 geological storage has been conducted to evaluate the feasibility of injecting and storing CO2 in the M4 depleted carbonate gas reservoir. The storage feasibility of M4 reservoir is impacted by interaction of the reservoir rock with carbonic acid formed by dissolution of injected CO2 in the water which has risen close to the cap-rock. The geomechanical study needs to assess the risk of CO2 leakage from the reservoir due to degradation of the integrity of the cap-rock by the injection operations, and interaction of the injected CO2 and carbonic acid with the cap and reservoir rocks.
TL;DR: In this paper, the authors investigated the formation of phase fluid inclusions in calcite veinlets in fine grained sandstones of the Upper Triassic Yangchang Formation in Ordos Basin, Northern China.
Patent•
20 May 2011
TL;DR: In this article, a method of recovering petroleum from dormant oil wells or increasing the production of oil wells is described, in which an alkali or alkali earth carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced in an oil layer.
Abstract: A method of recovering petroleum from dormant oil wells or increasing the production of oil wells is disclosed. An alkali or alkali earth carbonate is introduced into a water layer associated with a subterranean petroleum reservoir and/or an explosive composition is introduced into an oil layer associated with a subterranean petroleum reservoir. CO2 gas is produced by reacting the alkali or alkali earth carbonate with an acid and/or by detonating the explosive composition. An explosive composition can be introduced and detonated to achieve sufficient CO2 gas production to increase pressure within the subterranean petroleum reservoir. Petroleum recovery can be further enhanced through the use of one or more techniques to reduce petroleum viscosity including sonication and microwave radiation.
TL;DR: In this article, the authors provided insight into the petroleum systems of the Levantine Basin using well and 2-D seismic data interpretations and PetroMod2D, which suggests that oil and gas accumulations exist in both structural and stratigraphic traps throughout the basin.
Abstract: The Levantine Basin has proven hydrocarbons, yet it is still a frontier basin. There have been significant oil and gas discoveries offshore the Nile Delta, e.g. several Pliocene gas plays and the Mango Well with ca. 10,000 bbls/day in Lower Cretaceous rocks and recently, Noble Energy discovered two gas “giants” (> 5 TCF and one estimated at 16 TFC) one of which is in a pre-Messinian strata in ca. 1,700 m (5,577 ft) water depth. Regional two-dimensional (2-D) petroleum system modeling suggests that source rocks generated hydrocarbons throughout the basin. This paper provides insight into the petroleum systems of the Levantine Basin using well and 2-D seismic data interpretations and PetroMod2D. Tectonics followed the general progression of the opening and closing of the Neo-Tethys Ocean: rift-extension, passive margin, and compression. The stratal package is up to 15 km thick and consists of mixed siliciclastic-carbonate-evaporite facies. Five potential source rock intervals (Triassic – Paleocene) are suggested. Kerogen in the older source rocks is fully transformed, whereas the younger source rocks are less mature. There are several potential reservoir and seal rocks. The model suggests that oil and gas accumulations exist in both structural and stratigraphic traps throughout the basin.
31 Dec 2011
TL;DR: In this article, an integrated geologic and geophysical study of the Bakken Petroleum System, in the Williston basin of North Dakota and Montana indicates that dolomite is needed for good reservoir performance in the Middle Bakken; regional and local fractures play a significant role in enhancing permeability and well production.
Abstract: An integrated geologic and geophysical study of the Bakken Petroleum System, in the Williston basin of North Dakota and Montana indicates that: (1) dolomite is needed for good reservoir performance in the Middle Bakken; (2) regional and local fractures play a significant role in enhancing permeability and well production, and it is important to recognize both because local fractures will dominate in on-structure locations; and (3) the organic-rich Bakken shale serves as both a source and reservoir rock. The Middle Bakken Member of the Bakken Formation is the target for horizontal drilling. The mineralogy across all the Middle Bakken lithofacies is very similar and is dominated by dolomite, calcite, and quartz. This Member is comprised of six lithofacies: (A) muddy lime wackestone, (B) bioturbated, argillaceous, calcareous, very fine-grained siltstone/sandstone, (C) planar to symmetrically ripple to undulose laminated, shaly, very fine-grained siltstone/sandstone, (D) contorted to massive fine-grained sandstone, to low angle, planar cross-laminated sandstone with thin discontinuous shale laminations, (E) finely inter-laminated, bioturbated, dolomitic mudstone and dolomitic siltstone/sandstone to calcitic, whole fossil, dolomitic lime wackestone, and (F) bioturbated, shaly, dolomitic siltstone. Lithofacies B, C, D, and E can all be reservoirs, if quartz and dolomite-rich (facies D) or dolomitized (facies B, C, E). Porosity averages 4-8%, permeability averages 0.001-0.01 mD or less. Dolomitic facies porosity is intercrystalline and tends to be greater than 6%. Permeability may reach values of 0.15 mD or greater. This appears to be a determinant of high productive wells in Elm Coulee, Parshall, and Sanish fields. Lithofacies G is organic-rich, pyritic brown/black mudstone and comprises the Bakken shales. These shales are siliceous, which increases brittleness and enhances fracture potential. Mechanical properties of the Bakken reveal that the shales have similar effective stress as the Middle Bakken suggesting that the shale will not contain induced fractures, and will contribute hydrocarbons from interconnected micro-fractures. Organic-rich shale impedance increases with a reduction in porosity and an increase in kerogen stiffness during the burial maturation process. Maturation can be directly related to impedance, and should be seismically mappable. Fractures enhance permeability and production. Regional fractures form an orthogonal set with a dominant NE-SW trend parallel to I1, and a less prominent NW-SE trend. Many horizontal wells are drilled perpendicular to the I1 direction to intersect these fractures. Local structures formed by basement tectonics or salt dissolution generate both hinge parallel and hinge oblique fractures that may overprint and dominate the regional fracture signature. Horizontal microfractures formed by oil expulsion in the Bakken shales, and connected and opened by hydrofracturing provide permeability pathways for oil flow into wells that have been hydro-fractured in the Middle Bakken lithofacies. Results from the lithofacies, mineral, and fracture analyses of this study were used to construct a dual porosity Petrel geo-model for a portion of the Elm Coulee Field. In this field, dolomitization enhances reservoir porosity and permeability. First year cumulative production helps locate areas of high well productivity and in deriving fracture swarm distribution. A fracture model was developed based on high productivity well distribution, and regional fracture distribution, and was combined with favorable matrix properties to build a dual porosity geo-model.
TL;DR: The German Society for Petroleum and Coal Science and Technology (DGMK) refers to a tight gas sandstone reservoir if permeabilities are < 0.6 mD as mentioned in this paper.
Abstract: In recent years, tight gas reservoirs have received increased exploration interest as new technological developments such as horizontal drilling and hydraulic fracturing simplify tight gas exploitation. The term “tight gas reservoir” is not uniformly defined. Law and Curtis [1] defined low permeability sandstone reservoirs as those exhibiting permeabilities <0.1 mD. This value has been committed since as a political margin in the United States to determine which wells deserve governmental funding for gas production [2]. In contrast, the German Society for Petroleum and Coal Science and Technology (DGMK) refers to a tight gas sandstone reservoir if permeabilities are <0.6 mD.
TL;DR: In this article, the TMGAS module for the TOUGH2 simulator is used to simulate the two-phase behavior of NaCl-dominated brines in equilibrium with a non-aqueous (NA) phase, made up of inorganic gases such as CO2 and H2S and hydrocarbons (pure as well as pseudo-components), up to the high pressures and temperatures found in deep sedimentary basins.
Abstract: The reinjection of sour or acid gas mixtures is often required for the exploitation of hydrocarbon reservoirs containing remarkable amounts of acid gases (H2S and CO2) to reduce the environmental impact of field exploitation and provide pressure support for enhanced oil recovery (EOR) purposes. Sour and acid gas injection in geological structures can be modelled with TMGAS, a new Equation of State (EOS) module for the TOUGH2 reservoir simulator. TMGAS can simulate the two-phase behaviour of NaCl-dominated brines in equilibrium with a non-aqueous (NA) phase, made up of inorganic gases such as CO2 and H2S and hydrocarbons (pure as well as pseudo-components), up to the high pressures (~100 MPa) and temperatures (~200°C) found in deep sedimentary basins. This study is focused on the near-wellbore processes driven by the injection of an acid gas mixture in a hypothetical high-pressure, under-saturated sour oil reservoir at a well-sector scale and at conditions for which the injected gas is fully miscible with the oil. Relevant-coupled processes are simulated, including the displacement of oil originally in place, the evaporation of connate brine, the salt concentration and consequent halite precipitation, as well as non-isothermal effects generated by the injection of the acid gas mixture at temperatures lower than initial reservoir temperature. Non-isothermal effects are studied by modelling in a coupled way wellbore and reservoir flow with a modified version of the TOUGH2 reservoir simulator. The described approach is limited to single-phase wellbore flow conditions occurring when injecting sour, acid or greenhouse gas mixtures in high-pressure geological structures.
Journal Article•
TL;DR: Based on the surface geological investigation,thin sections study of profile and wells, the authors analyzed the characteristics and the relationship of reservoir bitumen with other minerals in outcrops,drilling cores by microscope, and had an oil to source correlation by geochemical methods.
Abstract: Based on the surface geological investigation ,thin sections study of profile and wells,this paper analyzed the characteristics and the relationship of reservoir bitumen with other minerals in outcrops,drilling cores by microscope,and had an oil to source correlation by geochemical methods. Some conclusions drawn are as follows:① Two generations reservoir bitumen have been found in the Sinian,but just one generation in the Lower Paleozoic. Reservoir bitumen in the Sinian is very abundant and its distribution is controlled by the unconformity karstification. Paleo oil pool of the Sinian is structural lithological oil pools. Slight porous reservoir (intercrystalline pores and intercrystalline solution pores) occurred in the Paleozoic,which controlled by the burial dissolution and recrystallization,and so on. ② Reservoir bitumen content of the Paleozoic is less and its distribution obviously controlled by lithology. The Paleozoic paleo oil pool is a little lithological oil reservoir. ③ The Sinian paleo oil poos in the Dingshan—Lintanchang structural belt is 8.63×108t,and oil cracking gas is 5348.698×108m3. The Silurian paleo oil pool in Liangcun is 2.62×104t,oil cracking gas is 1.62×107m3. ④ Reservoir bitumen from the Sinian to the Paleozoic is a thermal evolution product. The Sinian and Cambrian reservoir bitumen is from the Cambrian source rocks,and the Silurian bitumen is from oil transformational migration and charging of the Sinian paleo oil pool. ⑤ Overall,reservoir bitumen from the Sinian to Paleozoic formation is closely related to the hydrocarbon generation of source rocks and tectonic evolution. The formation time of the first generation bitumen of the Sinian is Caledonian,and formation time of the second generation bitumen of the Sinian and bitumen is from the Cambrian to Permian,is from high temperature cracking in Indosinian—Yanshanian. The gas from oil cracking is one of the most important gas resources from the Sinian to Lower Paleozoic (including Permian) ,and the Ordovician and Silurian has favorable exploration prespective,owing to transformational migration of oil cracking gas in the Sichuan basin,especially in Eastern Sichuan and Eastern Chongqing.