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1.
Seismic surveys successfully imaged a small scale CO2 injection (1,600 ton) conducted in a brine aquifer of the Frio Formation near Houston, Texas. These time-lapse borehole seismic surveys, crosswell and vertical seismic profile (VSP), were acquired to monitor the CO2 distribution using two boreholes (the new injection well and a pre-existing well used for monitoring) which are 30 m apart at a depth of 1,500 m. The crosswell survey provided a high-resolution image of the CO2 distribution between the wells via tomographic imaging of the P-wave velocity decrease (up to 500 m/s). The simultaneously acquired S-wave tomography showed little change in S-wave velocity, as expected for fluid substitution. A rock physics model was used to estimate CO2 saturations of 10–20% from the P-wave velocity change. The VSP survey resolved a large (∼70%) change in reflection amplitude for the Frio horizon. This CO2 induced reflection amplitude change allowed estimation of the CO2 extent beyond the monitor well and on three azimuths. The VSP result is compared with numerical modeling of CO2 saturations and is seismically modeled using the velocity change estimated in the crosswell survey.  相似文献   

2.
Mechanical damage (e.g. faults and fractures) related to tectonic forces and/or variations in formation pore pressures may enable the leakage of fluids through otherwise effective seal rocks. Characterisation of faults and fractures within seals is therefore essential for the assessment of long-term trap integrity in potential CO2 storage sites. 3D seismic reflection data are used to describe a previously unrecognised network of extensive, small Miocene-age faults with displacement of generally <30 m and lengths that vary between ～300 and 2500 m above the Snapper Field, in the Gippsland Basin. The Snapper Field is a nearly depleted oil and gas field that presents an attractive site for potential CO2 storage due its structural closure and because it has effectively retained significant natural hydrocarbon (including CO2) columns over geological time-scales. Volume-based seismic attributes reveal that this fault system is located within the Oligocene Lakes Entrance Formation of the Seaspray Group, which acts as the regional seal to the Latrobe Group reservoirs in the Gippsland Basin. Detailed analysis of fault lengths and linkages suggests that the Miocene faults are non-tectonic, polygonal faults, although the displacement analysis of fault segments reveals strong correlations with the both the structure of the underlying Top Latrobe surface and normal faults that segment the Latrobe Group reservoirs, suggesting that the development of this fault system has been influenced by underlying structures. The geological evidence for long-term retention of hydrocarbons within the Snapper Field suggests that this fault system has not compromised the integrity of the Lakes Entrance Formation seal, although elevated pore pressures during CO2 injection could potentially lead to reactivation of these structures.  相似文献   

3.
Geological storage of CO2 in the offshore Gippsland Basin, Australia, is being investigated by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) as a possible method for storing the very large volumes of CO2 emissions from the nearby Latrobe Valley area. A storage capacity of about 50 million tonnes of CO2 per annum for a 40-year injection period is required, which will necessitate several individual storage sites to be used both sequentially and simultaneously, but timed such that existing hydrocarbon assets will not be compromised. Detailed characterisation focussed on the Kingfish Field area as the first site to be potentially used, in the anticipation that this oil field will be depleted within the period 2015–2025. The potential injection targets are the interbedded sandstones of the Paleocene-Eocene upper Latrobe Group, regionally sealed by the Lakes Entrance Formation. The research identified several features to the offshore Gippsland Basin that make it particularly favourable for CO2 storage. These include: a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping and dissolution; non-reactive reservoir units that have high injectivity; a thin, suitably reactive, lower permeability marginal reservoir just below the regional seal providing mineral trapping; several depleted oil fields that provide storage capacity coupled with a transient production-induced flow regime that enhances containment; and long migration pathways beneath a competent regional seal. This study has shown that the Gippsland Basin has sufficient capacity to store very large volumes of CO2. It may provide a solution to the problem of substantially reducing greenhouse gas emissions from future coal developments in the Latrobe Valley.  相似文献   

4.
A numerical model was developed to investigate the potential to detect fluid migration in a (homogeneous, isotropic, with constant pressure lateral boundaries) porous and permeable interval overlying an imperfect primary seal of a geologic CO2 storage formation. The seal imperfection was modeled as a single higher-permeability zone in an otherwise low-permeability seal, with the center of that zone offset from the CO2 injection well by 1400 m. Pressure response resulting from fluid migration through the high-permeability zone was detectable up to 1650 m from the centroid of that zone at the base of the monitored interval after 30 years of CO2 injection (detection limit = 0.1 MPa pressure increase); no pressure response was detectable at the top of the monitored interval at the same point in time. CO2 saturation response could be up to 774 m from the center of the high-permeability zone at the bottom of the monitored interval, and 1103 m at the top (saturation detection limit = 0.01). More than 6% of the injected CO2, by mass, migrated out of primary containment after 130 years of site performance (including 30 years of active injection) in the case where the zone of seal imperfection had a moderately high permeability (10??17 m2 or 0.01 mD). Free-phase CO2 saturation monitoring at the top of the overlying interval provides favorable spatial coverage for detecting fluid migration across the primary seal. Improved sensitivity of detection for pressure perturbation will benefit time of detection above an imperfect seal.  相似文献   

5.
CO2 pilot injection studies, with site-specific geologic assessment and engineering reservoir design, can be instrumental for demonstrating both incremental enhanced oil recovery and permanent geologic storage of greenhouse gases. The purpose of this paper is to present the geologic and reservoir analyses in support of a field pilot test that will evaluate the technical and economic feasibility of commercial-scale CO2-enhanced oil recovery to increase oil recovery and extend the productive life of the Citronelle Oil Field, the largest conventional oil field in Alabama (SE USA). Screening of reservoir depth, oil gravity, reservoir pressure, reservoir temperature, and oil composition indicates that the Cretaceous-age Donovan sand, which has produced more than 169 × 106 bbl in Citronelle Oil Field, is amenable to miscible CO2 flooding. The project team has selected an 81 ha (200 ac) 5-spot test site with one central gas injector, two producers, and two initially temporarily abandoned production wells that are now in production. Injection is planned in two separate phases, each consisting of 6,804 t (7,500 short tons) of food-grade CO2. The Citronelle Unit B-19-10 #2 well (Permit No. 3232) is the CO2 injector for the first injection test. The 14-1 and 16-2 sands of the upper Donovan are the target zones. These sandstone units consist of fine to medium-grained sandstone that is enveloped by variegated mudstone. Both of these sandstone units were selected based on the distribution of perforated zones in the test pattern, production history, and the ability to correlate individual sandstone units in geophysical well logs. The pilot injections will evaluate the applicability of tertiary oil recovery to Citronelle Field and will provide a large volume of information on the pressure response of the reservoirs, the mobility of fluids, time to breakthrough, and CO2 sweep efficiency. The results of the pilot injections will aid in the formulation of commercial-scale reservoir management strategies that can be applied to Citronelle Field and other geologically heterogeneous oil fields and the design of similar pilot injection projects.  相似文献   

6.
A field facility located in Bozeman, Montana provides the opportunity to test methods to detect, locate, and quantify potential CO2 leakage from geologic storage sites. From 9 July to 7 August 2008, 0.3 t CO2 day−1 were injected from a 100-m long, ~2.5-m deep horizontal well. Repeated measurements of soil CO2 fluxes on a grid characterized the spatio-temporal evolution of the surface leakage signal and quantified the surface leakage rate. Infrared CO2 concentration sensors installed in the soil at 30 cm depth at 0–10 m from the well and at 4 cm above the ground at 0 and 5 m from the well recorded surface breakthrough of CO2 leakage and migration of CO2 leakage through the soil. Temporal variations in CO2 concentrations were correlated with atmospheric and soil temperature, wind speed, atmospheric pressure, rainfall, and CO2 injection rate.  相似文献   

7.
The CO2 migrated from deeper to shallower layers may change its phase state from supercritical state to gaseous state (called phase transition). This phase transition makes both viscosity and density of CO2 experience a sharp variation, which may induce the CO2 further penetration into shallow layers. This is a critical and dangerous situation for the security of CO2 geological storage. However, the assessment of caprock sealing efficiency with a fully coupled multi-physical model is still missing on this phase transition effect. This study extends our previous fully coupled multi-physical model to include this phase transition effect. The dramatic changes of CO2 viscosity and density are incorporated into the model. The impacts of temperature and pressure on caprock sealing efficiency (expressed by CO2 penetration depth) are then numerically investigated for a caprock layer at the depth of 800 m. The changes of CO2 physical properties with gas partial pressure and formation temperature in the phase transition zone are explored. It is observed that phase transition revises the linear relationship of CO2 penetration depth and time square root as well as penetration depth. The real physical properties of CO2 in the phase transition zone are critical to the safety of CO2 sequestration. Pressure and temperature have different impact mechanisms on the security of CO2 geological storage.  相似文献   

8.
This paper studied the CO2-EGR in Altmark natural gas field with numerical simulations. The hydro-mechanical coupled simulations were run using a linked simulator TOUGH2MP-FLAC3D. In order to consider the gas mixing process, EOS7C was implemented in TOUGH2MP. A multi-layered 3D model (4.4 km × 2 km × 1 km) which consists of the whole reservoir, caprock and base rock was generated based on a history-matched PETREL model, originally built by GDF SUEZ E&P Deutschland GmbH for Altmark natural gas field. The model is heterogeneous and discretized into 26,015 grid blocks. In the simulation, 100,000 t CO2 was injected in the reservoir through well S13 within 2 years, while gas was produced from the well S14. Some sensitivity analyses were also carried out. Simulation results show that CO2 tends to migrate toward the production well S14 along a NW–SE fault. It reached the observation wells S1 and S16 after 2 years, but no breakthrough occurred in the production well. After 2 years of CO2 injection, the reservoir pressure increased by 2.5 bar, which is beneficial for gas recovery. The largest uplift (1 mm) occurred at the bottom of the caprock. The deformation was small (elastic) and caprock integrity was not affected. With the injection rate doubled the average pressure increased by 5.3 bar. Even then the CO2 did not reach the production well S14 after 2 years of injection. It could be concluded that the previous flow field was established during the primary gas production history. This former flow field, including CO2 injection/CH4 production rate during CO2-EGR and fault directions and intensity are the most important factors affecting the CO2 transport.  相似文献   

9.
In the context of carbon capture and storage, deep underground injection of CO2 induces the geomechanical changes within and around the injection zone and their impact on CO2 storage security should be evaluated. In this study, we conduct coupled multiphase fluid flow and geomechanical modeling to investigate such geomechanical changes, focusing on probabilistic analysis of injection-induced fracture reactivation (such as shear slip) that could lead to enhanced permeability and CO2 migration across otherwise low-permeability caprock formations. Fracture reactivation in terms of shear slip was analyzed by implicitly considering the fracture orientations generated using the Latin hypercube sampling method, in one case using published fracture statistics from a CO2 storage site. The analysis was conducted by a coupled multiphase fluid flow and geomechanical simulation to first calculate the three-dimensional stress evolution during a hypothetical CO2 injection operation and then evaluate the probability of shear slip considering the statistical fracture distribution and a Coulomb failure analysis. We evaluate the probability of shear slip at different points within the injection zone and in the caprock just above the injection zone and relate this to the potential for opening of new flow paths through the caprock. Our analysis showed that a reverse faulting stress field would be most favorable for avoiding fracture shear reactivation, but site-specific analyses will be required because of strong dependency of the local stress field and fracture orientations.  相似文献   

10.
《Applied Geochemistry》2000,15(3):265-279
The conditions for mineral alteration and formation damage during CO2 treatment of Tensleep sandstone reservoirs in northern Wyoming, USA, were examined through core-flooding laboratory experiments carried out under simulated reservoir conditions (80°C and 166 bars). Subsurface cores from the Tensleep sandstone, which were cemented by dolomite and anhydrite, and synthetic brines were used. The brines used were (Ca, Mg, Na)SO4–NaCl solution (9.69 g/l total dissolved solids) for Run 1 and a 0.25 mol/l NaCl solution for Run 2. The solution used in Run 1 was saturated with respect to anhydrite at run conditions, which is characteristic of Tensleep Formation waters.Three major reactions took place during flooding, including (1) dissolution of dolomite, (2) alteration of K-feldspar to form kaolinite, and (3) precipitation (in Run 1) or dissolution (in Run 2) of anhydrite. All sample solutions remained undersaturated with respect to carbonates. The permeability of all the cores (except one used in Run 2) decreased during the experiments despite the dissolution of authigenic cement. Kaolinite crystal growth occurring in pore throats likely reduced the permeability.Application of the experimental results to reservoirs in the Tensleep Formation indicates that an injection solution will obtain saturation with respect to dolomite (and anhydrite) in the immediate vicinity of the injection well. The injection of NaCl-type water, which can be obtained from other formations, causes a greater increase in porosity than the injection of Tensleep Formation waters because of the dissolution of both dolomite and anhydrite cements.  相似文献   

11.
Hyperspectral plant signatures can be used as a short-term, as well as long-term (100-year timescale) monitoring technique to verify that CO2 sequestration fields have not been compromised. An influx of CO2 gas into the soil can stress vegetation, which causes changes in the visible to near-infrared reflectance spectral signature of the vegetation. For 29 days, beginning on July 9, 2008, pure carbon dioxide gas was released through a 100-m long horizontal injection well, at a flow rate of 300 kg day−1. Spectral signatures were recorded almost daily from an unmown patch of plants over the injection with a “FieldSpec Pro” spectrometer by Analytical Spectral Devices, Inc. Measurements were taken both inside and outside of the CO2 leak zone to normalize observations for other environmental factors affecting the plants. Four to five days after the injection began, stress was observed in the spectral signatures of plants within 1 m of the well. After approximately 10 days, moderate to high amounts of stress were measured out to 2.5 m from the well. This spatial distribution corresponded to areas of high CO2 flux from the injection. Airborne hyperspectral imagery, acquired by Resonon, Inc. of Bozeman, MT using their hyperspectral camera, also showed the same pattern of plant stress. Spectral signatures of the plants were also compared to the CO2 concentrations in the soil, which indicated that the lower limit of soil CO2 needed to stress vegetation is between 4 and 8% by volume.  相似文献   

12.
The most suitable candidates for subsurface storage of CO2 are depleted gas fields. Their ability to retain CO2 can however be influenced by the effect which impurities in the CO2 stream (e.g. H2S and SO2) have on the mineralogy of reservoir and seal. In order to investigate the effects of SO2 we carried out laboratory experiments on reservoir and cap rock core samples from gas fields in the northeast of the Netherlands. The rock samples were contained in reactor vessels for 30 days in contact with CO2 and 100 ppm SO2 under in-situ conditions (300 bar, 100 °C). The vessels also contained brine with the same composition as in the actual reservoir. Furthermore equilibrium modeling was carried out using PHREEQC software in order to model the experiments on caprock samples.After the experiments the permeability of the reservoir samples had increased by a factor of 1.2–2.2 as a result of dissolution of primary reservoir minerals. Analysis of the associated brine samples before and after the experiments showed that concentrations of K, Si and Al had increased, indicative of silicate mineral dissolution.In the caprock samples, composed of carbonate and anhydrite minerals, permeability changed by a factor of 0.79–23. The increase in permeability is proportional to the amount of carbonate in the caprock. With higher carbonate content in comparison with anhydrite the permeability increase is higher due to the additional carbonate dissolution. This dependency of permeability variations was verified by the modeling study. Hence, caprock with a higher anhydrite content in comparison with carbonate minerals has a lower risk of leakage after co-injection of 100 ppmv SO2 with CO2.  相似文献   

13.
Motivated by the rapid increase in atmospheric CO2 due to human activities since the Industrial Revolution, and the climate changes it produced, the world’s concerned scientific community has made a huge effort to investigate the global carbon cycle. However, the results reveal that the global CO2 budget cannot be balanced, unless a “missing sink” is invoked. Although numerous studies claimed to find the “missing sink”, none of those claims has been widely accepted. This current study showed that alkaline soil on land are absorbing CO2 at a rate of 0.3–3.0 μmol m−2 s−1 with an inorganic, non-biological process. The intensity of this CO2 absorption is determined by the salinity, alkalinity, temperature and water content of the saline/alkaline soils, which are widely distributed on land. Further studies revealed that high salinity or alkalinity positively affected the CO2 absorbing intensity, while high temperature and water content had a negative effect on the CO2 absorbing intensity of these soils. This inorganic, non-biological process of CO2 absorption by alkaline soils might have significant implications to the global carbon budget accounting.  相似文献   

14.
付广  杨敬博 《地球科学》2013,38(4):783-791
为了研究南堡凹陷中浅层油气成藏规律, 采用区域性盖层厚度与断裂断距大小比较和与油气分布关系分析的研究方法, 对断盖配置对沿断裂运移油气的封闭作用进行了研究.结果表明: 断盖配置对沿断裂运移油气有3级封闭作用: (1)当盖层厚度大于断裂断距, 且断接厚度大于一定值时, 盖层与断裂配置对沿断裂运移油气可起完全封闭作用; (2)当盖层厚度大于断裂断距, 但断接厚度小于一定值时, 断盖配置对沿断裂运移油气可起部分封闭作用; (3)当盖层厚度小于断距, 断接厚度小于零时, 断盖配置对沿断裂运移油气无封闭作用.南堡凹陷3套区域性盖层中东二段泥岩和馆三段火山岩2套区域性盖层与断裂配置对沿断裂运移油气均具有完全、部分和无封闭三级作用, 明下段泥岩区域性盖层与断裂配置仅具完全封闭作用.3套区域性盖层与断裂配置的封闭作用之间, 空间不同配置对南堡凹陷中浅层油气聚集分布层位和区域的控制作用主要表现在以下3个方面: (1)南堡2号地区东二段区域性盖层与断裂配置为完全封闭, 油气主要分布在其下; (2)南堡1~5区块东二段区域性盖层与断裂配置为部分或无封闭, 馆三段区域性盖层与断裂配置为完全封闭, 油气主要分布在东一段和馆四段; (3)南堡1号和4号局部地区东二段和馆三段区域性盖层与断裂配置为部分或无封闭, 明下段区域性盖层与断裂配置为完全封闭, 油气从下至上皆有分布.   相似文献   

15.
Miller field of the North Sea has had high concentrations of natural CO2 for ~70 Ma. It is an ideal analog for the long-term fate of CO2 during engineered storage, particularly for formation of carbonate minerals that permanently lock up CO2 in solid form. The Brae Formation reservoir sandstone contains an unusually high quantity of calcite concretions; however, C and O stable isotopic signatures suggest that these are not related to the present-day CO2 charge. Margins of the concretions are corroded, probably because of reduced pH due to CO2 influx. Dispersed calcite cements are also present, some of which postdate the CO2 charge and, therefore, are the products of mineral trapping. It is calculated that only a minority of the reservoired CO2 in Miller (6–24%) has been sequestrated in carbonates, even after 70 Ma of CO2 emplacement. Most of the CO2 accumulation is dissolved in pore fluids. Therefore, in a reservoir similar to the Brae Formation, engineered CO2 storage must rely on physical retention mechanisms because mineral trapping is both incomplete and slow.  相似文献   

16.
We have used density functional theory to investigate the stability of MgAl2O4 polymorphs under pressure. Our results can reasonably explain the transition sequence of MgAl2O4 polymorphs observed in previous experiments. The spinel phase (stable at ambient conditions) dissociates into periclase and corundum at 14 GPa. With increasing pressure, a phase change from the two oxides to a calcium-ferrite phase occurs, and finally transforms to a calcium-titanate phase at 68 GPa. The calcium-titanate phase is stable up to at least 150 GPa, and we did not observe a stability field for a hexagonal phase or periclase + Rh2O3(II)-type Al2O3. The bulk moduli of the phases calculated in this study are in good agreement with those measured in high-pressure experiments. Our results differ from those of a previous study using similar methods. We attribute this inconsistency to an incomplete optimization of a cell shape and ionic positions at high pressures in the previous calculations.  相似文献   

17.
Numerical models are essential tools in fully understanding the fate of injected CO2 for commercial-scale sequestration projects and should be included in the life cycle of a project. Common practice involves modeling the behavior of CO2 during and after injection using site-specific reservoir and caprock properties. Little has been done to systematically evaluate and compare the effects of a broad but realistic range of reservoir and caprock properties on potential CO2 leakage through caprocks. This effort requires sampling the physically measurable range of caprock and reservoir properties, and performing numerical simulations of CO2 migration and leakage. In this study, factors affecting CO2 leakage through intact caprocks are identified. Their physical ranges are determined from the literature from various field sites. A quasi-Monte Carlo sampling approach is used such that the full range of caprock and reservoir properties can be evaluated without bias and redundant simulations. For each set of sampled properties, the migration of injected CO2 is simulated for up to 200 years using the water–salt–CO2 operational mode of the STOMP simulator. Preliminary results show that critical factors determining CO2 leakage rate through caprocks are, in decreasing order of significance, the caprock thickness, caprock permeability, reservoir permeability, caprock porosity, and reservoir porosity. This study provides a function for prediction of potential CO2 leakage risk due to permeation of intact caprock and identifies a range of acceptable seal thicknesses and permeability for sequestration projects. The study includes an evaluation of the dependence of CO2 injectivity on reservoir properties.  相似文献   

18.
One of the uncertainties in the field of carbon dioxide capture and storage (CCS) is caused by the parameterization of geochemical models. The application of geochemical models contributes significantly to calculate the fate of the CO2 after its injection. The choice of the thermodynamic database used, the selection of the secondary mineral assemblage as well as the option to calculate pressure dependent equilibrium constants influence the CO2 trapping potential and trapping mechanism. Scenario analyses were conducted applying a geochemical batch equilibrium model for a virtual CO2 injection into a saline Keuper aquifer. The amount of CO2 which could be trapped in the formation water and in the form of carbonates was calculated using the model code PHREEQC. Thereby, four thermodynamic datasets were used to calculate the thermodynamic equilibria. Furthermore, the equilibrium constants were re-calculated with the code SUPCRT92, which also applied a pressure correction to the equilibrium constants. Varying the thermodynamic database caused a range of 61% in the amount of trapped CO2 calculated. Simultaneously, the assemblage of secondary minerals was varied, and the potential secondary minerals dawsonite and K-mica were included in several scenarios. The selection of the secondary mineral assemblage caused a range of 74% in the calculated amount of trapped CO2. Correcting the equilibrium constants with respect to a pressure of 125 bars had an influence of 11% on the amount of trapped CO2. This illustrates the need for incorporating sensitivity analyses into reaction pathway modeling.  相似文献   

19.
Capture and geological sequestration of CO2 from energy production is proposed to help mitigate climate change caused by anthropogenic emissions of CO2 and other greenhouse gases. Performance goals set by the US Department of Energy for CO2 storage permanence include retention of at least 99% of injected CO2 which requires detailed assessments of each potential storage site’s geologic system, including reservoir(s) and seal(s). The objective of this study was to review relevant basin-wide physical and chemical characteristics of geological seals considered for saline reservoir CO2 sequestration in the United States. Results showed that the seal strata can exhibit substantial heterogeneity in the composition, structural, and fluid transport characteristics on a basin scale. Analysis of available field and wellbore core data reveal several common inter-basin features of the seals, including the occurrence of quartz, dolomite, illite, calcite, and glauconite minerals along with structural features containing fractures, faults, and salt structures. In certain localities within the examined basins, some seal strata also serve as source rock for oil and gas production and can be subject to salt intrusions. The regional features identified in this study can help guide modeling, laboratory, and field studies needed to assess local seal performances within the examined basins.  相似文献   

20.
Geological sequestration of CO2 into depleted hydrocarbon reserviors or saline aquifers presents the enormous potential to reduce greenhouse gas emission from fossil fuels. However, it may give rise to a complicated coupling physical and chemical process. One of the processes is the hydro-mechanical impact of CO2 injection. During the injection project, the increase of pore pressures of storing formations can induce the instability, which finally results in a catastrophic failure of disposal sites. This paper focuses mainly on the role of CO2-saturated water in the fracturing behavior of rocks. To investigate how much the dissolved CO2 can influence the pore pressure change of rocks, acoustic emission (AE) experiments were performed on sandstone and granite samples under triaxial conditions. The main innovation of this paper is to propose a time dependent porosity method to simulate the abrupt failure process, which is observed in the laboratory and induced by the pore pressure change due to the volume dilatancy of rocks, using a finite element scheme associated with two-phase characteristics. The results successfully explained the phenomena obtained in the physical experiments.  相似文献   

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