Monitoring gas production and C O2 injection at the Sleipner field using time-lapse gravimetry

Geophysics ◽  
2008 ◽  
Vol 73 (6) ◽  
pp. WA155-WA161 ◽  
Author(s):  
Håvard Alnes ◽  
Ola Eiken ◽  
Torkjell Stenvold
Keyword(s):  
Simulation Model ◽  
Gravity Data ◽  
Time Lapse ◽  
Average Density ◽  
Gas Production ◽  
Gravity Gradient ◽  
Water Influx ◽  
Vertical Gravity Gradient ◽  
Plume Geometry ◽  
Best Fit

Thirty seafloor gravity stations have been placed above the carbon dioxide [Formula: see text] injection site and producing gas reservoir at the Sleipner Øst Ty field. Gravity and depth measurements from 2002 and 2005 reveal vertical changes of the permanently deployed benchmarks, probably caused by seafloor erosion and biologic activity (fish). The original gravity data have been reprocessed, resulting in slightly different gravity-change values compared with earlier published results. Observed gravity changes are caused by height variances, gas production and water influx in the Ty Formation, and [Formula: see text] injection in the Utsira Formation. Simultaneous matches to models for these effects have been made. The latest simulation model of the Ty Formation was fitted by permitting a scale factor, and the gravity contribution from the [Formula: see text] plume was determined by using the plume geometry as observed in 4D seismic data and varying the average density. The best-fit vertical gravity gradient is [Formula: see text], and the response from the Ty Formation suggests more water influx than expected in the presurvey simulation model. The best-fit average density of [Formula: see text] is [Formula: see text]. Estimates of the reservoir temperature combined with the equation of state for [Formula: see text] indicate an upper bound on [Formula: see text] density of [Formula: see text]. The gravity data suggest a lower bound of [Formula: see text] at 95% confidence.

scholarly journals Analysis of Groundwater Decline and Land Subsidence by using of Microgravity and Vertical Gravity Gradient Over Time Method

2014 ◽  
Vol 15 (1) ◽  
pp. 7 ◽  
Author(s):  
Suhayat Minardi ◽  
Hiden Hiden ◽  
Daharta Dahrin ◽  
Mahmud Yusuf
Keyword(s):  
Gravity Anomaly ◽  
Land Subsidence ◽  
Gravity Data ◽  
Vertical Gradient ◽  
Time Lapse ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity ◽  
Groundwater Decline ◽  
Over Time

Studies have been conducted to identify the occurrence of subsidence, a decline of groundwater, and to model the causes of subsidence in areas of Jakarta based on response of microgravity anomaly and vertical gravity gradient over time. Based on the processing and interpretation of gravity data advance of the time concluded that by using a combination of time lapse microgravity and its vertical gradient have been able to localize the source of the gravity anomaly and the results are strongly support the results of filtering to separate the source of the anomaly. The subsidence that occurs predominantly due to resettlement (in West and North Jakarta), caused by the extraction of groundwater and resettlement (in Central and East Jakarta), and dominated due to the extraction of groundwater (in South Jakarta).Keywords : Groundwater, time lapse micogravity, time lapse vertical gradient, resettlement, subsidence

Estimating saturation and density changes caused by CO2 injection at Sleipner — Using time-lapse seismic amplitude-variation-with-offset and time-lapse gravity

2017 ◽  
Vol 5 (2) ◽  
pp. T243-T257 ◽  
Author(s):  
Martin Landrø ◽  
Mark Zumberge
Keyword(s):  
Gravity Data ◽  
Time Lapse ◽  
Co2 Injection ◽  
Injection Point ◽  
Amplitude Variation With Offset ◽  
Seismic Method ◽  
Seismic Amplitude ◽  
Gravity Measurements ◽  
Measured Time ◽  
Best Fit

We have developed a calibrated, simple time-lapse seismic method for estimating saturation changes from the [Formula: see text]-storage project at Sleipner offshore Norway. This seismic method works well to map changes when [Formula: see text] is migrating laterally away from the injection point. However, it is challenging to detect changes occurring below [Formula: see text] layers that have already been charged by some [Formula: see text]. Not only is this partly caused by the seismic shadow effects, but also by the fact that the velocity sensitivity for [Formula: see text] change in saturation from 0.3 to 1.0 is significantly less than saturation changes from zero to 0.3. To circumvent the seismic shadow zone problem, we combine the time-lapse seismic method with time-lapse gravity measurements. This is done by a simple forward modeling of gravity changes based on the seismically derived saturation changes, letting these saturation changes be scaled by an arbitrary constant and then by minimizing the least-squares error to obtain the best fit between the scaled saturation changes and the measured time-lapse gravity data. In this way, we are able to exploit the complementary properties of time-lapse seismic and gravity data.

VARIATIONS OF VERTICAL GRAVITY GRADIENT IN NEW YORK CITY AND ALPINE, NEW JERSEY

Geophysics ◽  
1969 ◽  
Vol 34 (2) ◽  
pp. 235-248 ◽  
Author(s):  
John T. Kuo ◽  
Mario Ottaviani ◽  
Shri K. Singh
Keyword(s):  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
Gravity Data ◽  
Tall Buildings ◽  
Base Station ◽  
Absolute Gravity ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient

Careful gravity measurements with La Coste‐Romberg geodetic gravimeters were carried out in tall buildings on a floor‐to‐floor basis in New York City and on the Armstrong Tower, Alpine, New Jersey. Corrections for the instrumental drift and tidal gravity variation and for the Bouguer effect, topography, mass of the buildings, and subway and basement excavations have been applied to the gravity data, which are tied to the absolute gravity value of the National Gravity Base Station of Washington, D. C. The observed gravity versus elevation curves are nonlinear, particularly near the surface of the ground; the slope of the observed gravity anomaly versus elevation curves reverses sign at an elevation of about 170 ft for the campus buildings and about 350 ft for the downtown buildings, and is nearly linear without a reversal for the Armstrong Tower. The vertical gradients vary substantially even within short distances. Comparisons of the corrected observed gradients with the theoretical gradients of gravity are made. The anomalous gradient anomalies are positive and are correlated with the positive isostatic surface gravity anomalies. Calibration of gravimeters against the observed vertical gradient of gravity to an accuracy of ±2 μgal is definitely feasible provided the gradient is predetermined to a comparable accuracy by a standard instrument.

Curvature of a geometric surface and curvature of gravity and magnetic anomalies

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. G15-G26 ◽  
Author(s):  
Xiong Li
Keyword(s):  
Gravity Data ◽  
Vertical Cylinder ◽  
Equipotential Surface ◽  
Magnetic Anomalies ◽  
Gravity Gradient ◽  
Gravity Gradients ◽  
Theoretical Derivation ◽  
Vertical Gravity Gradient ◽  
Gravity And Magnetic ◽  
Geometric Surface

Curvature describes how much a line deviates from being straight or a surface from being flat. When curvature is used to interpret gravity and magnetic anomalies, we try to delineate geometric information of subsurface structures from an observed nongeometric quantity. In this work, I evaluated curvature attributes of the equipotential surface as functions of gravity gradients and analyzed the differences between the theoretical derivation and a practical application. I computed curvature of a synthetic model that consisted of representative structures (ridge, valley, basin, dome, and vertical cylinder) and curvature of the equipotential surface, gravity, and vertical gravity gradient (which is equivalent to the magnetic reduction-to-the-pole result) due to the same model. A comparison of curvature of such a geometric surface and curvature of different gravity quantities was then made to help understand these curvature differences and an indirect link between curvature of gravity data and actual structures. Finally, I applied curvature analysis to a magnetic anomaly grid in the Gaspé belt of Quebec, Canada, to illustrate its useful property of enhancing subtle features.

scholarly journals 13 million years of seafloor spreading throughout the Red Sea Basin

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nico Augustin ◽  
Froukje M. van der Zwan ◽  
Colin W. Devey ◽  
Bryndís Brandsdóttir
Keyword(s):  
Red Sea ◽  
Gravity Data ◽  
Ocean Basin ◽  
Gravity Gradient ◽  
Ocean Ridges ◽  
Spreading Ridges ◽  
Vertical Gravity Gradient ◽  
Slow Spreading ◽  
Vertical Gravity ◽  
High Resolution Bathymetry

AbstractThe crustal and tectonic structure of the Red Sea and especially the maximum northward extent of the (ultra)slow Red Sea spreading centre has been debated—mainly due to a lack of detailed data. Here, we use a compilation of earthquake and vertical gravity gradient data together with high-resolution bathymetry to show that ocean spreading is occurring throughout the entire basin and is similar in style to that at other (ultra)slow spreading mid-ocean ridges globally, with only one first-order offset along the axis. Off-axis traces of axial volcanic highs, typical features of (ultra)slow-spreading ridges, are clearly visible in gravity data although buried under thick salt and sediments. This allows us to define a minimum off-axis extent of oceanic crust of <55 km off the coast along the complete basin. Hence, the Red Sea is a mature ocean basin in which spreading began along its entire length 13 Ma ago.

Integrating time-lapse gravity, production, and geological structure data in a gas reservoir study.

2020 ◽  
pp. 1-63
Author(s):  
Andrea Balza ◽  
Yaoguo Li
Keyword(s):  
Structural Information ◽  
Gravity Data ◽  
Time Lapse ◽  
Density Contrast ◽  
Water Yield ◽  
Production Data ◽  
Complementary Information ◽  
Gas Reservoir ◽  
Fluid Movement ◽  
Water Influx

Time-lapse gravity is most commonly used to monitor fluid movement and is especially useful when monitoring water encroachment in a gas reservoir. Although time-lapse gravity data are directly sensitive to the fluid saturation changes in reservoirs, it is still necessary to integrate multiple types of data with complementary information to enhance the time-lapse gravity interpretation. When monitoring water-influx in a reservoir, the changes in water yield in production wells may directly indicate saturation changes with time and provide such complementary information about the areas of fluid movement. We present a workflow to invert a time-lapse gravity data set and production data to help monitor the edge water encroachment through a case study at the Sebei gas field in Western China. Three time-lapse gravity surveys were acquired between 2011 and 2013 and production data were also collected from 286 wells during the same period of time. We integrate the two data sets and the structural information in the reservoir through a framework of constrained time-lapse gravity inversion. In this workflow, we incorporate the information from the production data into the inversion by converting the gas and water yield into a reference model. We also incorporate geological structural information through spatially varying bound constraints. Through this approach, we construct a set of time-lapse density contrast models that are consistent with the time-lapse gravity data, production data, and structural information. The resultant density contrast models better delineate the regions of the reservoir with increased water influx and also enable us to produce improved porosity estimations in the reservoir.

Temperature Control Planning Tool for Multi-Lift Resurfacing of Airport Pavements

2019 ◽  
Vol 2673 (7) ◽  
pp. 380-389 ◽  
Author(s):  
Longjia Chu ◽  
Baihe Zhu ◽  
T. F. Fwa
Keyword(s):  
Simulation Model ◽  
Temperature Control ◽  
Time Variation ◽  
Time Window ◽  
Asphalt Mixture ◽  
Time Lapse ◽  
Planning Tool ◽  
Time Duration ◽  
Deformation And Failure ◽  
Temperature Time

Overnight repairs and resurfacing of runway or taxiway pavements are common in busy airports. The time window available for such repair and resurfacing works is often limited. A common problem encountered is to ensure that the newly compacted asphalt mixture has cooled down sufficiently before receiving aircraft loadings, so as to avoid premature deformation and failure of the asphalt mixture. In this regard, a simulation model that provides a prediction of the temperature–time variation trend of each compacted pavement lift in a multi-lift asphalt course laying would be a valuable planning tool for temperature control. Information on the temperature cooling trend of an asphalt layer helps to estimate the time duration available for effective compaction during laying, as well as the time lapse needed before the pavement is sufficiently stable to receive traffic. A finite element simulation model is presented in this study to predict the temperature–time variation trends of successive asphalt lifts in a multi-lift asphalt mixture laying operation. The numerical model was developed based on the theory of thermodynamics taking into account the heat transfer effects of solar radiation, convection, and conduction. The model was calibrated and validated using data from a field trial involving a two-lift and a three-lift laying of asphalt mixtures. Illustrative examples are presented to demonstrate the applications of the simulation model as a temperature control planning tool for repair and resurfacing operations of airport pavements.

scholarly journals Analisis dan Optimasi Pengaruh Suhu Gas Umpan Pada Kinerja Acid Gas Removal Unit

2021 ◽  
Vol 1 ◽  
pp. 67-74
Author(s):  
Iwan Febrianto ◽  
Nelson Saksono
Keyword(s):  
Simulation Model ◽  
Flow Rate ◽  
Gas Production ◽  
Gas Content ◽  
Production Test ◽  
Reservoir Pressure ◽  
Gas Temperature ◽  
Separation Unit ◽  
Acid Gas ◽  
Gas Removal

The Gas Gathering Station (GGS) in field X processes gas from 16 (sixteen) wells before being sent as selling gas to consumers. The sixteen wells have decreased in good pressure since 2011, thus affecting the performance of the Acid Gas Removal Unit (AGRU). The GGS consists of 4 (four) main units, namely the Manifold Production/ Test, the Separation Unit, the Acid Gas Removal Unit (AGRU), the Dehydration Unit (DHU). The AGRU facility in field X is designed to reduce the acid gas content of CO2 by 21 mol% with a feed gas capacity of 85 MMSCFD. A decrease in reservoir pressure caused an increase in the feed gas temperature and an increase in the water content of the well. Based on the reconstruction of the design conditions into the simulation model, the amine composition consisting of MDEA 0.3618 and MEA 0.088 wt fraction to obtain the percentage of CO2 in the 5% mol sales gas. The increase in feed gas temperature up to 146 F caused foaming due to condensation of heavy hydrocarbon fraction, so it was necessary to modify it by adding a chiller to cool the feed gas to become 60 F. Based on the simulation, the flow rate of gas entering AGRU could reach 83.7 MMSCFD. There was an increase in gas production of 38.1 MMSCFD and condensate of 1,376 BPD. Economically, the addition of a chiller modification project was feasible with the economical parameters of NPV US$ 132,000,000, IRR 348.19%, POT 0.31 year and PV ratio 19.06.

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