scholarly journals Time-lapse gravity data for monitoring and modeling artificial recharge through a thick unsaturated zone

2016 ◽  
Vol 52 (9) ◽  
pp. 7244-7261 ◽  
Author(s):  
Jeffrey Kennedy ◽  
Ty P. A. Ferré ◽  
Benjamin Creutzfeldt
Keyword(s):  
Unsaturated Zone ◽  
Artificial Recharge ◽  
Gravity Data ◽  
Time Lapse

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.

scholarly journals Quantifying sediment mass redistribution from joint time-lapse gravimetry and photogrammetry surveys

2019 ◽  
Author(s):  
Maxime Mouyen ◽  
Philippe Steer ◽  
Kuo-Jen Chang ◽  
Nicolas Le Moigne ◽  
Cheinway Hwang ◽  
...  
Keyword(s):  
Gravity Data ◽  
River Sediments ◽  
Time Lapse ◽  
New Combination ◽  
Gravity Changes ◽  
Sediment Mass ◽  
Mass Redistribution ◽  
Sediment Redistribution ◽  
Average Loss ◽  
Slow Landslide

Abstract. The accurate quantification of sediment mass redistribution is central to the study of surface processes, yet it remains a challenging task. Here we test a new combination of terrestrial gravity and drone photogrammetry methods to quantify sediment redistribution over a 1-km2 area. Gravity and photogrammetry are complementary methods. Indeed, gravity changes are sensitive to mass changes and to their location. Thus, by using photogrammetry data to constrain this location, the sediment mass can be properly estimated from the gravity data. We carried out 3 joint gravity-photogrammetry surveys, once a year in 2015, 2016 and 2017 over a 1-km2 area in southern Taiwan featuring both a wide meander of the Laonong River and a slow landslide. We first removed the gravity changes from non-sediment effects, such as tides, groundwater, surface displacements and air pressure variations. Then, we inverted the density of the sediment, with an attempt to distinguish the density of the landslide from the density of the river sediments. We eventually estimate an average loss of 4.7 ± 0.4 × 109 kg of sediment from 2015 to 2017, mostly due to the slow landslide. Although the gravity devices used in this study are expensive and need week-long surveys, new instrumentation progresses shall enable dense and continuous measurements at lower cost, making this method relevant to improve the estimation of erosion, sediment transfer and deposition in landscapes.

History Matching Time-Lapse Surface-Gravity and Well-Pressure Data With Ensemble Smoother for Estimating Gas Field Aquifer Support—A 3D Numerical Study

SPE Journal ◽  
2012 ◽  
Vol 17 (04) ◽  
pp. 966-980 ◽  
Author(s):  
M.. Glegola ◽  
P.. Ditmar ◽  
R.G.. G. Hanea ◽  
O.. Eiken ◽  
F.C.. C. Vossepoel ◽  
...  
Keyword(s):  
History Matching ◽  
Numerical Study ◽  
Gravity Data ◽  
Time Lapse ◽  
Added Value ◽  
Pressure Data ◽  
Production Forecast ◽  
Gas Field ◽  
Ensemble Smoother ◽  
Reservoir State

Summary Water influx is an important factor influencing production of gas reservoirs with an active aquifer. However, aquifer properties such as size, porosity, and permeability are typically uncertain and make predictions of field performance challenging. The observed pressure decline is inherently nonunique with respect to water influx, and large uncertainties in the actual reservoir state are common. Time-lapse (4D) gravimetry, which is a direct measure of a subsurface mass redistribution, has the potential to provide valuable information in this context. Recent improvements in instrumentation and data-acquisition and -processing procedures have made time-lapse gravimetry a mature monitoring technique, both for land and offshore applications. However, despite an increasing number of gas fields in which gravimetric monitoring has been applied, little has been published on the added value of gravity data in a broader context of modern reservoir management on the basis of the closed-loop concept. The way in which gravity data can contribute to improved reservoir characterization, production-forecast accuracy, and hydrocarbon-reserves estimation is still to be addressed in many respects. In this paper, we investigate the added value of gravimetric observations for gas-field-production monitoring and aquifer-support estimation. We perform a numerical study with a realistic 3D gas field model that contains a large and complex aquifer system. The aquifer support and other reservoir parameters (i.e., porosity, permeability, reservoir top and bottom horizons) are estimated simultaneously using the ensemble smoother (ES). We consider three cases in which gravity only is assimilated, pressure only is assimilated, and gravity and pressure data are assimilated jointly. We show that a combined estimation of the aquifer support with the permeability field, porosity field, and reservoir structure is a very challenging and nonunique history-matching problem, in which gravity certainly has an added value. Pressure data alone may not discriminate between different reservoir scenarios. Combining pressure and gravity data may help to reduce the nonuniqueness problem and provide not only an improved gas- and water-production forecast and gas-in-place evaluation, but also a more-accurate reservoir-state description.

Modeling a Thick Unsaturated Zone at San Gorgonio Pass, California: Lessons Learned after Five Years of Artificial Recharge

2012 ◽  
Vol 11 (4) ◽  
pp. vzj2012.0043 ◽  
Author(s):  
Alan L. Flint ◽  
Kevin M. Ellett ◽  
Allen H. Christensen ◽  
Peter Martin
Keyword(s):  
Unsaturated Zone ◽  
Artificial Recharge ◽  
Lessons Learned

A geophysical investigation of the active Hockley Fault System near Houston, Texas

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. B177-B185 ◽  
Author(s):  
Shuhab D. Khan ◽  
Robert R. Stewart ◽  
Maisam Otoum ◽  
Li Chang
Keyword(s):  
Ground Penetrating Radar ◽  
Fault Location ◽  
Gravity Data ◽  
Time Lapse ◽  
Radar Data ◽  
Airborne Lidar ◽  
Fault System ◽  
Geophysical Investigation ◽  
Geophysical Surveys ◽  
Ground Penetrating

Sedimentation and deformation toward the Gulf of Mexico Basin cause faulting in the coastal regions. In particular, many active (but non-seismic) faults underlie the Houston metropolitan area. Using geophysical data, we have examined the Hockley Fault System in northwest Harris County. Airborne LiDAR is an effective tool to identify fault scarps and we have used it to identify several new faults and assemble an updated map for the faults in Houston and surrounding areas. Two different LiDAR data sets (from 2001 to 2008) provide time-lapse images and suggest elevation changes across the Hockley Fault System at the rate of 10.9 mm/yr. This rate is further supported by GPS data from a station located on the downthrown side of the Hockley Fault System indicating movement at 13.8 mm/yr. To help illuminate the subsurface character of the faults, we undertook geophysical surveys (ground-penetrating radar, seismic reflection, and gravity) across two strands of the Hockley Fault System. Ground-penetrating radar data show discontinuous events to a depth of 10 m at the main fault location. Seismic data, from a vibroseis survey along a 1-km line perpendicular to the fault strike, indicate faulting to at least 300-m depth. The faults have a dip of about 70°. Gravity data show distinct changes across the fault. However, there are two contrasting Bouguer anomalies depending on the location of the transects and their underlying geology. Our geophysical surveys were challenged by urban features (especially traffic and access). However, the survey results consistently locate the fault and hold significant potential to understand its deformational features as well as assist in associated building zoning.

scholarly journals Absolute and Relative Gravity Measurements at Volcanoes: Current State and New Developments Under the NEWTON-g Project

2020 ◽  
Author(s):  
F. Greco ◽  
D. Carbone ◽  
F. Cannavò ◽  
A. A. Messina ◽  
G. Siligato
Keyword(s):  
Gravity Data ◽  
Time Lapse ◽  
Active Volcano ◽  
Superconducting Gravimeter ◽  
Mount Etna ◽  
Micro Electro Mechanical Systems ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Gravity Measurements ◽  
Mt Etna

AbstractGravity changes associated with volcanic processes occur over a wide range of time scales, from minutes to years and with magnitudes between a few and a few hundred microGal. High-precision instruments are needed to detect such small signals and both time-lapse surveys along networks of stations, and continuous measurements at single points, are accomplished. Continuous volcano gravimetry is mostly carried out through relative gravimeters, either superconducting instruments, providing higher quality data, or the more widely used spring meters. On the other hand, time-lapse surveys can be carried out with relative (spring) gravimeters, that measure gravity differences between pairs of stations, or by absolute gravimeters, capable of measuring the absolute value of the gravitational acceleration at the observation point. Here we present the state-of-the-art of terrestrial gravity measurements to monitor and study active volcanoes and the possibilities of new gravimeters that are under development. In particular, we present data from a mini array of three iGrav superconducting gravimeters (SGs) at Mount Etna (the first network of SGs ever installed on an active volcano). A comparison between continuous gravity measurements recorded through the iGrav#016 superconducting gravimeter at Serra La Nave station (1730 m a.s.l.) and absolute gravity data collected with the Microg LaCoste FG5#238 gravimeter in the framework of repeated campaigns is also presented. Furthermore, we introduce the Horizon 2020 NEWTON-g project (New Tools for Terrain Gravimetry), funded under the FET-OPEN Research and Innovation Actions call, Work Programme 2016–2017 (Grant Agreement No 801221). In the framework of this project, we aim to develop a field-compatible gravity imager, including an array of low-costs Micro-Electro-Mechanical Systems (MEMS)-based relative gravimeters, anchored on an absolute quantum gravimeter. After the design and production phases, the gravity imager will be field-tested at Mt. Etna (Italy) during the last 2 years of the project.

scholarly journals Quantifying sediment mass redistribution from joint time-lapse gravimetry and photogrammetry surveys

2020 ◽  
Vol 8 (2) ◽  
pp. 555-577
Author(s):  
Maxime Mouyen ◽  
Philippe Steer ◽  
Kuo-Jen Chang ◽  
Nicolas Le Moigne ◽  
Cheinway Hwang ◽  
...  
Keyword(s):  
Gravity Data ◽  
River Sediments ◽  
Time Lapse ◽  
New Combination ◽  
Gravity Changes ◽  
Surface Displacements ◽  
Sediment Mass ◽  
Mass Redistribution ◽  
Average Loss ◽  
Slow Landslide

Abstract. The accurate quantification of sediment mass redistribution is central to the study of surface processes, yet it remains a challenging task. Here we test a new combination of terrestrial gravity and drone photogrammetry methods to quantify sediment mass redistribution over a 1 km2 area. Gravity and photogrammetry are complementary methods. Indeed, gravity changes are sensitive to mass changes and to their location. Thus, by using photogrammetry data to constrain this location, the sediment mass can be properly estimated from the gravity data. We carried out three joint gravimetry–photogrammetry surveys, once a year in 2015, 2016 and 2017, over a 1 km2 area in southern Taiwan, featuring both a wide meander of the Laonong River and a slow landslide. We first removed the gravity changes from non-sediment effects, such as tides, groundwater, surface displacements and air pressure variations. Then, we inverted the density of the sediment with an attempt to distinguish the density of the landslide from the density of the river sediments. We eventually estimate an average loss of 3.7 ± 0.4 × 109 kg of sediment from 2015 to 2017 mostly due to the slow landslide. Although the gravity devices used in this study are expensive and need week-long surveys, new instrumentation currently being developed will enable dense and continuous measurements at lower cost, making the method that has been developed and tested in this study well-suited for the estimation of erosion, sediment transfer and deposition in landscapes.

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