Sensitivity analysis of seismic reflectivity to partial gas saturation

2005 ◽  
Author(s):  
Carmen T. Gomez ◽  
Robert H. Tatham
Keyword(s):  
Sensitivity Analysis ◽  
Gas Saturation ◽  
Seismic Reflectivity

Sensitivity analysis of seismic reflectivity to partial gas saturation

Geophysics ◽  
2007 ◽  
Vol 72 (3) ◽  
pp. C45-C57 ◽  
Author(s):  
Carmen T. Gomez ◽  
Robert H. Tatham
Keyword(s):  
Sensitivity Analysis ◽  
Shale Gas ◽  
Poisson’S Ratio ◽  
Essential Element ◽  
Elastic Parameter ◽  
Poisson's Ratio ◽  
Density Contrast ◽  
Water Contact ◽  
Gas Saturation ◽  
Seismic Reflectivity

We analyze the sensitivity of seismic reflectivity to contrasts in density, seismic propagation velocities, Poisson’s ratio, and gas saturation using the complete Zoeppritz equations. Sensitivities of reflection coefficients to each bulk elastic parameter are computed as the partial derivatives of the seismic reflectivities, relative to each parameter. The sensitivity of reflectivity to gas saturation is then calculated as the full derivative of the reflectivities with respect to gas saturation, assuming both a homogeneous and a patchy distribution of gas in the pore fluids. We compute sensitivities for a sealing shale/gas-sand interface and a gas-sand/wet-sand (gas-water contact, GWC) interface. For the SH-SH reflectivity, the effect of density contrast is strongest in the 30°–50° range of incidence angles for the fluid-fluid interface and at nearer offsets for the shale/gas-sand interface. P-SV reflectivity forthe fluid-fluid interfaces is more sensitive to density contrast in the range of angles of incidence from 30° to 60°. The overall response of P-SV reflectivity to gas saturation throughout all offsets is dominated by the Poisson’s ratio of the gas sand. In the case of P-P reflectivity, the sensitivity to gas saturation increases with increasing incidence angles. The sensitivity of P-SV reflectivity to gas saturation tends to be greatest in the 20°–40° range of incidence angles. For SH-SH reflectivity, the sensitivity to gas saturation for most offsets is controlled mainly by the density contrast, and the sensitivity to density decreases with increasing offset. There is still not a generally accepted seismic reflection method to discriminate commercial gas concentrations from low gas saturation. From the sensitivity analysis, we conclude that the use of P-SV or SH-SH amplitude variation with offset (AVO), integrated with the P-P AVO, will be an essential element in understanding this problem fully.

Reservoir Simulation Studies for Planning Monitoring Schemes for CO2 Storage

2021 ◽  
Author(s):  
Georgios Nikolakopoulos-Skelly ◽  
Marie Ann Giddins ◽  
Rong Xu ◽  
Chioma Ezeogu ◽  
Matthew Jackson
Keyword(s):  
Sensitivity Analysis ◽  
Reservoir Simulation ◽  
Co2 Storage ◽  
Storage Period ◽  
Model Parameters ◽  
Pressure Curve ◽  
Observation Well ◽  
Gas Saturation ◽  
Critical Gas Saturation ◽  
Co2 Plume

Abstract In this paper, we describe an approach to designing monitoring schemes for carbon dioxide sequestration in saline aquifers. Changes in key parameters are investigated over timescales of up to a thousand years. The study addresses movement of the CO2 plume, possible locations for observation wells and the period for which a storage location should be monitored. For the initial sensitivity analysis, we use a simple homogeneous reservoir simulation model to understand how reservoir, operational and model parameters affect the amount of mobile CO2 remaining at different times over the storage period. The parameters with the greatest impact are taken forward to uncertainty studies, which are conducted on two reservoir models with more realistic geological characteristics: one with lateral extensive baffles and one with sand channels. For these cases, we investigate the movement of the CO2 plume and its arrival at possible locations for an observation well. Results from the sensitivity analysis indicate that the most influential parameters are horizontal permeability, dipping angle, critical gas saturation, salinity, the period of injection and the capillary pressure curve. The results from the uncertainty studies indicate that for the two heterogeneous models, a reasonable monitoring period is in the range of 60 to 150 years and that the movement of the plume probably stops after approximately 100 years. The arrival time of CO2 at the observation well can be predicted with greater confidence when the well is in close proximity to the injector and in the direction in which CO2 will preferably move. A correlation analysis on the uncertain parameters shows that the main contributor affecting the amount of mobile CO2 is critical gas saturation, followed by dipping angle and the period of injection. While previous studies focus on how different parameters affect immobilization of CO2, this study aims to develop a methodology to plan long-term monitoring of mobile CO2. Prediction of the expected plume movement can help to determine suitable observation well locations and reasonable timescales for the monitoring process.

Aplikasi Metode Hungarian Dalam Optimalisasi Waktu Penugasan Karyawan dan Keuntungan Produksi Home Industry

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Empya Charlie ◽  
Siti Rusdiana ◽  
Rini Oktavia
Keyword(s):  
Sensitivity Analysis ◽  
Optimal Solution ◽  
Optimal Scheduling ◽  
Total Work ◽  
Work Time ◽  
Hungarian Method ◽  
Total Work Time

Penelitian ini bertujuan untuk mengoptimalkan penjadwalan karyawan di CV. Karya Indah Bordir dalam melakukan tugas-tugas tertentu menggunakan metode Hungaria, serta menganalisis sensitivitas solusi optimal jika ada pengurangan waktu karyawan untuk menyelesaikan tugas-tugas. Metode Hongaria diterapkan pada proses bordir yang melibatkan 11 karyawan dan 10 tugas. Hasil penjadwalan yang optimal meminimalkan waktu produksi bordir perusahaan. Hasil penjadwalan optimal yang ditemukan adalah: karyawan 1 mengerjakan tas Mambo, karyawan 2 mengerjakan tas Elli, karyawan 3 mengerjakan tas Lonjong, karyawan 4 mengerjakan tas Tampang bunga, karyawan 6 mengerjakan tas Ransel, karyawan 7 mengerjakan tas Tima, karyawan 8 mengerjakan tas Keong, karyawan 9 mengerjakan tas Alexa, karyawan 10 mengerjakan tas Luna, dan karyawan 11 mengerjakan tas Mikha, dengan total waktu kerja adalah 13,7 jam. Setelah metode Hongaria diterapkan, CV. Karya Indah Bordir mendapat peningkatan pendapatan sebanyak 9,09%. Analisis sensitivitas dilakukan dengan mengurangi waktu karyawan dalam menyulam tas. Hasil analisis sensitivitas adalah beberapa batasan untuk variabel basis dan non basis untuk mempertahankan solusi optimal.   This research has a purpose to optimize the scheduling of employees in CV. Karya Indah Bordir in doing certain tasks using Hungarian method, as well as analyzing the sensitivity of the optimal solution if there is a reduction on the employees time to finish the tasks. The Hungarian method was applied on the embroidery process involving 11 employees and 10 tasks. The optimal scheduling result minimize the time of the embroidery production of the company. The optimal scheduling result found is: employee 1 does the Mambo bag, employee 2 does the Elli bag, employee 3 does the Lonjong bag, employee 4 does the Tampang bunga bag, employee 6 does the Ransel, employee 7 does the Tima bag, employee 8 does the Keong bag, employee 9 does the Alexa bag, employees 10 does the Luna bag, and employee 11 does the Mikha bag, with the total work time is 13,7 hours. After the Hungarian method was applied, CV. Karya Indah Bordir got the increasing revenue as much as 9,09 %. The sensitivity analysis was conducted by reducing the time of the employees take in embroidery the bags. The results of the sensitivity analysis are some boundaries for basis and non basis variables to maintain the optimal solution. 

Sensitivity Analysis and Selection of Check Index of Signal Intersection Simulation Model Based on VISSIM

2019 ◽  
Vol 2 (5) ◽  
Author(s):  
Mengda Zhang ◽  
Chenjing Zhou ◽  
Tian-tian Zhang ◽  
Yan Han
Keyword(s):  
Sensitivity Analysis ◽  
Simulation Model ◽  
Optimal Process ◽  
Parameter Calibration ◽  
Index Set ◽  
The Core ◽  
Core Module ◽  
Simulation Parameter ◽  
Simulation Parameters ◽  
Selection Of

Selecting check index quantitatively is the core of the calibration of micro traffic simulation parameters at signal intersection. Five indexes in the node (intersection) module of VISSIM were selected as the check index set. Twelve simulation parameters in the core module were selected as the simulation parameters set. Optimal process of parameter calibration was proposed and model of the intersection of Huangcun west street and Xinghua street in Beijing was built in VISSIM to verify it. The sensitivity analysis between each check index and simulation parameter in their own set was conducted respectively. Sensitive parameter sets of different check indices were obtained and compared. The results show that different indexes have different size of set, and average vehicle delay's is maximum, so it's necessary to select index quantitatively. The results can provide references for scientific selection of the check indexes and improve the study efficiency of parameter calibration.

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