The Experts below are selected from a list of 516 Experts worldwide ranked by ideXlab platform
Le Luo - One of the best experts on this subject based on the ideXlab platform.
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A numerical model to evaluate formation properties through pressure-transient analysis with alternate polymer flooding
Advances in Geo-Energy Research, 2019Co-Authors: Jia Zhang, Shiqing Cheng, Changyu Zhu, Le LuoAbstract:A numerical pressure transient analysis method of composite model with alternate polymer flooding is presented, which is demonstrated by field test data provided by China National Petroleum Corporation. Polymer concentration distribution and viscosity distribution are obtained on the basis of polymer rheological model, considering shear Effect, convection, diffusion, inaccessible pore volume and permeability reduction of polymer. Pressure analysis mathematical model is established by considering Wellbore Storage Effect and skin Effect. Type curves are then developed from mathematical model which have seven sections and parameter sensitivity is analyzed, among which the transient sections of low-concentration and high-concentration hydrolyzed polyacrylamides (HPAM) solution, high-concentration HPAM solution and crude oil show obvious concave shape on pressure derivative curve due to different viscosities of three zones. Formation parameters and viscosity distribution of polymer solution can be calculated by type-curve matching. The polymer flooding field tests prove that the three-zone composite model can reasonably calculate formation parameters in onshore oilfield with alternate polymer flooding, which demonstrate the application potential of the analysis method.
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A numerical model to evaluate formation properties through pressure-transient analysis with alternate polymer flooding
Advances in Geo-Energy Research, 2019Co-Authors: Zhang Jia, Cheng Shiqing, Zhu Changyu, Le LuoAbstract:A numerical pressure transient analysis method of composite model with alternate polymer flooding is presented, which is demonstrated by field test data provided by China National Petroleum Corporation. Polymer concentration distribution and viscosity distribution are obtained on the basis of polymer rheological model, considering shear Effect, convection, diffusion, inaccessible pore volume and permeability reduction of polymer. Pressure analysis mathematical model is established by considering Wellbore Storage Effect and skin Effect. Type curves are then developed from mathematical model which have seven sections and parameter sensitivity is analyzed, among which the transient sections of low-concentration and high-concentration hydrolyzed polyacrylamides (HPAM) solution, high-concentration HPAM solution and crude oil show obvious concave shape on pressure derivative curve due to different viscosities of three zones. Formation parameters and viscosity distribution of polymer solution can be calculated by type-curve matching. The polymer flooding field tests prove that the three-zone composite model can reasonably calculate formation parameters in onshore oilfield with alternate polymer flooding, which demonstrate the application potential of the analysis method.Cited as: Zhang, J., Cheng, S., Zhu, C., Luo, L. A numerical model to evaluate formation properties through pressure-transient analysis with alternate polymer flooding. Advances in Geo-Energy Research, 2019, 3(1): 94-103, doi: 10.26804/ager.2019.01.0
Chih Tse Wang - One of the best experts on this subject based on the ideXlab platform.
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A Semianalytical Solution for Residual Drawdown at a Finite Diameter Well in a Confined Aquifer
JAWRA Journal of the American Water Resources Association, 2013Co-Authors: Hund-der Yeh, Chih Tse WangAbstract:After the end of pumping the water level in the observation well starts to recover and the reduced drawdown during the recovery period is named as the residual drawdown. Traditional approaches in analyzing the data of residual drawdown for estimating the aquifer hydraulic parameters are mostly based on the application of superposition principle and Theis equation. In addition, the Effect of Wellbore Storage is commonly ignored in the evaluation even if the test well has a finite diameter. In this article, we develop a mathematical model for describing the residual drawdown with considering the Wellbore Storage Effect and the existing drawdown distribution produced by the pumping part of the test. The Laplace-domain solution of the model is derived using the Laplace transform technique and the time-domain result is inverted based on the Stehfest algorithm. This new solution shows that the residual drawdown associated with the boundary and initial conditions are related to the well drawdown and the aquifer drawdown, respectively. The well residual drawdown will be overestimated by the Theis residual drawdown solution in the early recovery part if neglecting the Wellbore Storage. On the other hand, the Theis residual drawdown solution can be used to approximate the present residual drawdown solution in the late recovery part of the test.
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Analysis of well residual drawdown after a constant-head test
Journal of Hydrology, 2009Co-Authors: Hund-der Yeh, Chih Tse WangAbstract:summary A recovery test measures the residual drawdown after an aquifer pumping test has ended and analyzes the recovery data to determine hydrogeological parameters such as transmissivity and Storage coefficient. To our knowledge, the solution for the distribution of residual drawdown following a constanthead test has never been presented. In this paper, we first develop a mathematical model that describes the residual drawdown taking into consideration the Wellbore-Storage Effect and the drawdown distribution occurring at the end of a previous constant-head test. Then, the Laplace-domain solution of the model is developed using the Laplace transforms and its time-domain solution is obtained using the Stehfest algorithm. Numerical results show that the distribution of residual drawdown depends on the boundary condition related to the well drawdown and the initial condition related to the aquifer drawdown. The well residual drawdown (i.e., the residual drawdown at Wellbore) during the early recovery period will be over-estimated by the approximate residual drawdown solution based on the Theis-type solution and superposition principle due to the neglect of Wellbore Storage. For a large recovery time, the Effect of Wellbore Storage is negligible and the approximate residual drawdown solution is therefore applicable.
Hund-der Yeh - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Groundwater Response to Oscillatory PumpingTest in Unconfined Aquifers: Consider the Effects of Initial Condition and Wellbore Storage
2018Co-Authors: Ching Sheng Huang, Ya-hsin Tsai, Hund-der Yeh, Tao YangAbstract:Abstract. Oscillatory pumping test (OPT) is an alternative to constant-head and constant-rate pumping tests for determining aquifer hydraulic parameters without water extraction. There is a large number of analytical models presented for the analyses of OPT. The combined Effects of Wellbore Storage and initial condition regarding the hydraulic head prior to OPT are commonly neglected in the existing models. This study aims to develop a new model for describing the hydraulic head fluctuation induced by OPT in an unconfined aquifer. The model contains a typical flow equation with an initial condition of static water table, inner boundary condition specified at the rim of a finite-radius well for incorporating Wellbore Storage Effect, and linearized free surface equation describing water table movement. The analytical solution of the model is derived by the Laplace transform and finite integral transform. Sensitivity analysis is carried out for exploring head response to the change in each of hydraulic parameters. Results suggest that head fluctuation due to OPT starts from the initial condition and gradually tends to simple harmonic motion (SHM) after a certain pumping time. A criterion for estimating the time to have SHM since OPT is graphically presented. The validity of assuming an infinitesimal well radius without Wellbore Storage Effect is investigated. The present solution agrees well to head fluctuation data observed at the Boise hydrogeophysical research site in southwestern Idaho.
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A Semianalytical Solution for Residual Drawdown at a Finite Diameter Well in a Confined Aquifer
JAWRA Journal of the American Water Resources Association, 2013Co-Authors: Hund-der Yeh, Chih Tse WangAbstract:After the end of pumping the water level in the observation well starts to recover and the reduced drawdown during the recovery period is named as the residual drawdown. Traditional approaches in analyzing the data of residual drawdown for estimating the aquifer hydraulic parameters are mostly based on the application of superposition principle and Theis equation. In addition, the Effect of Wellbore Storage is commonly ignored in the evaluation even if the test well has a finite diameter. In this article, we develop a mathematical model for describing the residual drawdown with considering the Wellbore Storage Effect and the existing drawdown distribution produced by the pumping part of the test. The Laplace-domain solution of the model is derived using the Laplace transform technique and the time-domain result is inverted based on the Stehfest algorithm. This new solution shows that the residual drawdown associated with the boundary and initial conditions are related to the well drawdown and the aquifer drawdown, respectively. The well residual drawdown will be overestimated by the Theis residual drawdown solution in the early recovery part if neglecting the Wellbore Storage. On the other hand, the Theis residual drawdown solution can be used to approximate the present residual drawdown solution in the late recovery part of the test.
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Analysis of well residual drawdown after a constant-head test
Journal of Hydrology, 2009Co-Authors: Hund-der Yeh, Chih Tse WangAbstract:summary A recovery test measures the residual drawdown after an aquifer pumping test has ended and analyzes the recovery data to determine hydrogeological parameters such as transmissivity and Storage coefficient. To our knowledge, the solution for the distribution of residual drawdown following a constanthead test has never been presented. In this paper, we first develop a mathematical model that describes the residual drawdown taking into consideration the Wellbore-Storage Effect and the drawdown distribution occurring at the end of a previous constant-head test. Then, the Laplace-domain solution of the model is developed using the Laplace transforms and its time-domain solution is obtained using the Stehfest algorithm. Numerical results show that the distribution of residual drawdown depends on the boundary condition related to the well drawdown and the initial condition related to the aquifer drawdown. The well residual drawdown (i.e., the residual drawdown at Wellbore) during the early recovery period will be over-estimated by the approximate residual drawdown solution based on the Theis-type solution and superposition principle due to the neglect of Wellbore Storage. For a large recovery time, the Effect of Wellbore Storage is negligible and the approximate residual drawdown solution is therefore applicable.
Salam Al-rbeawi - One of the best experts on this subject based on the ideXlab platform.
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Restoring disrupted data by Wellbore Storage Effect using analytical models and type-curve matching techniques
International Journal of Oil Gas and Coal Technology, 2019Co-Authors: Salam Al-rbeawiAbstract:This paper introduces new techniques for restoring disrupted data by Wellbore Storage. The proposed techniques are applicable for reservoirs depleted by horizontal wells and hydraulic fractures. Several analytical models describe early time data have been generated. The relationships of the peak points (humps) with the pressure, pressure derivative and production time have been mathematically formulated in this study for different Wellbore Storage coefficients. Two complete sets of type curves have been generated for horizontal wells and fractured formations considering different skin factors and Wellbore Storage coefficients. The study has shown that early radial flow for short Wellbores is more affected by Wellbore Storage while for long horizontal wells; early linear flow is the most affected flow regime. The study emphasises the applicability of early time data for characterising formations that could be controlled by Wellbore Storage Effect by proposing different relationships between Wellbore Storage dominated flow and other flow regimes. [Received: October 2, 2016; Accepted: December 7, 2016]
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Analytical models & type-curve matching techniques for reservoir characterization using Wellbore Storage dominated flow regime
KeAi, 2018Co-Authors: Salam Al-rbeawiAbstract:The applicability of early time data in reservoir characterization is not always considered worthy. Early time data is usually controlled by Wellbore Storage Effect. This Effect may last for pseudo-radial flow or even boundary dominated flow. Eliminating this Effect is an option for restoring real data. Using the data with this Effect is another option that could be used successfully for reservoir characterization.This paper introduces new techniques for restoring disrupted data by Wellbore Storage at early time production. The proposed techniques are applicable for reservoirs depleted by horizontal wells and hydraulic fractures. Several analytical models describe early time data, controlled by Wellbore Storage Effect, have been generated for both horizontal wells and horizontal wells intersecting multiple hydraulic fractures. The relationships of the peak points (humps) with the pressure, pressure derivative and production time have been mathematically formulated in this study for different Wellbore Storage coefficients. For horizontal wells, a complete set of type curves has been included for different Wellbore lengths, skin factors and Wellbore Storage coefficients. Another complete set of type curves has been established for fractured formations based on the number of hydraulic fractures, spacing between fractures, and Wellbore Storage coefficient.The study has shown that early radial flow for short to moderate horizontal wells is the most affected by Wellbore Storage while for long horizontal wells; early linear flow is the most affected flow regime by Wellbore Storage Effect. The study has also emphasized the applicability of early time data for characterizing the formations even though they could be controlled by Wellbore Storage Effect. As a matter of fact, this paper has found out that Wellbore Storage dominated flow could have remarkable relationships with the other flow regimes might be developed during the entire production times. These relationships can be used to properly describe the formations and quantify some of their characteristics. Keywords: Reservoir engineering, Reservoir modeling and simulation, Pressure transient analysis, Reservoir characterization, Wellbore Storage Effect, Skin factor, Reservoir flow regimes, Pressure behavior
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Analytical models & type-curve matching techniques for reservoir characterization using Wellbore Storage dominated flow regime
Petroleum, 2017Co-Authors: Salam Al-rbeawiAbstract:Abstract The applicability of early time data in reservoir characterization is not always considered worthy. Early time data is usually controlled by Wellbore Storage Effect. This Effect may last for pseudo-radial flow or even boundary dominated flow. Eliminating this Effect is an option for restoring real data. Using the data with this Effect is another option that could be used successfully for reservoir characterization. This paper introduces new techniques for restoring disrupted data by Wellbore Storage at early time production. The proposed techniques are applicable for reservoirs depleted by horizontal wells and hydraulic fractures. Several analytical models describe early time data, controlled by Wellbore Storage Effect, have been generated for both horizontal wells and horizontal wells intersecting multiple hydraulic fractures. The relationships of the peak points (humps) with the pressure, pressure derivative and production time have been mathematically formulated in this study for different Wellbore Storage coefficients. For horizontal wells, a complete set of type curves has been included for different Wellbore lengths, skin factors and Wellbore Storage coefficients. Another complete set of type curves has been established for fractured formations based on the number of hydraulic fractures, spacing between fractures, and Wellbore Storage coefficient. The study has shown that early radial flow for short to moderate horizontal wells is the most affected by Wellbore Storage while for long horizontal wells; early linear flow is the most affected flow regime by Wellbore Storage Effect. The study has also emphasized the applicability of early time data for characterizing the formations even though they could be controlled by Wellbore Storage Effect. As a matter of fact, this paper has found out that Wellbore Storage dominated flow could have remarkable relationships with the other flow regimes might be developed during the entire production times. These relationships can be used to properly describe the formations and quantify some of their characteristics.
Shiqing Cheng - One of the best experts on this subject based on the ideXlab platform.
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A numerical model to evaluate formation properties through pressure-transient analysis with alternate polymer flooding
Advances in Geo-Energy Research, 2019Co-Authors: Jia Zhang, Shiqing Cheng, Changyu Zhu, Le LuoAbstract:A numerical pressure transient analysis method of composite model with alternate polymer flooding is presented, which is demonstrated by field test data provided by China National Petroleum Corporation. Polymer concentration distribution and viscosity distribution are obtained on the basis of polymer rheological model, considering shear Effect, convection, diffusion, inaccessible pore volume and permeability reduction of polymer. Pressure analysis mathematical model is established by considering Wellbore Storage Effect and skin Effect. Type curves are then developed from mathematical model which have seven sections and parameter sensitivity is analyzed, among which the transient sections of low-concentration and high-concentration hydrolyzed polyacrylamides (HPAM) solution, high-concentration HPAM solution and crude oil show obvious concave shape on pressure derivative curve due to different viscosities of three zones. Formation parameters and viscosity distribution of polymer solution can be calculated by type-curve matching. The polymer flooding field tests prove that the three-zone composite model can reasonably calculate formation parameters in onshore oilfield with alternate polymer flooding, which demonstrate the application potential of the analysis method.
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pressure transient analysis of water injectors considering the multiple closures of waterflood induced fractures in tight reservoirs case studies in changqing oilfield china
Journal of Petroleum Science and Engineering, 2019Co-Authors: Youwei He, Shiqing Cheng, Kaidi Zhang, Yang Wang, Haiyang YuAbstract:Abstract There is growing evidence showing that water injection may induce formation fracturing, and the injection well may experience multiple fracture closures during fracture falloff period. Such dynamic behavior of waterflood-induced fractures (WIFs) needs to be carefully assessed and controlled through a waterflooding program. The objective of this study is to develop a pressure transient analysis procedure to analyze the bottom-hole pressure (BHP) responses of water injection wells with the consideration of the dynamic behavior of WIFs. We propose a rigorous physical process that integrates mini-fractures initiation, communication, propagation and closure throughout waterflooding. The piecewise function is used to characterize the consecutive closure of fractures during the shut-in period. Based on the proposed model, the pressure-transient solutions are obtained and the type curves are plotted. Results indicate that the consecutive fractures closure lowers the rate of pressure drop and results in the fluctuations of the pressure derivative curve. During the field-testing period, the water that stored in the WIFs would be squeezed into the matrix since there are no proppants inside, which behaves similar with Wellbore Storage Effect. Meanwhile, due to the different stress conditions in the fracture walls, they close successively after shutting in the well, which results in the multiple Storage Effect that characterized by several unit slopes in the pressure derivative curve. Finally, several cases studies from Changqing Oilfield have validated the practicability of the models to evaluate the BHP performances of water injectors.
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Research Article Numerical Well Testing Interpretation Model and Applications in Crossflow Double-Layer Reservoirs by Polymer Flooding
2016Co-Authors: Shiqing ChengAbstract:which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This work presents numerical well testing interpretation model and analysis techniques to evaluate formation by using pressure transient data acquired with logging tools in crossflow double-layer reservoirs by polymer flooding. A well testing model is established based on rheology experiments and by considering shear, diffusion, convection, inaccessible pore volume (IPV), permeability reduction, Wellbore Storage Effect, and skin factors. The type curves were then developed based on this model, and parameter sensitivity is analyzed. Our research shows that the type curves have five segments with different flow status: (I) wellbor
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Numerical Well Testing Interpretation Model and Applications in Crossflow Double-Layer Reservoirs by Polymer Flooding
TheScientificWorldJournal, 2014Co-Authors: Hui Guo, Tiantian Zhang, Bo Xian, Shiqing ChengAbstract:This work presents numerical well testing interpretation model and analysis techniques to evaluate formation by using pressure transient data acquired with logging tools in crossflow double-layer reservoirs by polymer flooding. A well testing model is established based on rheology experiments and by considering shear, diffusion, convection, inaccessible pore volume (IPV), permeability reduction, Wellbore Storage Effect, and skin factors. The type curves were then developed based on this model, and parameter sensitivity is analyzed. Our research shows that the type curves have five segments with different flow status: (I) Wellbore Storage section, (II) intermediate flow section (transient section), (III) mid-radial flow section, (IV) crossflow section (from low permeability layer to high permeability layer), and (V) systematic radial flow section. The polymer flooding field tests prove that our model can accurately determine formation parameters in crossflow double-layer reservoirs by polymer flooding. Moreover, formation damage caused by polymer flooding can also be evaluated by comparison of the interpreted permeability with initial layered permeability before polymer flooding. Comparison of the analysis of numerical solution based on flow mechanism with observed polymer flooding field test data highlights the potential for the application of this interpretation method in formation evaluation and enhanced oil recovery (EOR).
