Numerical Modeling of Coupled Fluid Flow and Geomechanical Stresses in a Petroleum Reservoir
01 Jun 2020-Journal of Energy Resources Technology-transactions of The Asme (American Society of Mechanical Engineers Digital Collection)-Vol. 142, Iss: 6
TL;DR: In this article, a fully coupled hydro and geomechanical model has been used to predict the transient pressure disturbance, reservoir deformation, and effective stress distribution in both homogeneous and heterogeneous reservoirs.
Abstract:
A fully coupled hydro and geomechanical model has been used to predict the transient pressure disturbance, reservoir deformation, and effective stress distribution in both homogeneous and heterogeneous reservoirs. The heterogeneous reservoir is conceptualized by explicitly considering the spatial distributions of porosity and permeability as against assuming it as constant values. The finite element method was used in the coupled model in conjunction with the poroelasticity. Transient pressure disturbance is significantly influenced by the overburden during the production in both homogeneous and heterogeneous reservoirs for all the perforation schemes. Perforation scheme 2 provides the optimum reservoir performance when compared with other three schemes in terms of transient pressure distribution and reservoir subsidence. It also has the ability to overcome both the water and gas coning problems when the reservoir fluid flow is driven by both gas cap and water drive mechanisms. A Biot–Willis coefficient is found to significantly influence both the pressure and stress distribution right from the wellbore to the reservoir boundary. Maximum effective stresses have been generated in the vicinity of the wellbore in the reservoir at a high Biot–Willis coefficient of 0.9. Thus, the present work clearly projects that a Biot–Willis coefficient of 0 cannot be treated to be a homogeneous reservoir by default, while the coupled effect of hydro and geomechanical stresses plays a very critical role. Therefore, the implementation of the coupled hydro and geomechanical numerical models can improve the prediction of transient reservoir behavior efficiently for the simple and complex geological systems effectively.
Citations
More filters
TL;DR: In this article, an integrated machine learning (ML)-response surface model (RSM)-autoregressive integrated moving average (ARIMA) model was used to enhance the heat production from a geothermal reservoir.
15 citations
TL;DR: In this paper , an improved mathematical model for the fully coupled thermo-hydro-geomechanical model was proposed to examine the variations in the Puga geothermal reservoir at between 4500 m from the surface with three, four, and seven hydraulic fractures in the reservoir along with four-spot, five-spot and seven-spot well patterns.
12 citations
TL;DR: In this article, an ANN architecture composed of eight hidden layers and 20 neurons in the hidden layer was used to predict the thermal drawdown of an EGS system with a satisfactory range (R2 > 0.99).
Abstract:
This work presents the prediction of thermal drawdown of an enhanced geothermal system (EGS) using artificial neural network (ANN). A three-dimensional numerical model of EGS was developed to generate the training and testing data sets for ANN. We have performed a quantitative study of geothermal energy production for various injection operating conditions and reservoir fracture aperture. Input parameters for ANN include temperature, mass flux, pressure, and fracture transmissivity, while the production well temperature is the output parameter. The Levenberg–Marquardt back-propagation learning algorithm, the tan-sigmoid, and the linear transfer function were used for the ANN optimization. The best results were obtained with an ANN architecture composed of eight hidden layers and 20 neurons in the hidden layer, which made it possible to predict the production temperature with a satisfactory range (R2 > 0.99). An appropriate accuracy of the ANN model was obtained with a percentage error less than (± 4.5). The results from the numerical simulations suggest that fracture transmissivity has less effect on thermal drawdown than the injection mass flux and temperature. From our results, we confirm that ANN modeling may predict the thermal drawdown of an EGS system with high accuracy.
11 citations
TL;DR: In this paper , a fully coupled dynamic thermo-hydro-mechanical (THM) model was employed to investigate the advantage and disadvantages of supercritical CO2 over water as geofluids.
Abstract:
In the present work, fully coupled dynamic thermo-hydro-mechanical (THM) model was employed to investigate the advantage and disadvantages of supercritical CO2 (SCCO2) over water as geofluids. Low-temperature zone was found in both SCCO2-EGS and water-EGS systems, but spatial expansion is higher in water-EGS. Although, the spatial expansion of SCCO2 into the rock matrix will help in the geo-sequestration. The expansion of stress and strain invaded zones were identified significantly in the vicinity of fracture and injection well. SCCO2-EGS system is giving better thermal breakthrough and geothermal life conditions compared to the water-EGS system. Reservoir flow impedance (RFI) and heat power are examined, and heat power are high in the water-EGS system. Minimum RFI is found in the SCCO2-EGS system at 45°C and 0.05 m/s. Maximum heat power for SCCO2-EGS was observed at 35°C, 20 MPa, and 0.15 m/s. Therefore, the developed dynamic THM model is having greater abilities to examine behaviour of SCCO2-EGS and water-EGS systems effectively. The variations occur in the rock matrix and the performance indicators are dependent on the type of fluid, injection/production velocities, initial reservoir pressure, injection temperature. The advantages of SCCO2-EGS system over the water-EGS system, providing a promising result to the geothermal industry as geofluid.
5 citations
TL;DR: In this article , the probabilistic analysis of land subsidence due to pumping is performed by Biot's poroelasticity and random field theory based on a case study.
Abstract: Abstract Land subsidence is a global problem in urban areas. The main cause of land subsidence is the pumping of subsurface water. It is of great significance to study the subsurface settlement and water flow of the lands due to pumping. In this study, the probabilistic analysis of land subsidence due to pumping is performed by Biot’s poroelasticity and random field theory based on a case study. The results show that the change of deformation of the aquifer is far less significant than the hydraulic head over the years. When considering the spatial variability of soil strength, the land subsidence suffers from great uncertainty when the correlation length is large. Nevertheless, the spatial variability of soil strength on the uncertainty of hydraulic head can be ignored. When considering the spatial variability of soil hydraulic conductivity, the uncertainty of the hydraulic head is mainly located near the bedrock and increases markedly along with the rise of the correlation length. Time is another important factor to increase the uncertainty of the hydraulic head. However, its contribution to the uncertainty of displacement is insignificant.
3 citations
References
More filters
01 Jan 2002
31 citations
31 citations
TL;DR: In this article, a fully coupled geomechanics and single-phase fluid flow model is developed to evaluate the combined effects of stress, fluid flow and reservoir property changes on well performance.
Abstract: A fully-coupled geomechanics and single-phase, fluid-flow model is developed to evaluate the combined effects of stress, fluid flow and reservoir property changes on well performance. In particular, we pay particular attention to the interpretation of pressure buildup tests and to changes in the production characteristics of wells. In general, for weak hydrocarbon reservoirs that exhibit nonlinear, elastic and plastic constitutive behaviors and stress-dependent properties such as permeability and porosity, the coupling effect may not be ignored in well test analysis. The coupled interaction between geomechanics and reservoir fluid production markedly affects the stress state and reservoir properties. Because we are using a coupled, numerical model, we evaluate the consequences of using simplified relationships (e.g., permeability as a function of pressure). Numerical analyses are performed to quantitatively assess the impact of reservoir stress-sensitivity on practical well test problems. The key variables investigated in the study, that are important in evaluating stress-sensitive reservoirs, include permeability, porosity, and constitutive behaviors of reservoir rock including hysteresis and loading conditions. The development of high-stress regions around wellbores and its consequences on well performance are considered. The numerical results from the study indicate that for analyzing highly stress-sensitive reservoirs, a fully-coupled geomechanics and fluid-flow modeling approach is necessary and the developed model employed in this study provides such a tool.
30 citations
01 Jan 1997
26 citations
01 Jan 2003
TL;DR: In this article, a finite element program for oil and gas reservoir simulation based on Biot's poroelastic theory is developed, where a simultaneous solution is sought for both the pore pressure and strain in the solid phase.
Abstract: We are developing a finite element program for oil and gas reservoir simulation based on Biot’s poroelastic theory, where a simultaneous solution is sought for both the pore pressure and strain in the solid phase. Several 2-D and 3-D cases are presented, which are compared with analytical solutions for verification of this approach. We have also applied this method to simulate surface subsidence due to gas and oil production in a subsurface reservoir. The development of this code is still in its initial stage, but the approach shows promise.
24 citations