The Effects of Geomechanics on the WAG Injection Model

Bataee, Mahmood; Irawan, Sonny; Majidaie, Saeed

doi:10.4043/24706-ms

Cited by 5 publications

References 11 publications

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Numerical Modeling of Flow and Temperature Distribution in Heterogeneous Wellbore Medium

Irawan

Bathaee

2015

All Days

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The mathematical model for flow and temperature distribution for the water alternating gas (WAG) process had been developed. Water alternating gas (WAG) injection has been a popular method for commercial gas injection projects worldwide. The injection of water and gas alternatively offers better mobility control of gas and hence, improves the volumetric sweep efficiency. The model is generated for the injection well with one cycle of water and one cycle of injected gas. There are some considerations for the three phases modeling in this study. The scope of the model is to develop the flow model for cylindrical, gravity segregation, turbulency effect due to the high injection rate, incompressible water, slightly compressible oil, compressible gas, IMPES method and with ignoring the tangential flow. The energy balance equation for the three phases could be expanded after the saturations from the flow part had been obtained. These are the conditions for solving the equation for temperature distribution: Cylindrical, implicit method, convection and conduction with ignoring tangential temperature gradient. In order to solve the governing equations, an analytical method had been used for the two and three phase systems around the wellbore; then a program had developed to do the iteration for implicit parts. The water, gas and oil pressures and saturations had been obtained in addition with the system temperature for homogeneous and heterogeneous media.

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Numerical Modeling of Flow and Temperature Distribution in Heterogeneous Wellbore Medium

Irawan

Bathaee

2015

All Days

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Effects of Injection Pressure on Wellbore Stress Using Flow-Stress Coupling Method

Bataee

Irawan

Ridha

et al. 2016

Day 2 Tue, August 23, 2016

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Enhanced Oil Recovery (EOR) injection methods are increasingly applied globally as the effective method in oil wells. Fluid injection alters the formation stress around the wellbore. In this study an iterative coupling method is proposed to evaluate wellbore stresses for one cycle of water alternating gas (WAG) injection. The effective parameters such as pressures, temperature, saturations and stresses are obtained for the multiphase flow condition using mathematical modeling. In this study, finite difference method is used to calculate pressure, temperature and saturations; and finite volume method is applied to evaluate stresses. Iterative coupling method is used to improve the accuracy of the results. The results show the pressure is boosted around wellbore after injection and how the water bank is pushed by injected gas. Maximum value of radial stress is obtained in the direction of horizontal maximum in-situ stress. Maximum value of tangential stress is determined in the direction of horizontal minimum in-situ stress. Vertical stress around the wellbore is not related to horizontal maximum and minimum in-situ stresses. The shear stress values are small in comparison with other stress types. The accuracy of model results are increased by iterative coupling, which the maximum correction is about 20 psi (0.14 MPa) for pressure. The developed model is capable to be applied in the wellbore to ensure stability for different injection or production cases.

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Wellbore Failure During Water-Alternating-Gas Injection by Use of Flow-Stress Coupling Method

et al. 2016

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Summary Accurate evaluation of failure pressure is crucial in the design of injection wells. Besides, in-situ stresses play an important role in obtaining the results. Pressure and rock stresses are related together as the role of effective-stress theorem. In fact, pressure changes with stress alteration caused by change in porosity and permeability. Therefore, it should be obtained with the coupling method. Moreover, to calculate pressure, temperature, and stress in the fully coupling method, a huge matrix should be solved, and it takes long processing time to implement it. Therefore, this study developed a wellbore geomechanical model for stability during injection by use of the iterative coupling method. The processing speed was enhanced in this study because the parameters were calculated separately. The parameters of pressure, temperature, saturation, and stress were obtained for the multiphase-flow condition with numerical modeling. Furthermore, in this study, the finite-difference method (FDM) had been used to solve pressure, temperature, and saturation, whereas the finite-volume method (FVM) was applied to solve the wellbore stress. On top of that, the iterative coupling method was used to improve the accuracy of the stress results. As a result, a correction of approximately 20 psi (0.14 MPa) was noted for pressure in relation to stress, which is 1 psi (6.89 kPa). Moreover, the Drucker-Prager failure criterion was used to model the fracturing on the basis of the stress results. Other than that, sensitivity analysis on horizontal maximum (σH) and minimum (σh) stresses showed that by increasing σH, the maximum injection pressures to avoid fracturing had been reduced, whereas in the case for σh, an increment was observed.

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The Effects of Geomechanics on the WAG Injection Model

Cited by 5 publications

References 11 publications

Numerical Modeling of Flow and Temperature Distribution in Heterogeneous Wellbore Medium

Numerical Modeling of Flow and Temperature Distribution in Heterogeneous Wellbore Medium

Effects of Injection Pressure on Wellbore Stress Using Flow-Stress Coupling Method

Wellbore Failure During Water-Alternating-Gas Injection by Use of Flow-Stress Coupling Method

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